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214 Cards in this Set
- Front
- Back
respiratory portion
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site of O2 and CO2 exchange b/w air and blood; includes respiratory bronchioles and alveoli
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conducting portion
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pipes air to and from lungs; warms, moistens, and cleanses air - includes nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles – lines w/ciliated pseudostratified columnar ep.
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nasal cavity
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region of the skull where air enters, and is conditioned and cleaned
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vestibule
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anterior portion of nasal cavity; ep. changes from keratinized to respiratory ep.
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nasal fossae
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2 regions of the nasal cavity divided by nasal septum
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olfactory region
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olfactory chemoreceptors are found in the olfactory epithelium in the superior conchae
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olfactory epithelium
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contains basal cells, supporting cells, and olfactory cells – bipolar neurons (apex = dendrite w/afferent axons below basement membrane)
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pharynx
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tube connecting pharynx to trachea; contains supporting cartilaginous plates, both hyaline and elastic
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larynx
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avascular, dense regular CT, branched bundles of skeletal tissue
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vestibular folds
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very vascular, loose CT, adipose, stratified ep.
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epiglottis
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flap at trachea that protects the larynx – stratified sq. ep., loose CT, elastic cartilage. Contains many lymphocytes.
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trachea
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airway that extends from larynx to bronchi; lined with respiratory mucosa; contains thickest basement membrane in body
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tracheal cartilage
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horseshoe shaped bands of hyaline cartilage that keep the tracheal lumen open
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tracheal muscle
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smooth muscle attaches to the perichondrium, bridging open Cs of cartilage; muscle contraction involved in cough reflex
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respiratory epithelium
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pseudostratified ciliated ep. lining the conducting portion of the respiratory system
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ciliated cells
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most abundant cell in respiratory ep.; ~ 300 cilia on apical surface of each cell which sweep mucus toward pharynx to be swallowed or expelled
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goblet cells
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2nd most abundant cells in respiratory epithelium; secrete mucus
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basal cells
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mitotic cells which adhere to the basement membrane via hemidesmosomes and do not extend to the lamina
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submucosal cells
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glandular tubes/asini located in the CT below respiratory ep. Connected to lumen via duct. Aid in generation of “sticky carpet”
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lungs
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respiratory organ
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lobes
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distinct sections of an organ, 3 R lobes and 2 L lobes in the lung
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visceral pleura
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thin inner layer of the pleura; elastic fibers are continuous with pulmonary parenchyma
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parietal pleura
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thick outer layer of the pleura
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pleura
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serous membrane covering lung; mesothelial cells on CT containing collagen and elastic fibers
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Bronchi
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cartilage plates replace rings of trachea, fewer goblets and glands, abundant elastic fibers, spiral bundles of smooth muscle
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Bronchioles
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cartilage is absent, no glands, abundant elastic fiber and smooth muscle; diameter 5mm
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Terminal bronchioles
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lined w/ciliated simple columnar ep. w/interspersed Clara cells
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clara cells
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plump cuboidal protein producing cells, protect against oxidative pollutants and inflammation
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respiratory bronchioles
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transition b/w conducting and respiratory portions; ciliated simple columnar and Clara cells become continuous with simple squamous near alveolar interruptions
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alveolar ducts
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– continuation of resp. bronchiole; walls contain only alveoli and smooth muscle
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alveolar sac
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alveolar space at duct terminals, no smooth muscle
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alveoli
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saclike protrusions of the resp. bronchioles, alveolar ducts, and alveolar sacs lined with squamous alveolar cells – spongy structure of lungs. Site of O2 and CO2 exchange b/w air and blood – held together by reticular and elastic fibers
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interalveolar septum
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alveolar wall that lies b/w 2 neighboring alveoli – 2 thin squamous layers on either side of a capillary
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squamous alveolar cells type I
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attenuated squamous cells making up 97% of alveolar lining – readily permeable to gas
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great alveolar cells type II (septal cells)
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rounded mitotic cells that give rise to type I cells. produce surfactant. Attached to type I via occluding and desmosomal junctions
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multi lamellar bodies
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vesicles w/in type II cells, continuously released @ apical surface
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surfactant
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aqueous coat of lamellar bodies lining alveolar surface, reduces surface tension which reduces effort of breathing and keeps alveoli open
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alveolar macrophages
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dust cells – brownish deposits found w/in interalveolar septum, often seen in smokers’ lungs
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alveolar pores
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spaces in interalveolar septum linking neighboring alveoli; equalize air pressure and promote air circulation
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blood air barrier
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separation between air in the alveoli and blood in the capillaries provided by a) surface lining/cytoplasm of alveolar squamous, b) fused basal laminae of alveolar & endothelial cells, and c) endothelial cytoplasm
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endocrine
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The endocrine system is an integrating system that coordinates the activities of cells and organs by sending chemical signals
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paracrine
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occurs when the hormones act locally whithout the need for transport by the blood. (ex. Islets of Langerhans are inhibited by hormones secreted by cells on the same islet.)
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autocrine
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when the hormone acts on the secreting cell.
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neuroendocrine
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when neurons send chemical signals into the blood stream.
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neurosecretion
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process of release of adenohypophysis hormones via nervous impulse passing down axons of the hypothalamus
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hormone
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molecules that function as the chemical signals (messages that transmit regulatory signals). They are released by specialized endocrine cells. They are secreted into the interstitial space then enter capillaries (no ducts are involved). Most act at a distance from site of secretion. Only small quantities needed (pf or ng range).
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secretory granule
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hormones for release into interstitial space and tehn into capillaries for circulation in blood.
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target cell
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tissues and organs on which the hormones act. They react because there are receptor sites that recognize the hormones. This initiates intracellular second messengers. Thus hormones will not influence all cells of the body. Endocrine glands are also target organs, providing hormone control through a feedback mechanism.
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receptor
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protein that accepts hormone and initiates secondary messenger.
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steroid binding protein
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cytoplasmic receptor involved in the mechanism of action of a steroid hormone. Steroid hormones are hydrophobic and enter target cells freely and THEN bind to receptor in cytpoplasm.
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second messenger
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activates hormonal cascade.
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cAMP
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secondary messenger involved in protein and peptide hormone activity.
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signal transduction
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game of telephone for hormones, e.g., sending the message down the line.
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protein kinase
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regulate the majority of cellular pathways, especially those involved in signal transduction, the transmission of signals within the cell
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hypothalamus
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links nervous system to endocrine system via pituitary gland. Regulates metabolic processes and other autonomic activities.
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hypophyseal portal system
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Portal system between hypothalamus and hypophysis that carries low MW polypeptide hormones from the hypothalamus to the endocrine cells of the pars distalis to regulate secretory activity of adenohypophysis.
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hypothalamo-hypophyeal tract
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System of 3 known sites of production of hormones that frees 3 groups of hormones. 1)hormones made in hypothalamus and released in p.n., 2) stimulating / inhibiting hormones made in hypothalamus, 3) hormones made in pars distalis
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median eminance
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a neurohemal organ containing the primary capillary bed of the hypophyseal portal system
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paraventricular nucleus
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Site in the hypothalamus where oxytocin is produced
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supraoptic nucleus
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Site in the hypothalamus where ADH is produced
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releasing and inhibiting hormones
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hypothalamic hormones stored in median eminence, released and transported to P.D. to inhibit / release of hormons
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GRH
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Growth hormone releasing hormone from hypothalamu
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GnRH
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Gonadotropin releasing hormone from hypothalamus
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Somatostatin
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local inhibition of other endocrine glands from hypothalamus
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Dopamine
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prolactin inhibiting hormone to balance prolactin production from hypothalamus
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TRH
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thyrotropin releasing hormone from hypothalamus
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CRH
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corticotropin releasing hormone from hypothalamus
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Epiphysis (pinneal)
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gland that mediates day length information through secretion of melatonin at night. Found in brain in the midline above diencephalon.
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Pinealiocyte
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main cells of epiphysis (pineal gland). Interstitial astrocytes.
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melatonin
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hormone that affects sleep wake cycles and gonadal function.
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Hypophsis (pituitary gland)
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lies in sella turcica, develops from oral ectoderm and from nerve tissue. Consists of 2 glands, neurohypophysis and adenohypophysis. Secretes numerous hormones controlling targets.
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rathke's pouch
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adenohypophysis formed from ectoderm of primitive mouth. This fissure is caused from separation of the base from oral cavity.
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sella turcica
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location in skull of pituitary gland
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adenohypophysis
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portion of hypophysis originating from ectoderm of primitive mouth. Has 3 regions: pas distalis, pars tuberalis and pars intermedia.
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neurohypophysis
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porion of hypophysis originating from nerve tissue. Has 2 parts: pars nervosa and infundibulum (neural stalk). Secretes ADH and oxytocin. 2 cell types: pituicytes (glial) and axons from neuronal cell bodies
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pars distalis (anterior lobe)
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largest portion of adenohypophysis. 3 cell types: Acidophil, Basophil and chromophobes. Pars distalis cells secrete FLAT PEG
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somatotropes
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secreted by acidophils of Pars distalis. Includes GH or STH
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mammotropes
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secreted by acidophils of Pars distalis. Includes prolactin
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gonadotropes
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secreted by basophils of Pars distalis. Includes LH and FSH
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thyrotropes
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secreted by basophils of Pars distalis. Includes TSH
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corticotropes
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secreted by basophils of Pars distalis. Includes ACTH and MSH
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pars tuberalis
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funnel shaped region surrounding the infundibulum of the neurohypophysis
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pars intermedia
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middle part of the adenohypophysis that has unknown function in humans. Developed from dorsal portion of rathke's pouch.
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neurosecretory cells
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cells that secrete the hormones of the neurohypophysis
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ADH
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anti-diurectic hormone, aka vasopressin. Increases water permeability of kidney collecting ducts and promotes smooth muscle contraction. Secreted by neurohypophysis.
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oxytocin
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hormone released by neurohyphysis, a nona aa cyclic polypeptide. In females, responsible for contraction of uterine smooth muscle and myoepithelial cells of mammary glands
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herring bodies
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clusters of granules in axonal swellings
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pituicytes
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type of branched glial cell found in neurohypophysis
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Adrenal Gland
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mixed gland located above the kidneys
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adrenal cortex
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outer edge of the adrenal gland, derived from the genital ridge mesoderm
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Zona glomerulosa
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"zone of cells in rounded clusters located in adrenal cortex, Secrete mineralocorticoids & aldosterone, Regulated by kidney & lung: renin-angiotensin system
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mineralcorticoids
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Secreted in the zona glomerulosa, stimulates resorption of Na by epithelia cells in kidney, salivary and sweat glands
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aldosterone
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Secreted in the zona glomerulosa, stimulates absorption of Na and Cl ions in kidney, which leads to increase in bp
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Zona fasciculate
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middle layer of polygonal cells in adrenal cortex, arranged in cords, secretes glucocorticoids, main target of ACTH
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glucocorticoids
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secreted in the zona fasciculate, stimulate the production of glucose and the conversion of glucose to glycogen
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cortisol
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secreted in the zona fasciculate, decreases the uptake of glycogen
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zona reticularis
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zone in adrenal cortex that is closest to the medulla, secretes weak androgens
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DHEA
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androgen secreted by the zona reticularis in the adrenal cortex, Tumor: masculinization of women, gynecomastia in men
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adrenal medulla
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located in center of adrenal gland and derived from neural crest, Cords of cells surrounded by an extensive network of fenestrated capillaries that drain into the adrenal vein, secretes sex steroids
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chromaffin cells
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located in adrenal medulla, produces catecholamines,: name given to cells which are responsive to dichromate dye
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catecholamines
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include epinephrine and norepinephrine, produced in chromaffin cells, mimics the action of the sympathetic nervous system - ”fight or flight” response.
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epinephrine
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represents 80% of catecholamine output, increased metabolism and O2 consumption, heat production
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norepinephrine
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catecholamine output, "fight or flight" response
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ganglion cells
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cells of the adrenal medulla, accentuating its function as a modified post-ganglionic sympathetic neuron, able to receive neural input, but with no axon or dendrites
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Endocrine pancreas
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entire pancreas derived from ENDODERM (like thyroid), cords of epithelial cells supported by reticular fibers, serous acini (exocrine part of pancreas) surround the islet and their secretions are collected by a network of ducts
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Islets of Langerhans
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located in the pancreas, roughly spherical aggregate of endocrine cells surround by a fenestrated capillary network
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beta cells
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basophilic cells in islets of langerhans, produce insulin
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insulin
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made by beta cells in Islets of Langerhans, stimulates glucose uptake in many cell types, stimulates liver to convert glucose to glycogen, stimulates adipose cells to convert glucose to triglycerides
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alpha cells
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adicophilic cells in Islets of Langershans, produce glucagon
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glucagon
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made by alpha cells in Islets of Langerhans, produce glucagon and store it in cytoplasmic granules, stimulates conversion of glycogen to glucose in LIVER
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delta cells
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located in the Islets of Langerhans, produce somatostatin
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somatostatin
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produced by delta cells in Islets of Langerhans, inhibits release of glucagon and insulin (dampens effects of Islet functions)
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F cells
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located in the islets of Langerhans, secrete pancreatic polypeptide (PP)
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PP
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pancreatic polypeptide, produced by F cells in the Islets of Langerhans, blocks secretion of stomatostatin and exocrine pancreatic enzymes
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thyroid gland
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Bilobed organ, lies across 2nd & 3rd cartilaginous rings of trachea, below the larynx, derived from endoderm,
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follicles
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lined by cuboidal epithelium, polarized cells with basement membrane on outside and apical side toward the follicle center, surrounded by extensive fenestrated capillary network, joined by junctional complexes
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colloid
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jelly-like filling of follicles in thyroid gland, contains thyroglobulin which is linked to iodine
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thyroglobulin
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Large protein made by follicle cells in thyroid gland that fill sphere of follicle, have tyrosines that can be iodinated to make MIT or DIT (precursors of T4,T3)
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T4 (thyroxine)
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(2 DIT combined) acts on all cells to increase metabolism and O2 consumption, heat production
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T3 (triiodothyronin)
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(1 DIT + 1 MIT) acts on all cells to increase metabolism and O2 consumption, heat production
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parafollicular cells
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(C or clear cells) larger and clear cells found between thyroid follicles, derived from neural crest, contain eosinophilic granules, produce calcitonin
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calcitonin
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protein hormone produced by the parafollicular cells, lowers levels of calcium in blood by inhibiting osteoclasts
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Parathyroid Gland
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Dorsal (posterior) side of thyroid gland, derived from the endoderm of the 3rd and 4th pharyneal pouches, has a capsule of reticular CT
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Chief Cells
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The dominant cells in the parathyroid gland, cuboidal, round nuclei, produce parathyroid hormone (PTH)
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Oxyphil Cells
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located in the parathyroid gland, larger cell than chief cell but same size nucleus, unknown function
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Renal Capsule
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a tough fibrous layer surrounding the kidney
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Hilum
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the concave medial border; nerves enter, blood and lymph vessels enter and exit, ureter exits
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Cortex
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outer portion of the kidney
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Medulla
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inner portion of kidney
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Medullar pyramids
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the medulla consists of 10 -18 conical or pyramidal structures
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Medullary rays
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parallel arrays of tubules leaving the base of each pyramid, entering cortex (medullary tissue that extends into the cortex)
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Renal Lobe
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portion of a kidney consisting of a renal pyramid and the renal cortex above it.
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Renal Lobule
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part of a renal lobe. It consists of the nephrons grouped around a single medullary ray, and draining into a single collecting duct
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Renal Papilla
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the tip of the renal pyramid; location where the kidneys converge at a traffic intersection. Transitional epithelium begins to be seen.
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Minor calyces
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Urine formed in the kidney passes through a papilla at the apex into the minor calyx then into the major calyx.
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Major calyces
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collects urine from multiple minor calyces before passing it through the renal pelvis into the ureter.
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Renal Column
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a medullary extension of the renal cortex in between the renal pyramids. It allows the cortex to be better anchored. Each column consists of lines of blood vessels and urinary tubes and a fibrous material.
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Renal sinus
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a cavity within the kidney which is occupied by the renal pelvis, renal calices, blood vessels, nerves and fat.
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Area Cribosa
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where large collecting ducts enter the minor calyx in the renal papilla
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Nephron
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functional unit of the kidney. Consists of: renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and—depending on who you ask—collecting tubules and ducts.
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Juxtamedullary nephrons
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1/7 of all nephrons; extra long Loop of Henle critical to establishment of a gradient of hypertonicity in the medullary interstitium
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Cortical Nephrons
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have shorter loops of Henle, don’t extend into medulla
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Renal Corpuscle
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a glomerulus surrounded by a double-walled epithelial capsule (Bowman’s capsule)
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Glomerulus
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capillary tuft surrounded by Bowman's capsule. Unlike most other capillary beds, the glomerulus drains into an efferent arteriole rather than a venule. The resistance of the arterioles results in high pressure in the glomerulus aiding the process of ultrafiltration where fluids and soluble materials in the blood are forced out of the capillaries and into Bowman's space.
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Bowman’s Capsule
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Double-walled epithelial capsule; internal (visceral) layer covers the capillaries of the glomerulus, external (parietal) layer forms outer limit of renal corpuscle. The urinary space is the lumen between.
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Vascular Pole
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where afferent artery enters and the efferent artery exits the renal corpuscle
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Afferent arteriole
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provides blood supply to each glomerulus
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Efferent Arteriole
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sends filtered blood through the vasa recta, collecting capillaries intertwined with the convoluted tubules that reabsorb substances before combing with efferent venules from other nephrons to form the renal vein, which rejoins the main bloodstream.
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Urinary pole
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where the proximal distal tubule begins
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Podocytes
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specialized cells of the visceral layer, from which arise primary processes, which in turn give rise to numerous foot processes (pedicles, secondary processes), that embrace the capillaries of the glomerulus. Basement membrane fused with basement membrane of the visceral layer.
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Foot processes
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form a barrier to the urinary space; interdigitate to define elongated spaces, the filtration slits, which work together with the fenestrated capillaries of the glomerulus to allow fluid and particles smaller than albumin to migrate into the urinary space.
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Proximal Convoluted Tubule
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at the urinary pole, the squamous epithelium of the parietal layer is continuous with the cuboidal epithelium of the PCT. These cells line the lumen with a brush border of microvilli and have apical canaliculi.
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Loop of Henle
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U-shaped structure consisting of thick and thin descending and ascending limbs.
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Distal Convoluted Tubule
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thick ascending limb penetrates the cortex to become the DCT. Simple cuboidal epithelium, no brush border, no apical canaliculi.
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Collecting Tubules & Ducts
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urine passes from DCT into collecting tubules that join up to form larger, straight collecting ducts
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Papillary Ducts
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AKA The terminal portions of the medullary collecting ducts are the "papillary ducts", which end at the renal papilla and empty into a minor calyx.
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Juxtaglomerular Apparatus
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=Macula Densa + Juxtaglomerular cells; plays a role in the maintenance of blood pressure in the body
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Juxtaglomerular cells
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modified smooth muscle cells of the afferent arteriole; detect blood pressure, release renin when stimulated by nerve or macula densa
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Macula Densa
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portion of the DCT that abuts the afferent arteriole; can detect the ionic strength of the filtrate, signals JG to release renin
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Mesangial cells
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reside in the matrix between the capillaries of the glomerulus. Function unknown
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Interlobular arteries (and veins)
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run in between the lobes of the kidney
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Arcuate arteries (and veins)
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form an arc in the cortex, define boundary between the medulla and cortex
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Intralobular arteries (and veins)
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run between medullary rays, give rise to afferent arteries, define boundaries between renal lobules
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Vasa Recta
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(straight vessels) follow the descending limb of the loop of Henle down into the medulla and return with the ascending limb.
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Transitional Epithelium
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multi-layered cells that can contract and expand, unlike a stratified epithelium, when distended you don’t see a layer of “squamous” nuclei below the luminal layer (i.e. there is no corneum or lucida)
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Facet cells
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AKA pillow cells. Large, round superficial cells of transitional epithelium. Have special membrane of thick plates that provide osmotic barrier between urine and tissue fluids.
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Urethra
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Carries urine from the bladder to the exterior. Apparently, there’s nothing interesting about the female urethra, except that it’s short, only deals with urine, and isn’t that great for keeping pathogens out of the bladder.
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Prostatic (urethra)
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portion of the male urethra that passes through the prostrate
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Membranous (urethra)
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stratified or pseudo stratified columnar epithelium. Surrounded by external (voluntary) sphincter.
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Bulbous (urethra)
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located in the corpus spongiosum, pseudo stratified columnar with stratified and squamous areas.
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Pendulous (urethra)
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located in the corpus spongiosum pseudo stratified columnar with stratified and squamous areas.
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Filtration Barrier
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Separates the urinary space and the blood in the capillaries of the glomerulus; consists of the fused basement membrane between podocytes and the fenestrated endothelial cells of the capillaries.
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Counter Current Systems
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a mechanism used to transfer some property of a fluid from one flowing current of fluid to another across a Semipermeable membrane
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Lymph
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originates as blood plasma that leaks from the capillaries of the circulatory system, becoming interstitial fluid, and filling the space between individual cells of tissue. Plasma is forced out of the capillaries and forced back in due to interactions of hydrostatic pressure (favoring movement out of the capillaries) and colloidal osmotic pressure(favoring movement into the capillaries). While out of the capillaries, the fluid mixes with the interstitial fluid, causing a gradual increase in the volume of fluid. Most of the fluid is returned to the capillaries. The excess interstitial fluid is collected by the lymphatic system and is processed by lymph nodes prior to being returned to the circulatory system. Once within the lymphatic system the fluid is called lymph, and has almost the same composition as the original interstitial fluid.
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Lymphatics
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secondary/peripheral lymphatic tissue= lymphocyte reactions, diffuse-epithelial surfaces, lymph node-lymph borne antigens, spleen-blood borne antigens
Primary/central lymphatic tissue= lymphocyte production and differentiation, bone marrow, thymus |
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Diffuse lymphatic tissue
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Lymphocytes accumulated in connective tissue
associated with non-keratinizing epithelium with little or incomplete connective tissue capsule, considerable variability in cellularity and organization, stratified squamous epithelium of vagina/esophagus, respiratory epithelium-Bronchus-Associated Lymphatic Tissue (BALT), transitional epithelium, Mucosal-Associated-Lymphatic-Tissue (MALT): tonsils and gut, elements of diffuse lymphatic tissue organization also found in nodules and follicles. Follicles are adynamic collection of B cells. Follicles reflect B cell response to antigen stimulation. Primary (1o ) follicle-accumulation of B cells resulting from antigen-driven B cell proliferation. Secondary (2o) follicle-actively producing B cells-region with mitotic lymphocytes in center=germinal center. |
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Peyer’s patches
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Lymphoid organs located in the sub mucosal tissue of the mammalian gut containing very high proportions of IgA secreting precursor cells. The patches have B and T dependent regions and germinal centres. A specialised epithelium lies between the patch and the intestine. Involved in gut associated immunity.
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Appendix
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A worm-shaped process projecting from the blind end of the caecum.
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Lymph node
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Effective Filters of Lymph, Sites for responses to lymph-borne antigens.
Lymphocyte compartments in the lymph node are Cortex->B-cells, Paracortex->T cells and dendritic cells and Medulla-> mixture B cells, plasma cells & macrophages> T cells. Lymphocytes enter the lymph node via the blood (high endothelial venules)and via afferent lymph from tissues. Lymphocytes leave the lymph node via efferent lymphatics. Lymph drains back into venous blood (thoracic duct). If lymphocytes encounter appropriate antigen in the lymph node, they proliferate and differentiate. If antigen is not encountered, lymphocytes pass through the lymph node and enter the lymph. Since lymph enters the venous circulation, lymph-borne cells can re-enter lymph nodes or other secondary lymphatic tissue via the blood. This process is called lymphocyte recirculation. Lymph node structure brings together antigen, antigen presenting cells, and lymphocytes to facilitate immune responses. 70% T-cells, 30% B-cells. |
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Lymph node capsule
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The lymph node is surrounded by a fibrous capsule, and inside the lymph node the fibrous capsule extends to form trabeculae. Thin reticular fibers form a supporting meshwork inside the node.
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Lymph node trabeculae
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bundles of dense connective tissue
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Lymph node cortex
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Antigen/T cell/B cell interactions first occur in the paracortex, antigen-activated B cells form follicles in cortex. The cortex contains the outer cortex, inner cortex, and paracortical region.
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Lymph node medulla
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mixture B cells, plasma cells & macrophages, contains medullary cords and mudellary sinuses
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Afferent Lymphatics
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A lymphatic vessel entering, or bringing lymph to a node
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lymph node Subscapular sinuses
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areas of loose lymphoid tissue (whose reticular fibril meshes are wide) situated immediately beneath the capsule. They are composed of a loose network of reticular cells and fibers. Lymph, containing antigens, lymphocytes, and APCs, circulates around the wide spaces of these sinuses after being delivered into these channels by the afferent lymphatic vessels.
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Lymph node Peritrabecular sinuses
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The part of the subscapular sinus that follows the oiuter edges of the trabeculae
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Lymph node Medullary sinuses
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dilated spaces that separate the medullary cords, bridged by reticular cells and fibers. They contain lymph, lymphocytes, often many macrophages, and sometimes even granulocytes if the lymph node is draining an infected region. These sinuses (which arise from the intermediate sinuses) join at the hilum delivering the lymph to the efferent lymph vessel of the lymph node.
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Lymph node Medullary cords
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branched, cordlike extensions of dense lymphoid tissue that arise in the inner cortex and separate the sinuses. They contain primarily B lymphocytes and often plasma cells and macrophages.
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Efferent lymphatics
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Lymphocytes leave the lymph node via efferent lymphatics. Lymph drains back into venous blood (thoracic duct).
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high endothelial venules
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High endothelial venules- Lymphocytes enter the lymph node via the blood (high endothelial venules) and via afferent lymph from tissues.
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Lymph node Hilus
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concave depression of lymph node through which arteries and nerves enter and veins and lymphatic vessels leave.
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Spleen
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the spleen is responsible for immune responses to blood borne antigens, blood filtration, removal of senescent RBC and platelets. The spleen is compartmentalized into red pulp and white pulp. The framework+ mesenchymal stromal cells make reticular fibers (type III collagen). NO LYMPHATIC SINUSES IN THE SPLEEN! 30% T-cells, 70% B-cells.
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Spleen Capsule
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dense connective tissue that surrounds the spleen from which emerges trabeculae which divide the splenic pulp into compartments.
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White pulp
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in spleen- T cell zone (associated with central artery,30% of splenic lymphocytes are T cells) and B cell zone(surrounds the T cell zone, ~70% of spenic lymphocytes are B cells), aggregates of lymphocytes, site of immune responses to blood-borne antigens, looks blue when stained, more dense than red pulp.
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Red pulp
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in spleen- network of venous sinuses suspended by framework of reticular cells and reticular fibers with bundles of dense connective tissue (trabeculae). Site of blood fitration, extensive system of venous sinuses; NO lymphatic vessels or lymphatic sinuses. Cords contains all formed elements of the blood and numerous macrophages. Repeating bands of reticular fiber represent strips of basement
membrane that hold the venous sinuses together. |
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Splenic cords
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in red pulp. They contain T and B cells, macrophages, plasma cells, and many blood cells. They are separated by irregularly shaped wide sinusoids.
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Spleen Marginal sinus
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marginal venous sinusoid separates white from red pulp and is often difficult to see.
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Spleen- Trabecular arteries
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The splenic artery divides as it penetrates the hilum, branching into trabecular arteries of various sizes that follow the course of the CT trabeculae.
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(PALS)
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periarterial lymphatic sheath, part of the white pulp
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Spleen- Central arteries
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When the trabecular arteries leave the trabeculae to enter the parenchyma, they are enveloped by a sheath of T lymphocytes, the PALS. Also called white pulp arteries.
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Spleen Sinusoids
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in the red pulp. Lined by elongated endothelial cells with the long axes parallel to the long axes of the sinusoids. Sinusoids are surrounded by an incomplete basal lamina, with spaces 2-3 micrometers in diameter or smaller, thus, only flexible cells can pass from the red pulp cords to the lumen of the sinusoids.
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Open vs. closed splenic circulation
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There are two proposed methods of the manner in which blood flows from the arterial capillaries of the red pulp to the interior of the sinusoids. In open circulation, formed elements of the blood are just dropped off into the parenchyma of the spleen. In closed circulation, the capillaries open directly into the sinusoids and the blood always remains in the vessels.
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Thymus
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thymus-derived Lymphocytes include HELPER/REGULATORY CD4+ cells and CYTOTOXIC CD8+ cells. The thymus is a primary lymphatic tissue which attains its peak development during youth. It has dual embryonic origin: lymphocytes arise in the boine marrow from cells of mesenchymal origin and these cells invade an epithelium primordium that has developed from the endoderm of the third and fourth pharyngeal pouches.
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Thymic cortex
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the peripheral dark zone of thymic lobules that contains antigen activated B-cells that have formed follicles. Stains darkly because of high density of lymphocytes. There are reticular fibers (type III collagen) in lymph node cortex.
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Thymic medulla
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mixture B cells, plasma cells & macrophages that contains a low density of lymphocytes (thymocytes) and predominance of epithelial cells. This is responsible for lighter staining. Medulla contains Hassall bodies.
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Hassal’s corpuscles (bodies)
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characteristic of the thymic medulla. They are of unknown function and contain flattened epithelial reticular cells that are arranged concentrically and are filled with keratin filaments. They sometimes calcify.
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Epithelial reticular cells in thymus
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Epithelial reticular cells are pleomorphic, stellate, non-phagocytic cells which seem to be supportive in function and are held together by desmosomes. They replace the fibroblastoid reticular cells found in other lymphoid organs. Other epithelial cells in the medulla have the ultrastructure of secretory cells. Although different epithelial cells throughout the thymus appear alike by light microscopy their ultrastructure and function varies.
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Thymic Septae
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interlobular connective tissue of thymus (?????)
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Thymic Lobules
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The thymus has a connective tissue capsule that penetrates the parenchyma and divides is into incomplete lobules, so that there is continuity between the cortex and the medulla of adjoining lobules. Each lobule has a peripheral dark zone (cortex) and inner light zone (medulla).
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Humoral immune response
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an adaptive immune response characterized by the production of antibodies produced by plasma cells derived from clones of activated B cells.
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Cellular immune response
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an adaptive immune response mediated by T-cells that (1) secrete cytokines that act on B cells, T cells, and on inflammatory cells such as macrophages and neutrophils, and (2) attack foreign cells or cells that exhibit foreign epitopes on their surfaces, such as cells infected by bacteria of viruses, and tumor cells.
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Filtration of blood
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accomplished by the spleen removing senescent RBCs in red pulp.
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Filtration of lymph
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occurs in the lymph node. Lymph percolates through lymphatic channels (sinuses) that are studded with macrophages.Lymphocytes enter the lymph node via the blood (high endothelial venules) and via afferent lymph from tissues. Lymphocytes leave the lymph node via efferent lymphatics. Lymph drains back into venous blood (thoracic duct). If lymphocytes encounter appropriate antigen in the lymph node, they proliferate and differentiate.
If antigen is not encountered, lymphocytes pass through the lymph node and enter the lymph. Since lymph enters the venous circulation, lymph-borne cells can re-enter lymph nodes or other secondary lymphatic tissue via the blood. This process is called lymphocyte recirculation. |
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smartest and sexiest medical/dental students ever?
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2007 Prematters
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