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46 Cards in this Set
- Front
- Back
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Primary functions of the urinary system
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- Adjust blood volume and blood pressure
- Regulate plasma ion concentrations (sodium, potassium, calcium) - Stabilize blood pH (if acid decrease H+, if basic increase H+) - Conserve nutrients - Remove drugs and toxins from blood |
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Identify the organs that make up the urinary system and identify their function
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Kidneys - produce urine
Ureters- conduct urine to bladder Bladder- stores urine Urethra- conducts urine to the exterior |
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Which organs of the urinary system are retroperitoneal?
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kidneys and ureters
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What is the kidney protected by?
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abdominal organs (anteriorly)
body wall musculature (laterally) 11th and 12th rob (posteriorly) |
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Kidney position maintained by?
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- overlying peritoneum
- adjacent visceral organs - supporting connective tissue 1) fibrous capsule (collagen fibers) 2) perinephric fat capsule (adipose) 3) renal fascia (connects to body wall) |
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Major structural landmarks of the kidney
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- Renal sinus
- renal cortex - renal medulla - renal papilla - renal column - kidney lobe - renal sinus - hilum (blood vessels and ureter enter/exit) - minor calyx - major calyx - renal pelvis |
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Nephron
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perform the essential functions of the kidney
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Two types of nephrons
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Cortical and Juxtamedullary
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Cortical nephron
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- 85% of all nephrons
- located primarily in the cortex - most regulatory functions |
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Juxtamedullary nephron
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- 15% of all nephrons
- long nephron loop extending deep into medulla - essential to producing concentrated urine |
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Regions of the nephron (2)
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- Renal corpuscle
- Renal tubules |
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Renal corpuscle primary function
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- where filtration of water and solutes occur
- collected in the surrounding capsular space - includes the glomerular capsule and the glomerulus (capillary network) - Filtration of water and inorganic and organic solutes from plasma - Retains: plasma proteins and blood cells |
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Define filtrate
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all solutes taken of of the blood and moved to capsular space
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Renal tubules primary function
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receive filtrate and modify it to create urine
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Renal tubules - sections
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- Proximal convoluted tubule (PCT)
- Nephron loop - distal concoluted tubule (DCT) |
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Proximal convoluted tubule (PCT)
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filtrate now called tubular fluid)
- primary location for reabsorption (60-70%) - reabsorption of glucose, amino acids, vitamins, ions - secretion: back into tubules, hydrogen ions, ammonium ions, creatinine, drugs and toxins |
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Nephron loop
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- two parts: descending and ascending limb
- establishes osmotic gradient for water reabsorption and solute movement - reabsorption of 25% of water - Reabsorbs sodium and chloride ions, water |
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Distal convoluted tubule (DCT)
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- further reabsorption and secretion
- more secretion occurs here compared to little reabsorption - reabsorption of VARIABLE amount of water under ADH stimulaton and VARIABLE amount of sodium ions under aldosterone stimulation - Secretion: back into tubules to become uring, hydrogen ions, ammonium ions, creatine, drugs, toxins - Has NA+/k+ pump (reabsorbs NA+ and secretes K+) - Has NA+/H+ pump (reabsorbs NA+ and secretes H+), important in pH |
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Collecting system
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- Collecting duct: collects fluid from many nephrons through medulla
- Papillary duct: collects fluid from multiple collecting ducts and delivers to minor calyx, reabsorbed in the RENAL CORTEX - Vasa recta: redistribution of water and solutes reabsorbed in the RENAL MEDULLA and stabilization of the concentration gradient of the renal medulla |
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Blood flow into the kidney
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renal artery --> segmental artery (between the lobe) --> arcuate artery (arch over pyramid) --> cortical radiate arteries (rays of sun) --> afferent arterioles --> glomerulus
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Blood flow out of the kidney
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glomerulus --> efferent arterioles --> cortical radiate veins --> arcuate vein --> interlobar veins --> renal vein
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Filtration at the renal corpuscle
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- Afferent arteriole (supplies individual nephrons)
- Glomerulus (filtration occurs here) - Efferent arteriole (drains the glomerules) - Peritubular capillaries (surround the entire renal tubule) - Vasa recta (after peritubular capillaries; ONLY in the juxtamedullary nephrons) |
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Organic waste products rid from the body by the kidney:
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Urea: by product of amino acid digestion
Creatinine: by product of creatine phosphate in muscle (creatine provides a quick burst of energy) Uric acid: by product of RNA digestion |
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Juxtaglomerular complex
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- junction of afferent arteriole and distal convoluted tubule
- produces and secretes renin when glomerular blood pressure falls (Renin increases BP) |
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Glomerular capsule
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- collects filtrate
- pariental layer (forms outer capsule) - visceral layer (on glomerular surface) - Podocytes (make up visceral layer) wrap glomerulus, help form filtration slits with their "feet" or pedicels |
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Mesangial cells
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control capillary diameter and blood flow
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Filtration membrane
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1) fenestrated glomerular capillaries
2) dense layer 3) filtration slits from podocytes |
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Factors controlling glomerular filtration
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- Glomerular hydrostatic pressure (GHP): pressure created by the flow of blood through glomerulous (increase BP)
- Capsular colloid pressue - Blood colloid osmotic pressure (BCOP): opposes filtration - Capsular hydrostatic pressure (CsHP): opposes filtration |
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Net filtration calculation
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GHP minus BCOP and CsHP = NFP
Positive NFP needed to favor filtration |
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Glomerular filtration rate (GFR)
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- Amount of filtrate produces by the kidney per minute
- direct correlation between GFR and GHP (decrease in GHP = decrease in GFR and vice versa) |
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Glomerular filtration rate (GFR) adjusted by:
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- Local control
- Central response |
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(GFR) adjusted by local control:
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autoregulation at the organ via constriction and dialation of vessels
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(GFR) adjusted by central responses:
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- includes other systems
- Endocrine response: initiated by the juxtaglomerular complex (Renin increases BP) - Neural response: autonomic nervous system control (epinepherin increases HR=increase BP=increase filtration) |
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Nephron loop: Thin descending limb
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- 25% reabsorption of H2O
- H2O pushed out to blood - absorbs water through osmosis - tubular fluid solute concentration increases |
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Nephron loop: Thick ascending limb
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- actively reabsorbs NA+ and CL- but is impermeable to water (cannot absorb water)
- tubular fluid solute concentration decreases |
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Countercurrent multiplication
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- countercurrent: fluid moving in opposite directions
- multiplication: effect increases with fluid movement - Needed to maintain concentration gradient and facilitate water reabsorption - more water is reabsorbed from the tubular fluid in the collecting duct - with water reabsorption, urea becomes more concentrated |
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Trace the pathway of urine from the kidneys to the external urethra
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collecting duct --> minor calyx --> Major calyx --> ureter --> bladder --> urethra
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Know the function of the Renin Angiotensin system
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- a hormone system that regulates blood pressure and water (fluid) balance.
- When blood volume is low, juxtaglomerular cells in the kidneys secrete renin directly into circulation which increases blood pressure - Aldosterone is secreted and causes the tubules of the kidneys to increase the reabsorption of sodium and water into the blood. This increases the volume of fluid in the body, which also increases blood pressure. |
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Why is maintaining a constant blood pressure in the kidneys so important?
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- Low blood pressure decreases the blood flow to the kidney, and since the kidney's function depends on adequate blood flow, it may not be able to do its job at such a low blood pressure.
- High blood pressure can cause proteins to leak into the kidney inappropriately so that protein ends up in the urine. Long-term this damages the filtering component of the kidney, which can rapidly lead to acute kidney injury |
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normal components that are found within the glomerular filtrate
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- contains water, ions (such as Na, K, Cl, Mg, Ca, H, etc.), bicarbonate, urea, uric acid, creatinine, any drugs or toxins
- Glomerular filtrate generally does not contain glucose (unless diabetic), large proteins or cells |
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identify hormones that would affect renal reabsorption
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- Antidiuretic hormone (ADH), which is secreted by the posterior pituitary gland is responsible for for making collecting tubules of nephrons in the kidneys permeable to water. This allows water to be reabsorbed into the body from the urine.
- Aldosterone, released by the adrenal cortex, also aids in the reabsorption of water by increasing the tubular reabsorption rate. However, it is also responsible for stimulating the tubules to reabsorb salts. |
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differentiate between renal pathologies
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add
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process of producing concentrated urine
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- The thin descending limb of the nephron loop is permeable to water but not solutes. This allows water reabsorption (pushed out) while keeping solutes in.
- The thick ascending limb is impermeable to water and most solutes - pumps remove sodium and chloride ions - The DCT and the collecting ducts have variable permeability to water (ADH presence) and sodium (Aldosterone) |
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steps of the micturition reflex local pathway
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- stretch of urinary bladder wall as it fills
- afferent impulses carried to the sacral spinal cord - parasympathetic motor response stimulates detrusor muscle to compress bladder |
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steps of the micturition reflex central pathway
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- interneuron relays sensation tothalamus and to cerebral cortex
- voluntary relaxation of the external urethral sphincter (causes relation of the internal urethral sphincter) |
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two types of water reabsorption that occur in the urinary system and the specific locations where they take place
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add
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