Kin 2Yy3 Cardiovascular System

Mediastinum

The area between the lungs, from the sternum to vertebral column.

Blunt point of cone.

Directed anteriorly, inferiorly, to the left.

Flace part opposite the apex.

Directed posteriorly, superiorly, to the right.

Superior right: Superior border of 3rd costal cartilage

Superior left: inferior border of 2nd costal cartilage.

Inferior right: superior border of 6th costal cartialage

Inferior left: 5th intercostal space

Whole thing slightly shifted to the left.

Pericardium.

Fibrous Pericardium - tough fibrous outer layer

Serous Pericardium - thin transparent inner layer.

Prevents over distention, acts as anchor.

Simple Squamous Epithelium

Parietal Pericardium - lines fibour outer layer

Visceral Pericardium - covers surface of heart

Pericardial cavity.

Pericardial fluid.

Epicardium.

Epicardium - visceral layer of serous pericardium

Myocardium - cardiac muscle

Endocardium - chamber lining and valves

2 upper atria.

2 lower ventricles.

Grooves on surface of heart.

Contain coronary blood vessels and fat.

Coronary - marks boundary between atria and ventricles

Anterior interventricular - boundary between ventricles (anteriorly)

Posterior interventricular - boundary between ventricles (posterior)

Coronary.

Atrioventircular - seperate atria and ventricles

Semilunar - separate ventricles and arteries

Tricuspid valve - Right AV valve

Bicuspid (mitral) valve - Left AV valve

Cusps fill up when pressure of blood in arteries is greater than pressure in heart, prevent blood from moving backwards into ventricles.

Aorta --> Coronary Arteries --> Heart Tissue --Coronary Sinus/Veins --> Right Atrium

Redundant connections of the heart supplying blood to the same region. If one artery becomes occluded, alternate routes provide blood.

Right coronary artery supplies the posterior interventricular artery.

Left coronary artery supplies the anterior interventricular artery.

Great cardiac vein - left side of heart

Small cardiac vein - right side of heart

Large venous cavity that empties into the right atrium.

Fibrous plate (connective tissue)

- allows for attachment of muscles and valves

- insulates electrical signals to control APs

Twists and pulls apex towards apex towards plate.

"Wrings heart out."

1-2, centrally located

At the z-disc

Smaller comparatively.

Doesn't contact t-tubules very often

Causes increased contraction time

Intercolated discs -specialized cardiac muscle cell-to-cell contacts.

Many gap junctions.

Desmosomes (staples) and Gap Junctions

Found at the intercalated discs.

SA: next to superior vena cava in right atrium

AV: interatrial septum

Generate spontaneous action potentials.

SA.

Is the one that actually starts the heart.

Cardiac muscle cells.

Less myofibrils - more for conducting than contracting.

AV node. Ensures the ventricles recieve AP after atria are done contracting.

SA Node --> Atria --> AV Node --> AV Bundle --> Left and Right Bundle Branches --> Purkinje Fibers

Purkinje Fibers > Left and Right Bundle Branches > AV Bundle

# of Gap Junctions

High extracellular Na+ and Ca2+, high intracellular K+

Na+ channels open.

K+ channels close

Ca2+ channels slowly open

Early repolarization.

Plateau Phase

Final Repolarization.

Some voltage-gated K+ channels open.

Na+ channels close.

Some Ca2+ channels are open, slow repolarization.

Slows contraction.

Voltage-gated K+ channels open.

Ca2+ channels close.

Na/K ATPase restores ion gradient.

-85 mV

They all fire. All APs are conducted from cell to cell.

Calcium Induced Calcium Release.

Movement of Ca2+ through plasma membrane and t-tubules into sarcoplasm stimulates release of Ca2+ from sarcoplasmic reticulum.

1) Pacemaker potential

2) Depolarization

3) Repolarization

Na+ leakage into the cell, causes resting potential to approach.

K+ channels close (prevent repolarization)

Ca2+ channels open.

K+ channels close.

Ca2+ channels close, K+ channels open.

Depolarization is almost entirely calcium.

Sodium is mainly used to reach threshold.

Absolute - completely insensitivity to stimulation

Relative - reduced sensitivity to stimulation

Prevent tetanic contraction.

P wave - atrial depolarization (contraction)

QRS complex - ventricular depolarization and atrial repolarization

T wave - atrial repolarization

atrial contract and begin to relax

Ventricles contract and begin to relax.

Systole (Ventricular contraction) and Diastole (Relaxation)

2.

Isovolumetric contraction and ejection

3.

1) Isovolumetric relaxation

2) Passive filling

3) Active ventricular filling

During atrial systole.

1) Semilunar valves closed, AV valves open, ventricular filling and atrial contraction

2) Semilunar valves closed, AV valves closed, isovolumetric ventricular contraction/relaxation or passive ventricular filling, atrial relaxation

3) Semilunar valves open, ventricular ejection, AV valves closed

SV = End diastolic volume - end systolic volume

Lubb,

AV valves closing at beginning of ventricular systole.

Dubb.

Semilunar valves closing at beginning of ventricular diastole.

Turbulent flow into ventricles.

Prevent eversion of the AV valves

Create tension in chordae tendinae

MAP = Cardiac Output x Peripheral Resistance

Stroke Volume x Heart Rate

Difference between CO at rest and at maximum CO.

PSNS and SNS

Increase HR (subsequently CO)

Increase contraction force (Increase in SV, susbsequently CO)

Vagus nerve = acetylcholine release

Hyperpolarize heart, longer to reach threshold.

(decreases HR)

(nor)epinephrine released from ardrenal medulla

Preload - amount of stretch controls force of contration

Afterload - pressure the ventricle must produce to overcome pressure in aorta

Starling's law of the heart

Norepinephrine.

Slowly, but for a longer period of time.

Positive correlation.

Too much or too little extracellular K+ decreases HR.

Medulla Oblongata

Low BP --> baroreceptors sense decreases --> cardioregulatory center in brain increases SNS and decreases PSNS --> (nor)epinephrine secretion from adrenal medulla --> increase HR and SV = increase in CO --> increase BP

Opposite for high.