Oxygen Transport System, CV anatomy

Ventilation vs Respiration

Ventilation: movement of air between atmosphere and lungs

Respiration: exchange of o2 and Co2 between lungs and blood

Aerobic metabolism

requires o2

uses all food sources; occurs in mitochondria (byproducts are water and CO2)

yields 38 ATPs per glucose

Anaerobic metabolism

Does not require o2

uses only glucose, in cytoplasm of cell (byproduct is lactic acid)

yields 2 ATP per glucose

O2 Transport Terms

Distribution: air traveling to areas in lung

Diffusion: movement of gases between alveoli and blood

Perfusion: blood is pushed through pulmonary capillaries by the heart

Circulation: blood is moved from pulmonary capillaries and heart through the body

Complications of obesity

Cardiometabolic (hypertrophy and hyperplasia of visceral adipocytes) → infiltration of heart (epicardial fat goes into ventricular and atrial myocardium) and weight of heart (fat and L ventricular hypertrophy) (increases stroke volume and cardiac work)

PT treatment of obesity

Endurance programs to increase energy expenditure, lowers CV risks, and improve respiratory muscle efficiency

What are the 3 layers of the heart (inside to out)

Endocardium (endothelium, myoelastic layer of SM and CT)

myocardium (contractile tissue) (thickest layer)

pericardium (visceral and parietal)

What lines the internal surface of all systems?

Squamous epithelium

Special structures of cardiac muscle

Intercalated discs and gap junctions (ionic continuity between cells and serves as electrical synapses)

Right Atrium

Receives deoxygenated blood (SVC, IVC, and coronary sinus)

Normal pressure 0-8 mmHg

Right Ventricle

Ejects blood into pulmonary circulation through pulmonary arteries

0-8 mmHg diastole and 15-30 mmHg systole

Left Atrium

Thicker wall than R atrium

4-12 mmHg normal filling pressure

Left Ventricle

Myocardium is 3x thicker than R Ventricle

80-120 mmHg systole and 4-12 mmHg diastole

Where are the atrioventricular valves and what do they do and what are they?

Attached to the papillary muscles of the myocardium by the chordae tendinae

Prevent backflow of blood from ventricles into atria during systole

Tricuspid (R) and bicuspid (L)

Where are the atrioventricular valves and what are they?

Between ventricles and arteries

Prevents backflow from arteries during diastole

Pulmonary valve and aortic valve

Function of endothelium in smooth muscles

Secretes agents that control clot formation (heparin, tPA, von willebrand)

Regulates vascular tone and blood flow (contraction: ACE; relaxation: NO2, and prostacyclin)

Layers of smooth muscle

Tunica intima, media (SM), externa/adventitia (type 1 collagen and elastic fibers)

Large vessels have vasa vasorum (helps large vessels with more metabolites)

Function of carotid sinuses

Baroreceptors monitoring arterial BP (sensory endings from CN IX) ~ chemoreceptors in carotid/aortic bodies

Dilates B ICA and aortic arches

Capillaries

Anastomosis of arterioles that permits metabolic exchange

Amt depends on metabolic needs of the tissue

Veins

Carry blood back to the heart; medium and large veins have valves to prevent backflow

Blood is under low pressure

Lymphatic system

collects excess interstitial fluid from tissue spaces and return it to the blood (vessels converge into two large trunks; thoracic duct and R lymphatic duct)

WBCs present but not RBCs

Pulmonary vs systemic circuit

Pulmonary: flow between lungs and heart by R heart

Systemic: flow between body and heart by L heart

Blood flow path

RA → tricuspid valve → RV → pulmonary semilunar valve (pulmonary trunk, arteries, lungs) → LA → bicuspid valve → LV → aortic semilunar valve (aorta, arteries, arterioles, capillaries, venules, veins)

Excitation of the heart

SA node (RA wall; sinus rhythm) → AV node (internodal pathway from atria to AV and bachman’s bundle from RA to LA) (can spontaneously depol; in interatrial septum above tricuspid valve) → Bundle of HIS (interventrricular septum → R and L bundle branches (in septum to conduct impulse to R and LV) → purkinje fibers

Phases of cardiac APs

Phase 4: resting membrane potential (-90mV) due to K leak channels

Phase 0: depolarization due to Na influx (fast Na channels opened)

Phase 1: repolarization due to K efflux and closure of Na channels; Ca channels open

Phase 2: plateau due to k efflux while ca prolongs depolarization

Phase 3: repolarization due to ca channel closure (pumped into ECF) and K channel opening

Purpose of Ca prolonging depolarization

Preventing tetany (prolonged contractions) that would interfere with pumping