PATH 3810 Cardiovascular System

divisions of the cardiovascular system

• blood circulatory system

• lymph vascular system

functions of the cardiovascular system

• transport of oxygen, nutrients, metabolic waste products, hormones, leukocytes

• temperature regulation

atria

upper two chambers of the heart that receive and collect blood

ventricles

lower two chambers of the heart that pump blood out of the heart

septum

muscle that divides the heart into left and right halves

valves

4 heart valves that prevent backflow of blood

tricuspid valve

found between RA and RV

pulmonary semilunar valve

found between RV and pulmonary artery

mitral (bicuspid) valve

found between LA and LV

aortic semilunar valve

found between LV and aorta

deoxygenated blood from the body flows through the

inferior and superior vena cava

the vena cavae empty into…

…the right atrium

blood from the right atrium passes through…

… the tricuspid valve

blood passes through the tricuspid valve into…

…the right ventricle

blood from the right ventricle passes through…

…the pulmonary semilunar valve

blood flows through the pulmonary semilunar valve into…

…the right and left pulmonary arteries

pulmonary arteries take blood to…

…the lungs

the lungs send the blood to…

…the pulmonary veins

the pulmonary veins enter blood into…

…the left atrium

blood from the left atrium flows through…

…the mitral valve

blood flows from the mitral valve to…

…the left ventricle

blood from the left ventricle passes through…

…the aortic valve

blood flows from the aortic valve to…

…the aorta

pulmonary circulation

movement of blood from the heart to the lungs to the heart

systemic circulation

movement of blood from the body to the heart to the body

Which side of the heart is larger?

the left side

tunica intima

endothelium (simple squamous)

loose CT

+/- internal elastic lamina

tunica media

smooth muscle cells, elastin, collagen, ground substance

+/- external elastic lamina

tunica adventitia

outer connective tissue and smaller blood vessels (vasa vasorum), nerves (nervi vasorum), and lymphatic vessels

cross-section of an artery

tunica intima of the heart

endocardium

tunica media of the heart

myocardium

tunica adventitia of the heart

epicardium/visceral pericardium

order of circulatory layers from innermost to outermost

tunica intima → tunica media → tunica adventitia

layers of the heart

skeletal muscle cross-section

skeletal muscle longitudinal section

smooth muscle cross-section

smooth muscle longitudinal section

cardiac muscle

intercalated discs

bind cardiac cells, transmit forces of contraction, provide areas of low electrical resistance

cardiac conduction system consists of

• sinoatrial node

• atrioventricular node

• bundle of His and Purkinje fibers

electron micrograph of cardiac muscle

the sinoatrial node is located…

…in the wall of the right atrium

impulse from the SA node passes through atria to…

…the atrioventricular node

the P-Q wave represents the

depolarization of the SA node, which causes atrial systole

the Q-R-S wave represents the

depolarization of the AV node, which causes ventricular systole

the S-T wave represents the

ventricles repolarizing

atrial repolarization is not seen on an EKG because

it happens during the AV impulse

P wave

atrial depolarization

QRS

ventricular depolarization

T wave

ventricular repolarization

purkinje fibers

purkinje fibers

specialized cardiac fibers that lie beneath the endocardium, then penetrate the myocardium

appear larger and with paler sarcoplasm than typical cardiac fibers

purkinje fibers

heart valves

leaflets of fibroelastic tissue (condensed endocardium)

covered by endothelium

prevent retrograde flow

cardiac valve

heart valve

arterial vessels

high-pressure distribution system from heart to capillaries

microcirculation vessels

capillary beds primarily concerned with gas, nutrient, waste exchange

venous vessels

low-pressure system collecting blood for return to the heart

endothelial cells

crucial in integrity and circulatory function of vessels

permeability barrier

secrete anticoagulants at rest and procoagulants when activated

secrete vasoconstrictive and vasodilative factors

anticoagulants produced by endothelial cells

prostacyclin

thrombomodulin

others

procoagulants secreted by endothelial cells

von willebrand factor

tissue factor

others

vasoconstrictive molecules secreted by endothelial cells

endothelin

vasodilative molecules secreted by endothelial cells

nitric oxide

arterioles

terminal branches of the arterial tree

arteries

elastic ± muscular, large diameter, thick tunica media with concentric layers of elastic laminae between collagen and smooth muscle

elastic artery under von giesin stain

elastic artery under h & e stain

muscular artery

muscular arteries have…

…internal elastic lamina, which lies between tunica intima and tunica media

…may include external elastic lamina, less prevalent as vessels get smaller

muscular artery

arterioles

progression from small muscular arteries to arterioles is gradual, involving loss of IEL and reduction in smooth muscle layers

arterioles

electron micrograph of arteriole

microcirculation

involves arterioles, capillaries, and venules

capillaries

lumen diameter similar to that of red blood cells

single layer of endothelial cells joined by tight junctions and supported by basement membrane

no medial or adventitial layers

weibel-palade bodies

store von willebrand factor (aka factor VII)

found in capillary endothelial cytoplasm

pericytes

flattened cells surrounding epithelium with contractile properties

may or may not be found at capillaries

types of capillaries

continuous

fenestrated

sinusoidal

continuous capillaries

endothelial cells joined by tight junctions

exchange across endothelium by passive diffusion, pinocytosis, intercellular mechanisms

fenestrated capillaries

located in tissues with extensive exchange

continuous basement membrane

fenestrations allow enhanced permeability

sinusoidal capillaries

large fenestrations with discontinuous basement membrane

larger lumen

found in bone marrow, spleen, liver

electron micrograph of capillary

electron micrographs of capillaries

venous system