cardiovascular Flashcards
heart wall layers
-epicardium -outer layer, also known as visceral pericardium
-myocardium -muscular wall of heart, contains cardiac muscle tissue, vasculature and nerves
-endocardium -inner layer, lining of epithelial cells
heart not reliant on
-nervous system for activation
-ANS and endocrine system can modulate function
right atrium
-receives blood from systemic circuit through the two great veins, superior and inferior vena cava
-also receives blood from coronary sinus
-anterior atrial wall and inner surface of auricle contain prominent muscular ridges called pectinate muscles [these aid atrial contraction]
coronary sinus
-large thin walled vein that opens into right atrium inferior to the connection with the inferior vena cava
-receives blood from coronary veins
right and left atria divided by
-interatrial septum
-features the fossa ovalis [oval depression]
-remnant of foramen ovale that closes after birth [foetus receives oxygen from placental blood and lungs are not functional]
left atrium
-receives blood from pulmonary circuit via four pulmonary veins [2 left pulmonary 2 right]
-some pectinate muscles on anterior inner surface
right ventricle
-thicker myocardium compared to both atria
-interior surface contains ridges called trabeculae carneae [convey part of hearts electrical conduction pathway]
-cone-shaped muscles [papillary muscles] extend from ventricle base [these anchor chordae tendineae of right atrioventricular valve]
left ventricle
-myocardium required to generate high blood pressure to force blood through systemic circuit
-inner surface contains trabeculae carneae
-papillary muscles anchor chordae tendineae
fibrous skeleton of the heart
-dense connective tissue forms rings around each of the four heart valves [prevents valves from stretching under load]
-acts as an insertion point for cardiac muscle cells
-electrically insulates atria from ventricles
atrioventricular valves
-2 key components [cusps that open/close, chordae tendineae that prevent cusps from eversion
-right AV valve has three cusps [tricuspid valve]
-left AV valve has two cusps [bicuspid/mitral valve]
semilunar valves
-aortic valve at base of aorta, pulmonary valve at base of pulmonary trunk
-valves open when blood pressure in 2 ventricles is higher than that in aorta and pulmonary trunk
hearts blood supply
-coronary arteries feed work cardiac tissue [left and right coronary arteries emerge from base of aorta
-coronary veins return this blood [merge into coronary sinus]
structure of blood vessels
-walls of arteries and veins have the same three layers
-tunica intima, tunica media, tunica externa
tunica intima
-innermost layer containing endothelial cells [very smooth to minimise friction]
-arteries also have a layer of elastic fibres [helps with distension and recoil]
tunica media
-middle layer made of elastic and smooth muscle fibres
-much thicker in arteries
-allows for vasoconstriction/dilation
tunica externa
-outermost layer
-constructed from connective tissue
-fuse with adjacent tissue to anchor vessel
elastic arteries
-largest arteries in body
-include aorta and pulmonary trunk
-contain a high proportion of elastic fibres in tunica media [elastic lamellae]
-help blood flow away from heart
ventricular systole and diastole
-systole -walls are distended [contraction/squeezing]
-diastole -recoil [relation/dilation]
muscular arteries
-distributing arteries
-tunica media contains more smooth muscle fibres and fewer elastic fibres compared to elastic arteries
-greater ability of vasoconstriction and vasodilation
-continuous partial muscle contraction known as vascular tone
vascular tone
-continuous partial pressure contraction
-helps maintain pressure and blood flow
-can be modulated to shunt blood to specific areas [digestive system, skeletal muscle]
arterioles
-400million in body
-only 1-2 layers of smooth muscle cells
-regulate blood flow across cap. networks [metarteriole runs into cap network, known as resistance vessels]
-precap. sphincters can contract and reduce blood flow across cap.
capillaries
-smallest blood vessels
-20 billion
-provides a huge surface area to aid diffusion of gases, nutrients, and wastes
-no tunica media/externa
-just a layer of endothelial cells with a basement membrane
-more numerous in metabolically active tissues
types of capillaries
-continuous cap.
-fenestrated cap.
-sinusoid cap.
continuous capillaries
-most numerous
-found in CNS, lungs, muscle and skin
-endothelial cells form a continuous tube
