Cardiovascular system Flashcards
what are the two systems that make up the cardiovascular system?
blood vascular system: closed supply and drainage system- a continous loop
lymphatic (vascular) system: open entry drainage system, a one way system
describe the ‘supply side’ of the cardiovasular system
arteries are the only supply path
major artiers positioned to avoid damage
important structures often receive supply from multiple sources eg the brain has 4
describe the ‘exchange network’ of the cardiovascular system
capillaries of varying degrees of permeability
-continous (controlled)
fenestrated (leaky)
sinusoidal (very leaky)
describe the ‘drainage’ aspect of the cardiovascular system
3 pathways for drainage
-deep veins
-superficial veins
-lymphatics
are veins or artieries larger?
cross sectional area of veins is x2 that of arteries
describe the flow of blood from the left side of the heart ( names of arteries it travels through)
comes from the left and right pulmonary arteries that have just come from the lungs so that the blood could be oxygenated. It initially flows through the left atrium into the left ventricle. finally it travels into the aorta so it can be distributed throughout the body
describe the flow of blood on the right side of the heart, names of veins etc
deoxygenated blood flows into the right atrium from both the superior and inferior vena cava as well as the coronary sinus. through the tricuspid valve it is pumped into the right venticle where it exits through the pulmonary valve
what is the purpose of valves
they allow for a one directional flow of blood to ensure that it doesnt flow backwards.
what are the 4 layers of the heart wall from out to in
epicardium
myocardium
endocardium
and pericardium
what is endocardium made of
squamous epithelium, loose irregular fiberous connective tissue
what is the function of pericardium
the sack that the heart sits in, for protection and lubrication
which ventricle has a greater muscle thickness and why
the left ventricle as it has to pump blood around the whole body. it is 3 times as thick as the muscle on the right ventricle.
describe the atrinoventricular valves
(function and names for left and right)
the valve between the atrium and the ventricle.
They prevent blood returning into the atrium during ventricular contraction.
right side- tricuspic valve
left side- bicuspid valve
what do atrinoventricular valves do during both diastole and systole
distole- the valves are open as its the filling phase
systole- the atrioventricular valves are closed.
describe the semilunar valves
(function and names for left and right)
seperate ventricles from blood transfer (arteries and veins)
they prevent blood from returning to the ventricles during filling
right side= pulmonary (semilunar) valve, 3 cusps
left side= aortic valve, 3 cusps
pushes open as blood flows out of the heart, then they close as blood starts to backflow. blood only flows in one direction
what is the function of the papillary muscles and the chordae tendineae?
structures to ensure that the valve leaflets dont close too hard during the systole phase.
what arteries deliver oxygenated blood around the heart?
right coronary artery, left coronary artery, circumflex artery, anterior interventricular artery
what are the veins that removed deoxygenated blood from around the heart?
small caridac vein, coronary sinus, great cardiac vein
what is the structure of the cardiac muscle
stirated, short branched cells. one or sometimes 2 nucleus in the centre of the cell. interconnected with neighbouring cells via intercollated disks
what connects actin to actin?
adhesion belts
function of desmosomes
linking cytokeratin with cytokeratin. When the sacromere is contracting it is pulling on the neighboring cells
what do gap junctions do?
they allow for electrochemical communication- propigating contractions through the movement of calcium.
features of conduction cells
peripheral myofibrils
have a central nucleus
lots of mitochondria and glycogen
lots of gap junctions- only some desmosomes and few adhesion belts
features of the tunica intimita
endothelium composed of simple squamous epotheloium- lines the lumen of all the vessels
the subendothelium- a sparce pad of loose fiberous connective tissue that cushions the endothelium
internal elastic lamina- condensed sheet of elastic tissue
what is the presence of internal elastic lamina in veins and arteries
well developed in arteries
less developed in veins
features of the tunica media
has circumferencial smooth muscle
a variable content of connective tissue fibres- many elastin and collagen
what is media thickness dependent on?
proportional to the vessel diametre and blood pressure.
low blood pressure= thinner media
features of the tunica adventita
loose fiberous connective tissue with a high collagen content and variable elastin
lymphatics and autonomic nerves also found in this region
what do larger vessels have in their adventita layer?
vasa vasorum- vessels for the vessel. The larger vessels get their own blood supply
arteriole function
theyre resistance vessels of the circulation, they determine blood pressure
narrower they are the higher the blood pressure is
what is the function of a venule
They ensure that blood can only move in one directon.
features of veins
shape, function
low pressure large volume systems
capacitance vessels- spare capacity so theyre able to hold additional blood volume
irregular flattened shape with large lumen and thin walls
what are the three layers of a vein
intima
media
adventitia
function and features of capillaries
site of exchange between blood and tissues
very thin walls, large cross sectional area= slow and smooth blood flow
what are the three types of capillaries and what is their diametre
continous 8-10um
fenestrated 8-10 um
sinusoidal 30-40um
features of continous capillaries
the least leaky
one red blood cell travels through the lumen at a time
features of the fenestrated capillaries
has physical pores that allow for things to move directly across the endothelial layer
features of the sinusodial cappillaries
large gaps with an incomplete basement membrane. The greater diametre of the capillary allows for other type of exhange to occur eg nutrients in the liver.
what type of capillaries complete diffusion through membrane
continious, fenestrated and sinusoidal