Cardiovascular system Flashcards
systems of the heart
Blood vascular - closed supply / drainage
Lymphatic vascular - open entry drainage
Organisation of cardiovascular system
Supply side - arteries, situated deep in trunk for protection
Exchange network - capillaries ( continuous, fenestrated and sinusoidal )
Drainage - Veins ( deep and superficial ), lymphatics
Heart structure - right and left atrium
right atrium - receives deoxygenated blood ( superior and inferior vena cava, coronary sinus )
Left atrium - receives oxygenated blood ( 4 pulmonary veins )
what are the 4 layers of the heart wall ?
Endocardium - squamous epithelium, purkinje fibres
Myocardium - thicker on left than right
Epicardium - visceral pericardium
Pericardium - fibrous ( visceral and parietal layers )
what are the heart valves and what do they do?
Atrioventricular valves ( AV ) - prevents back flow into atria, right = tricuspid, left = bicuspid ( mitral )
Semilunar valves - prevent back flow into the ventricles, right = pulmonary, left = aortic
controlled b chordae tendindzd
What are the phases of the heart ?
Diastole - filling phase ( AV open, semilunar shut )
Systole - ejection phase ( AV shut, semilunar open )
How does the cardiac circulation work?
Right coronary artery - supplies right ventricular wall
Left coronary artery - branches towards the left ventricle
Circumflex artery - supplies the posterior and left lateral side of heart
Small cardiac vein - drains right side of the heart
Great cardiac vein - drains left side of the heart
Coronary sinus - drains into the right atrium
cardiac muscle cell structure
striated, interconnected via intercalated disks
Adhesion belts - link actin to actin ( vertical portion )
Desmosomes - link cytokeratin together, fuse two skeletons together
Gap junctions - communication, horizontal
Creates synchronisation between the cells
what is the structure of a blood vessel ?
Tunica intima
Tunica media
Tunica adventitia
What is the tunica intima ?
Simple squamous epithelium
Sub-endothelium (loose FCT)
Internal elastic lamina ( well developed in arteries but not in veins )
What is the tunica media ?
Smooth muscle
Variable content of connective tissue fibres
thickness proportional to vessel diameter and blood pressure ( thinner in veins thicker in arteries )
Tunica Adventitia ( often the thickest layer ) - Loose FCT, high content of collagen, in larger vessels adventitia contains the vasa vasorum
What is the function and demand of the capillaries ?
they are the site of exchange between blood and tissue
needs: thin walls, large surface area and slow, smooth blood flow
What are the capillary structures ?
Continuous - continuous cellular barrier
Fenestrated - leaky, physical openings in the cells ( some things can pass through ), basement membrane is still in tact
Sinusoidal - very leaky, lots of fenestrations, basement membrane incomplete, RBC can’t leave
What is the lymph vascular system ?
Its function is to drain excess tissue fluid and plasma proteins
filter foreign material
screen for foreign antigens
absorb fat from intestine and transport to blood
What is the structure of a lymphatic vessel ?
large fingerlike projections that sit amongst capillaries
lacteals rain fat-laden lymph into collecting vessels called cisterns chyli
larger thin walled collecting vessels have numerous valves to prevent back flow
Drainage system
right Side of face, neck shoulder, chest and upper limb all drain into the right subclavian vein
Everything else into the left subclavian vein
Cardiovascular circuits
Systemic - goes everywhere ( left )
Pulmonary - goes to lungs then back to the heart (right)
How do the contractions of the heart work / occur ?
Atria contract first and then the ventricles ( valves open and close to direct blood )
Before heart beat - everything is relaxed ) valves closed )
atria contract - AV open, blood pushed from atria to the ventricles
Atria relax and ventricles contract - AV closed, semilunar open, blood ejected into the body
Ventricles then relax - valves closed
What is the cellular mechanism of cardiac contraction ?
Most abundant proteins = actin and myosin
Thick and thin filaments
Calcium binds them and creates a contraction
Every muscle fibre contracts
extent of cross bridges is not maximised at rest
Max contraction = max calcium
Circuit pressures?
Pulmonary circuit has a much lower pressure
Pulse pressure is the difference between systole and diastole
Mean pressure - always slightly lower than midway
Pulmonary circuit
Has less resistance than the systemic circuit
more pressure goes into the blood that goes to the systemic circuit instead of the pulmonary circuit
Blood flow calculation
Q = change in P / R Q = flow P = pressure difference R = resistance
What are contractile cells ?
striated appearance
focus on contracting the heart
What are electrical cells ?
pale
move electrical signal from cell to cell as quickly as possible
