Cardiovascular System Flashcards
(13 cards)
Functions of cardiovascular system
Transportation of O2, nutrients and metabolites to the tissues and the removal of metabolic waste products
Involvement in homeostatic mechanisms .
Key role I’m regulation of body temperature
Distribution of hormones to the tissues and secretion of some hormones.
Why surrounds the heart
The heart is surrounded by a fibrous sac called rhthe pericardium : this protects the heart by providing lubrication during its constant movement, also helps to anchor the heart against the diaphragm and the spine
How do valves control blood flow
Valves control the direction of blood flow through the heart with main 4 : tricuspid,pulmonary, mitral and aortic
They work by the increase pressure forcing the valve to open , and then this forces blood out of the heart reducing the pressure and so valves shut, making sure there is no back flow of blood.
What’s the SAN node
A heart beat is formed in the SAN node , generating own action potentials, this is what creates the individual contractions in the heart. All initated by pace maker cells, spreading gradually throughout the whole heart.
What’s the systole phase ?
Systole phase:
Blood in heart via pulmonary and aortic valve , begins to contract and atrioventricular valves close (isovolumetric phase), then pressure increases enough to open valves , allowing blood to leave the heart, due to contraction of heart muscle
What’s the diastole phase
Causes Pullman’s aortic valve to close as pressure is reduced and pressure on outside of heart closed theses valves - no blood entering or leaving (isovolumetric relaxation). When pressure in ventricles Is lower, atrioventricular valves open to fill the ventricles , increasing pressure , filling completely.
Pulmonary circulation
The pulmonary circulation - connected to the heart in series which means that the entire blood volume has to pass through it every time it circulates the body.
Systematic circulation
The systematic circulation - connected to the heart in parallel which means that there is a choice of what part of the body receive more or less of the available blood.
Typical cardiac values
Typical values ( for average person)
Total blood volume: 5 litres - 7% Of body weight
Cardiac output: 5 litres/min
What’s fluid dynamics
Incompressible, can’t squeeze fluid (eg. Blood) and so contractions of the ventricles generate pressure whiled is transferred to the blood causing it to flow along the blood vessels = driving pressure ( flow created by the pressure difference between two points)
Flow requires a pressure difference, but the amount of flow depends on pressure difference, not absolute values of pressure
Increase in pressure increases flow
Increase in resistance decreases flow
What’s poiseuilles law
It states that the flow of fluid is related to a number of factors: the viscosity of the fluid, the pressure gradient across the tubing, and the length and diameter of the tubing
The larger the radius the smaller the resistance.
What’s cross sectional areas
The narrower the vessel the faster the flow
Flow velocity of blood in the cardiovascular system depends on the radius of all vessels at a similar distance from the heart.
In tissues, the large cross-sectional area and very low blood flow velocity is very important for diffusion of gases and exchange of nutrients/waste
Darcys law
Pressure difference/ resistance
