The circulation of blood Flashcards
What are the core components of the cardiovascular system?
- Heart
- Blood Vessels
- Brain
- Kidneys
- Adrenal Glands
What is the function of the cardiovascular system?
- to maintain an adaptable supply of blood to tissues in order to supply nutrients and signalling molecules and to remove waste products
- to establish pressure differentials across tissues for capillary exchange
What is the physics of blood flow called?
Haemodynamics
What is the flow of blood from point A to point B determined by?
- Resistance, R
- Pressure difference, P
What is the equation to work out flow?
Flow = difference in pressure/ difference in resistance
What is resistance determined by?
- Length of vessel (easier to flow through smaller vessel)
- Radius of vessel
- Fluid viscosity
What is the flow of blood proportional to?
The radius of the vessel to the power of 4 (r^4)
What is the rate of blood flow through the vessels proportional to?
The diameter of the vessel
What do small changes in arteriole diameter do?
Drastically alter tissue blood flow
What has the greatest impact on how we control the flow of blood through the body?
The diameter of the blood vessel
How is a pressure gradient generated?
Through contraction of the heart muscle
What is systole?
Contraction of the chambers of the heart
What is diastole?
Relaxation of the chambers of the heart
What units is cardiac pressure in?
mm of mercury (mmHg)
Are cardiac pressures higher during systole or diastole?
Systole
Why is systole in the left ventricle greater?
Because it needs to pump blood around the body
How do the elastic vessels ensure that a pressure wave is continued as blood enters the circulation?
Bulges at high pressure because of the presence of blood and then undergoes a recoil in order to move the blood through the circulation and keep it at high pressure
When do the large and medium elastic arteries need to act as ‘pressure reservoirs’? (maintain the pressure gradient)?
During the diastolic phase
List the vessels in order of pressure gradient from highest to lowest
- left ventricle
- aorta
- large arteries
- small arteries
- arterioles
- capillaries
- veins (very low)
What is a high blood pressure?
Over 140 systolic pressure and over 90 diastolic pressure
What is pre-high blood pressure?
120-140 systolic pressure and 80-90 diastolic pressure
What is ideal blood pressure?
90 – 120 systolic pressure and 60 – 80 diastolic pressure
What is low blood pressure?
70-90 systolic pressure and 40-60 diastolic pressure
What is low blood pressure called?
hypotension
What is high blood pressure called?
Hypertension
What happens to people’s blood pressure as they age?
Their blood pressure increases as their blood vessels become less elastic (doesn’t mean they are hypertensive)
In a graph showing blood pressure where with you see the systolic pressure and the diastolic pressure?
the systolic pressure will be the higher value, the diastolic pressure will be the lower value
When will the pressure gradient be interrupted in a blood pressure graph and what is this called?
When the valves open and close. This is called the dicrotic notch