Introduction to CVS Flashcards
Why do we need a CVS?
- Temperature regulation
- Pump blood through the lungs and carry oxygen
- Transport nutrients to muscles and organs
- Circulates hormones and immune mediators
- Connection to the lymphatic system
- Human reproduction
What is passive diffusion?
Is the random undirected thermal movement of molecules
the relation between time of diffusion and distance
t ∝d^2
What does the CVS use
CVS uses convection to provide fast and directional transport
What does the heart create and using what in convection formation?
The heart creates a pressure gradient using metabolic energy
What does output of blood from the heart create?
The output of blood at high pressure creates a pressure difference with distant blood vessels
Average pressure in aorta
> 100 mmHg
Average pressure in vein
5-10 mmHg
What does pressure difference drive?
Pressure difference drives blood flow
Systole
Contraction
Diastole
Relaxation
What are the brain and myocardium usually regarding cardiac output?
Myocardium and brain are relatively under perfused
Why does the under perfusion of myocardium and brain lead to clinical problems?
Can lead to angina, stroke
Equation of cardiac output
Cardiac output=Heart rate x stroke volume
What is the cardiac output?
Volume of blood expelled from the left ventricle per minute
What factors affect cardiac output?
Filling pressure
Sympathetic and parasympathetic nerves
Chemical factors and hormones
Why is blood flow and blood pressure so critical?
Critical for correct bodily function
Equation for blood flow
Pressure difference/Resistance
Systemic circualtion
120/80 mmHg
Pulmonary circulation
25/15 mmHg
Sequence of aortic blood vessels
Aorta–>Arteries–>Arterioles
Sequence of vena blood vessels
Veina–>Venules–>Vena cava
Equation for blood velocity?
Blood flow/(cross sectional area x nr^2)
What are capillaries made up of and what advantage does it give them
Capillaries made up millions of small vessels giving a very large cross section
What is the aorta and comment on CSA?
Aorta is one large artery and has a low cross sectional area
Why is velocity much slower in capillaries?
Velocity much slower in capillaries allowing gaseous/nutrients exchange to occur
Comment on circulation in series
Same blood supply between organs
Lower perfusion pressures
Medically significant if first organ perfused
Comment on circulation in parallel
Safeguard O2 supply in organs
Most organs supplied this way
What are the three layers of the blood vessels?
Inner layer-Endothelium
Middle layer-Smooth muscle
External layer-External elastic membrane
What are the four functional groups of blood vessels?
Arteries
Arterioles
Capillaries
Venules and veins
What do arteries accommodate and convert?
Large arteries accommodate and convert intermittent ejection into continuous flow
What do arterioles control?
Control BP and regulate blood flow
What is the function of capillaries?
Nutrients delivery to cell tissue water and lymph formation removal of metabolic waste
What do venules and veins control?
Control filling pressure and provide reservoir of blood
