Overview of the Function of the Cardiovascular System Flashcards
What is the main function of the cardiovascular system?
Bulk flow system that transports carbon dioxide and oxygen around the body
What are the five major functions of the cardiovascular system?
- Oxygen and Carbon Dioxide Transport.
- Nutrient and Waste Product Transport.
- Disease Protection and Healing.
- Hormone Delivery.
- Body Temperature Regulation.
Where does the right side of the heart pump blood?
Into pulmonary circulation - to the lungs where gas exchange takes place
Oxygen diffuses into the blood
Carbon dioxide diffusing out of the blood
Where does the left side of the heart pump blood?
Into systemic circulation - around the body
Oxygenated blood goes to the left side of the heart which pumps oxygenated blood through the systemic circulation.
Oxygen diffuses from the blood into tissues and organs
Carbon dioxide diffusing into of the blood from the tissues and organs
What is the cardiovascular system responsible for transporting?
O2 and CO2
Nutrients - specifically talking about kidneys that excrete metabolites in the urine
Metabolites
Hormones
Heat
Why is the CVS flexible?
Pump can vary output
Vessels can redirect blood flow to where its needed most
Vessels can store blood
What does it mean when saying that the pumps in the CVS are in series?
Out put must be equal
Output of right side but be equal to the out put of the left side of the heart
What would happen if one side of the heart pumped a little bit more than the other?
Blood would accumulate in the lungs
How are most vascular beds arranged?
In parallel which means they receive oxygenated blood at the same time
All tissues get oxygenated blood
Allows regional redirection of blood- eg during exercise less blood can be sent to gut and liver and more can be sent to head, arms and legs
What would happen if vascular beds were arranged in series?
Head would receive oxygenated blood first, legs would receive blood that is slightly less oxygenated, and arms would receive deoxygenated blood
What vascular beds are arranged in series and why?
Gut and liver - arranged in series
Nutrients absorbed in gut can then be sent to the liver to be metabolised
What does Darcy’s law state?
Flow = difference in pressure/resistance
Why is there a difference of pressure in the left and right side of the heart?
High pressure - left
Low pressure - right
High pressure side is what will push blood into the arteries out of the left side of the heart and into the systemic circulation
To have blood return to the right side of the heart, we need lower pressure
What is the pressure on the left and right hand side of the heart called?
LHS - mean arterial pressure
RHS - central venous pressure
Pressure difference = mean arterial pressure - central venous pressure
When can mean arterial pressure increase and how does the heart respond?
During exercise - responds by pushing more blood out into arteries, increasing mean arterial pressure
Increasing blood being pushed out into arteries will increase blood going out into vascular beds
What controls resistance and flow to vascular beds?
Arterioles acting as taps
Resistance is controlled by radius^4
Selectively redirects blood flow
How can arterioles control resistance?
During exercise, can turn off “tap” to gut and liver which can increase blood flow to arms, legs and head
What major vessels that carry blood away from the heart?
Arteries
What are the resistance vessels?
Arterioles - can change diameter and how much blood flow is going to vascular beds
What are the smallest blood vessels and what takes place in them?
Capillaries - exchange of oxygen and carbon dioxide take place
What are veins and venules?
Often called capacitance vessels
Blood is stored in them
Collect poorly oxygenated blood and push it back to the right side of the heart
What is fractional distribution of blood?
Proportion of veins and venules vs rest of systemic circulation
Describe the aorta
Elastic artery (one of two in body, the other being the pulmonary trunk)
Wide lumen
Thick elastic wall - contains lots of elastin
Damp pressure variation
Why is it important that the aorta has a wide lumen?
So it has very low resistance meaning blood will flow very easily from left ventricle into the aorta and off into systemic circulation
Why is it important that the aorta has a thick elastic wall?
During heart contraction when blood is squeezed from left ventricle into the aorta, it can absorb some of the increase in pressure and the walls of aorta stretch
During relaxation, walls of aorta will return back to their original size because they are elastic
What vessels does blood encounter on their way to systemic circulation?
Aorta
Arteries
Arterioles
Capillaries
Venules/veins
Features of arteries
Muscular
Wide lumen - low resistance so blood can easily flow towards systemic circulation
Strong, thick, non-elastic wall
Low resistance conduit
Features of arterioles
Resistance vessels
Narrow lumen
Thick contractile wall
Control resistance and flow
Allow regional redirection of blood
Features of capillaries
Smallest blood vessel - very large surface area: volume ratio helps with this. Helps oxygen diffuse from blood into tissues easily and allow CO2 to go the other way
Narrow lumen - diameter of red blood cell
Thin wall - one layer of endothelial cell thick
Features of veins and venules
Capacitance vessels - ability to store blood
Wide lumen
Thin distensible wall
Low resistance conduit and reservior
Allows fractional distribution of blood between veins and rest of circulation
What does the (interartial) septum do?
The interatrial septum is a thin wall of tissue that separates the right and left atria of the heart
What is the role of the atrium?
Receive blood
RA - blood from systemic circulation
LA - blood from lungs
What is the role of the ventricle?
Pump blood
RV - to lungs
LV - to aorta and then systemic circulation
What are the two parts of the vena cava?
Superior and inferior
S - returns blood from part of body above the heart
I - returns blood from part of body below the level of the heart
What is the role of the pulmonary trunk?
Takes deoxygenated blood from the right ventricles to the pulmonary arteries.
Pulmonary trunk spilts into left and right pulmonary artery
What do the left and right pulmonary arteries do?
Carry blood to left and right lungs respectively
What does the pulmonary vein do?
Carry oxygenated blood to left atrium
What does the aortic valve do?
Valve between left ventricle and aorta
Where can the pulmonary trunk be found?
Valve between right ventricle and pulmonary trunk
What are the semi lunar valves?
Aortic and pulmonary valve
Because they have three cusps which look like half moon shaped
Valves are open when heart is in systole
Where is the tricuspid valve found?
Right atrium and right ventricle
Where is the mitral valve found?
Left atrium and left ventricle
What is the role of a valve?
Prevent back flow of blood in the heart
What is the job of the mitral and tricuspid valve?
Prevent regurgitation of blood from ventricle back onto the atrium
What is the role of the chordae tendinae and papillary muscles?
When heart muscle contracts, heart shortens, chordae tendinae are too long and take tension off valves which is why they are attached to papillary muscles
Papillary muscles contract at the same time as ventricles, maintains tension on chordae tendinae and prevent valves from inverting into the atrial cavity during systole.
What is the role of the myocardium?
Heart muscle responsible for the contractile function of the cardiac pump.
What are the five major functions of the cardiovascular system?
- Oxygen and Carbon Dioxide Transport.
- Nutrient and Waste Product Transport.
- Disease Protection and Healing.
- Hormone Delivery.
- Body Temperature Regulation.
