overview and function of the cardiovascular system Flashcards
what is the function of the cardiovascular system?
acts as a bulk flow system which transports things around the body
what are examples of things that the cardiovascular system transports around the body?
- oxygen and carbon dioxide
- nutrients
- metabolites
- hormones
- heat
how is the cardiovascular system flexible?
- pump can vary output
- vessels can redirect blood
- vessels can store blood
are pumps in the cardiovascular system in series or parallel and what does this mean?
series - output must be equal (left and right side of the heart)
are vascular beds in series or parallel, and what does this mean?
parallel - all tissues gets oxygenated blood and allows regional redirection of blood
are all vascular beds in parallel?
no, some are in series
what are examples of vascular beds that are in series?
- hypothalamus and anterior pituitary
- gut and the liver
why are some vascular beds in series?
allows blood to flow directly from one place to where it next needs to go, such as carrying nutrients from the gut to the liver
how should the percentage of cardiac output compare to the percentage of oxygen consumption?
they should be about the same
what are examples of organs where the cardiac output and oxygen consumption are not in balance?
- kidneys (more cardiac output than oxygen consumption)
- skin (more cardiac output than oxygen consumption)
- ♡ (more oxygen consumption than cardiac output)
why do the kidneys receive a greater cardiac output than oxygen consumption?
they filter the blood
why does the skin receive a greater cardiac output than oxygen consumption?
thermoregulation, blood is sent there to cool it and maintain body temperature
why does the heart have a greater oxygen consumption than cardiac output?
each time it contracts it cuts of its own blood supply
how can blood be redirected during exercise?
altering the resistance of different vessels
what formula relates flow to pressure and resistance?
how is flow proportional to the difference in pressure?
directly proportional
how is flow proportional to the resistance?
inversely proportional
What is the formula to describe pressure difference?
mean arterial pressure - central venous pressure
what is resistance controlled by?
the radius of a vessel
what is the relationship between resistance and the radius of a vessel?
inversely proportional
resistance = to the radius to the power of 4
what happens to mean arterial pressure during exercise and why?
mean arterial pressure increases due to the heart pumping harder
what does increasing the mean arterial pressure do to the pressure difference between vessels?
increases it
how is blood directed during exercise?
changing the resistance of different vessels
what are examples of different vessles?
- aorta
- arteries
- arterioles
- capillaries
- venules
- veins
what are the 3 different kinds of arteries?
- elastic
- muscular
- resistance
what kind of artery is the aorta?
elastic artery
what kind of artery are arteries?
muscular arteries
what kind or artery are arterioles?
resistance vessels
what are the characteristics of elastic arteries?
- wide lumen
- elastic wall
- damp pressure variations
what are characteristics of muscular arteries?
- wide lumen
- strong non-elastic wall
- low resistance conduit
what are characteristics of resistance vessels?
- narrow lumen
- thick contractile wall
- control resistance and therefore flow
- allow regional redirection of blood
what kind of vessels are capillaries?
exchange vessels
what are characteristics of exchange vessels?
- narrow lumen
- thin wall
what kind of vessels are venules and veins?
capacitance vessels
what are characteristics of capacitance vessels?
- wide lumen
- distensible wall
- low resistance conduit
- acts as reservoir
- allows fractional distribution of blood between veins and the rest of circulation
what does a vessels characteristics relate to?
its function
what do thick walls allow?
greater pressure to be contained
what do elastic walls allow?
- to absorb more energy to stop blood pressure going too high once the heart beats
- to release energy preventing it from going too low once the heart is relaxed
how thick are the walls of the capillaries?
1 cell thick to allow diffusion to occur
what does capillaries having a narrow lumen mean for their surface area to volume ratio?
high surface area to volume ratio
what percentage of blood is in the veins and venules at any one time?
2/3
What is A?
Pulmonary vein
What is B?
Superior vena cava
What is C?
Inteatrial septum
What is D?
Right atrium
What is E?
Right AV valve
What is F?
Inferior vena cava
What is G?
Right ventricle
What is H?
Pulmonary and aortic valves
What is I?
Interventricular septum
What is J?
Left AV valve
What is K?
Left ventricle
What is L?
Pulmonary trunk
What is M?
pulmonary vein
What is N?
left atrium
What is O?
pulmonary artery
what is the myocardium?
muscular tissue of the heart
what is the atrium?
where blood returns to
what does the septum do?
separates the 2 halves of the heart
what is the ventricle?
chamber that ejects blood out of the heart
where does the aorta carry blood from and to?
from the heart to systemic circulation
what does the vena cava do?
returns blood to the heart from systemic circulation
where does the pulmonary trunk carry blood from and to?
from the heart to the lungs
where do the pulmonary veins carry blood from and to?
from the lungs to the heart
what are the chordae tendinae?
thin chords that attach to AV valves to prevent them from turning inside out
what are papillary muscle?
attached to chordae tendinae to maintain tension and support preventing the valves from turning inside out once the heart contracts
how many pumps are in the heart?
2
which wall of the heart is the thickest?
left ventricle due to pumping blood to the whole body, whereas the right is just to the lungs
what do valves in the heart do?
prevent backflow of blood
what are the 2 kinds of valves?
semi-lunar valves (SL)
atrioventricular valves (AV)
what are the two semi-lunar (SL) valves?
aortic valve
pulmonary valve
what are the two atrio-ventricular (AV) valves?
mitral valve
tricuspid valve
