Overview of the Function of the Cardiovascular System Flashcards
What is the function of the cardiovascular system?
It is a bulk flow system that transports: O2 and CO2, nutrients, metabolites, hormones, heat around the body.
How is the cardiovascular system flexible? 3 points
Pump can vary output Vessels can redirect blood (vasoconstriction) Vessels can store blood
Are pumps in the cardiovascular system in series or parallel and what does this mean?
Series, therefore output must be equal (left and right side of the heart).
Are vascular beds in series or parallel, and what does this mean? 2 points
Parallel, this means all tissues gets oxygenated blood and allows regional redirection of blood
What are examples of vascular beds that are in series? 2 point
Hypothalamus and anterior pituitary Gut and the liver
Why are the hypothalamus and anterior pituitary gland not in parallel?
So that hormones released by the hypothalamus are not diluted before the reach the anterior pituitary gland.
Why are the gut and liver capillary beds in series?
So that nutrients and products of digestion can be processed by the liver before they reach the rest of the body.
How should the percentage of cardiac output compare to the percentage of oxygen consumption?
They should be roughly the same.
What are examples of organs where the cardiac output and oxygen consumption are not in balance?
Kidneys (cardiac output > oxygen consumption) Skin (cardiac output > oxygen consumption) Heart (oxygen consumption > cardiac output)
Why do the kidneys receive a greater cardiac output than oxygen consumption?
Blood filtration
Why does the skin receive a greater cardiac output than oxygen consumption?
Thermoregulation, homeostatic mechanism
Why does the heart have a greater oxygen consumption than cardiac out?
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 is the equation for flow in the CVS?
Flow = Pressure difference/resistance
What mechanism is used to alter flow?
The resistance of blood vessels, this is done by altering radius of vessels (vasoconstriction/vasodilation).
What is the pressure difference in the CVS?
Mean Arterial Pressure – Central Venous Pressure
How is flow proportional to the difference in pressure?
directly proportional
How is flow proportional to the resistance?
inversely proportional
What is the relationship between resistance and the radius of a vessel?
Inversely proportional to the radius to the power of 4.
Which vessels control the resistance of vascular beds?
arterioles
Outline the vessels of the systemic CVS starting at the left side of the heart to the right side.
- aorta 2. arteries 3. arterioles 4. capillaries 5. venules 6. veins 7. vena cava
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 redirected during exercise?
By changing the resistance of different vessels.
What are the 3 different kinds of arteries?
Elastic Muscular Resistance
What kind of artery is the aorta?
elastic
What kind of artery are arteries?
muscular
What kind or artery are arterioles?
resistance
What are the characteristics of elastic arteries? 3 points
Wide lumen Elastic wall Damp pressure variations
What is the structure and function of arterioles? 4 points
narrow lumen thick contractile wall Allows control of resistance and therefore flow, this allows regional redirection of blood.
What kind of vessels are capillaries?
exchange
Describe the structure and function of capillaries? 3 points
narrow lumen thin, single celled endothelial wall Large surface area to volume ratio
What are the capacitance vessels and why are they called this?
venules and veins So called as like a capacitor stores current the capacitance vessels store blood.
What is the structure of the capacitance vessels? 4 points
wide lumen distensible wall low resistance conduit allows fractional distribution of blood between veins & rest of circulation (esp. heart).
What does a vessels characteristics relate to?
its function
What do thick walls allow?
Greater pressure to be contained
What do elastic walls allow? 2 points
More energy can be absorbed to prevent BP going to high once the heart beats, and to release energy preventing it from going to low once the heart is relaxed.
Why are the walls of capillaries 1 cell thick?
To allow diffusion to occur.
What percentage of blood is in the veins and venules at any one time?
2/3
Why does the aorta have an elastic wall? 2 points
To store energy during the contraction of the heart, and use it to pump blood while the heart is relaxing.
What is the structure and function of he muscular arteries?
wide lumen strong non-elastic wall They act as the low resistance conduit to transport blood to the peripheries as easily a possible.
What is the capacitance vessels function during exercise?
The blood stored in these vessels can be utilised during exercise.
What is A?
What is its function?
Pulmonary vein
Transports oxygenated blood from the lungs to the heart.
What is B?
Superior vena cava
What is C?
Interatrial septum
What is D?
Right atrium
What is E?
Tricuspid valve (Right atrioventricular valve)
What is F?
Inferior vena cava
What is G?
Right ventricle
What is H?
Pulmoary valve
&
Aortic valve
What is I?
Interventricular septum
What is J?
Mitral valve (left atrioventricular valve)
What is K?
Left ventricle
What is L?
Pulmonary trunk
What is M?
Pulmonary vein (L)
What is N?
Left atrium
What is O?
Left pulmonary artery
What is P?
Aorta
What separates the two sides of the heart?
interventricular septum
What is the myocardium?
The muscle tissue that makes up the wall of the heart.
What is the name of the two inlet valves in the heart?
tricuspid valve
mitral valve
Cord-like tendons that connect the mitral and tricuspid valves to the myocardium are called _________ ___________.
Chordae tendinae
___________________ attach to chordae tendinae to maintain tension and prevent the valves from turning inside out once the heart contracts.
papillary muscles
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?
AV valves
Semi-lunar valves
