the cardiovascular system Flashcards
what does the pulmonary circuit do
carries deoxygenated blood to the lungs and oxygenated blood back to the heart
what does the systemic circuit do
carries oxygenated blood to the body tissues and deoxygenated blood back to the heart
what is diastole
the relaxation phase of the heart
what is systole
the contraction phase of the heart
what does the SA node do
it initiates the heartbeat
what is stroke volume determined by
venous return- if more blood enters the heart, more blood will be pumped out
ejection fraction
the % of blood pumped out of the left ventricle, per beat.
what are pocket valves
one way valves that prevent the back flow of blood/ one direction flow
what is muscle pump
veins situated between skeletal muscles which help squeeze blood back to the heart when they contract and relax
what is the respiratory pump
during exercise, breathing increases deeper in the thorax and abdomen
smooth muscle
thin layer of smooth muscle helps squeeze blood back towards the heart
gravity
blood from upper body is aided in its return by gravity
what is frank starling law
when SV increases in response to an increase in the volume of blood filling in the left ventricle
what is cardiac output
the amount/volume of blood pumped out of the left ventricle per minute
examples of cardiac responses to exercise:changes in HR
HR increases (how much by is depending on the intensity of the exercise)
HR increases in direct proportion to exercise intensity
where is the cardiac control centre located
medulla oblongata (brain stem)
what controls the CCC
the autonomic nervous system- it is an involuntary nervous system
what are the three main influences of the ANS
intrinsic control
hormonal control
neural control
what do chemoreceptors do
informs the brain if CO2 levels increase, O2 levels decrease or if PH levels rise
what do proprioceptors do
detects if movement has been increased or decreased
what do baroreceptors do
dectect if blood flow and blood pressure increases or decreases
what does the sympathetic nervous system do
increases HR
sends a signal via the accelerator nerve to the SA nerve to increase HR
what does the parasympathetic nervous system do
decreases HR
sends a signal via the vagus nerve to the SA node to decrease HR
which part of the autonomic nervous system is in control of HR when a person is at rest
the parasympathetic nervous system
what hormone is released when the PNS is keeping the HR down
acetylcholine
what are the two layers of blood
45% cells
55% plasma
how many layers thick are arteries
3 layers thick
what are arteries
blood vessels that carry blood away from the heart via the aorta
how do arteries control blood flow
they vasodilate and vasoconstrict
what type of blood do arteries carry
they usually carry highly oxygenated blood, with the exception of the pulmonary artery
how do arteries/arterioles change shape and regulate blood flow
they have a layer of smooth muscle
what do precapillary sphincters do
they vasodilate and vasocontrict
what are capillaries
they are the smallest and thinnest blood vessels in the body
what do capillaries do
they transport the oxygen rich red blood cells through them allowing oxygen to diffuse into the muscles and carbon dioxide out
how many layers thick is a capillary
1 thin layer wall (allows for the movement of oxygen and carbon dioxide between the capillaries and blood to be made easier)
what do veins do
carry deoxygenated blood back to the heart
how many layers thick are veins
3 layers thick
what type of blood do veins carry
mostly carry deoxygenated blood, with the exception of the pulmonary vein
where do veins carry blood towards
the heart
what is vascular shunting
blood is diverted to the working muscles and away from the non-essential organs
what is vasodilation
smooth muscle relaxes to make the inside of the arterioles wider
what is vasocontriction
smooth muscle contracts to make the inside of the arterioles narrower
what are precapillary sphincters
rings of muscle at the junction between the arterioles and capillaries
what do precapillary sphincters do
they can effectively ‘open’ or ‘close’ the capillaries leading to the muscles or organs
what happens to O2 during exercise
it diffuses into the capillaries that are supplying muscle with oxygen
what stores O2 in the muscle
myoglobin as it has a high affinity for O2
where does aerobic respiration take place within the muscle
the mitochondria
what is myoglobin
a protien that stores O2 in the muscle
how much CO2 is transported around the body in the blood as hydrogen carbonate
70%
why is carbon dioxide produced
it is produced by the muscles as a waste product that diffuses into the blood stream
what is cardiac drift
the upward drift of heart rate over time, coupled with a progressive decline in stroke volume and the continued maintenance of cardiac output
what effects cardiac drift
an increase in core temperature and body water losses
