circulation Flashcards
what is an open circulatory system
blood isn’t contained within blood vessels, but pumped directly into body cavities
what is a closed circulatory system
blood is pumped around the body and is always contained in a network of blood vessels
what is the name given to arteries and veins that connect to the head and neck
carotid ___
what is the name given to arteries and veins that connect to the lungs
pulmonary ___
what is the name given to arteries and veins that connect to the liver
hepatic ___
what is the name given to arteries and veins that connect to the kidneys
renal ____
what are capillaries and how are hey adapted to their function
tiny blood vessels that connect arterioles and venules
small + 1 cell thick - decreased diffusion distance increasing the rate of gas exchange
how are arteries adapted to their function
muscular, elastic walls : withstand high blood pressure
narrow lumen: maintain high blood pressure
what are arterioles
small arteries which branch from larger arteries and connect to capillaries
what are venules
small veins that connect capillaries to larger veins
what are veins and how are they adapted to their function
carry blood towards heart
thinner walls, thicker lumen
have valves so blood doesn’t back flow (with gravity)
what is tissue fluid
the body fluid surrounding the cells in tissues
what is in tissue fluid
contains water and nutrients
holds waste products released by cells due to metabolism
define water potential
potential of water to move from one place to another
what is the equation for water potential
water potential = pressure potential + solute potential
how does tissue fluid form
- in capillaries, at arteriole end, blood pressure is higher
- so water moves out of capillary by osmosis
how does tissue fluid drain
- at venue end of capillary, hydrostatic pressure is lower
- so water moves back into capillary
- by the lymphatic system
how much tissue fluid drains into the lymphatic system
5-10%
what happens during ventricular systole (contraction)
atria: relaxes
ventricles: contracts
semi-lunar valves: open
filling/ejection: artery ejection
how does higher blood pressure form more tissue fluid
faster blood flow
more water squeezed out
more tissue fluid formed
builds at bottom of body due to graviy
what happens during atrial systole ( contraction)
atria: contracts
ventricles: relaxes
semi-lunar valves: closed
filling/ejection: ventricle fills
what happens during ventricular diastole (relaxation)
atria: relaxes
ventricles: relaxes
semi-lunar valves: closed
filling/ejection: atrial filling
what is it called when the heart contracts involentarily
meiogenic
can contract + relax without external nervous system
how blood moves through heart
Deoxygenated Blood:
Enters the right atrium from the body via the vena cava.
Moves to the right ventricle.
Pumped to the lungs through the pulmonary arteries for oxygenation.
Oxygenated Blood:
Returns to the left atrium from the lungs via the pulmonary veins.
Moves to the left ventricle.
Pumped to the rest of the body through the aorta.
what are the parts of the heart involved in the electrical conduction system of the heart 6
SAN
AV node
non-conducting tissue
his bundle
right + left bundle branches
purkinje fibres
what part of the heart starts electrical activity
and where is it
SAN
found near vena cava
what happens after SAN starts electrical impulse
there is a wave of excitation across the atria causing atrial systole (contraction)
what prevents the electricity immediately flowing into the ventricles
non-conducting tissue
where is the wave of electricity then directed to after the non-conducting tissue redirects it
the AV node
what does the AV node do
causes a delay
allowing blood to flow into the ventricle and allowing atria to fully contract
when electrical wave reaches ventricles, how does it move
to bundle of his
down right and left bundle branches
up purkinje fibres
what direction does the contraction move in the ventricles
from base, upwards
forcing blood up and out through arteries
what is the P wave on a electrocardiogram
atrial contraction
what is the QRS wave on an electrocardiogram
activation of ventricles
what id the T wave on an electrocardiogram
recovery wave
what causes increased CO2 in blood
increased muscular/metabollic activity
making tissue cells respire, producing CO2
what happens to the blood ph when there is more co2 in the blood
ph decreases as carbonic acid forms
what detects the change in ph in blood and where are they
chemoreceptors
in the carotid arteries in the neck
what do the chemoreceptors do when the ph of blood is lower
it sends an increased frequency of impulses to the medulla oblongata
where is the medulla oblongata
the brain
what does the medulla oblongata do when it has and increased frequency of impulses
it increases the frequency of impulses down the sympathetic nerve to the SAN
increasing heart rate
how are capillaries adapted for exchange of substances 4
-permeable walls
-single cell thick walls
-small - SA:V ratio
-narrow lumen reduces blood flow + rbc in contact w walls
