6380747
Description
Mind Map by Caramel Kitty, updated more than 1 year ago
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Created by Caramel Kitty
about 8 years ago
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The Circulatory System
- Heart
- blood is kept circulating
throughout the body by means
of a muscular pump; the heart
- relaxes
- fills up with blood
- fills up with blood
- contracts
- blood is squeezed out
- blood circulates through
blood vessels which direct
blood flow round the body
- blood circulates through
blood vessels which direct
blood flow round the body
- blood is squeezed out
- blood is kept circulating
throughout the body by means
of a muscular pump; the heart
- Arteries
- blood vessels that carry blood away from heart
- need to be able to withstand the
immense pressure of the blood as
it is forced out of the heart
- have thick, muscular
and elastic walls
- elastic layer is much thicker
in arteries near the heart
- elasticity enables
artery wall to stretch
and recoil or spring
back
- this helps to push the blood in
spurts along the artery and
also gives rise to the pulse
- this helps to push the blood in
spurts along the artery and
also gives rise to the pulse
- elasticity enables
artery wall to stretch
and recoil or spring
back
- elastic layer is much thicker
in arteries near the heart
- have thick, muscular
and elastic walls
- constricts
- lumen becomes narrower & less
blood flows through per unit time
- lumen becomes narrower & less
blood flows through per unit time
- dilates
- lumen becomes wider & more blood
flows through it per unit time
- lumen becomes wider & more blood
flows through it per unit time
- most arteries carry oxygenated blood
- except pulmonary arteries
- carry deoxygenated blood from heart to lungs
- carry deoxygenated blood from heart to lungs
- except pulmonary arteries
- blood vessels that carry blood away from heart
- Arterioles
- aorta -> arteries -> arterioles -> capillaries
- aorta -> arteries -> arterioles -> capillaries
- Blood Capillaries
- found between the cells of almost all tissues
- have walls made up of only a single layer of flattened cells (endothelium)
- endothelium is partially permeable
- enables certain substances to diffuse quickly through the capillary walls
- enables certain substances to diffuse quickly through the capillary walls
- endothelium is partially permeable
- branch repeatedly
- numerous branches provide a large surface area for
exchange of substances between blood & tissue cells
- numerous branches provide a large surface area for
exchange of substances between blood & tissue cells
- total cross-sectional area increases when arteriole branch into capillaries
- this lowers blood pressure in capillaries
- flow of blood is slowed down, giving more time for exchange of substances
- flow of blood is slowed down, giving more time for exchange of substances
- this lowers blood pressure in capillaries
- found between the cells of almost all tissues
- Venules
- before the capillaries leave an organ or tissue,
they unite to form small veins called venules
- before the capillaries leave an organ or tissue,
they unite to form small veins called venules
- Veins
- venules in turn join to form bigger veins
- carry blood back to the heart
- blood pressure in veins is much
lower than in the arteries
- blood flows more slowly and smoothly
- walls do not need to be as thick and muscular
as of those arteries of about the same size
- walls do not need to be as thick and muscular
as of those arteries of about the same size
- blood flows more slowly and smoothly
- contain less elastic tissue
- semi-lunar valves
- prevent blood from flowing backwards
- prevent blood from flowing backwards
- venules in turn join to form bigger veins
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