34015822
Description
Mind Map by Esme Harcourt, updated more than 1 year ago
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Created by Esme Harcourt
over 2 years ago
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Blood Vessels
- Transporting blood in vessels
allows it to be pumped at high
pressure delivering nutrients
and removing wave more
efficiently
- The circulatory system has 5 different types of
vessel: arteries, arterioles, capillaries, venules, and
veins
- The heart pumps blood into arteries. As arteries
(blood away) get smaller they become arterioles. As
arterioles get smaller, they become capillaries (where
exchange happens). Capillaries rejoin to form venules
(back to heart). Venules join together to form veins.
Veins return blood back to the heart
- Arteries = away, deoxygenated blood
Veins = towards, oxygenated blood
- The heart pumps blood into arteries. As arteries
(blood away) get smaller they become arterioles. As
arterioles get smaller, they become capillaries (where
exchange happens). Capillaries rejoin to form venules
(back to heart). Venules join together to form veins.
Veins return blood back to the heart
- These vessels are adapted to different roles
based on their relative distance from the
heart
- All have a smooth and thin inner layer of
cells called the endothelium.
- Arteries carry blood away from the heart at high
pressure
- To cope with the high pressure, artery walls are very thick.
They have thick layers of elastic tissue and smooth muscle
encased in a thick outer layer of collagen
- Arterioles have a similar structure to arteries but they
are smaller and have relatively thinner muscle and
elastic layers, due to the pressure decrease
- Contraction of smooth muscle constricts the arteriole
and is used to control the flow of blood through the
body
- Eventually the blood reaches the smallest vessels in the
body - the capillaries
- Capillaries have very thin walls consisting of just
the single-celled layer of endothelium. This is
where exchange happens, so oxygen and CO2
can come in/out
- The lumen of capillaries is very narrow and can
squeeze red blood cells against the endothelium
to improve transfer of oxygen
- The increased resistance greatly slows the flow of the
blood in the capillary beds, reducing the pressure.
- Veins carry low pressure blood back to the heart,
through the venules first, then to the veins
- Vein walls are not thick and the
lumen is very wide to maximise
blood flow
- Veins are the only vessels with valves, which
ensure the low pressure blood only flows in the
right direction
- Veins are often surrounded by skeletal muscles,
which when contracted, compress the veins and
push the blood along
- Venules are smaller than veins, and they lack
valves. They deliver blood from the capillary
beds to the veins
- Vein walls are not thick and the
lumen is very wide to maximise
blood flow
- Veins carry low pressure blood back to the heart,
through the venules first, then to the veins
- Capillaries have very thin walls consisting of just
the single-celled layer of endothelium. This is
where exchange happens, so oxygen and CO2
can come in/out
- Contraction of smooth muscle constricts the arteriole
and is used to control the flow of blood through the
body
- To cope with the high pressure, artery walls are very thick.
They have thick layers of elastic tissue and smooth muscle
encased in a thick outer layer of collagen
- All have a smooth and thin inner layer of
cells called the endothelium.
- Esmeralda Harcourt
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