transport in mammals Flashcards
what type is the mammalian circulatory system
A closed double circulation consisting of a heart, blood vessels and blood.
inner layer of blood vessels
tunica intima made up of squamous epithelium cells, vary smooth to minimise friction.
middle layer of blood vessels
tunica media, contains smooth muscle, collagen and elastic fibre
outer layer of blood vessels
tunica externa, contains elastic fibres and collagen fibres
function of arteries
To transport blood from the heart to living tissue
structure of artery
small lumen, thick walls especially tunica media
why are the artery walls thick
blood is at high pressure, so the arteries need to be strong with thick walls. There are lots of elastic fibres in the tunica media which allows the walls to stretch as pulses of blood surge through at high pressure.
Why is their lots of elastic fibre in the artery walls
So that they don’t burst. So that the artery walls can stretch as high pressured blood surges through, making the artery wider and reducing the pressure. It recoils when low pressure blood goes through so that the artery becomes narrower and the pressure increases. This evens out the flow of blood.
function of capillaries
To take blood as close as possible to the cells.
What is a capillary bed
A network of capillary’s
How are capillary’s adapted for their role
Small so can get as close as possible to the cells, the walls are one cell thick so the oxygen doesn’t have to diffuse far.
pressure of blood in capillary’s
low
structure of capillary’s
the walls are made up of a single layer of endothelial cells.
function of veins
to return blood to the heart
thickness of vein walls
thin as the blood pressure is low, they have the same three layers as arteries
in veins how is blood returned to the heart
When you tense your muscles, they squeeze on the veins in your leg raising the pressure. To keep the blood flowing in the right direction, the semilunar valves allow the blood to move towards the heart but not away from it.
Where is blood normally taken from
veins as they have low pressure.
what is blood composed of?
cells floating in plasma
what is blood plasma composed of
water with a variety of substances dissolved into it. Solutes include plasma proteins, glucose and urea.
what is tissue fluid?
As blood flows through capillaries, some plasma leaks out through the gaps between the cells in the walls of the capillary, into the spaces between the cells of the tissue. Identical to blood plasma but has fewer protein molecules as they cant get through the gaps in the capillary walls, thought white blood cells can
how does tissue fluid leave and enter the capillary
It leaves the capillary due too blood pressure and enters it again due to osmosis as the blood contains more protein molecules. More fluid moves out of the capillary then back in
What is tissue fluid used for
Surrounds each cells, exchange of materials occurs between the cells and the blood
what is lymph
The tissue fluid which is not returned to the capillary’s, and is returned to the blood system via the lymph vessels or lymphatics. Virtually identical to tissue fluid
Structure of lymphatics
Are tiny bind ending vessels, they have valves which allow tissue fluid to flow in but stops it from leaking out. The valves are wide enough to let protein molecules pass through which is important as they are too big to get into blood capillary’s, if the protein was not taken away you would die in 24 hours
Composition of lymph in different parts of the body
Near the liver it has a high concentration of proteins, a high concentration of lipids in the wall of the small intestine after a meal.
How is lymph moved
by contraction of muscles around the vessels, they have smooth muscle in their walls which can contract to move it on. Has valves so moves in the right direction.
Where is lymph returned to the veins
Lymphatics join to form lymph vessels which transports lymph to the subclavian veins.
