KA5 U2 Flashcards
(16 cards)
Explain the moving of blood within the heart
Blood circulates from the heart, through the arteries, to the capaliries, then to the veins and back to the heart.
What happens as blood moves away from the heart
Decrease in blood pressure.
Blood vessel structure
Role of elastic fibres in arteries
Arteries elastic fibres stretch and recoil to accommodate blood after each contraction of the heart
Role of muscle fibre
The smooth muscle fibre can contract causing vasoconstriction and decreased blood flow to capaliries
Role of muscle fibre part 2
Or they can relax causing vasoconstriction and decrease blood flow to capaliries
What do capaliries do
Allow exchange of substances In blood with their tissue through thin walls
What can capaliries carry
Oxygen and blood and glucose
Whats differnet about veins compared to arteries
They have valves, and they carry away blood from the heart along with them having a thin smooth layer of muscle tissue
Blood arriving at the artery side of a capillary bed is
at a Higher pressure than the blood in the capillaries, so blood is forced into these narrow capillaries
What happens when blood is forced into these narrow capillaries
It undergoes pressure filtration which causes plasma to pass through the capillary walls into the tissue fluid
Tissue fluid supplies cells with?
Glucose
Oxygen
And other substances by diffusion
Carbon dioxide and other wastes diffuse out the
Cells and into the tissue fluid where they will be excreted from the body
Tissue fluid and blood plasma are similar in composition but
Plasma proteins are too big to be filieterd through capillary walls into the
What is excess tissue which doesn’t return to the blood called
Lymph
What is lymph absorbed by
Lymphatic vessels and return to the circulator system
