Physiology and Health Unit 2 KA 5 Flashcards
Structure and Function of Arteries, Capillaries and Veins
What are the three types of Blood vessel?
1) Arteries
2) Capillaries
3) Veins
Arteries divide up to form ____
(Fill in the blank)
Arteries divide up to form Capillaries
Capillaries join up to make ____
(Fill in the blank)
Capillaries join up to make Veins
What is the function of an Artery?
The function of an Artery is to carry blood away from the heart at high pressure
What is the function of a Capillary?
The function of a Capillary is to allow the exchange of substances
What is the function of a Vein?
The function of a Vein is to carry blood to the heart under low pressure
Describe the wall structure of an Artery (3) -
- Thick outer wall
- Thick layer of muscle and elastic fibres
- Endothelium lining the narrow lumen
Why do Arteries require strength and elasticity?
-Elastic walls are needed to withstand the surge of blood when the heart contracts.
-Smooth muscle is needed as it can contract for vasoconstriction/vasodilation
(blood vessels narrow/widen)
What do Arteries carry?
Arteries carry oxygen and nutrients
What does a pulse indicate?
A pulse indicates that blood is flowing through an Artery
Describe the wall structure of Capillaries (2) -
- Very thin outer wall (1 cell thick)
- Very narrow lumen
Why do Capillaries require thin walls?
Capillaries require thin walls so materials can be easily exchanged
(materials - gas, food, wastes)
Capillaries form networks through organs/tissues, this gives them a large ____ ____
(Fill in the blank)
Surface area
What leaves/enters Capillaries?
Oxygen leaves Capillaries
Carbon Dioxide enters Cappilaries
Describe the wall structure of Veins (3) -
- Thin outer wall
- Thin layer of muscle and elastic fibres
- Endothelium lining the wide lumen
- contain valves
What is the purpose of Valves inside Veins?
The purpose of valves is to prevent the backflow of blood
What do Veins carry?
Veins carry Carbon dioxide and wastes
Why do Veins need a wide lumen?
Veins need a wide lumen so there is less resistance to blood flow
What is Blood pressure like in Arteries compared to Veins?
Blood pressure in the Arteries is higher than in the Veins
(as blood moves away from the heart, bp decreases)
What does Vasoconstriction do to blood flow?
Vasoconstriction reduces blood flow as the smooth muscle contracts
What does Vasodilation do to blood flow?
Vasodilation increases blood flow as the smooth muscle relaxes
What does Blood consist of? (4)
1) Red blood cells
2) White blood cells
3) Platelets
4) Plasma
What does Plasma contain that tissue fluid doesn’t?
Plasma contains plasma proteins and tissue fluid does not
What happens when blood enters the Capillaries?
Blood enters the Capillaries by diffusion and undergoes pressure filtration
(Plasma proteins are too big to diffuse into tissue fluid)
What does Tissue fluid supply cells with?
Tissue fluid supplies cells with glucose, oxygen and other substances
What happens to most of the Tissue fluid?
Most of the tissue fluid returns to the blood in the capillaries
How is excess Tissue fluid absorbed?
Excess tissue fluid is absorbed by thin-walled lympathic vessels, the fluid is now called lymph
