The Structure and Function of Arteries, Veins and Capillaries Flashcards
What is the blood circulation?
Heart - Arteries - Capillaries - Veins - Heart
What happens to the blood pressure as it moves away from the heart?
Decreases
Endothelial lining of central lumen of blood vessels is surrounded by what?
Layers of tissue
What do the Arteries do?
Carry’s blood away from the heart
What is the outer layer of an Artery made out of?
A layer of connective tissue containing elastic fibres
What is the middle layer of an Artery made out of?
A layer of smooth muscle containing elastic fibres
What is the word to describe an Artery’s central cavity?
Narrow lumen
What do the Elastic Fibres in the Artery allow it to do?
This allows them to stretch and recoil to accommodate the surge of blood after each heartbeat
What is the function of the Smooth Muscle in Arteries?
Allow it to contract (vasoconstrict) and dilate (vasodilate) to control blood flow to where it is needed
What is the Capillaries referred to and why?
The exchange vessel as it is where all exchange with tissues occurs due to thins walls (one cell thick)
What is the function of Veins?
To carry blood back to the heart
What is the outer layer of a Vein made out of?
Layer of connective tissue containing elastic fibres
What is the middle layer of a Vein made out of?
A thin muscular middle layer with connective tissue
What is the word to describe a Vein’s central cavity?
A wide lumen (which reduces resistance)
Why are Vein’s walls thin?
This is due to blood being carried back to the heart at a low pressure
Why do Vein’s have valves?
To prevent blood backflow
What does Plasma do in relation to capillaries?
It is forced out of the capillaries due to it arriving at high pressure from arteries and passes tissue fluid into surrounding cells
Because tissue fluid has a high concentration, what happens?
Tissue fluid has a high concentration of soluble food, oxygen and useful ions, these diffuse down a concentration gradient into nearby cells and substances such as carbon dioxide and urea diffuse out into tissue fluid
Where does most of the tissue fluid return to and how does it go there?
It returns back to the capillaries by Osmosis
Some tissue fluid doesnt return to the blood and is absorbed into thin walled Lymphatic Vessels. What is the tissue fluid now known as?
Lymph
What does the Lymphatic System do to the Lymph?
Returns it to the Circulatory System
