KA5 - Pathway Of Blood Flashcards
Explain the pathway of blood
Blood circulates from the heart through the arteries to the capillaries then to the veins and back to the heart.
What happens to blood pressure as the blood moves away from the heart?
It decreases
What are the 3 main types of blood vessels in the circulatory system?
Arteries
Veins
Capillaries
What is the name given to the central channel through which blood flows in a blood vessel?
The central lumen
What surrounds the central lumen?
The endothelium lining
What is the function of arteries?
To carry blood away from the heart at high pressure
Describe the structure of an artery(4)
- Narrow central lumen
- The endothelium lining surrounding the central lumen
- Middle layer connecting smooth muscle to elastic fibres
- Thick outer layer of connective tissues containing more elastic fibres
Why must arteries have elastic walls?
To accommodate the surge of blood after each contraction of the heart
What is vasodilation
During exercises, arteries leading to working muscles undergo vasodilation. The central lumen becomes wider allowing for an increased blood flow to the muscles involved.
What is vasoconstriction?
At the same time, arteries leading to abdominal muscles undergo vasoconstriction. The central lumen becomes narrower, reducing blood flow to these muscles for a short time.
What is the function of capillaries
To allow the exchange of substances with tissues
How does the structure of capillaries enable them to carry out its function?
Their walls are only one cell thick allowing substances to diffuse with ease
What is the function of veins?
To carry blood towards the heart at low pressure
Describe the structure of a vein(5)
- Wide central lumen
- The endothelium lining surrounding the central lumen
- A thinner muscular wall than arteries
- A thin outer layer of connective tissue containing elastic fibres
- Valves to prevent the back flow of blood
What are the 3 components of blood?
Red blood cells
White blood cells
Plasma
What does plasma transport as well as red and white blood cells?
Glucose Oxygen Carbon dioxide Fat Protiens
What is pressure filtration?
Pressure filtration is the process by which plasma passes through the capillary walls into the tissues fluid surrounding the cells
What happens during pressure filtration?
Tissue fluid provides cells with useful substances which as glucose and oxygen. Carbon dioxide and other metabolic wastes diffuse out of the cells and into the tissue fluid to be removed by the body.
Much of the fluid returns to the blood at the venous end of the capillary by osmosis.
What is the name given to excess tidier fluid?
Lymph
What happens to the lymph?
It is absorbed by lymphatic vessels which return it to the circulatory system
