Blood vessels and haemoglobin Flashcards
What are the three types of blood vessel?
Arteries
Capillaries
Veins
What do arteries do?
Carry blood from the heart to the rest of the body
What are the walls like on arteries?
Thick and muscular and have elastic tissue to cope with the high pressures produced by the heart beat
The inside of the wall the endothelium if folded allowing the artery to expand this also helps it to help cope with the high pressures
All arteries carry what type of blood?
Oxygenated blood except for the pulmonary arteries which takes deoxygenated blood to the lungs
What do arteries branch into?
Capillaries, (smallest of the blood vessels) Substances like glucose and oxygen are exchanged between cells and capillaries, so they are adapted for efficient diffusion
How are capillaries adapted for efficient diffusion?
They are only one cell thick to make the diffusion pathway shorter and capillaries are also connected to veins
Where do veins take blood?
Back to the heart under low pressure, wider than arteries with very little elastic or muscle tissue. Veins also contain valves to stop backflow.
How is blood in the veins helped to move?
The muscles around the vein contract to help move along the blood, all veins contain deoxygenated blood except for pulmonary veins that carry oxygenatedblood to the heart
What is tssue fluid?
Tissue fluid is the fluid that surrounds cells in tissues
What is tissue fluid made from?
Substances that leave the blood (oxygen, water and nutrients)
What do cells take in from the tissue fluid?
Oxygen and nutrients, however cells also release metabollic waste into it.
In a capillary bed ( a network of capillaries in an area of tissue) substances move out of the capillaries into the tissue fluid by what?
Pressure filtration
What is pressure filtration?
At the start of the capillary bed nearest the arteries the hyrostatic pressure inside the capillaries is greater than the pressure in the tissue fluid. This difference in pressure forces out the capillaries and into the spaces around the cells forming tissue fluid
As fluid leaves the pressure reduces in the capillaries so the pressure is much lower at the end of the capillary bed that’s nearest the vein
Due to this fluid loss, the water potential at the end of the capillaries nearest the veins is lower than the water potential in the fluid tissue so some water reenters the capillaries from the tissue fluid at the vein end by osmosis
Tissue fluid doesn’t contain red blood cells or big proteins because there too large to be pushed out through the capillary walls
Not all tissue fluid reenters the capillaries at the vein end of the capillary bed, some excess tissue fluid is left over. This extra fluid eventually gets returned to the blood through the what?
Lymphatic system- a kind of drainage system, made up of lymph vessels.
What are the small lymph vessels called?
The lymph capillaries, excess tissue fluid passes into the lymph vessels. Once inside it is called lymph
