Blood Vessels Flashcards
What is the function of the veins?
Carry deoxygenated blood back to heart from the body.
Which vein is the exception?
Pulmonary vein that carries oxygenated blood to heart from lungs
What is the structure of veins?
Thin walls with little elastic fibres and muscle tissue. Has large lumen and contains valves.
Why do veins have a large lumen?
To allow blood to flow under a low pressure.
Why do valves have veins?
To prevent the backflow of blood that is under a low pressure
What is the function of the arteries?
They carry oxygenated blood from the heart to the rest of the body.
Which artery is the exception?
Pulmonary artery that carries deoxygenated blood to the lungs.
Describe the structure of the arteries?
Thick muscular walls containing elastic tissue. Smaller lumen than veins. More collagen and a folded endothelium layer.
Why do the arteries have smaller lumen than veins?
To keep the pressure inside the arteries high.
Why do arteries not contain valves?
Backflow of blood is unlikely due to the high pressure therefore no need to try and prevent it.
How does the structure of muscle in the arteries walls help aid its function?
So the artery can dilate and constrict to change shape. This allows more or less blood to flow.
How does collages aid in the function of arteries?
It is strong and helps prevent the artery walls bursting at high pressures.
How does elastic tissue help in the function of arteries?
To allow stretch and recoil at high pressures. This forces blood out at higher pressures and keeps the flow constant.
What’s the function of the capillaries?
They connect arteries to veins.
Substances like amino acids, glucose and oxygen are exchanged between cells and capillaries by diffusion.
What is the fluid called that is squeezed out of capillaries?
Tissue fluid
Describe the structure of a capillary?
Thin walls only one cell thick.
Made of endothelium only.
How big is the lumen of a capillary compared to arteries and veins?
Extremely small compared to veins and arteries.
Are there any valves inside capillaries?
No
Why are capillary walls only one cell thick?
To allow easy and efficient diffusion of substances from blood to tissue fluid.
Why is blood flow slowed down when it gets to he capillary beds?
To prevent bursting of the capillaries.
To allow efficient gas and substance exchange (slower flow=more diffusion)
Name 3 adaptations of capillaries.
- Large SA.
- Total cross sectional area is greater than the arteriole that supplies them.
- Walls are a single endothelial cell thick.
What do the capillaries do?
Form a network through all the tissues of the body to provide every cell with the substances they need.
Plasma is 55% of the blood. What is it?
A yellow liquid that carries; Dissolved glucose Amino acids Mineral ions Hormones RBCs WBCs Platelets
What are the three large plasma proteins?
Albumin
Fibrinogen
Globulins
What’s the function of albumin?
Maintain osmotic balance
What’s the function of fibrinogen?
Blood clotting
What’s the function of globulins?
Transport and immunity
What are the functions of the blood?
Transport O2 and CO2 to and from cells
Transport digested food from small intestine
Transport nitrogenous waste to excretory organs
Transport chemical messengers and hormones
Transport food from storage compounds to cells
Transport platelets to damaged areas
Transport cells and antibodies involved in immune system.
What is lymph?
Tissue fluid that doesn’t return to the blood vessels.
What does lymph have less of compared to plasma and tissue fluid?
Oxygen and nutrients
What do lymph vessels contain?
Valves to prevent backflow
Where does lymph return to the blood?
Through the left subclavian vein under the collar bone.
What is the role of the lymphatic system?
To defend the body of foreign bacteria or invading pathogens
What is the equation for filtration pressure?
Hydrostatic pressure - oncotic pressure= FP
