blood and tissue fluid

Question 1

what is plasma?

Answer 1

carries dissolved sugars, ions, proteins and amino acids
- makes up 55% of blood

Question 2

what are platelets?

Answer 2

fragments of bone marrow cells which are involved in clotting

Question 3

what is the function of blood?

Answer 3

• transports CO2 / O2, digested food, hormones and cells
• maintains body temperature
• pH buffer

Question 4

what is the function of tissue fluid?

Answer 4

facilitates substance exchange (diffusion)

Question 5

explain how tissue fluid is formed in the capillaries

Answer 5

• water and dissolved substances are forced out of capillary at arteriole end due to high pressure
• these substances form the tissue fluid
• larger components eg rbcs, remain in capillary
• some of the water diffuses back into the capillary at the venule end via osmosis
• the loss of water and the concentration of plasma proteins in the capillary lowers its water potential

Question 6

what are the purposes of tissue fluid being formed?

Answer 6

• more efficient exchange of substances between the blood supply and cells
• delivers glucose and oxygen to cells surrounding the capillary

Question 7

what is hydrostatic pressure?

Answer 7

• The pressure from the heart beat forcing liquid out through the junctions of the capillary
• This is high at the arteriole end of the capillary and lower at the venule end because pressure is lost in the capillary network.

Question 8

what is oncotic pressure?

Answer 8

The result of the water potential in the capillary due to the plasma proteins. The proteins attract free water molecules, lowering the water potential of the plasma

Question 9

Explain where in the capillaries is hydrostatic pressure high and low, and where oncotic pressure is high and low.

Answer 9

Arterial end:

Hydrostatic blood pressure is higher then oncotic pressure= water and solutes are forced out of capillary to form tissue fluid
net pressure is out
Venous end:

Oncotic pressure is higher then hydrostatic pressure= 90% of tissue fluid returns by osmosis to the capillary. It has given up much of its oxygen and nutrients but has picked up carbon dioxide and other waste
net pressure is in

Question 10

What is the equation for calculating filtration pressure?

Answer 10

Hydrostatic pressure - oncotic pressure = filtration pressure
mm Hg

Question 11

Explain where the remaining 10% of the tissue fluid that does not return to the blood capillary goes

Answer 11

• it enters the lymphatic system and becomes lymph.
• The lymph capillaries are blind-ended vessels with bigger fenestrations then blood capillaries, and the excess tissue fluid drains into the lymph vessels, becoming lymph

Question 12

Explain the difference in composition of the lymph compared to tissue fluid.

Answer 12

• lower concentration of oxygen and nutrients
• lower concentration of oxygen and nutrients
• contains fatty acids which have been absorbed from the villi in the small intestine

Question 13

Describe and explain the movement of lymph around the body.

Answer 13

• lymph moves through the lymph vessels because of the pressure on the walls caused by contracting muscles
• eventually the lymph system drains into the blood system, when the left and right lymphatic duct drain into the left and right subclavian veins

Question 14

What are lymph nodes?

Answer 14

• found at points along the lymphatic system
• lymphocytes (leucocytes that produce antibodies) accumulate at the lymph nodes before entering the blood stream.
• phagocytic cells are also found at the lymph nodes and these engulf and digest any bacteria that are found at the lymph.

Question 15

State and explain some of the possible causes of excess tissue fluid remaining in the tissues, causing swelling

Answer 15

• State and explain some of the possible causes of excess tissue fluid remaining in the tissues, causing swelling
• State and explain some of the possible causes of excess tissue fluid remaining in the tissues, causing swelling
• a blockage in the lymphatic system= by a filarial parasite