The Blood/ Tissue Fluid/ Lymph

Question 1

What is the blood made up of

Answer 1

• plasma: yellow liquid which carries lots of components eg glucose, aminos, minerals, hormones, plasma proteins( maintains osmotic pressure), fibrinogen(clotting), globulins
• red blood cells: red biconcave discs responsible for carrying oxygen
• white blood cells which are part of the immune response

Question 2

What are the functions of the blood

Answer 2

• transport oxygen to and CO2 from the respiring cells
• transport digested food from the small intestine
• transport nitrogenous waste products from cells the excretory organs
• transport hormones
• transport food molecules from storage compounds to cells that need them
• transport platelets to damaged areas
• transport cells and antibodies involved in the immune response

Question 3

How is tissue fluid formed

Answer 3

• in the capillaries substances dissolved in the plasma can pass through gaps in the capillary walls except from plasma proteins
• plasma proteins give the blood a low water potential of -3.3kpa
• the hydrostatic pressure from pulse surges have a pressure of 4.6kpa, this pressure difference means that fluid is squeezed out of the cells and fills spaces between the cells
• tissue has same composition as plasma without RBC

Question 4

How does the pressure difference change in the capillary and what does that do to tissue fluid

Answer 4

• at the arterial end the hydrostatic pressure 4.6kpa and the osmotic pressure -3.3kpa this is due to the pulse surge of the heart
• at the venous end the hydrostatic pressure 2.3kpa and the osmotic pressure -3.3kpa, it loses hydrostatic pressure due to the pulse surge being lost and causes 90% of tissue fluid to move back into the blood vessels

Question 5

What is lymph

Answer 5

• the 10% of tissue fluid that does not re-enter capillaries is known as lymph
• it has the same composition as tissue fluid with less oxygen and nutrients, however containing fatty acids from villi
• the lymph capillaries join up to create lymph vessels, the fluid is transported through them by squeezing of the muscles
• lymph returns to the blood in the veins in under the collar bone

Question 6

What is the role of lymph nodes

Answer 6

• lymph nodes are found along the lymph vessels
• lymphocytes build up at the lymph nodes when needed and produce antibodies which are then passed into the blood
• lymph nodes also intercept bacteria and other debris found in the lymph which are infested by phagocytes found in the nodes
• lymph nodes enlarge when they detect pathogens as a mechanism to show sign of illness