Blood, tissue fluid & lymph 8.3

Question 1

what is the function of blood plasma

Answer 1

it carries a variety of other components including dissolved glucose and amino acids, mineral ions, hormones and the large plasma proteins including albumin, fibrinogen and globulins.
Plamsa also transports red blood cells and the many different types of white blood cells and also platelets

Question 2

what are platelets

Answer 2

Platelets are fragments of large cells called megakaryocytes found in the red bone marrow, and they are involved in the clotting mechanism of the blood.

Question 3

What percentage of the blood is plasma

Answer 3

Plasma makes up 55% of the blood by volume

Question 4

Name examples of what the blood transports

Answer 4

-Oxygen to, and carbon dioxide from, the respiring cells
-Digested food from the small intestine
-Nitrogenous waste products from the cells to the excretory organs
-Chemical messages (hormones)
-Food molecules from the storage compounds to the cells that need them
-Platelets to damaged areas
-Cells and antibodies involved in the immune response

Question 5

what are fenestrations

Answer 5

it means the gaps or openings

Question 6

What can pass through the capillary walls from blood plasma

Answer 6

The substances dissolved in plasma can pass through the fenestrations in the capillary walls, with the exception of the large plasma proteins

Question 7

what is oncotic pressure

Answer 7

Oncotic pressure is the tendency of water to move into the blood by osmosis
-3.3 kPa

Question 8

How does albumin link to oncotic pressure

Answer 8

The plasma protein albumin has an osmotic effect. They give the blood in the capillaries a relatively low water potential compared to the surrounding fluid. As a result water has a tendency to move into the blood in the capillaries from the surrounding fluid by osmosis

Question 9

what is hydrostatic pressure

Answer 9

As blood flows through the arterioles into the capillaries, it is still under pressure from the surge of blood that occurs every time the heart contracts

Question 10

How does hydrostatic pressure effect the arterial end of the capillary

Answer 10

At the arterial end of the capillary, the hydrostatic pressure forcing fluid out of the capillaries is relatively high at about 4.6 kPa. It is higher than the oncotic pressure attracting water in by osmosis, so fluid is squeezed out of the capillaries

Question 11

what is tissue fluid

Answer 11

The fluid squeezed out of the capillary by the high hydrostatic forces that fills the space between the cells

Question 12

what is the composition of tissue fluid

Answer 12

Tissue fluid has the same composition as the plasma, without the red blood cells and the plasma proteins. Diffusion takes place between the blood and the cells through the tissue fluid

Question 13

Explain what happens to the blood as it moves through the capillary and what happens to the forces that act on the environment

Answer 13

As the blood moves through the capillaries the hydrostatic pressure falls to around 2.3 kPa in the vessels as fluid has moved out and the pulse in completely lost.
The oncotic pressure is still -3.3kPa, so it is now stronger than the hydrostatic pressure, so water moves back into the capillaries by osmosis as it approaches the venous end of the capillaries.
By the time the blood returns to the veins, 90% of the tissue fluid is back in the blood vessels

Question 14

What happens to the 10% of the tissue fluid that does not return to the capillaries

Answer 14

10% of the liquid that leaves the blood vessels drains into a system of blind-ended tubes called lymph capillaries, where it is known as lymph.

Question 15

what is the composition of lymph

Answer 15

Lymph is similar in composition to plasma and tissue fluid but has less oxygen and fewer nutrients, it also contains fatty acids which have been absorbed into the lymph from the villi of the small intestine

Question 15

How is lymph transported through the lymphatic system and name a way the system is adapted to help this

Answer 15

The lymph capillaries join up to form larger vessels. The fluid is transported through them by the squeezing of the body muscles, there are also valves in place like those in veins to prevent backflow

Question 15

where does lymph return to the blood

Answer 15

the lymph returns to the blood by flowing into the right and left subclavian veins (under the clavicle or collar bone).

Question 16

where are lymph nodes found and what is there function

Answer 16

Lymph nodes are found along the lymph vessels
The neck, armpits, stomach and groin are sites of major lymph nodes

they store lymophcytes when necessary
Lymph nodes intercept bacteria and other debris from the lymph, which are ingested by phagocytes found in the nodes

Question 17

what are lymphocytes

Answer 17

Lymphocytes build up in the lymph node when necessary and produce antibodies, which are then passed into the blood

Question 18

what could enlarged lymph nodes do a sign of

Answer 18

Enlarged lymph nodes are a sign that the body is fighting off an invading pathogen.