Blood: L20 - Components of Blood and Blood Function

Question 1

What does the blood transport?

Answer 1

Dissipates heat (From metabolic reactions). Transports nutrients, oxygen, water, solutes. Disposes of carbon dioxide, waste products. Transports hormones for homeostasis. Transports phagocytic cells (WBC), antibodies, coagulation factors.

Question 2

What is the role of blood in immune responses?

Answer 2

Immediate defence of body to foreign particles, first line of defence. Blood carries the cells of the immune system, including phagocytes, lymphocytes (with associated antibodies) and other white blood cells. These immune cells identify and destroy pathogenic organisms, in order to prevent illness.

Question 3

What is the role of blood in coagulation?

Answer 3

Blood transports platelets and coagulation factors to sites of injury to allow blood clotting. The endothelial cells that line blood vessels provide the site of action for platelets. This preserves fluid volume, without these factors, one little cut can be fatal. Prevent bleeding.

Question 4

How much blood would a 70kg male have in terms of actual amount and percentage of body mass amount? What factors vary this value and how?

Answer 4

A 70kg male would have about 5-6L of blood, which is 6-8% of their total body mass. Blood volume is proportional to lean body mass. Leaner people will have a higher blood volume for their weight, whereas people with a higher proportion of fat (e.g women) will have a lower blood volume for their weight.

Question 5

What are the relative amounts of the main components of blood?

Answer 5

Blood is composed of:
Plasma = 55%, 90% of plasma is water, rest of it is solutes (e.g proteins, nutrients, waste products, respiratory gases).
Buffy coat = 1% - WBCs and platelets.
RBC = 45%. (Also known as erythrocytes).

Question 6

What is ECF comprised of?

Answer 6

Blood (plasma being the fluid portion) and Interstitial fluid.

Question 7

Describe the 3 main plasma proteins.

Answer 7

Albumin = most abundant plasma protein, therefore help maintain osmotic pressure (by concentration of proteins in blood). Buffer blood to avoid extreme changes in pH. Transport insoluble substances (e.g steroid hormones, some coagulation factors).
Globulin = most kinds of antibodies e.g immunoglobulin, therefore important for fighting infection and maintaining immunity.
Fibrinogens = precursor to fibrin which is used for coagulation. Fibrin forms a mesh that catches platelets to form a clot.

Question 8

Another name for ‘white blood cells’ is?

Answer 8

Leukocytes - immune cells.

Question 9

The 2 categories of white blood cells are?

Answer 9

Granulocytes and agranulocytes (mononuclear cells).

Question 10

Another name for platelets are? Where are they found?

Answer 10

Thrombocytes in the buffy coat.

Question 11

Another name for the ancestor cells which all blood cells originate from? 2 categories?

Answer 11

Progenitor cells. Myeloid stem cells (most capacity to differentiate via cascade of events) and lymphoid stem cells.

Question 12

What is haematocrit? What is another name for haematocrit?

Answer 12

The fraction of centrifuged blood made up of erythrocytes is the haematocrit. It is also known as Packed Cell Volume.

Question 13

What is the equation for measuring amount of haematocrit in centrifuged blood? What are the normal values for men and women?

Answer 13

X/(X+Y) Where X=amount of RBCs and X+Y=total.
Males: 0.4 to 0.54
Females: 0.37 to 0.47.

Question 14

What type of WBC is a neutrophil? Proportion of it in terms of all WBCs? Name it’s function.

Answer 14

Granulocyte. (65%) It is a phagocyte.

Question 15

What type of WBC is a basophil? Proportion of it in terms of all WBCs? Explain it’s function.

Answer 15

Granulocyte. (secrete histamine, involved in inflammatory response).

Question 16

What type of WBC is a eosinophil? Proportion of it in terms of all WBCs? Name it’s function.

Answer 16

Granulocyte. (2-5%) It is involved in allergic reactions.

Question 17

Do granulocytes or agranulocytes have just one nuclei and one lobe?

Answer 17

Agranulocytes.

Question 18

What type of WBC is a lymphocyte? Proportion of it in terms of all WBCs? Explain it’s function. Describe it’s structure.

Answer 18

Agranulocytes. (25%) Lymphocytes include B and T cells, which are involved in adaptive immune response. They have very large nuclei and very little cytoplasm.

Question 19

What type of WBC is a monocyte? Describe it’s function.

Answer 19

Agranulocytes. They are phagocytic cells. When they migrate into body tissues they become tissue macrophages. They have a horse-shoe shaped nucleus are are larger than lymphocytes.

Question 20

Describe the shape of a RBC and why this is important? Do RBCs have a nucleus? Long life span?

Answer 20

Has a biconcave ring indents on both sides, allowing increased surface area to volume ratio so diffusion is more efficient which is important for gas transport.
No nucleus.
Short life span (about 120 days).

Question 21

Size of RBCs?

Answer 21

6-8um in diamter, approximately the same size as a capillary, RBCs can squeeze through capillaries slightly smaller than themselves as they are flexible.

Question 22

What makes up a third weigh of RBCs to do with gas exchange? How much of this protein will an adult male and female have in a litre of blood?

Answer 22

Haemoglobin, which carries oxygen and carbon dioxide using 4 x Fe2+ haem molecules each holding a gas molecule each.
Males: 140-180g/L
Females: 120-160g/L.

Question 23

What is Erythropoesis the process of? Where does it take place?

Answer 23

Process of RBC production. Takes place in bone marrow.

Question 24

What is the hormone that stimulates erythropoesis? Where is the hormone made?

Answer 24

Erythropoietin (EPO), which is synthesised in the kidneys and enhanced by testosterone.

Question 25

Briefly describe the feedback loop of synthesising EPO.

Answer 25

EPO synthesis, and thus erythropoesis occurs in a negative feedback loop: RBC levels (and therefore oxygen delivery to tissues) fall, this is sensed by the kidneys, which increase EPO synthesis in response, and RBC levels return to normal.

Question 26

What ingredients does erythropoesis require?

Answer 26

Vitamin B12 (for DNA synthesis and cell replication, iron (for haem synthesis), folic acid and thymine.

Question 27

Where are RBCs broken down? What do they break down into?

Answer 27

RBCs break down in capillaries. Removed damaged/dead RBCs by macrophages.
Globin proteins –> Amino acids.
Haem –> degraded into iron and bilirubin.
(Both can be re-used for erythropoesis)

Question 28

What does bilirubin do?

Answer 28

A pigment breakdown product that cannot be reused so it is transported to the liver to be excreted in bile. If bilirubin builds up too much, the pigment deposits in the skin and causes a person to appear yellow, this condition is called jaundice and is common in newborns.

Question 29

What is the name of the term when Hb levels are too low?

Answer 29

Anaemia.

Women =

Question 30

What are the consequences of anaemia?

Answer 30

Less Hb means that blood carries less oxygen, and, in turn, delivers less oxygen to the tissues.

Question 31

How can anaemia occur? (3 causes)

Answer 31

1. Decreased ‘production’ of RBCs resulting from reduced proliferation (e.g iron deficiency, low EPO).
2. Increased ‘destruction’ of RBCs, resulting from cellular defect or autoimmune disorder, or genetics (e.g sickle cell anaemia), or extracellular mechanisms (e.g chemotherapy medications).
3. Bleeding acutely (e.g an arterial puncture) or chronically (e.g gastrointestinal bleeding).

Question 32

Show a pathway for how to increase sport performance starting from increasing a hormone.

Answer 32

Erythropoietin –> Erythrocytes –> Increased oxygen capacity –> increasing performance.