Blood 1

Question 1

How is blood circulated around the body?

Answer 1

Blood travels around the body in blood vessels. Arteries carry oxygenated blood away from the heart and veins carry deoxygenated blood to the heart.

Question 2

What are the differences between arteries and veins?

Answer 2

• Blood travels around the body in blood vessels. Arteries carry oxygenated blood away from the heart and veins carry deoxygenated blood to the heart.
• Veins have valves to prevent back flow whereas arteries do not have valves.
• Veins have a wider lumen than arteries
• Arteries have a thicker tunica media than veins - and so have a thicker layer of smooth muscle for contraction

Question 3

Discuss the functions of blood

Answer 3

• Plasma transports solutes
• Transports hormones
• Supplies the tissues with oxygen
• Carries metabolic waste away from tissue to specialist organs
• Immune function due to the presence of WBC - both innate and adaptive responses
• Prevents the loss of blood through coagulation
• Hydration of tissues and organs
• Homeostasis - regulates body temperature and pH (bicarbonate ion in the buffer solution and other dissolves solutes in the blood help maintain this)

Question 4

Describe which components of the blood are involved in tissue oxygenation

Answer 4

RBC contain a tetramer protein known as haemoglobin. Each subunit in haemoglobin has a prosthetic group known as haem. Haem contains an iron ion; as a result it can associate with oxygen at the lungs and disassociate with oxygen at the tissues. Iron can exists in different oxidation states and so can bind to oxygen.

Question 5

Describe which components of the blood are involved in fighting infection

Answer 5

White blood cells:

• Plasma cells - produce antibodies (a type of B cell)
• Neutrophils - phagocyte
• Eosinophils - Anti-parasitic activity
• Basophils - Involved in inflammatory reactions. Contain the anticoagulant heparin.
• Mast cells - Involved in inflammatory and allergic reactions and the release of histamine
• Complement protein. These are activated when we encounter pathogens and are linked to specific immune cells.
• Platelets work with WBC

Question 6

How is the red blood cell adapted for its function?

Answer 6

• Cytoskeleton made of spectrin - spectrin is deformable so it can change shape and fit through small capillaries
• No nucleus - increase SA for haemoglobin
• No mitochondria - So all oxygen in the red blood cell is transported to tissues. Obtain its energy by aerobic glycolysis.

Question 7

Describe how the blood is involved in hormone distribution

Answer 7

Important in endocrine hormones. The specific endocrine glands will secrete hormones into the blood. The blood will then transport the hormone to the target cell some distance away from the secretory cell.

Examples:
Insulin - master regulator of metabolism (regulates lipid metabolism, amino acid metabolism and glucose)
Oestrogen, Testosterone and Progesterone
Vasopressin - Involved with the uptake of water
Adrenaline

Question 8

Describe which components of the blood are involved in clotting

Answer 8

Involves both cellular and non-cellular elements working in conjunction with each other:

• Platelets - usually found in a round shape but when they encounter an injury, they become activated and so change shape, accumulate and aggregate. A protein network sets on top of the plug.
• Proteins such as fibrinogen.
• Enzymes such as thrombin and clotting factors.

Question 9

Describe how the different blood cells are produced from one cell and which cells appertain to which blood cell line

Answer 9

All blood cells are produced from one stem cell in the bone marrow known as the multi-potential hematopoietic stem cell.

This can then go down different lineages: the myeloid linage or the lymphoid lineage.

If it goes down the myeloid lineage, the stem cell will differentiate into the common myeloid progenitor. This can then differentiate into megakaryotes (which will give rise to platelets), erythrocytes, myelobalsts (which can give rise to, neutrophils, basophils and eosinophils through differentiation. It can also give rise to monocytes - which will give rise to macrophages) and mast cells.

If it goes down the lymphoid linage, the common stem cell will differentiate into the common lymphoid progenitor. This can then differentiate into natural killer cells or small lymphocytes (with will give rise to T cells or B cells which can further differentiate).

Question 10

What is the difference between serum and plasma?

Answer 10

Serum = plasma - blood clotting factors

Question 11

What is the hematocrits?

Answer 11

The percentage of red blood cell mass in the sample.

Question 12

What is the percentage composition of the different components of the blood?

Answer 12

• Red blood cells (45%) (Hematocrits)
• White elements - white blood cells and platelets. (>1%)
• Plasma (55%)

Question 13

How do anticoagulants work?

Answer 13

Collate the calcium in the blood, thereby preventing the blood clotting.

Question 14

What are the different key proteins found in the blood? What are the functions?

Answer 14

• Albumin - Maintains osmotic pressure of the blood and transports insoluble components (e.g. fatty acids)
• Immunoglobulins - antibodies used in immunity
• Fibrinogen - essential for clotting

Question 15

Discuss the ABO blood group and understand which type blood can be used as a donor for a patient of each ABO type

Answer 15

Blood group A - The erythrocytes have the A antigens on the surface. The plasma has anti-B antigens.
Can receive red blood cells from: A and O
Can receive plasma from: AB and A

Blood group B: Has B antigens on the surface of the erythrocyte and has anti-A antibodies in the plasma.
Can receive red blood cells from: B and O
Can receive plasma from: AB and B

Blood group AB: Has both A and B antigens on the surface of the erythrocyte but has no antibodies in the plasma.
Can receive red blood cells from: A, B, AB and O
Can receive plasma from: AB, A and B

Blood group O: Has no antigens on the surface of the red blood cells and both anti-A and anti-B antibodies in the plasma.
Can receive red blood cells from: O
Can receive plasma from: AB, A, B and O

Question 16

What is the difference in production of antibodies in the ABO system and the Rhesus system?

Answer 16

The ABO antibodies are produced spontaneously ate birth and their levels continue to rise until 15-16 where they reach adult levels.

The Rhesus anti-D antibody is only produced once the Rhesus negative individual is exposed to the Rhesus positive blood.

Question 17

What happens when you give a type A patient, type B blood?

Answer 17

The agglutinins in the type B blood will cause the red blood cells too agglutinate. This is then cause lysis of the blood cells.

Question 18

Discuss the Rhesus blood group and how this can lead to haemolytic syndrome of the newborn

Answer 18

There is another ion channel antigen called Rhesus antigen. Those with the antigen are Rh positive and those without are Rh negative..

If a mother is Rh negative and the unborn child is Rh positive, it can lead to haemolytic anaemia. In her first pregnancy, the body placenta prevents the two bloods mixing - even though they come into very close contact. When the mother gives birth, the placenta ruptures and the blood is mixed. This means that the mother starts producing the anti-D antibody (against the Rh positive blood) to protect the mother as it is foreign. In the second pregnancy, if the baby is again Rh positive, these anti-D antibodies can pass over the placenta into the baby and cause haemolytic anaemia. In order to combat this, if there is an event where the blood would mix, the mother is given anti-D antibodies, so that the babies blood in the mother is destroyed. As a result, the mother does not need to create her own antibodies and there is a reduced risk of haemolytic anaemia in future pregnancies.

Question 19

What is the effect of an acute haemolytic reaction?

Answer 19

1. Red blood cells block the blood vessels leading to micro thrombi, causing them to become hypoxic.
2. Lysis of the red blood cells causes haemoglobin and iron to be released into the bloodstream. These components are very toxic to the kidney and so can lead to acute renal failure.
3. Can lead to Disseminated Intravascular Coagulation - if there are all of the clotting factors are being used by on all of the micro thrombi, this can lead to bleeding as the clotting factors cannot be replaced fast enough.