B&I blood

Question 1

Arterial pressure is maintained by…?

Answer 1

Elastic vessel walls that contain an abundance of smooth muscle

Question 2

Venous pressure is LOWER than arterial pressure because…?

What is required in veins to prevent back flow?

Answer 2

Veins are not elastic

One way valves are required to prevent back flow

Question 3

A loss of blood over_% is fatal? Why?

Answer 3

20% - due to impaired pressure and flow and tissue starve of oxygen

Question 4

What causes hypertension (high blood pressure)?

What does this result in?

Answer 4

Narrowing/hardening of the arteries

Results in reduced flow in the arteries and coagulation

Question 5

Why does inhaled cyanide stop heart activity in seconds?

Answer 5

CN targets Fe2+ in cytochrome C oxidase in the mitochondria, which stops respiration and the production of ATP

Question 6

A buffer is needed to prevent rapid change in blood pH as a variance of 0.2 from normal pH can cause acidosis or alkalosis.
What is the normal pH in blood?
What is a good buffer?

Answer 6

pH7.4

Buffers: albumin, phosphate, bicarbonate, creatine

Question 7

Blood separates into 3 components upon low speed centrifugation. These are…?

Answer 7

1. Packed red cells - 40%
2. Buffy coat - 10% (containing white cells)
3. Plasma 50% (containing soluble proteins, lipids and platelets)

Question 8

What is plasma? (2)

Answer 8

• The viscous liquid fraction of UNcoagulated blood

- Carries cells and proteins throughout the body

Question 9

What is serum? (2)

Answer 9

• Blood without fibrinogen and cells

- The straw coloured liquid that remains after coagulation (cream after a fatty meal)

Question 10

What is albumin? (5)

Answer 10

• Accounts for ~50% of total blood protein (most common)
• Maintain OSMOTIC PRESSURE
• Binds/transports small molecules and proteins
• Good buffer
• Still has fibrinogen

Question 11

What is fibrinogen? (2)

Answer 11

• Second most abundant protein

- Cleaved by THROMBIN (in coagulation cascade) to form FIBRIN that cross links to form the blood clot

Question 12

What is immunoglobulin (Ig)? (4)

Answer 12

ANTIBODIES responsible for immunity
~10% of total blood protein
- Diverse antigen binding proteins produced by B lymphocyte
- Ig becomes elevated in diseases

Question 13

What are compliment proteins? (3)

Answer 13

• Zymogens that OPSONISE invading organisms for phagocytosis
• Important for immune response
• 9 major components (C3 is major component)

Question 14

What are coagulation proteins? (4)

Answer 14

• 13 proteins that initiate cleavage of FIBRINOGEN to FIBRIN to form the clot
• THROMBIN is the central enzyme in this process
• Calcium is an essential component in this process
• HAEMOPHILIA (uncontrolled bleeding) can result from an error in this process

Question 15

Describe erythrocytes/RBC (3)

Answer 15

• Most abundant (compared to leukocytes)
• Solely for O2 transport
• Flat, NO nucleus (so survive radio therapy)

Question 16

What are myeloid cells? (2)

Name the 4 myeloid cells

Answer 16

• Important cells in innate immunity and phagocytosis
• Have a range of receptors that bind immune complexes
  Neutrophils, monocytes (become macrophages), basophils, eosinophils

Question 17

What are the 2 lymphoid cells?

Where do they originate?

Answer 17

B lymphocytes - antibody adaptive immunity
T lymphocytes - cellular adaptive immunity (developed in thymus)
Both originate in bone marrow

Question 18

Describe leukocytes/WBC (3)

Answer 18

• Involved in immunity
• Neutrophil most abundant - responds to infection
• WBC not as abundant as RBC

Question 19

What are the functions of platelets? (2)

Answer 19

• Coagulation

- Tissue repair

Question 20

Describe haematopoeisis (3)

Answer 20

• All blood cells originate from a single pluripotent human stem cell (CD34+)
• This cell is rare but important
• Resides in bone marrow but has high conc in umbilical cord (saved for stem cell transplants)

Question 21

Describe the function of GM-CSF, G-CSF and EPO (erythropoetin)

Answer 21

Regulate blood

• GM-CSF - speeds up WBC repopulation
• EPO - drives production of RBC (drug ^O2)
• G-CSF - production of granulocytes and mature neutrophils

Question 22

Why do cells need O2?

Why are the lungs important?

Answer 22

ATP - energy for bodily functions

Lungs provide vast surface for O2 CO2 exchange

Question 23

What is the alveoli?

Answer 23

Small membrane where O2 can diffuse in blood (changes colour - venous is dark red, arterial is bright red and foamy)

Question 24

Describe hameoglobin (4)

Answer 24

• Carries O2 to tissue
• Has 4 haem molecules, each binded to ferrous iron atom (this allows blood to bind to O2)
• Raises potential to bind oxygen x7
• Assists in association and dissociation of oxygen

Question 25

What is the compliment cascade? (2)

Answer 25

- Proteolytic (breakdown of proteins to smaller amino acids etc.) cascade essential for innate immunity - Convertases are irreversibly bound through a covalent bond

Question 26

Why are electrolytes an important blood component? (3)

Answer 26

- Isotonicity (equal conc in solutions on either side of membrane) - Buffering - Regulation of membrane channels/ion pumps (Ca, K)

Question 27

What regulates the association and dissociation of O2 from haem? (2)

Answer 27

Partial pressure of O2 (pO2) - O2 readily associates with haem in the lungs (at atmospheric pO2) and dissociates in the tissues (delivering O2 to cells)

Question 28

What are the 3 different pathways of the compliment cascade?

Answer 28

1. Classical - mediated by antibodies IgM or IgG binding to microbe surface which is then bound by compliment C1 2. Lectin - carbohydrate 3. Alternative

Question 29

What is opsonisation?

Answer 29

Deposition of complement on microbes, essential for phagocytosis

Question 30

What are anaphylotoxins? | How are they produced?

Answer 30

- Powerful chemoattractants that attract and activate neutrophils - Produced by cleavage of C3, C4 and C5 to small fragments C3a, C4a, C5a

Question 31

What happens in the end stage of complement (C5 onwards)?

Answer 31

Lytic pore forms that cause some bacteria to lyse - this is the membrane attack complex (MAC)

Question 32

What are the negatives in the complement cascade? (2)

Answer 32

- People with deficiencies in a compliment component are susceptible to chronic infections - Many microbes produce proteins calle VIRULENCE FACTORS that inhibit the cascade

Question 33

What are the factors involved in the intrinsic and extrinsic pathways of coagulation?

Answer 33

Intrinsic: XII, XI, IX, VIII (8-12) - caused by CONTACT with surfaces Extrinsic: V, VII (5, 7, 10) - caused by TISSUE damage Both: X

Question 34

What is the function of factor Xa in the coagulation pathway?

Answer 34

Converts prothrombin to thrombin

Question 35

What is coagulation? (2)

Answer 35

- Thrombin converts fibrinogen to fibrin to form a clot | - ie. Liquid changing to solid/semi-solid

Question 36

What is the role of plasminogen in coagulation? | What are the two common plasminogen activators?

Answer 36

- Plasminogen is converted to active plasmin and dissolves the clot ("thrombolysis") - TPA, streptokinase