Blood system

Question 1

function of blood

Answer 1

transport, immune response, coagulation

Question 2

composition of blood plasma

Answer 2

• 90% water
• 10% solutes including plasma proteins, nutrients, waste products etc

Question 3

3 groups of plasma proteins

Answer 3

1. albumins - maintain osmotic pressure; hormones, coagulation factors
2. globulins - antibodies
3. fibrinogen - blood clotting

Question 4

cells in blood

Answer 4

• erythrocytes (RBCs)
• leukocytes (WBCs)
• Thrombocytes (platelets)

Question 5

types of WBCs

Answer 5

1. granulocytes
2. monocytes
3. lymphocytes

Question 6

types of granulocytes

Answer 6

1. neutrophils
2. basophils
3. eosinophils

Question 7

what does blood transport

Answer 7

O2, nutrients, CO2, hormones, phagocytic cells, antibodies, coagulation factors

Question 8

function of neutrophils

Answer 8

cellular defence - phagocytosis

Question 9

function of basophils

Answer 9

anticoagulation and inflammatory response

Question 10

function of eosinophils

Answer 10

cellular defence and anti-inflammatory

Question 11

function of monocytes

Answer 11

aggressive phagocytosis of bacteria, debris etc

Question 12

function of lymphocytes

Answer 12

humoral defence - secrete antibodies

Question 13

features of neutrophils

Answer 13

• 65% of blood cells
• multilobed nucleus
• small pink staining granules

Question 14

features of basophils

Answer 14

• <1% of blood cells
• 2-lobed nucleus
• large purple stained granules

Question 16

features of eosinophils

Answer 16

• 2-5% of blood cells
• 2-lobed nucleus
• large orange stained granules

Question 17

features of monocytes

Answer 17

• 3-8% of blood cells
• horse-shoe shaped nucleus
• steel blue colour

Question 18

features of lymphocytes

Answer 18

• 25% of blood cells
• round nucleus
• little cytoplasm

Question 19

features of RBC

Answer 19

• Biconcave disc shape for large surface area: volume ratio
• Flexibility for movement though narrow capillaries
• Contain large amounts of Hb- 1/3 of weight of RBC

Question 20

features of RBC production (erythropoiesis)

Answer 20

• stimulated by erythropoietin (EPO)
• requires folic acid, vit B12, thymine, iron
• controlled by homeostatic mechanism with EPO
• helped by testosterone
• decrease in RBC sensed by kidneys

Question 21

destruction of RBCs

Answer 21

• life span = 120 days
• break apart in capillaries
• fragments removed by macrophages
• iron recycled in bone marrow, amino acids to produce more proteins, bilirubin pigment transported to liver and excreted in bile

Question 22

anaemia definition and causes

Answer 22

• A reduction in the concentration of Hb (reduced O2 carrying capacity of blood- insufficient to supply tissues)

causes:

• decreased production of RBCs
• increased destruction of RBCs
• severe bleeding

Question 23

3 components of haemostatic response to injury

Answer 23

• Blood vessels vasoconstrict (stage I haemostasis)
• Platelets form the platelet plug (stage I haemostasis)
• Coagulation cascade: sequential series of chemical reactions of clotting factors, resulting in the formation of a fibrin clot (stage II and III haemostasis)

Question 24

stage 1 haemostasis

Answer 24

1. Vessel damage
2. altered endothelial surface
3. exposure of sub-endothelium
4. platelets get activated and begin to aggregate (form platelet plug)
5. activated platelet release mediators (e.g. ADP, thromboxane A2) that activate more platelets (platelet plug gets bigger) and constrict blood vessels

Question 25

stage 2 of haemostasis

Answer 25

* Prothrombin, prothrombin activator and calcium to be released, which produces thrombin which combines with fibrinogen to make fibrin (the spider-web like mesh stuff that holds all platelets together) * intrinsic or extrinsic pathways

Question 26

intrinsic pathway

Answer 26

* Intrinsic pathway already has everything (clotting factors) in blood * clotting factors XII, XI and IX

Question 27

extrinsic pathway

Answer 27

* Extrinsic pathway requires tissue factor (from sub-endothelium) to be activated * clotting factor VII

Question 28

common pathway

Answer 28

* Pathways join to form a common pathway at production of "Activated factor X" * factor X converts prothrombin to thrombin, which then converts fibrinogen to fibrin (forming a clot) * Ca2+ is essential for the common pathway

Question 29

haemophilia A

Answer 29

absence of factor VIII

Question 30

haemophilia B

Answer 30

absence of factor IX

Question 31

haemophilia C

Answer 31

absence of factor XI

Question 32

opposing clot formation

Answer 32

* Endothelial surface is normally **smooth** – prevents platelets adhering * **Prostacyclin** (from endothelium) inhibits aggregation * **Nitric Oxide** (from endothelium) vasodilates and inhibits aggregation * **Tissue Factor Pathway Inhibitor** (from endothel.) binds TF/VIIa complex & inhibits extrinsic pathway * **Thrombin** is inhibited via antithrombins * **Warfarin** – drug that impair liver’s use of vitamin K – slow down clotting * **Aspirin - inhibits platelet aggregation**

Question 33

dissolving blood clots

Answer 33

* fibrinolysis (occurs simultaneously with clot formation) * Plasminogen and particularly t-PA (tissue Plasminogen Activator) incorporated into the Blood clot

Question 34

ABO blood group

Answer 34

* RBCs have membrane proteins (antigens) that are genetically determined and inherited * We have naturally occurring antibodies to antigen that is not present on our own Red blood cells * AB has antigens A and B so neither antibodies * O has antigens for neither A nor B so both antibodies

Question 35

blood transfusions

Answer 35

* Type O = universal donor * Type AB = universal recipient

Question 36

rhesus system for blood type classification

Answer 36

* based on presence of D antigen - individuals with D antigen are rhesus positive (85% of population) * No pre-formed natural antibodies (these develop slowly so does not affect developing Rh+ foetus in Rh- mother) * if another Rh+ foetus born, can fix this by giving mother anti-D antibody at first delivery to prevent antibody development