generakl

Question 1

What layer of an embryo forms connective tissue?

Answer 1

mesoderm (mesenchyme)

Question 2

What cell types can mesenchymal cells mature into?

Answer 2

• mast cells
• fibroblasts
• chondroblasts
• osteoblasts
• adipocytes

Question 3

what is a ‘blast’ cell?

Answer 3

an undifferentiated cell

Question 4

What is a reactive O2 species?

Answer 4

A highly reactive oxygen compound which is a free radical or easily converted into one within cells

Question 5

Which is the most potent ROS?

Answer 5

Hydroxyl radical - OH.

Question 6

What are endogenous and exogenous sources of ROS’s?

Answer 6

exogenous - UV radiation, tobacco, drugs

endogenous - NADP, e- transfer chain (resp.)

Question 7

Steps of oxygen reduction:

Answer 7

Question 8

What is respiratory burst?

Answer 8

ann immune defense against bacteria

sudden ROS release by immune cells during phagocytosis

NADH oxidase to reduce O2 -> O2.-

this is released which forms hydroxide then chain reaction

Question 9

what is myeloperoxidase

Answer 9

neutrophils + monocytes use myeloperoxidase to combine H2O2 with Cl- to form ClO- (hypochlorite)

hypochlorite damages bacterial cell wall/membrane

Question 10

how do cells detoxify ROS?

Answer 10

• superoxide dismutase - 2O2 + 2H+ -> H2O2 +O2
• catalase (in peroxisomes) - 2H2O2 -> 2H2O + O2

Question 11

how can vitamin c reform vit. E

Answer 11

reacts with supraoxide/hydroxide

vitamin E is reducing agent so can end propagation

Question 12

cellular compartmentalisation

Answer 12

respiratory burst occurs within phagosomes so chemmicals do not get out and cause harm

Question 13

Henderson Hasslebach equation:

Answer 13

Question 14

Platelet plug:

Answer 14

1. vWF binds to exposed collagen
2. platelets bind to vWF, become activated
3. active platelets release thromboxane A2 + ADP, activating nearby platelets
4. other platelets activate + aggregate
5. undamaged epithelium releases NO + prostacyclin (inhibit platelet aggregation)

Question 15

why do platelets have high actin + myosin?

Answer 15

to allow contraction for compression + strengthening of platelet plug

Question 16

Fibrin stabilisation

Answer 16

fibrin originally a loose mesh of strands

stabilised by factor XIIIa - forms covalent cross links

Question 17

Thrombin actions

Answer 17

• catalyses formation of fibrin from fibrinogen and XIII -> XIII
• catalyses VIII -> VIIIa (Xa formation)
• aids platelet activation, making them display receptors for clotting factors

Question 18

Intrinsic pathway

Answer 18

• Exposed collagen - contact activation
• factor XII -> XIIa, XI -> XIa
• X -> Xa (via VIIIa cofactor)
• Xa catalyses prothrombin -> thrombin
• thrombin also catalyses VIII -> VIIIA (positive feedback)

Question 19

Extrinsic pathway

Answer 19

• Tissue factor protein on all cell membranes (exposed to blood when damaged)
• TF causes VII -> VIIa
• VIIa catalyses X -> Xa

Question 20

Vitamin K

Answer 20

forms clotting factors + prothrombin

fat soluble (bile salts needed for absorption)

Question 21

Anticlotting

Answer 21

• TFPI (tissue factor pathway inhibitor) - inhibits X -> Xa via VIIa
• antithrombin - inactivates thrombin (increased activity when bound to heparin)
• thrombomodulin + protein C - inactivate cofactors VIIIa + Va (intrinsic)

Question 22

fibrinolysis

Answer 22

plasminogen -> plasmin

plasmin digests fibrin, dissolving clot

Question 23

type 1 hypersensitivity first exposure

Answer 23

• allergen phagocytosed by antigen-presenting cell
• activates Th cell, interleukins help to form Th2 cell
• B-cells activated, divide into IgE secreting plasma cells
• eosinophils activated
• IgE also binds to mast cells

Question 24

type 1 hypersensitivity 2nd exposure

Answer 24

• mast cell comes into contact with allergen
• histamine release
• Binds to H1 receptors
  
  • smooth muscle contraction (narrowed airways
  • vasodilation, increased vessel permeability