Lipids And Cel Membranes

Question 1

Cell to cell communication

Answer 1

Synthesis of signal
Release of signalling molecule by exocytosis diffusion to cell to cell contact
Transport signal to target cell
Detection by receptor protein
Change in cellular metabolism, function etc
Removal of signal or desensitisation

Question 2

Two types of signalling

Answer 2

Long range and short range

Question 3

Long range signal

Answer 3

Endocrine

Neurotransmitters

Question 4

Endocrine

Answer 4

Where hormones is released by endocrine cells and carried in bloodstream to distal target cells

Example FSH released form pituitary acts on ovary

Question 5

Example of neurotransmission

Answer 5

Breathing phrenic and thoracic nerves send impulses from brain to diaphragm

Question 6

Short range signalling

Answer 6

Paracrine
Autocrine
Membrane bound proteins interact

Question 7

Paracrine

Answer 7

Signalling molecules only affect cells in close proximity to secreting cell

Ex somatostatin release by pancreas acts locally as can neurotransmittion be local

Question 8

Autocrine

Answer 8

Cells respond to substances that they themselves release

NT and Growth factors bind to cells that release them

Question 9

Membrane bound proteins interact to signal

Answer 9

Signaling by plasma membrane attached proteins

Ex signalling by T cells in immune systems

Question 10

Ex of multiple types of signalling occurring simultaneously

Answer 10

Insulin released form pancreatic beta fuels acts in autocrine paracrine and endocrine matter

Question 11

Lipid soluble signalling molecules

Answer 11

Bind inteacellular receptors rest bing to membrane bound receptors on surface

Question 12

Examples of cell surface receptor

Answer 12

Ligand gated ion channels
G protein coupled receptor
Kinase liked receptors

Question 13

Example of intracellular receptors

Answer 13

Nuclear receptors

Question 14

Signals that alter protein function are

Answer 14

Fast

Question 15

Signals that alter protein synthesis are

Answer 15

Slow

Question 16

Altered protein synthesis or function work by

Answer 16

Altering cytoplasmic machery and hence altering cel behaviour

Question 17

Examples of lipid soluble molecules

Answer 17

Cortisol
Estradiol
Thyroxine
Testosterone

Question 18

What happens during lipid molecule synthesis

Answer 18

Cortisol passes through plasma membrane
Reacts with intracellular receptor protein causing conformational change
Can now pass through into nucleus
Complex activates target gene via regulatory region causing transcription to occur

Question 19

Inositol phospholipid signalling pathway

Answer 19

PIP2 is phospholipid found in enzyme bilateral

Substrate of enzyme phosplipase C (plc)

Plc liberates two signalling molecules from PIP2 - IP3 and DAG

Opens calcium channel

Question 20

What happens to calcium in response to IP3 release

Answer 20

Calcium conc inc in cell

Calcium binds to protein to regulate their function

Question 21

Substrates for PKC to activate it are

Answer 21

Tumor suppressor p53. Prevents tumor formation

CAv 1.2 - heart muscle contraction

IKKa - B cell activation

Question 22

What happens to IP3 after signal

Answer 22

Referred back to membrane as PIP2

Question 23

What are eicosanoids (prostanoid)

Answer 23

Inflammatory mediators

Local hormones - specific effect on target cel close to site of formation

Rapidly degradedo so not transported to distal sites within the body

Question 24

Main eicosanoids (prostanoids)

Answer 24

Prostaglandins
Theomboxanes
Leukotrienes

20C with double bonds

Question 25

Source of eicosanoids

Answer 25

Arachidonic acid (20:4)

Question 26

Biosynthesis of eicosanoids Initial and rate limiting step

Answer 26

Liberation of arachidnoic acid by phospholipids A2 PLA2 ``` PLA2 Serotonin receptors Glutamate receptor 1 Some cytokine receptors An increase in calcium ```

Question 27

How can arachidonic scid be metabolised

Answer 27

Cyclooxygenase and peroxidase to give prostaglandins and theomboxanes Lipocygenases to give leukotrienes

Question 28

Prostaglandins

Answer 28

Synthesised in all tissue and cell types Vasoconstriction dilation Inhibitor promote platelet aggregation EP1 - vasoconstriction EP2 - vasodilation Inflammatory response. Thermoregulation fever and pain

Question 29

Thromboxanes

Answer 29

Synthesised in platelets clotting Short lived Thromboxane A2 TXA 2 had prothrombotic properties Stimulate platelet aggregation Vasoconstrictor

Question 30

Leukotrienes

Answer 30

Synthesised in WBC and contain double bonds Some contain cystine in structure - anaphylactic shock Heavily implicated in Asthma and allergy

Question 31

Platelet activating factor

Answer 31

By product of arichdonic acid liberation not an eicosanoid Synthesised in leukocytes and injured tissue Platelet aggregation Vasoconstriction Inflammation Immune response

Question 32

What are NSAIDs

Answer 32

Inhibit cuclooxugenases and hence the formation of prostaglandins involved in pain fever and inflammation ( blockchannel where arschidonste enters COX active site) Inhibit blood clotting by clocking thrombocytes tmformstion in blood platelets

Question 33

How does aspirin work

Answer 33

Acetylates serine hydroxyl group preventing aracidonate bidning IRREVERSIBLE resybthesis of COX1 to restore activity

Question 34

Aspirin anticoagulant

Answer 34

Thirnboxnae A2 stjualtes blood platelet in clotting COX1 inhibiton - inhibition of theomboxane formation Long lived because platelets lack nucleus and connor make new enzyme s

Question 35

Aspirin

Answer 35

Cox1 inhibitin

Question 36

Dexamethasone

Answer 36

Glucocorticoid Inhibitos cox2 induces PLAw inhibitor Arthritis chemotherapy

Question 37

Iloprost

Answer 37

Activates prostacyclin receptor Pulmonary hypertension

Question 38

Zileuton

Answer 38

5-lipoxygenase inhibitor and his inhibits leukotriene synthesis Asthma

Question 39

Zafirukast

Answer 39

Inhibits leukotriene by blockingrecepto Asthma

Question 40

Dipyridamole

Answer 40

Inhibits thromboxane A2 synthesis Pulmonary hypertension Stoke pretentious with aspirin