Cell Signalling and the Endocrine System Flashcards Preview

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Flashcards in Cell Signalling and the Endocrine System Deck (19)
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1

what is the function of a ligand-gated ion channel

when activated, by binding of a ligand/hormone, they will allow movement of ions in or out of the cell
(ie depolarisation or hyperpolarisation of plasma membrane)
(occurs in milliseconds)

2

in what direction do ions move through a ligand-gated ion channel

down the conc. gradient, ie from area of higher charge to lower

3

what types of endocrine receptors are membrane-bound

ligand-gated ion channels, G-protein coupled receptors(GPCR), Kinase-linked receptors

4

describe the general mechanism of a G-protein coupled receptor(GPCR)

agonist(eg hormone) binds to receptor bringing conformation change of GPCR which allows activation of signalling response

5

give an example of a hormone and a GPCR in the endocrine system

adrenaline, binds to B2 adrenoreceptor which is a GPCR, activates signalling response of enzyme to convert ATP to cAMP, and ultimately results in bronchodilation
(occurs in seconds)

6

describe how the action of a GPCR ends

ends when GTP bound to the alpha-subunit hydrolyses to become GDP, so self-limits the action

7

what happens when the agonist/hormone dissociates from the GPCR

resets confirmation of GPCR, subunits return to original positions, ready to receive another agonist and repeat process

8

what is an adrenoreceptor

a receptor bound and activated by the neurotransmitters/hormones adrenaline and noradrenaline

9

what is the principal transduction of the a1 adrenoceptor(it is a GPCR)

Galpha-subunit q, activates phospholipase, which increase IP3 and DAG

10

what is the principal transduction of the a2 adrenoceptor

Galpha-subunit i, inhibits adenylyl cyclase, decreasing cAMP and Ca2+ channels, increasing K+ channels

11

what is the principal transduction of the B1, B2 and B3 adrenoceptors

Galpha-subunit s, stimulation of adenylyl cyclase, increasing cAMP

12

give an example of a hormone that is an agonist for Kinase-linked receptors

insulin

13

describe what happens when a hormone/agonist binds to a Kinase-linked receptors

dimerisation of receptor, with subsequent phosphorylation by ATP of tyrosine residues linked to receptor

14

what binds to the phosphorylated tyrosine residues in a Kinase-linked receptor action

relay proteins

15

describe the signalling response of a Kinase-linked receptor

diversified, different relay proteins bind to the tyrosine residues and illicit varied cellular responses
(response occurs in hours)

16

in order from fastest to slowest order the endocrine receptors

Ligand-gated(milliseconds), GPCR(seconds), Kinase-linked(hours)

17

what is autocrine regulation

when chemicals(ie signalling molecules) released from the cells bind to receptors on or in the cells they are released from

18

what is paracrine regulation

when chemicals(ie signalling molecules) released from the cells bind to receptors on adjacent cells

19

what is endocrine regulation

when chemicals(ie signalling molecules), released from the secretory cells are transported(usually by circulatory system) to target cells elsewhere in body