Cell Signalling and the Endocrine System Flashcards

1
Q

what is the function of a ligand-gated ion channel

A

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)

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2
Q

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

A

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

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3
Q

what types of endocrine receptors are membrane-bound

A

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

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4
Q

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

A

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

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5
Q

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

A

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)

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6
Q

describe how the action of a GPCR ends

A

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

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7
Q

what happens when the agonist/hormone dissociates from the GPCR

A

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

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8
Q

what is an adrenoreceptor

A

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

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9
Q

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

A

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

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10
Q

what is the principal transduction of the a2 adrenoceptor

A

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

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11
Q

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

A

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

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12
Q

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

A

insulin

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13
Q

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

A

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

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14
Q

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

A

relay proteins

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15
Q

describe the signalling response of a Kinase-linked receptor

A

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

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16
Q

in order from fastest to slowest order the endocrine receptors

A

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

17
Q

what is autocrine regulation

A

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

18
Q

what is paracrine regulation

A

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

19
Q

what is endocrine regulation

A

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