week 1 - introduction to cell signalling

Question 1

where are intracellular receptors found?

Answer 1

cytoplasm or nucleus

Question 2

what is autocrine signalling

Answer 2

communication in which a signal is released by a cell and then acts on the same cell, causing alteration or effect

Question 3

autocrine regulation of somatostatin in the stomach

Answer 3

1. somatostatin is secreted by D cells in the gastric glands
2. somatostatin binds to SST2R receptors -> inhibiting adenyl cyclase
3. decrease in cAMP results in a decrease of gastric acid secretion
4. somatostatin also binds to SST2R receptors on D cells -> results in a negative feedback loop and reduced somatostatin secretion

Question 4

what is paracrine signalling

Answer 4

cells communicate over relatively short distances by secreting small molecules on to nearby cells

Question 5

histamine in the stomach - paracrine

Answer 5

1. histamine is secreted by the enterochromaffin in response to stimulation by acetylcholine
   2.histamine binds to H2 receptors with subsequent activation of adenyl cyclase
2. increase in cAMP increases the number of proton pumps -> increasing gastric acid secretion

Question 6

what is endocrine signalling

Answer 6

communication in which cell(s) transmit and receive information, signals or directions between itself and environments

Question 7

hypophyseal portal system - endocrine communication

Answer 7

hormones such as ACTH are secreted from cells of the pituitary glands into the connected circulatory vasculature

Question 8

what is the synaptic cleft

Answer 8

the space between a neuron and its target cell

Question 9

do chemical synapses have a gap between the neuron and the target cell

Answer 9

yes

Question 10

do electrical synapses have a gap between the neuron and the target cell

Answer 10

no

Question 11

what is a role of voltage-gated calcium channels

Answer 11

they release neurotransmitters into the synaptic cleft

Question 12

what do action potentials determine

Answer 12

the duration and amount of neurotransmitters that are released into the synaptic cleft

Question 13

what can action potentials result in

Answer 13

more calcium entering the neuron at the axon terminal

Question 14

what is the most common inhibitory neurotransmitter in the brain

Answer 14

gamma-aminobutyric acid

Question 15

name three catecholamines

Answer 15

dopamine, epinephrine, norepinephrine

Question 16

do inotropic or metabotropic neurotransmitter receptors move more slowly

Answer 16

metabotropic

Question 17

how is acetylcholine removed from the postsynaptic membrane

Answer 17

by enzymatic deactivation

Question 18

what is structural depression

Answer 18

describes the type of plasticity that occurs when entire neurons are lost due to decreased activity

Question 19

what is synaptic transmission

Answer 19

electrical signal, action potentials originate on cell bodies of neurons

Question 20

what are ligand gated ion channels

Answer 20

integral membrane proteins that contain a pore which allows the regulated flow of selected ions across the plasma membrane

Question 21

why do ions flow in and out of ligand gated ion channels

Answer 21

due to hyperpolarisation/depolarisation due to binding of/against neurotransmitter/hormone

Question 22

what are G-protein coupled receptors

Answer 22

receptors that work primarily through second messenger activity and allow for signal amplification

Question 23

what are kinase-linked receptors (enzyme-coupled)

Answer 23

protein phosphorylation leads to gene transcription which leads to protein synthesis then cellular effects

Question 24

what are nuclear receptors and steroid action

Answer 24

intracellular receptors that are generally bound by steroid hormones

Question 25

what is depolarisation

Answer 25

when the membrane changes from negative to positive

Question 26

what are adrenoreceptors

Answer 26

bound and activated by the neurotransmitter/hormones adrenaline and noradrenaline