week 1 - introduction to cell signalling Flashcards
where are intracellular receptors found?
cytoplasm or nucleus
what is autocrine signalling
communication in which a signal is released by a cell and then acts on the same cell, causing alteration or effect
autocrine regulation of somatostatin in the stomach
- somatostatin is secreted by D cells in the gastric glands
- somatostatin binds to SST2R receptors -> inhibiting adenyl cyclase
- decrease in cAMP results in a decrease of gastric acid secretion
- somatostatin also binds to SST2R receptors on D cells -> results in a negative feedback loop and reduced somatostatin secretion
what is paracrine signalling
cells communicate over relatively short distances by secreting small molecules on to nearby cells
histamine in the stomach - paracrine
- histamine is secreted by the enterochromaffin in response to stimulation by acetylcholine
2.histamine binds to H2 receptors with subsequent activation of adenyl cyclase - increase in cAMP increases the number of proton pumps -> increasing gastric acid secretion
what is endocrine signalling
communication in which cell(s) transmit and receive information, signals or directions between itself and environments
hypophyseal portal system - endocrine communication
hormones such as ACTH are secreted from cells of the pituitary glands into the connected circulatory vasculature
what is the synaptic cleft
the space between a neuron and its target cell
do chemical synapses have a gap between the neuron and the target cell
yes
do electrical synapses have a gap between the neuron and the target cell
no
what is a role of voltage-gated calcium channels
they release neurotransmitters into the synaptic cleft
what do action potentials determine
the duration and amount of neurotransmitters that are released into the synaptic cleft
what can action potentials result in
more calcium entering the neuron at the axon terminal
what is the most common inhibitory neurotransmitter in the brain
gamma-aminobutyric acid
name three catecholamines
dopamine, epinephrine, norepinephrine
do inotropic or metabotropic neurotransmitter receptors move more slowly
metabotropic
how is acetylcholine removed from the postsynaptic membrane
by enzymatic deactivation
what is structural depression
describes the type of plasticity that occurs when entire neurons are lost due to decreased activity
what is synaptic transmission
electrical signal, action potentials originate on cell bodies of neurons
what are ligand gated ion channels
integral membrane proteins that contain a pore which allows the regulated flow of selected ions across the plasma membrane
why do ions flow in and out of ligand gated ion channels
due to hyperpolarisation/depolarisation due to binding of/against neurotransmitter/hormone
what are G-protein coupled receptors
receptors that work primarily through second messenger activity and allow for signal amplification
what are kinase-linked receptors (enzyme-coupled)
protein phosphorylation leads to gene transcription which leads to protein synthesis then cellular effects
what are nuclear receptors and steroid action
intracellular receptors that are generally bound by steroid hormones
what is depolarisation
when the membrane changes from negative to positive
what are adrenoreceptors
bound and activated by the neurotransmitter/hormones adrenaline and noradrenaline
