Lecture 7 - Cell Communication I, General Principles Flashcards
what are the 5 types of cell to cell communication?
contact-dependant communication paracrine communication autocrine communication synaptic communication endocrine communication
what is contact-dependent communication?
communication by gap junctions or molecules on the cell surface where the signalling cell interacts with the target cell through a membrane-bound signal molecule
what is paracrine communication?
the signalling cell releases a local hormone into the extracellular space (e.g lumen) producing effects on the neighbouring target cells in a local environment
what is autocrine communication?
the signalling cell produces a local hormone that acts upon the receptor that produced it (acts on itself)
what is synaptic communication?
a neuron initiates an AP from the cell body and propagates it down the axon to the synapse to be diffused into the target cell aka the neurotransmitter is diffused
what is endocrine communication?
an endocrine cell produces a hormone and releases it into the bloodstream where it binds to a receptor on a distant target cell
what is a hormone?
a signalling molecule that is transported in the blood
what is the relationship between a hormone and a target cell?
hormones produced do not specifically find the target cell the target cell just expresses a specific receptor for a specific hormone
what is the flight or fight response?
during stressful situations a coordinated multiple organ response is initiated
where can circulating hormones be excreted?
hormones circulating in the bloodstream can excreted in the urine or faeces
what inactivates or activates hormones?
metabolism
what are hormones classified by?
by their chemical composition
what are the 3 classes of hormones?
peptide hormones
amine hormones
steroid hormones
what are peptide hormones composed?
composed of amino acids up to large proteins
what is the effect of peptide hormones?
effects the endocrine system through the hormones of GH or FSH
what are amine hormones?
hormones derived from the amino acid tyrosine
what are 4 examples of amine hormones?
dopamine
norepinephrine
epinephrine
thyroid hormones
what are amine hormones packaged into vesicles by?
packaged by catecholamines into vesicles
what is a catecholamine?
a monoamine neurotransmitter
what are steroid hormones?
hormones synthesised from cholesterol that are produced on command and provide long lasting effects upon slow synthesis
what is the relationship between steroid hormones and vesicles?
steroid hormones are lipid soluble therefore they cannot not be packaged into vesicles as vesicles are composed of fats so they would just diffuse or ‘leak’ out of the vesicle
what is the rate determining of steroid hormones?
synthesis of steroid hormones
what is hormone targeting?
when the secretory cell produces a chemical messenger that will only bind to the receptor specific for the chemical messenger to produce a response
what is synergy?
when there are 2 signalling molecules that produce the same effect both molecules will interact together to produce a bigger effect than if they were working separately
what is the effect of synergy?
the maximum combined response is bigger than the addition of the maximum individual responses
when is the only time synergy can occur?
when both individual stimuli are producing their maximal responses by second messengers improving translation
why are steroid hormones produced on command?
because they are lipid-soluble and cannot be packaged into vesicles so they are released into the bloodstream
what are peptide hormones?
water-soluble hormones that are produced and stored until required that produce rapid short lasting effects only when activated
what is the relationship between peptide hormones and the cell membrane?
peptide hormones cannot cross the cell membrane therefore they must travel in the blood bound to carrier protein
what receptors do lipophilic molecules use?
use cell surface receptors
how do lipophilic molecules use cell surface receptors?
the signal molecule binds to plasma membrane receptors on the plasma membrane and intracellular receptors package the signal molecule into vesicles at the golgi apparatus.
where does lipophilic molecule synthesis occur?
occurs at the rER
where does storage of lipophilic molecules occur?
occurs at secretory vesicles
how are lipophilic molecules secreted?
secreted by exocytosis
what are second messengers?
intracellular signalling proteins that act on multiple target proteins that each perform a different function
what is a common example of a second messenger?
cAMP produced from the first messenger by a signalling molecule that causes kinases to phosphorylate other molecules
where does second messenger transcription activation begin?
begins at the metabotropic receptor
what does second messenger transcription activate?
activates proteins that function as transcription factors
what do primary response genes synthesise?
in the nucleus primary response genes synthesise different transcription factors from mRNA
what do cell-specific genes produce?
produces mRNA
what does the mRNA produced by cell-specific genes synthesise?
synthesises proteins that mediate the cells response to the first messenger (e.g proliferation and differentation)