Term
| why are signalling systems are needed? |
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Definition
to coordinate activities of the cells/tissues in a multicelluar organism
eg. neurotransmission, coordination of developmental processes, Homeostatis |
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Term
| name 3 types of signalling between cells |
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Definition
free diffusion - between cells
via cytoplasmic connections
by cell-to-cell contact |
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Term
| singalling by free diffusion is classified into 3 types according to the distances involved. what are they? |
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Definition
Autocrine - singalling and reception in same cell
Paracrine - signalling between nearby cells
Endocrine - signalling between distant cells by hormones |
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Term
t or f?
in autocrine signalling, the cell secretes signals that modify its own behaviour? |
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Definition
true.
this is often associted with growth regulation which can be postive or negative |
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Term
| paracrine signalling involves messages to neigbouring cells. are these effects long or short lived? |
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Definition
short lived.
these are important in coordinating the actions of neighbouring cells in embryonic development and also in synaptic signalling |
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Term
| pituitary, adrenal and thyoroid gland are examples of endrocine ductless glands. where do these glands secret hormones into? |
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Definition
| extracelluar spaces - these then diffuse into the circulatory system |
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Term
| name the fastest mode of cell-to-cell communication? |
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Definition
via cytoplasmic connections.
signal transfer through pores in the membrane of cells. eg, muscle cells in heart communicate through gap junctions allowing all heart cells to contract simultaneously |
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Term
ligands are usually ................
receptors are usually ............
cell-to-cell contact signalling involves specific interactions between surface molecules of one cell and receptors of another cell |
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Definition
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Term
| what is the difference between local regulators and hormones? |
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Definition
local regualators act on cells in the vacinity (auto and paracrine signalling)
hormones act at distance (endocrine signalling) |
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Term
| growth factors, gases, prostoglandins and neurotransmitters are all examples of which regulator? |
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Definition
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Term
| growth factors are proteins that stimulate cell ............... |
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Definition
proliferation.
they may have more than 1 target cell thus > 1 function. eg. NGF nerve growth factor |
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Term
| nitric oxide is synthesised from arginine by nitric oxide synthase. it acts as a paracrine signal molecule and induces what effect in the cardiovascular system? |
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Definition
vasodilation.
it has a half life is between 1-5 seconds |
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Term
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Definition
modified fattly acids
they function to excite the uterine wall during childbirth and induction of fever and inflammation |
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Term
| acetylcholine, biogenic amines (serotonin), amino acids (eg. glutamate) and neuropeptides (eg. endorphins) are examples of what? |
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Definition
Neurotransmitters.
some of these can be inhibitory and some exicatory. some can be either.
some occur both in the CNS and PNS |
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Term
| which system controls hormone production? |
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Definition
| the neuroendocrine system with the control centre being the hypothalamus |
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Term
| when there is a low pH in the duodenum, which cells secrete secretin that stimulates the pancrease to release more bicarbonate? |
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Definition
S cells.
the bicarbonate release increases the pH. |
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Term
| what is the normal homeostatis of body temp? |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| normal blood glucose level? |
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Definition
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Term
| if you have > 120mg/100ml glucose in blood you are? |
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Definition
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Term
| if you have < 80mg/100ml glucose in blood you are? |
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Definition
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Term
| if blood glucose level is too high which cells of the pancrease release a substance and what is the effect of this? |
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Definition
beta cells of pancrease release insulin.
causes body cells to take up more glucose
liver takes glucose and stores as glycogen |
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Term
| what happens when blood glucose level is low? |
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Definition
alpha cells of pancrease release glucagon.
liver breaks down glycogen and release glucose to the blood |
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Term
| name the two main classes of hormones? |
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Definition
peptides and proteins eg. insulin
steriods eg. testosterone |
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Term
| insulin works by triggering events within cell cytoplasm through second messenges. what must it initially do? |
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Definition
| binds to receptor on cell surface |
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Term
| what is testosterone manufactured from? |
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Definition
cholesterol.
testosterone can pass across lipid bilayer of pm and bind to receptors within cells. |
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Term
| signal transduction is the conversion of a signal at a cell surface to a specific cellular response. this is a multistep process. what are the 3 stages? |
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Definition
reception of signal
transduction of signal
cellular response - output response |
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Term
| in reception of signal at the cell surface what changes the conformation of the receptor protein? |
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Definition
| the binding of a signal molecule to the specific receptor protein |
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Term
| in transduction of the signal how is the signal amplified? |
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Definition
multistep pathways eg. protein phosphorylation by protein kinases.
multistep pathways can provide more opportunities for coordination and regulation |
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Term
| signal transduction pathway results in an output. this may involve action in the nucleus or occur in the c............m |
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Definition
cytoplasm
some pathways regulate the activity of an enzyme
others activate transcription factors |
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Term
t or f?
different cells have different collections of proteins? |
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Definition
true.
these differences result in specificity in responding to signals. |
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Term
| what helps cells coordinate incoming signals? |
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Definition
| Pathway branching and cross-talk |
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Term
| what does auxin (an amino acid derivative) do? |
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Definition
| responsible for plant body development like bicoid in drosophila melanogaster |
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Term
| what do cytokinins (adenine derivatives) do? |
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Definition
| promote cell division and cytokinesis in roots and shoots. are a plant growth substance (phytohormone) - a chemical that regulates plant growth |
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Term
| Gibberelins. what do they do in plants? |
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Definition
| plant hormones, they regulate growth influencing developmental processes such as stem elongation |
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Term
| what role does absisic acid have? |
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Definition
| plant hormone involved in bud dormancy |
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Term
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Definition
| promote cell elongation and cell division |
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Term
| name a difference between signal transduction between plant vs animals |
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Definition
a single plant hormone may be produced by more than one cell type.
there is no conventional circulatory system in plant signsl transduction |
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