Topic G Flashcards by Devanshi Pandit

3 Steps of how a motor neuron passes info to a skeletal muscle cell

1) Signal binds to receptor
2) Signal transduction
3) Change in cell behaviour

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4 types of signal response

preprogrammed response
one signal triggers several responses
signals amplified during transduction
signals integrated during transduction

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contact dependent signalling

cells are adjacent
Signal: membrane protein
Example: Apoptosis

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paracrine signalling

local cells
Signal: diffusible molecules released locally
Example: Cancer cells

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Synaptic signalling

distant cells
Signal: diffusible molecules delivered by cell extension
Example: Neurons

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Endocrine signalling

distant cells
Signal: diffusible molecules delivered by circulatory system
Example: Adrenaline, Insulin, Estrogen

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4 types of signals

small proteins, small organic molecules, gasses, extracellular vesicles

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True/False Nitric Oxide uses diffusion and needs a receptor

False! It does diffuse but does not require a receptor

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Cell surface receptors

ion-channel coupled receptors, G-protein coupled receptors, Enzyme coupled receptors

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Example of ion-channel coupled receptors

AChR

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example of G-protein coupled receptors

Adrenaline receptor

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example of Enzyme coupled receptors

insulin receptor

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Intracellular receptors and example

steroid hormone receptors, e.g. Estrogen receptor

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When do G-coupled receptors activate

when signal arrives

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When do G-coupled receptors deavtivate

when signals leave

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Kinases

put phosphates onto target proteins

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many proteins are regulated by ……

phosphorylation

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Kinase inactive ….. target on/off

kinase inactive target off

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kinase active …… target active/inactive

kinase active target active

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adrenaline

fight or flight response

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what releases adrenaline

adrenal gland cells

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how is adrenaline released

regulated exocytosis

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pathway of releasing adrenaline

adrenaline receptor is activated and activates G protein that produces cyclic AMP from ATP which activates an inhibitor that releases PKA (kinase active) which turns on the target protein

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3 responses of adrenaline

a) liver cells break down glycogen
b) heart pacemaker cells increase rate of AP
c) skeletal muscle break down glycogen

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Deactivation (2 things happen)

1) removal of adrenaline by diffusion, degradation, and uptake 2) phosphodiesterase breakdown cAMP inside of cells

Medical significance of adrenaline

epipens used to treat severe allergic reactions

3 steps of enzyme coupled receptors

1) signal molecule dimerizes the receptor 2) dimerized receptor phosphorylates itself 3) phosphorylated receptor activates other proteins

importance of glucose

mobile carbohydrates

pancreas function

make digestive enzymes for gut

which cells have the most glucagon receptors

liver cells

alpha islet cells (~1%)

release glucagon proteins that bind to receptors in liver cells when blood glucose concentration is low (leaves through GLUT)

beta islet cells (~1%)

release insulin proteins when blood glucose concentration is high

why is insulin signalling important

insulins signal that blood glucose concentration is high

insulin is a small ___

protein

insulin is released by

regulated exocytosis

2insulin receptors are ___ and ___ attached

permanently and loosely

true or false insulin protein is a tetramer

false, it is a dimer

when insulin binds to the insulin receptor what happens

brings the subunits close enough to phosphorylate each other

responses of insulin (2)

a) fat and muscle cells display insulin receptors | b) import and store glucose (kinase cascade)

insulin ___ glycogen synthase

activates

when glycogen is synthesized _____ breakdown decreases

glycogen

Deactivation

removal of insulin > subunits move apart > phosphatases remove phosphate groups > pinocytosis beings back using GLUT

Diabetes mellitus (type 1 and 2)

inability to regulate blood glucose 1- problem with insulin 2- problem with insulin recpetors

Type 1 Diabetes cause

body's own immune system kills insulin producing cells

Type 2 Diabetes cause

prolonged overeating leads to "full" fat cells deliberately displaying fewer insulin receptors

treating diabetes

monitoring glucose levels, insulin and healthy diet

steroid molecules (2)

hydrophobic molecules, made from cholesterol

globular proteins

carry steroid hormones in circulatory system

Steroid hormone receptors (2)

intracellular receptors and transcription factors

purpose of estrogen signalling

sex determination of females

Steps of estrogen activation

1) gonads in embryo becomes ovaries or testes 2) synthesis sex hormones and and do meiosis 3) sex hormones travel to other cells 4) sex hormones enter cells 5) activate transcription factors that turn on target genes

sex of xxy

male

SHBG

both estrogen and testosterone use, sex hormone binding globular protein

Medical significance of estrogen

a) birth control to prevent release of oocytes | b) cancer- some cancer cells make too many estrogen receptors

what toxins does coffee contain

caffeine

what toxins do poppies contain

morphine

what toxins do cannbis contain

cannbinoids

what toxins does tobacco contain

nicotine

What does nicotine do? (2)

target AChR on neurons resulting in increased activity in brains pleasure centre target AChR on adrenal glands

Nicotine is an ____ which ___ these receptors

agonist, activates

what does caffeine do (2)

target PDE in adrenaline pathway as a competitive inhibitor | target adenosine receptors telling the brain its tired

medical use of caffeine

help breathe and boost lung function

morphine source and medical use

natural, fast acting analgesic

heroin source and medical use

synthetic, none

codeine source and medical use

synthetic, slow-acting analgesic (slowly converts into morphine by liver enzymes)

fetanyl source and medical use

synthetic, extremely fast-acting analgesic

Do to treat overdose

naloxone is an antagonist which blocks these receptors

what do cannibinoids target

CB recpetors

THC

increase in euphoria, decrease in pain, strong agonist

CBD

decrease in euphoria, increase in pain, weak antagonist

if there is more THC than CBD

intoxication

Medical uses of cannibis

``` multiple sclerosis (drug called savitex 1:1 TBC to CBD) sedation on endoscopic procedures ```

Topic G Flashcards

(72 cards)