examplify Review Flashcards by Ellie Matthews

Describe the sodium pump

Exchanges extracellular K+ for intracellular Na+

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Which transporter buffers changes in pH only via acid extrusion

Na-H-exchanger

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How do you resist cell shrinking

Osmotically active ions causes osmotic gradient

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Water moves by following

Osmotic gradients

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Explain why resting membrane potential is not the same as the equilibrium potential for potassium

Cell is not purely permeable to potassium
Movement of other ions occurs
Cell is slightly less negative than Ek

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What does increasing membrane permeability for a particular ion do

Move membrane potential towards Ek for that ion

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How does Na-K-ATPase contribute to resting membrane potential

Active transport of ions is responsible for entire membrane potential

Sets up and maintains ionic gradients that generate resting membrane potential

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When nerve cell becomes highly permeable to Na+ what is new potential

+55mV depolarisation

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What type of gating is involved in signalling at neuromuscular junction

Ligand gated (Ach is ligand)

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What process is involved in repolarisation of a cell membrane

Opening of potassium channels

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Calcium binds to synaptotagmin to form

Snare complex

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Neurotransmitter released from vesicle binds to

nACh receptors

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2 clinically relevant aspects of neurotransmitter release

Disease processes can alter the sequence e.g. myasthenia gravis altering the nACh receptors

Drugs can be used to block this process for therapeutic benefit e.g. succinylcholine causing muscle weakness during anaesthesia

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Substrate in M1 receptor

PIP2

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Substrate in alpha 2 and beta 1 receptor

AMP

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outcome of M1 receptor

Increased IP3

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Outcome of alpha 2 receptor

Decreased cAMP

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outcome of beta 1 receptor

Increased cAMP

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Which target protein will the intracellulair messenger created act upon after activation of G alpha s

PKA

Adenylyl Cyclase creates cAMP, which targets PKA

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What happens to level of secondary messenger when M2 muscarinic acetyl choline receptor is stimulated

Decreased cAMP

M2 receptors coupled with G alpha I : adenylyl cyclase inhibited causing reduced cAMP

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G alpha I causes

Decrease cAMP

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Ryanodine receptors are on the

Endoplasmic reticulum/sarcoplasmic reticulum

Calcium entering cytoplasm causes a

Calcium spark

Ions released into cytosol after calcium spark allow

Actin filaments to bind to troponin C causing crossbridge cycling

What is SOC

store operated channel

What does SOC do

Slow release of calcium when all other sources have been depleted

What is PMCA

plasma membrane calcium ATPase

What does PMCA do

Quickly export calcium back into extracellular space (main carrier)

What does NCX do

Expel calcium when PMCA lowers intracellular concentrations

What is SERCA

sarco endoplasmic reticulum calcium ATPASE

what does SERCA do

Used with NCX to rapidly re establish calcium gradients in excitable cells by sending calcium back into cytoplasm

What does CICR do

Ligand gates ion channel opening linked via ryanodine receptor to calcium release by SER/ER

What does calmodulin do (CaM)

Intracellular sensor of calcium ion conc, modulates activity of PMCA

Which calcium channel is essential in regulating CICR

Ryanodine receptors on endoplasmic reticulum

Sympathetic has short

Pre ganglionic

PNS uses

mAChR on post

SNS uses

Adrenoreceptors on post

PNS nuclei are found in

Brainstem and sacral region of spinal cord

SNS is found in

Thora columbar region of spinal cord

What does a beta 1 antagonist do

Speed up heart

What does antagonising M2 receptor do

Tachycardia

Beta blockers work on

Beta 1

Side effects of antagonist of muscarinic receptors in lungs

Dry mouth Constipation Urinary retention Sludge limited

Myasthenia gravis key points

Augmented effect of Ach as prevents degradation

Symptoms of pheochromocytoma

Noradrenaline and adrenaline | Headaches, palpitations, swelling

Organs most affected by beta blockers

Brain kidneys GI tract | Brain disturbances, urinary dysfunction, diarrhoea

Most likely cause of adverse side effects of drug treatments

Binding of active ingredient to sites other than those intended

What is efficacy

100% efficacy (emax) is maximum response achievable from a drug within a particular system or tissue of the body

What is EC50

concentration of drug that elicits half the maximal response of a full agonist

What is intrinsic efficacy

How effective a drug or ligand is at inducing active conformation of target protein

What is Kd

Dissociation constant for binding of a ligand to a receptor

What is potency

Dose of a drug required to produce a specific effect of given intensity usually EC50

What means High potency and affinity

Lowest Emax/EC50

Difference between phase 1 and 2 drug metabolism

Both alter drug structure Phase 1- retains acidity or becomes active Phase 2- inactivated and made more prone to elimination