examplify Review Flashcards
Describe the sodium pump
Exchanges extracellular K+ for intracellular Na+
Which transporter buffers changes in pH only via acid extrusion
Na-H-exchanger
How do you resist cell shrinking
Osmotically active ions causes osmotic gradient
Water moves by following
Osmotic gradients
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
What does increasing membrane permeability for a particular ion do
Move membrane potential towards Ek for that ion
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
When nerve cell becomes highly permeable to Na+ what is new potential
+55mV depolarisation
What type of gating is involved in signalling at neuromuscular junction
Ligand gated (Ach is ligand)
What process is involved in repolarisation of a cell membrane
Opening of potassium channels
Calcium binds to synaptotagmin to form
Snare complex
Neurotransmitter released from vesicle binds to
nACh receptors
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
Substrate in M1 receptor
PIP2
Substrate in alpha 2 and beta 1 receptor
AMP
outcome of M1 receptor
Increased IP3
Outcome of alpha 2 receptor
Decreased cAMP
outcome of beta 1 receptor
Increased cAMP
Which target protein will the intracellulair messenger created act upon after activation of G alpha s
PKA
Adenylyl Cyclase creates cAMP, which targets PKA
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
G alpha I causes
Decrease cAMP
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
