Physiology + Pharmacology Flashcards
What do all cells require to correctly function?
Constant Internal Conditions, must be in a fluid environment.
Broadly, how is a constant internal environment achieved and maintained?
Homeostasis
What strucutre is responsible for preventing unwanted particles entering body tissues at exchange surfaces?
Tight junctions
What difference in osmolarity between the cell and its environment is needed to prevent lysis?
They must have a near equal osmolarity.
What 3 fluid environment make up the internal environment of the body?
Blood plasma, Interstitial Fluid, and Intracellular fluid
What is perfusion?
The passage of through the circulatory system or lymphatic system to an organ or tissue.
What vital parameters are controlled across the entire body?
Arterial blood pressure + blood volume
What vital parameters are controlled across the internal environment:
Plasma levels of O2, nutrients and electrolytes.
Core temperature.
What vital parameters are controlled across the cellular level?
ATP and Ion levels
What are the 4 components of the response mechanism to disruptions to a steady state?
Receptors -> control centre - > output -> effector
Where are the control centres located controlling homeostasis?
The hypothalamus + brainstem
What is meant by the term redundancy?
Multiple mechanisms used to reduce the chance of failure.
What do negative feedback loops do?
When a physiological adjustment occurs they work in the opposite direction, returning parameters to their original level.
What do positive feedback loops do?
When a physiological adjustment occurs they work in the same direction, to further move a parameter from its original level/value.
What is pharmacology?
The study of mechanisms by which drugs affect the function of living systems.
What are the fundamental principles of pharmacology?
Drug action must be explicable in terms of chemical interactions
Drug molecules must be bound to particular constituents of cells to produce an effect.
Drug molecules exert chemical influence on one or more constituents of cells in order to produce a pharmacological response.
Main difference between the neural and hormonal system in homeostatic mechanisms?
Neural is faster + hormonal is slower
What medium is used to transport hormones across large distances?
The blood
Where are hormone receptors within a cell?
The cell surface, in its cytosol or in its nucleus.
Peptide hormone synthesis:
From amino acids
Amino acid derived hormone synthesis:
Derived from tyrosine -> synthesis req. specific enzymes
Steroid hormone synthesis:
Metabolites of cholesterol + req. specific enzymes.
Secretion of Peptide hormones:
Secretory granules undergo exocytosis
Secretion of Amino acid derived hormones:
Vesicles via exocytosis (except thyroid hormone)
Secretion of Steroid hormones:
Lipid soluble and can diffuse out.
Location of receptors for Peptide hormones:
Cell membrane surface
Location of receptors for Amino acid derived hormones:
Cell membrane surface
Location of receptors for Steroid hormones:
Intracellular receptors in cytosol or nucleus.
what are the main 7 endocrine glands?
Pituitary (ant and pos)
Thyroid
Parathyroids
Adrenal (cortex and medulla)
Ovaries
Testes
Endocrine Pancreas
Endocrine tissues other than the 7 main glands:
Hypothalamus
Kidney
GI tract
Heart
Liver
Adipose tissue
What are the two “blurred line” categories of hormones?
Paracrine factors + neurpeptides
Neruopeptides:
Molecules that operate as both hormones and neurotransmitters
Thyroid gland: Hormones
Tyrosine - T3 and T4:
Pro-hormones produced by follicular cells and stored extracellularly as prohormone in colloid
What is colloid?
Extracellular purple fluid.
What chemical is used by the thyroid to initiate Tyrosine uptake into the blood.
Iodine is used to uptake tyrosine from the colloid into the follicular cells and then into the capillaries via faciliated diffusion.
What processes is tyrosine a key hormone for?
Development, Growth, and metabolism.
What does the parathyroid gland secrete?
Parathyroid hormone (PTH)
What does PTH target?
Bone tissues, GI system and the kidneys
What is the role of PTH in the body?
To regulate the plasma levels of Ca2+ and phosphate
Adrenal cortex secretions:
Steroid hormones, Glucocorticoids, and mineralocorticoids.
Example of a Mineralocorticoid:
Aldosterone
Example of a Glucocorticoid:
Cortisol
Adrenal Medulla secretions:
Adrenaline and Noradrenaline
What group are adrenaline and noradrenaline a part of?
Catecholamines
What cells release adrenaline in the adrenal medulla?
Chromaffin cells
What cells secrete testosterone within the testes?
Leydig cells
What is the function of testosterone:
Stimulates proteins synthesis and leads to development and growth
What hormone is secreted by the testes?
Testosterone.
What is secreted by the endocrine pancreas?
Insulin and glucagon.
What cells in the endocrine pancreas secrete insulin?
Ꞵ cells
What cells in the endocrine pancreas secrete glucagon?
α Cells
What is the Adenohypophysis?
The anterior lobe of the pituitary gland (develops from an upward projection of the pharynx)
What is the Neurohypophysis?
The posterior lobe of pituitary (develops from a downward projection of the brain)
What is the portal system?
The movement of blood from one tissue to another without returning to the heart.
What is the hypophyseal system?
A system of blood vessels in microcirculation at the base of the brain, connecting the hypothalamus with the ANS posterior.
What are tropic hormones?
Hormones which effect the release/expression of other hormones often by stimulating glands. e.g TSH (thyroid stimulating hormone)
What are the 3 ways hormone secretion is regulated?
neural mechanisms, Tropic hormone action, and positive/negative feedback loops.
Who was responsible for the foundations behind the concept of receptors?
Langley
What chemical from what plant was used in Langley’s experiments?
Pilocarpine from jaborandi trees.
What effect on frogs and dogs does pilocarpine have?
Slower heart rate + increased saliva production.
What are the two antagonistic hormones langley used?
Pilocarpine + Atropine
When comparing affinity what is meant by relative mass?
Concentration
What is affinity?
The tendency of a chemical/molecule to bind to a receptor
What are receptors?
they are macromolecular proteins that serve as recognition sites. Or they can be any cell protein that binds to a molecule/drug with an effect on some intracellular activity.
What information is taken from receptors to design drug?
The structure of receptors.
What information is taken from receptors to design drug?
The structure of receptors.
What information is taken from receptors to design drug?
The structure of receptors.
What is the general pathway of chemical communication and cell signalling:
Extracellular signal molecules bind to specific receptors -> intracellular signals -> alters cell behaviour
How many cells can most extracellular signal molecules act on?
More than one, allowing for coordinated responses.
What is meant by the amplification of cell signalling?
The initial signal protein may cause a secondary cascade e.g a cAMP pathway.
What are the 4 types f intercellular communication?
contact-dependent, paracrine, synaptic, and endocrine
Paracrine Signalling: Summary
Paracrine signals are released by cells in the extracellular fluid and act locally
Contact-Dependent Signalling: Summary
A cell-surface-bound signal molecule binds to a receptor protein on an adjacent cell
Synaptic Signalling: Summary
Neuronal signals are transmitted electrically along a nerve cell axon, when it reaches the nerve terminal it causes the release of neurotransmitters onto adjacent cells across synapses.
Endocrine Signalling: Summary
Hormones produced by enodcrine glands are secreted into the bloodstream and are distributed widely across the body.
What are the two main functions of contact-dependent signalling?
Development and Immune responses (T-cells)
What is an example of the therapeutic manipulation of contact-dependent signalling?
CAR T immunotherapy: Uses contact-dependent signalling to kill cancer cells -> use CAR (engineered receptors designed to recognise cancer cells) -> inserted into genome of patient T-cells
What is meant by autocrine signalling?
A type of paracrine signalling where the mediators released are received by the cell which released them.
What are the 3 main functions of paracrine signalling?
Inflammation, cell proliferation and wound healing.
How are the chemical messengers stored in paracrine signalling?
Stored in vesicles or are synthesised on demand.
What is an example of the pharmacological manipulation of paracrine signalling?
Counter allergy medications bind to histamine receptors and block histamine action -> preventing swelling and itch. Some drugs regulate the intracellular signalling induced by chemical messengers.
What effect does Nitric Oxide have on smooth muscle cells?
NO causes smooth muscle to relax and causes vasodilation.
How does Viagra work?
Viagra inhibits the enzyme responsible for the breakdown of cGMP, prolonging the action of NO.
Where do drugs acting on neurotransmission act?
Either the pre or post synaptic neurone. At pre -> influences neurotransmitter synthesis, storage, or release. At post -> influences neurotrans. receptors
What is an example of the pharmacological manipulation of endocrine signalling?
Treatments for type 1 and type 2 diabetes.
Type 1: Drugs mimic insulin
Type 2: Drugs increase signalling through insulin receptor
Anaphylaxis: Adrenaline auto-injectors
What are bioassays used for?
To measure the pharmacological activity of new or chemically undefined substances, To investigate endogenous mediators, and to measure drug toxicity and unwanted effects.
What is defined as a mediator?
A chemical, peptide, or protein that conveys information from one cell to another.
When are mediators released?
In response to a stimulus of some kind, a mediator is released and produces a particular biological response.
What are the criteria req. for a substance to be a mediator?
-Must be released from cells in sufficient amounts to produce a biological action on target cells within an appropriate time frame.
-Application of an authentic sample of the mediator reproduces its biological effect.
- Interference with the synthesis, release, or action ablates or modulates the original biological repsonse.
What is ablation?
The removal or destruction from an object by vaporisation, chipping, erosive processes or by other means.
What are the two ways in which chemical mediators are synthesised?
Synthesis of smaller molecular mediators is regulated by by specific enzymes. Synthesis of peptides is regulated by transcription.
What in the cell determines which mediators are produced?
The genes and enzymes active in the cell.
How many types of mediator can a single cell produce?
A single cell can produce multiple types of mediator.
How many types of mediator can a single vesicle store?
More than one type of mediator
What is constitutive secretion?
Secretion of vesicles occurs continuously with small amounts stored in a cell. (e.g the release of plasma proteins and clotting factors by liver cells)
What is meant by regulated secretion?
Occurs in response to increaseed intracellular Ca2+ or other intracellular signals -> significant amount of stored secretory vesicles released.
What are the two main groupd of chemical mediators?
Mediators that are pre-formed and mediators that ar eproduced on demand.
What is different about the way the two main groups of mediators are released by cells?
Pre-formed mediators are stored in vesicles and are released by exocytosis, whereas mediators produced on demand are released by diffusion or constitutive secretion.
Difference in speed of the two main mediator groups?
Pre-formed mediators work more rapidly, whereas on demand mediators take longer to act.
Examples of on demand mediators:
NO, and prostaglandins
Examples of pre-formed mediators:
Noradrenaline and peptide mediators.
What is the type of secretion by which pre-formed mediators are released by?
Regulated secretion
What is the name of the hypothesis which predicted the existence of vesicles?
The quantal hypothesis.
What piece of apparatus was used to identify vesicles?
Transmission Electron microscope
What is the name of the sensor protein which allows for vesicles to detect calcium in regulated secretion?
Synaptotagmin.
How does synaptotagmin aid regulated exocytosis?
Allows for the vesicles to bind to membrane proteins in the presence of Ca2+ -> allows for
membrane fusion
Why is termination of neurotransmitter action necessary?
To ensure neurotransmission accurately represents the action potential frequency.
What are the two mechanisms by which neurotransmitter action is terminated?
Enzyme action (breakdown of neurotransmitters at synapses)
Uptake of neurotransmitters into pre-synaptic neurone or supporting cells. (Transport proteins in the plasma membrane and vesicular transporters)
What would therapeutic drugs interfering with neurotransmission be used for?
Alleviation of symptoms of neurological conditions
Examples of drugs that interfere with neurotrasmission:
Prozac(Fluoxetine) -> targets transporters -> prevents the reuptake of neurotransmitters
What is the benefit of synthesising drugs with greater specificity to a receptor?
Fewer side effects as the drug binds to less receptors unintentionally.
What are the 4 classes of proteins commonly targeted by drugs?
Enzymes, Transporters, Ion Channels, Receptors
Example of drugs that target ion channels in neurotransmission:
Lignocaine and Gabapentin
What are ion channels?
Transmembrane proteins that allow for non-lipophilic molecules/ions to cross the membrane
What does Lignocaine bind to when regulating neurotransmission?
Lignocaine blocks Na+ channels, inhibiting the formation of action potentials.
Example of illegal drug that targets receptors involved in cell communication:
Morphine (opium)
What are the uses of using drugs that target receptors in cell communication:
Regulate cellular processes, enable the communication between cells, and allows for the coordination of tissue/organ/bodily responses.
How many families of receptors exist within the mammalian genome?
25
What is the definition of receptors in pharmacology?
Proteins that serve as recognition sites and allow the binding of chemical mediators.
What are the 3 functions of Receptors?
regulation of cellular processes, chemical recognition and binding, and intracellular signal generation.
What are the 4 main classes/ super families of receptor?
Ligand-gated ion channels, G protein-coupled receptors, kinase-linked receptors, and Nuclear receptors.
What are the shared characteristics of receptors on the cell surface membrane?
-Transmembrane segments of 20-25 hydrophobic amino acids
-Extracellular ligand binding domain
What are the characteristics/features of nuclear receptors?
-Regulate gene transcription
-DNA-linked
-Ligand bound can cross the plasma membrane (lipophilic)
Example of a nuclear receptor:
Oestrogen Receptors
What is a ligand?
Any molecule that binds to the receptor
What is an agonist?
Drug or chemical mediators that bind to a receptor to produce a response.
What is an antagonist?
Drugs that prevent or inhibit the response of an agonist, they bind to the receptor however don’t elicit a response.
-Majority of clinically useful drugs
Examples of Agonists:
Pilocarpine, nicotine, acetylcholine, and morphine
Examples of Antagonists:
Atropine and curare
Example of malfunction of ligand-gated receptors causing disease:
myasthenia gravis -> 1/2000 -> Muscle weakness in neuromuscular junction -> treated with anti-cholinesterase (prevent breakdown of ACh) and immunosuppresants
What factors effect how long a chemical signal lasts?
How long the agonist is present, how long the downstream effects remain active, the mechanisms involving the termination of the signalling.
What is the order of the 4 receptor classes in order of speed (fastest to slowest)
ligand-gated ion channels (ms) -> G-protein-coupled receptors (s) -> Kinase-linked receptors (h) ~ nuclear receptors (h)
Why do kinase-linked receptors and nuclear receptors have similar transduction speeds?
Both of their pathways involve gene transcription and gene synthesis before cellular effects are experienced.
Summarise what a ligand-gated ion channel does to induce a change in a cell:
It changes the permeability of a cell to a specific ion (hyperpolarisation or depolarisation)
Summarise what a G protein-couple receptor does to induce a change in a cell:
G protein activated upon mediator binding to receptor -> either binds to ion channels or effector which synthesises second messengers -> induce effects.
Summarise what a Kinase-linked receptor does to induce a change in a cell:
upon binding -> phosphorylates a secondary messenger -> leads to gene transcription -> protein synthesis -> cell effected
What is the alternative name for ligand-gated ion channels?
Ionotropic receptors
Structure of Ligand-gated ion channels:
3-5 subunits (proteins)
Each subunit has 2-4 transmembrane domains
Complex of subunits arranged to form an aqueous pore
What is meant by a desensitised state?
Where an agonist is bound to a receptor however has no effect.
What are two key examples of ligand-gated ion channels?
nAChR - Nicotinic Acetylcholine Receptor (At NMJ, Autonomic Ganglion Neuron, and Brain Neurons) and Glutamate receptor
What are the Agonist and Antagonist that work at nAChR?
Agonist: ACh, Nicotine
Antagonist: tubocurarine
What differs between sub-types of receptors within a family?
Their subunit compositions and pharmacology
What does the nomenclature of receptor describe?
The receptors subunit composition.
What type of diseases can be caused by the malfunction of ligand-gates receptors?
Autoimmune diseases e.g (myasthenia gravis)
Which two types of receptors are most often used by chemical mediators/neurotransmitters?
Ligand gated ion channels and G protein-coupled receptors.
How many proteins make up a G protein coupled receptor?
A single protein.
How many transmembrane domains does a G protein coupled receptor have?
7 transmembrane domains (7TM)
How many genes code for GPCRs?
800+
What is an “orphan” GPCR?
A GPCR with an unknown ligand to bind to.
What occurs in a GPCR following the binding of an agonist?
signal transduction occurs via the activation of heterotrimeric G proteins.
How can GPCRs link?
Different GPCRs can target the same heterotrimeric G protein, allowing for the interaction between some GPCR pathways.
In depth signal transduction of Heterotrimeric G proteins:
Upon ligand binding to the receptor, receptor-G protein undergoes conformational change promoting the exchange of GDP for GTP -> G protein dissociates from receptor + ligand disociates -> alpha-GTP and Beta Gamma subunits dissociate -> Both subunits interact with enzymes, before reassembly of the trimer and association with the receptor.
What are the types of effectors:
Ion channels and enzymes
What are 2nd messengers?
Small diffusible molecules that spread a signal.
What are Ga(s) and Ga(i)
Ga(s) is a stimulatory G protein complex and Ga(i) is an inhibitory G protein complex. Both acct on Adenylyl cyclase.
What does Adenylyl cyclase catalyse?
The conversion of ATP to cAMP.
What cAMP regulate?
The activity of other proteins involved in the signal transuction (including PKA)
What effect does cAMP have on PKA activity?
cAMP increases PKA activity.
What is PKA?
Protein kinase A -> enzyme involved in signal transduction
Does cAMP have different effects in different cells?
Yes, cAMP has a variety of effects specific to tissues.
How does PKA regulate “downstream” effectors?
Phosphorylates proteins to activate proteins. e.g Ion channels, receptors, metabolic enzymes, signalling proteins, or transcription factors.
What does phospholipase C do?
Breaks down the bonds between lipids, producing DAG (Diacyl glycerol) and IP3. DAG activated PK C and IP£ activated ligand binding channels on the ER -> allowing for Ca2+ to leave into the cytosol.
What protein complex activates Phospholipase C?
Ga(i)
What two pathways are used for smooth muscle contraction:
GPCRs coupled with Gq proteins + PLC signalling (Phospholipase C)
What is the advantage of cross-talk between receptors?
Allows for multiple stimuli to be responsible for specific changes to cell behaviour, allowing for control/more deliberate responses to changes to the external/internal environment.
What are the major components of the Nervous System?
The afferent Somatic Nervous system and Visceral nerves.
The CNS
The Efferent Somatic Nervous System (V)
and the Autonomic nervous system (IV)
The effectors (Skeletal muscle + smooth muscle, cardiac muscle, glands)
What are visceral nerves?
Sensory nerves within organs that detect internal changes
What are the two major efferent pathways of the ANS:
Sympathetic and Parasympathetic:
What is the generalised term for the sympathetic ANS pathway?
Fight or Flight
What is the generalised term for the parasympathetic ANS pathway?
Rest and digest
When is the sympathetic pathway activated?
Exercise, Excitement, emergency, embarrassment
When is the parasympathetic pathway activated?
Digestion, defecation and diuresis
How is the sympathetic pathway activated?
Co-ordinated, whole body response or discrete and organ specific.
How is the parasympathetic pathway activated?
Function in a discrete organ specific manner.
Effect of sympathetic stimulation on: Eyes
Pupil dilation -> increase visual field and observation abilities
Effect of sympathetic stimulation on: Heart
heart rate increases + contractility-> effects atria and ventricle -> increases supply of oxygenated blood to organs
Effect of sympathetic stimulation on: Blood vessels
Blood vessels at surface constrict -> more blood is directed to heart and muscles -> less digestion -> more blood at liver for glycolysis
Effect of sympathetic stimulation on: Lungs
bronchodilation -> increases airflow and maintains gaseous concentration gradient to maximise gaseous exchange.
Effect of sympathetic stimulation on: Liver
Glycolysis + gluconeogenesis -> increase blood sugar levels to provide glucose to muscles for respiration
What is contractility?
The force of heart contraction.
Effect of parasympathetic stimulation on: Eyes
Pupils constrict
Effect of parasympathetic stimulation on: heart
Heart rate decreases -> only effects atria
Effect of parasympathetic stimulation on: Gastrointestinal tract
Increase secretion
Effect of parasympathetic stimulation on: Bladder
contraction -> forces diuresis
Effect of parasympathetic stimulation on: reproductive organs
maintains erection
One word to describe the relationship between the sympathetic and parasympathetic division:
Synergistically
What is the benefit of the sympathetic and parasympathetic divisions antagonistic interactions:
Allows for rapid precise control of tissue function
What structures are solely innervated by the sympathetic division?
Sweat glands, Hair follicles, blood vessel smooth muscle, the adrenal medulla.
What is the general organisation of the ANS?
The CNS with preganglionic neurons -> linked to postganglionic neuron in the peripheral ganglion -> linked to target cell.
What are two essential components of the ANS within the CNS?
The spinal cord and Brainstem nuclei.
Role of the spinal cord in the ANS:
Mediates autonomic reflexes, Receives sensory afferent and brainstem input.
Role of the Brainstem nuclei in the ANS:
Mediate autonomic reflexes.
What does the hypothalamus control?
Hunger, thermoregulation, Circadian rhythms, water balance, sex drive, reproduction
Other than the hypothalamus what else regulates ANS output?
Forebrain + Visceral Afferent neurons
What is the role of the Forebrain in the ANS?
Minimal conscious conrtical control. e.g Anxiety can lead to GI disturbance + fear initiates fight or flight.
What is the role of Visceral Afferents in the ANS?
Sensory input from visceral afferent neurons takes priority over cortical functions -> e.g bladder distension will cause diuresis.
What is the importance of the vagus nerve in the ANS?
The Vagus nerve carries 80% of total parasympathetic outflow. It also contains many of the visceral afferents and therefore is responsible for much of the ANS stimulation
What is the primary neurotransmitter of preganglionic neurones?
ACh
What does ACh activate on a post synaptic cell?
nicotinic ACh receptors (ligand channels) -> allowing the entry of Na+ and K+ leading to excitation
Organisation of the sympathetic pathway:
Short cholinergic preganglionic neurons from thoracic and lumbar spinal cord -> long, adrenergic postganglionic neurons -> tissue expresses alpha and beta adrenergic receptors.
Meaning of Adrenergic:
Releases adrenaline (epinephrine), noradrenaline
Where are cervical neurons located?
The neck
Where are thoracic neurons located?
near the thorax
Where are lumbar neurons located?
The lower back
Where are sacral neurons located?
near the tail bone
What neuronal pathway is an exception in the sympathetic division?
The innervation of the adrenal medulla. Adrenaline is used and acts as hormone -> transported in the blood.
Organisation of the parasympathetic division:
long, cholinergic preganglionic neurons from the brainstem and sacral spinal cord -> short, cholinergic postganglionic neurons -> target tissues express ACh receptors
What does cholinergic mean?
Involves Acetylcholine e.g secretes ACh
What are the two prinicipal transmitters in the Auntonomic Nervous System?
Acetylcholine and Noradrenaline
Cholinergic receptors:
Either nicotinic or muscarinic:
(Muscarinic -> 5 subtypes)
Found on postsynaptic neurons in parasympathetic ganglion neurons and sweat glands.
Antagonists for Nicotinic Cholinergic Receptors:
Curare
Antagonists for Muscarinic Cholinergic Receptors:
Atropine
What are the effects of M1, M3, and M5 mAChR action?
Gq, ↑PLC, ↑IP3, ↑ intracellular Ca2+
What is IP3?
A chemical messenger produced by the hydrolysis of PIP2 -> works with DAG to transduce a biological signal.
What are the effects of M2 and M4 mAChR action?
Gi ↓Adenylyl cyclase ↓ cAMP
How many subtypes of mAChR (muscarinic acetylcholine receptors) are there?
5: M1, M2, M3, M4, M5
Main location of mAChR M1 receptors:
Autonomic ganglia, Glands, Cerebral Cortex
Main location of mAChR M2 receptors:
Atria (heart) + CNS (widely distributed in nodal tissues)
Main location of mAChR M3 receptors:
Exocrine Glands, Smooth muscle (eye, airways, bladder), Blood vessels (endothelium)
Main location of mAChR M4 receptors:
CNS
Main location of mAChR M5 receptors:
CNS, salivary glands, iris /ciliary muscle
Functional response of mAChR M1 receptors:
Gastric secretion + CNS excitation
Functional response of mAChR M2 receptors:
Cardiac + neuronal Inhibition: activate GIRK K+ channels and inhibit L-type Ca2+ channels
Functional response of mAChR M3 receptors:
Gastric + salivary secretion
Vasodilation
Ocular Accommodaiton
Functional response of mAChR M4 receptors:
Enhanced locomotion
Functional response of mAChR M5 receptors:
Not known
What are GIRK Potassium Channels?
G protein-activated inward rectifying K+ channels -> inhibit/work against the generation of an action potential
What type of receptor of M1 and M3 mAChRs?
Gq coupled receptors
What are the dangers of muscarine?
In high dosages can cause nausea -> lower blood pressure -> increases secretions of tears, saliva and sweat -> abdominal pain -> and Death from cardiac + respiratory failure.
Why is the clinical use of mAChr limited?
Most mAChR agonists aren’t selective and will cause many unintentional side effects.
What are the two mAChR agonists used clinically?
Cevimeline and Pilocarpine
Cevimeline treatment:
-M3 selective
-Improves salivary and lacrimal secretions in Sjogren’s syndrome (Dry mouth and eyes)
Pilocarpine treatment:
Non-selective mAChR agonist
-Applied as eyedrops to treat glaucoma
What is Glaucoma?
Glaucoma describes a group of eye conditions affecting vision which can cause blindness.
What causes Glaucoma?
Drainage tubes (trabecular meshwork) within the eye become slightly blocked, preventing eye fluid from draining and increasing intraocular pressure -> leading to optic nerve damage
Muscarinic Antagonists:
Atropine Example
Atropine:
-non-selective mAChR antagonist
-Can be used to reverse poisoning by antichoninesterases
-Reverse action of mAChR agonists
Muscarinic Antagonists:
treatments
Pirenzipine (M1 selective) - treats peptic ulcers
Darifenacin (M3 selective) - treats overactive bladder
What is the term used to describe drugs acting indirectly to enhance cholinergic transmission?
Cholinomimetic
Anticholinesterase drugs:
Physostigmine used topically to treat glaucoma
Other clinical uses: Reverse action of neuromuscular blocking drugs after an operation
- Treatment of myasthenia gravis,
Alzheimer’s Disease
What are the different types of adrenoreceptors?
Alpha 1, Alpha 1, Beta 1, Beta 2
What cells release adrenaline?
Chromaffin cells
What cells release noradrenaline?
sympathetic neurons
Clinical uses of adrenoceptor agonists:
Adrenaline (non selective): Cardiac arrest + Anaphylaxis
B2 Selective Respiratory System: Bronchodilator + Nasal Decongestant