Smooth Muscle Physiology Flashcards by Eve McCulloch

What are the differences of skeletal cardiac and smooth muscle by type

Skeletal - straited and voluntary (somatic innervation by a and y motor neurons)
Cardaic - straited and involuntary
Smooth - untraited and involuntary
autonomic intervation (sympathetic and parasymapethic postganglionic fibres)

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what is the differences of skeletal cardiac and smooth muscle by individual muscle fibres

Skeletal - large elgoanted cylindrical and possess multiple nuclei
Cardiac - large cylindrical and poss multiple nuclei
Smooth - small spindle shaped and posses one nucleuis

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What does straited mean
what does voulntary and involuntary mean

straited means it contains scaramoeres
voluntary means you can control it will involuntary means it does it rest and digest and fight or flight

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Function of Smooth Musucle in different locations
Vasculature
Airways
Urinary System

Vasculature - controls diameter regulated flow and pressure
Airways - controls diameter regualted flow and resistance
Urinary - propulsion of urine into ureters bladder tone tone of internal sphincter of bladder

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Function of Smooth Musucle in different locations
Reproductive tract
Gatrintestinal tract
Skin

Male - secretion of sement
Female - proulsion of egg in fallopian tubes partiution in uterues
Skin - Pili erection

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What is the difference in shape and function of smooth muscle in the artery bronchiole and colon

Artery - arrned cyclindrial around the arteries contract and relax for blood pressure
Bronchole - small airways of lungs with muscle allow reduce increase bore of airways increase partial pressure more surface area
Colon - medtaite repulsive movement some curvature

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What is Multiunit smooth muscle
Allow
Word
how they function
example

electrical isolation of cells allows finer motor control
Tonic
Function individually
Iris and vas feernes

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What is Unitary
Permit
Function
Example
Word

gAP JUNCTIONS PERMIT COORDINATED CONTRACTION
function as a syncytium
stomach urinary bladder and bronchioles
Phasic

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What does Tonic and Phasic

Phasic constanltu engaged which provides a level of contraction (tone)
Tonic - slightly more contraction when stimulated controlling movements

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Function of relaxation to contracted

Contrctile arhcolines to a cytoplasm in the cell membrane (dense bodies) rather than the structural protein
Net like structure muscle cross bridges are formed sliding mechanism is ended pulled relaxed and contracted

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Xontractile machinery of Smooth Muscle

relies on sliding filament mechanism of generated during actin myosin cross bridge formation to facilitate contraction

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Cross bridge formation and sliding filament in smooth muscle

driven by a rise in CA which binds to calmodulin
Ca calmodulin complex actovayes myosin light chain kinase
Myosin light chiaan is phospahted on the myosin head
Phosphoylation of myosin head ‘cock’s it and increases its ATPase activity reading it to interact with actin to form a cross bridge

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Factors (2) affecting straited muscle cross bridge formation
CAS

incresed intraceullar Ca
stretch (Frank Sarling relationship)

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Factors affecting smooth msucle cross bridge formation (3)
CIP

Increase intracellular Ca
Phophylation of myosin light chain kinase
Inhibition of myosin light chain phopahtase

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What is calmodulin

Mulifunctional Ca2+ binding protien present in the cytoplasm of all eykarytoic cells
Ca can affect the protein and changes the light chain kinase
Calmodulin - Ca calmodium - CaM associated with a CaM kinase

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What does relaxation of smooth involve

Drop in Ca and Depohoyrlation

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How does Ca return to preexcitation cocentrations

Membrane bound Ca ATPase and Na Ca exchanges exepl calcium from the cell and calcium is sequestered into stores by sarco (endoplasmic reticulum calcium) ATPase (SERCA)

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How does depohosylation occur

Myosin light chain phopahtase

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How is innervation by autonomic nverous system in:
Aterial smooth muscle
Other smooth muscle
other point

Aterial - symapethic with noradrenaline
Other - both para and symapethic with acetylcholine
vast networks of nerual supply

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What is Parhamoechical coupling

process which agent causes a chnage in smooth muscle without change in membrane potential
involved production of intraceullar second messengers that wither contract or relax

what is Parhmoemchaical coupling important second messerngers

IP3 cuasinc contraction
cGMP and cAMP cuasing relaxtion

what is electrochemical coupling

opening of plasma membrane voltage actiavted L type Ca channels in response to depolarisation with or without action potential generation

Steps for Pharmocochemical coupling

Hormone Binds to GPCR
Phophildase PIP2 -> IP3 + DAG
DAG causes PKC activation CP17 decreases MLCK in myosin head
actives activity of MLCK no action potential

steps for phasmochemical coupling

Calicum binds to Sarplasmic
Ca exits cytoplasmi inudes release activation of myosin cross bride contractionaction optential opening L type calcium channels

Steps for restoring Ca

Sodium Ca cell membrane uses electrochemical graident sodium inside is low Calcium out extracellular Ca ATPase ATP

Regulation of smooth muscle tone receptors

Regulation of Smooth muscle tone uses L type Ca channels and GPCR Gq to bring Ca into the cell

Regulation of smooth muscle tone binding

The ca binds to the calmodulin to form a Ca Calmodulin complex that makes MLCK Active

Regulation of smooth muscle tone contraction

Active MLCK phosphorylates MLC which causes a contraction

Regulation of smooth muscle tone relaxation

Cyclic GMP actives PKG which makes MLCP active Active MLCP dephorylates MLC which causes relaxation

NO moving into the smooth muscle cell

Organ Nitrates from tissues comes into the smooth muscle cell from endothelial cell

Endothelium dependent vasodialtion relaxation

NO activates guanylate cyclase which breaks down GTP to cGMP causing the activation of Protien Kinase G causing relaxation

Endothelial making NO citrulline

the vasodilating substances increase the Ca in the endothelial cell which binds to calmodulin and this complex Ca calmodulin complex activates eNOS which actives L arginine + O2 to form No + citrulline which goes into the smooth muscle cell

how does PKG cause relaxation

PKG can increase activity of membrane bound potassium channels. the channels respond to voltage membrane potential which reduces calmodulin complex and reduces MLK causing relaxation

PKg stimulates and actives

PKG stimulates MLCP , PMCA , SERCA and activates K+ channels that cause hyperpolarisation and inactive Ca channels

what is angina

Angia means that there is no sufficent supply of blood the myocardium with oxygen Agina is caused fixed vessel narrowing and endothelial dysfunction

stable vs unstable angina

stable angina is episodic brought on by exertion relieved by rest and unstable angina is symptomatic even at rest

NO production and relaxation

Organic Nitrates act directly on the smooth muscle cell to increase NO production. same signalling cascade as endogenous NO release leads to smooth muscle relaxation and therefore vasodilation

action and where of NO

Acts primarily on veins to reduce preload and oxygen demand in the myocardium. secondary action on the coronary collaterals to improve oxygen delivery to the ischaemic myocardium

Relief of NO

this system gets relief given fast acting or can also get a longer working one reduce symptoms and exploits NO in the skeletal muscle cell

Effects of organic nitrates on Venodilation:

Effects of organic nitrates on Venodilation: this primary action of organic nitrates is to induce venodilation venodilation reduces venous pressure and the venous return to the heart this reduces work of the heart reduces oxygen demand

effect of organic nitrates on the coronary collaterals diagram

when there is atheromatous plaque means there is less blood flow to the ischaemic myocardium however organic nitrate dilates the collateral which means both sides are even

Glyceryl Trinitrate

Glyceryl Trinitrate - do no directly release NO biologically inactive, have a half-life of 40 mins and have a low bioavailability

Isosorbide Dinitrate

Isosorbide Dinitrate - do no directly release NO , biologically inactive , half life of 2 - 4 hours and bioavailability varies

conditions managed by phasrmacological manipulation of smooth muscle consequences

conditions managed by phasrmacological manipulation of smooth muscle consequences include left ventricular hypertrophy , renal failure , stroke

Calicum blockers act on what

Calcium channel blockers act at L type calcium channels on vascular smooth muscle but also at l type calcium channels in cardiac myocytes

three main classes of calcium channels blockers

the three classes of calcium channels blockers: dihydropridines , benzothiazepines and phenylalkylamines

what do KATP channel openers cause

K channel openers in serve hypertension can be used with beta blocker and diuretics and opens KATP channels in the smooth muscle cell membrane and hyperpolarise the smooth muscle cell

a blockers

a1 adrenoreceptors are the first part of the signalling cascade that ultimately leads to smooth muscle contraction following activation of sympathetic nervous system leading to vasodilation