Muscular Tissue Flashcards
Cell membrane of a muscle cell
Sarcolemma
Cytoplasm of cell membrane
Sarcoplasm
To forcefully shorten
Contractility
Response to stimuli
Excitability
To stretch or to extend
Extensibility
To return to its normal length after stretch
Elasticity
It is a rod like long contractile fiber
Myofibril
Sac like membrane for contraction and relaxation
Sarcoplasmic reticulum
Thick muscle contraction and cell motility
Thick (myosin)
Thin muscle contraction
Thin (actin)
It is attached to the bone, skin, or fascia
Skeletal muscles
It is a connective tissue that seperates single muscle fibers (surrounds the muscle fibers)
Endomysium
Covering of fasciculus which transmit lateral contractile (surrounds the bundle of muscle fibers)
Perimysium
Allows muscle to contract and move while maintaining structural integrity (surrounds the muscle)
Epimysium
Transmit mechanical action
Fascicle
One muscle bundle
Fasciculus
What is the nervous control of skeletal muscle?
CNS
What is the appearance of skeletal muscle?
Single, very long, cylindrical, multinucleated with striations
Stimulation of single muscle to contract by ANS
En toto or En masse
A zone where there is no A band
Henzen zone
Region of I band to I band
Sacromere
What is the manner of contraction of skeletal muscle?
Very rapid
Time of twitch
0.1 second
Time of stimulation
0.01 second
Time of contraction
0.03 second
Time of relaxation
0.04 second
It connects the branching of myofilaments to contract at the same time
Intercalated disks
Cells and muscles for 1 function only
Synctium
What are the 2 synctia of heart?
Atrial and ventricular
Function of atrial synctium
To contract
Function if ventricular
Pump out blood
(Left - other body parts, right - lungs)
Appearance of cardiac muscle
Branching chains of cells, unicleated or binucleated, with striations
What is the nervous control of cardiac muslce
ANS
What happens in en toto or en masse
- Stimulation of one muscle cell to contract by ANS
- SA node stimulates all muscle cells of atrial synctium to contract and relax.
- Then stimulation of AV nodes - stimulates the ventricular synctium to contract and relax
= rythmic contraction of heart
Nerve fibers surrounding entire ventricles
Bundle of His
What is SA node
Considered as pacemaker to determine beat of heart
Meaning of SA node
Sinoatrial node
Meaning of AV node
Atrioventricular node
Series of involuntary wavelike contraction of smooth muscles
Peristalsis
-Attach to hair follicles in skin
-In walls of hollow organs like blood vessels and GI tract
-non striated
Smooth muscles
Nervous control of smooth muscles
ANS - medulla oblongata
Manner of contraction if smooth muscles
-slow wave like contraction
What happens of manner of contraction of smooth muscles
Stimulation of initial cells to contract by ANS, then stimulated by ANS the next muscle then proceed until the last muscle cell to contract
What is the arrangement of myofilaments in smooth muscles
Irregularly arranged (diagonally)
What is attached to dense bodies?
Intermediate filament bundle
True or false: therr are more thick filaments in smooth muscles
True
There is no troponin complex in smooth muscle
Yes
A synapse or connection between motor neuron and muscle fiber
Neuromuscular junction
Are the nerves that innervate muscle fibers / or the glands
Motor neurons
Single motor neuron and the muscle fibers it innervate
Motor unit
What happens when axon approaches muscle?
It divides into terminal branches and loses its myelin sheath and form junction with one or more muscle fiber
It is called when the axon terminal is enlarged into a knoblike structure which fits into shallow depression in underlying muscle fiber
Terminal button
Where does acetylcholine came from?
Stored in synaptic vesicle
Where does action potential arrives? And what will happen?
It arrives in pre-synaptic terminal and cause volted gated ca2+ channels to open
How action potential is initiated
When the cell body has received enough excitatory signals from other neurons
What makes the action potential be able to open the voltage-gated ca2+ channels?
-Action potential depolarizes the membrane and opens voltage-gated channels
-Carries electrical properties which the voltage-gated channel will RESPOND TO OPEN
When Ca2+ uptake in terminal what does it cause
Release neurotransmitters (acetylcholine) into synaptic cleft
Another term for post synaptic cleft
Motor end plate
What does motor end plate contains? And what is it for?
It contains nicotinic receptors for acetylcholine
Enumerate the process of neuromuscular junction (before end plate potential)
- Action potential arrives at pre-synaptic terminal causing the voltage-gated ca2+ channels to open.
- Ca2+ releases neurotransmitters (acetylcholine) from synaptic vesicle to synaptic cleft
- Ach travels across synaptic cleft to motor end plate.
- Motor end plate contains nicotinic receptors where Ach binds
- Ach binds to the alpha subunit of the nicotinic receptors resulting to conformational change
- Na influx K efflux
- Causing the central core channels to open and increase the permeability of Na+ and K+
- Sodium enter muscle fiber
(Ach molecules combine with receptor sites cause to open ligand-gated Na+ channels for Na+)
What happens in end plate potential?
- When the ion channels open in the posylt synaptic membrane both Na+ and K+ flow down their concentration gradient
- In their resting potential, Na+ has more net driving force than K+
- Ach triggers opening channels more Na+ moves inwards, K+ outwards
- Depolarization happens
- Called end plate potential
When small quanta (packets) of Ach are released randomly from nerve cell at rest, each produce smallest possible change in membrane potential of motor end plate
Miniature EPP
When nerve impulse reaches the ending, the number of quanta release increases by several folds
Large EPP
It destroyes Ach so that no new AP arise
Acetylcholinesterase
When the electrical respojse is turned off by AchE what will happen to Ach
Will degrade into choline and acetate
How many percent of choline is returned to the presynaptic terminal?
50%
Who is responsible for returning the 50% choline to presynaptic terminal
Na+ choline transport
Myosin heads bound to what?
ADP and phosphate molecule
What happens in sliding filament theory
- Nerve impulse reaches muscle cells, ca2+ is released from Sr then bound to troponin - causes the tropomyosin molecule change or shift in position to expose binding sites (myosin binding site) - actin myofilament
- Myosin heads bind to the binding sites of the actin proteins, releasing first the phosphates
- then two filaments glide past one another, propelled by a head first movement of the myosin units then ADP released.
- New ATP molecules bind to the myosin bind to the myosin heads causing separation of the actin-myosin cross bridge (stopping motion) then ATP goes to ADP to provide power for the myosin head.
It is the middle of I band and the boundary of contraction
Z disk/Z-line
A zone which will disappear in contraction with no A bands and I bands
Henzen zone
Where does sarcomere exist?
Z-line to Z-line
It is the dark middle band and has overlapping thick and thin filaments
A band
It is the end of A band with thin filaments only
I band
It hold the myosin filaments to the Z-line
Titin proteins
What does T-tubules associate with?
SR
What does T-tubules serve
To rapidly conduct electrical excitation and communicate with SR
It is composed of many myosin molecules has tail region and 2 globular heads
Thick filament structure
It is composed of actin protein
Thin filament structure
It is the protein spirals around actin helix
Tropomyosin
It has binding sites for myosin cross bridges
Actin filaments