Muscle Tissue Slides

General Muscle Characteristics

contraction(shortening),

bundles,

elongated(stretched),

Sarcoplasm

- cytoplasm- includes myosin/actin protein that contract

Sarcoplasmic Reticulum

Strores calcium ions for contraction

Sarcolemma

Cell Membrane

Striated

Skeletal, Cardiac

Non Striated

Smooth

Multinucleated

Skelatal

Single Nuclei

Cardiac, Smooth Muscle

Multiple Nuclei

Skeletal

Skelatal Muscle

Peripheral Nuclei(Nucleus sits on edge)

Can’t divide, limited regeneration, satellite cells do the repairing

Rich blood supply- nutrient delivery

Neuromotor Unit: neuron and muscle fiber interaction for contracting

attached to bones through tendons

Satellite Cell

Important for muscle repair and recovery

Limited regenerative muscle repair

lil bumps

Epinysium

Surrounds the entire muscle, largest one

Perimysium

surrounds bundle of fibers called fascicle

contains larger blood vessels

Endomysium

Supports each muscle cell

Contains capillaries- smallest blood vessel in body

Smallest

Myosin

Myofibril

thick filament

Actin

Thin filament

myofibril

Sarcomere

Myofibril between two z discs

ZIMHAZ

z disc, I band, M line, H zone, A band, Z disk

Sarcomeres produce

Banding pattern in Skeletal muscle

shortening of sarcomere produces contraction(generate force)

Muscle order

Muscle— Fascicle— Muscle fiber— sacromere— Myofibril— myofilament

Z disc

anchor thin filament and define sarcomere boundaries

A band

region that contains thick filaments myosin overlaps with actin, dark

I band

contains only thin filaments/actin, light

H zone

central region of a band with only thick filaments

M line

Midpoint of sarcomere thick filaments are anchored

What happends to I band during contraction

gets shorter

What happends to A band during contraction

Not change length

What happends to H zone during contraction

Center is thick and gets shorter

What happends to z line during contraction

move closer together

What happens during sarcomere contraction

Thin filaments go toward M line, z disc comes closer/NO actin myosin filament gets shorter tho

Involuntary movement Muscles

Cardiac Heart

Smooth intestines

Voluntary movement

Skelatal move bones tendons

How is one muscle fiber organized

T Tubules- carries signals into fiber

Terminal Cisternae- store and release calcium

Triads- T tubule and 2 Terminal Cisternae/ signal trigger calcium release

Muscle organized

Triad

T tubule

Terminal Cisternae

T Tubules

Carry signal into fiber

Terminal Cisterna

stores and realease calcium

Triad

Signal calcium release

Neuromuscular Junction

synapse between motor neuron and a skeletal muscle fiber

What binds to receptors on muscle muscle fiber’s cell membrane which is also called

ACh(acetylcholine)

Sarcolemma (Muscle cell membrane)

ACh that binds to sarcolemma triggers what

Action potential in muscle fiber

Muscle contraction

What does the pre-synaptic terminal contain?

axon terminal, neurotransmitter release site

What is the synaptic cleft?

Narrow gap for neurotransmitter diffusion

What is post synaptic membrane?

receptors to recieve signals from sarcolemma in skelatal muscle

Excitatory Synapse

Increase likelihood of action potential

Inhibitory Synapse

Decrease Action potential likelihood

What type of receptor channel does neuromuscular junction use?

Ligand gated ion channel

What is myasthenia gravis?

disease that blocks/destroys acetylcholine receptors at neuromuscular junction

Muscle weakness

drooping eyelids, difficulty swallowing, muscle fatigue

Acetylcholinesterase (AChE)

Enzyme breaks down acetylcholine in synapse

stops muscle avivation agter nerve signl

Treatment for Myasthenia Gravis

Acetylcholinesterase Inhibitor- Pyridostigmine

increase ACh levels and muscle activation

Motor Unit

One motor neuron(single axon)+ all muscle fibers it innervates

Small motor Unit purpose

Few fibers per neuron gives precision

ex: eye and finger muscles

Large motor Unit Purpose

Many fibers per neuron

Strength- thigh and back

Cardiac Muscle

Mononucleated cells

Smaller than skeletal with central nucleus

Striated, sacromeres presesent

Do NOT divide- NO satellite cells, limited regeneration

Intercalated discs

Special feature of cardiac muscle, contain gap junction, and desmosomes

If one cell is excited, impulse spreads to neighbors=coordinated contraction

What has Extensive Capillary Network?

continuous oxygen supply for cardiac muscle

highly resistant to hypoxia- low o2

Autorhythmicity

Specialized Cardiac muscle rhythm.. auto rhythm so involuntary signal without brain

Pacemaker- make the signal and conducting system like Pukinje fibers carry it

Smooth Muscle Characteristics

Non striated(No sarcomeres ;actin and myosin are arranged differently)

Spontaneously Active- smooth muscle can contract on its own

Involuntary

maintains tone- partially contracted all the time

What muscle is spindle shaped

Smooth muscle

Nucleus becomes corkscrew shaped when contracted

What Muscle has Dense bodies

Smooth

No Sacromeres means its anchored in Dense bodies

Common locations of smooth muscle?

Hollow Organ walls: blood vessel, lymphatic vessels, digestive tract, excretory duct, tracheobronchial tree

Myoepithelial cells

Specilized smooth muscle in exocrine gland, help with secretion

salivary gland mammary gland

What Makes up a Triad

One transverse T tublule and 2 Terminal Cisterna

Function of Tubules for Skelatal muscle contraction

• Conducting sarcolemmal action potentioals

• Signals into fiber

Dense bodies

Functional achoring site for thin actin filaments in smooth muscle cells

Sarcoplasmic Reticulum

Responsible for storing, release calcium

H zone

only has thick filament and lacks any thin filaments