Ch.10 Muscle Tissue - Mr. Meagher's Science · PDF fileSmooth Muscle Tissue Physiology of...

Ch.10 Muscle Tissue

Copyright 2009, John Wiley & Sons, Inc.

Preview Chapter 10

In groups we will define the following terms

1. Skeletal muscle

2. Smooth muscle

3. Cardiac muscle

4. Sarcomere

5. Myofibril

6. Myofilament

7. Sarcoplasmic reticulum

8. Motor neurons

9. Neuromuscular junction (aka synapse)

10. Neurotransmitter



Overview of Muscular Tissue Types of Muscular Tissue

The three types of muscular tissue Skeletal

Cardiac

Smooth


Skeletal Muscle Tissue So named because most skeletal muscles move

bones

Skeletal muscle tissue is striated: Alternating light and dark bands (striations) as seen when

examined with a microscope

Skeletal muscle tissue works mainly in a voluntarymanner


Cardiac Muscle Tissue

Found only in the walls of the heart

Striated like skeletal muscle

Action is involuntary


Smooth Muscle Tissue

Located in the walls of hollow internal structures Blood vessels, airways, and many organs

Lacks the striations of skeletal and cardiac muscle tissue

involuntary


Overview of Muscular Tissue Functions of Muscular Tissue

Producing Body Movements

Walking and running

Stabilizing Body Positions

Posture

Moving Substances Within the Body

Heart muscle pumping blood

Moving substances in the digestive tract

Generating heat

Shivering increases heat production


Overview of Muscular Tissue

Properties of Muscular Tissue Excitability

Ability to respond to stimuli

Contractility Ability to contract forcefully

Extensibility Ability to stretch

Elasticity Ability to return to an original length


Skeletal Muscle Tissue Connective Tissue

Components

Fascia Dense sheet of

irregular connective tissue that surrounds muscles

Epimysium Separates muscle

fibers into bundles called fascicles

Perimysium Surrounds numerous

bundles of fascicles


Skeletal Muscle Tissue Endomysium

Separates individual muscle fibers from one another

Tendon Cord that attach a

muscle to a bone

Aponeurosis Broad, flattened

tendon


Skeletal Muscle Tissue Nerve and Blood

Supply

Neurons that stimulate skeletal muscle to contract are somatic motor neurons


Skeletal Muscle Tissue Microscopic Anatomy The number of skeletal muscle fibers is set before you

are born Most of these cells last a lifetime

Muscle growth occurs by hypertrophy An enlargement of existing muscle fibers

Testosterone and human growth hormone stimulate hypertrophy


Skeletal Muscle Tissue


Skeletal Muscle Tissue Sarcolemma

The plasma membrane of a muscle cell

Transverse (T tubules) Tunnel in from the plasma membrane

Muscle action potentials travel through the T tubules

Sarcoplasm, the cytoplasm of a muscle fiber


Skeletal Muscle Tissue Myofibrils

Thread like structures which contract.

Sarcoplasmic reticulum (SR) Membranous sacs which encircles each myofibril

Stores calcium ions (Ca++)

Release of Ca++ triggers muscle contraction

Filaments Function in the contractile process

Two types of filaments (Thick and Thin)

Sarcomeres Compartments of arranged filaments

Basic functional unit of a myofibril


Sarcomere


Contraction and Relaxation of Skeletal Muscle


Skeletal Muscle Tissue Z discs

Separate one sarcomere from the next

A band Thick and thin filaments overlap

I band Lighter, contains thin filaments but no thick filaments

H zone Center of each A band which contains thick but no thin filaments

M line Supporting proteins that hold the thick filaments together in the H

zone


Skeletal Muscle Tissue Contractile Proteins

Myosin Thick filaments

Functions as a motor protein which can achieve motion

Convert ATP to energy of motion

Actin Thin filaments

Actin molecules provide a site where a myosin head can attach

Tropomyosin and troponin are also part of the thin filament

Structural Proteins Titin

Stabilize the position of myosin

Dystrophin Links thin filaments to the sarcolemma



Myosin heads attach to and “walk” along the thin filaments at both ends of a sarcomere

Progressively pulling the thin filaments toward the center of the sarcomere

Leading to shortening of the entire muscle

https://youtu.be/hr1M4SaF1D4





The onset of contraction begins with the SR releasing calcium ions into the muscle cell

Where they bind to actin opening the myosin binding sites



Botulinum toxin Blocks release of ACh from synaptic vesicles

May be found in improperly canned foods A tiny amount can cause death by paralyzing respiratory

muscles

Used as a medicine (Botox®) Strabismus (crossed eyes)

Blepharospasm (uncontrollable blinking)

Spasms of the vocal cords that interfere with speech

Cosmetic treatment to relax muscles that cause facial wrinkles

Alleviate chronic back pain due to muscle spasms in the lumbar region



Curare A plant poison used by South American Indians on

arrows and blowgun darts

Causes muscle paralysis by blocking ACh receptors inhibiting Na+ ion channels

Derivatives of curare are used during surgery to relax skeletal muscles

Anticholinesterase Slow actions of acetylcholinesterase and removal of

ACh

Can strengthen weak muscle contractions Ex: Neostigmine

Treatment for myasthenia gravis

Antidote for curare poisoning

Terminate the effects of curare after surgery


Muscle Metabolism


Types of Skeletal Muscle Fibers

Slow Oxidative Fibers (SO fibers) Smallest in diameter

Least powerful type of muscle fibers

Appear dark red (more myoglobin)

Generate ATP mainly by aerobic cellular respiration

Have a slow speed of contraction

Very resistant to fatigue

Adapted for endurance-type activities such as running a marathon



Fast Glycolytic Fibers (FG fibers) Largest in diameter

Generate the most powerful contractions

Have low myoglobin content

Few mitochondria

Appear white in color

Generate ATP mainly by glycolysis

Fatigue quickly

Adapted for intense anaerobic movements of short duration Weight lifting



Fast Oxidative–Glycolytic Fibers (FOG fibers) Intermediate in diameter

between the other two types of fibers

Have a dark red appearance

Generate considerable ATP by aerobic cellular respiration

Moderately high resistance to fatigue

Generate some ATP by anaerobic glycolysis

Contribute to activities such as walking and sprinting


Smooth Muscle Tissue Physiology of Smooth Muscle

Contraction lasts longer than skeletal muscle contraction

Contractions are initiated by Ca++ flow primarily from the interstitial fluid

Ca++ move slowly out of the muscle fiber delaying relaxation

Able to sustain long-term muscle tone Prolonged presence of Ca++ in the cell provides for a state of

continued partial contraction

Important in the: Gastrointestinal tract where a steady pressure is maintained on

the contents of the tract

In the walls of blood vessels which maintain a steady pressure on blood


Regeneration of Muscular Tissue Hyperplasia

An increase in the number of fibers

Skeletal muscle has limited regenerative abilities Growth of skeletal muscle after birth is due mainly to

hypertrophy

Satellite cells divide slowly and fuse with existing fibers Assist in muscle growth

Repair of damaged fibers

Cardiac muscle can undergo hypertrophy in response to increased workload Many athletes have enlarged hearts

Smooth muscle in the uterus retain their capacity for division

Online Quiz

Search/Google: “anatomy and physiology online quiz”

Look for this website: http://highered.mcgraw-hill.com/

Go to Chapter 9

Copy and answer #1-20 (skip 5, 10, 11, 16)

ONLY COPY THE CORRECT ANSWER!


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Videos

Muscle Contraction: https://youtu.be/hr1M4SaF1D4

NMJ animation: http://youtu.be/7wM5_aUn2qs

Crash course: https://youtu.be/Ktv-CaOt6UQ



http://youtu.be/7wM5_aUn2qs

https://youtu.be/Ktv-CaOt6UQ

Ch.10 Muscle Tissue - Mr. Meagher's Science · PDF fileSmooth Muscle Tissue Physiology of...

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