activity 4 - muscular tissues

7/27/2019 Activity 4 - Muscular Tissues

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MUSCULAR

TISSUES

Activity 4


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MUSCULARTISSUES

MOTION mediated by

muscle cells / myofibers /

muscle fibers. Conversion of chemical

energy (ATP) into mechanical

energy by the contractile

apparatus of muscle cells.


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Interaction ofactin and

myosinmediates the

contraction of muscle cells.Actin and myosin form

myofilaments arranged

parallel to the direction of

cellular contraction.


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LOCATION APPEARANCE STIMULATION TYPE OF ACTIVITY

Composed of gross

named muscles (e.g.

biceps, triceps)

attached to the

skeleton and/or

fascia of limbs, body

wall, and head/neck.

Large, long,

unbranched, cylindrical

fibers with transverse

striations (stripes)

arranged in parallel

bundles;

multiple,peripherally

located nuclei.

Voluntary (or

reflexive) by somatic

nervous system.

Strong, quick

intermittent (phasic)

contraction abobve

a baseline tonus;

acts primarily to

produce movement

or resist gravity.

SKELETAL MUSCLE


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LOGITUDINALSECTIONOFASKELETAL

MUSCLE


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HISTOLOGYOFSKELETAL

MUSCLE

Longitudinal section


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Cremaster muscle myofibrils


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TONGUE - STRIATED MUSCLE: THE CORE OF THE TONGUE CONTAINSINTERLACING BUNDLES OF STRIATED FIBERS THAT RUN IN THREE

PLANES: (A) longitudinal, (B)vertical, AND (C)transverse.


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HYPERTROPHY

With constant useskeletal muscle

undergoes

HYPERTOPHY OF USE

Number of cel ls does not

change

Amount o fcontract i le

material in EACHmyof iberincreases

AN EXAMPLE OF

HYPERTROPHY OF USE


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Muscle of the heart(myocardium) and

adjacent portions of

the great vessels

(aorta, vena cava)

Branching andanastomosing shorter

fibers with transverse

striations (stripes)

running parallel and

connected end-to-end

by complex junctions

(intercalated discs).Single, central nucleus

Involuntary;intrinsically

(myogenically)

stimulated and

propagated; rate and

strength of contraction

modified by autonomic

nervous system.

Strong, quick,continuous rhythmic

contraction, acts to

pump blood from

the heart.

CARDIAC MUSCLE


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http://webanatomy.net/histology/muscle_histology.htm


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INTERCALATED DISK

- diagnostic feature of CM


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INTERCALATED DISKS

Special structure for

COMMUNICATION &

ADHESION

3-D interlocking ofadjacent cells atends

Includes adhering

junctions & gap

junctions


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Walls of hollowviscera and blood

vessels, iris and

ciliary nody of the

eye; attached to hair

follicle of the skin

(arrector pili muscle)

Single oragglomerated, small,

spindle-shaped

fibers without

striations; single,

central nucleus.

Involuntary byautonomic nervous

system (ANS)

Weak, slow, rhythmic,or sustained tonic

contraction; acts

mainly to propel

substances (peristalsis)

and to restrict flow

(vasoconstriction) and

sphincteric activity.

SMOOTH MUSCLE


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SMOOTHMUSCLES

Largest smooth muscle cells - uterus duringpregnancy (12x600 m).

Smallest - around small arterioles (1x10 m).

Contain one centrally placed nucleus.The chromatin is finely granular and the

nucleus contains 2-5 nucleoli.

Innervated by the autonomic nervoussystem.

Visceral muscles - involuntary muscles.


21/36/Fankhauser/Labs/Anatomy_&_Physiology/A&P201/Muscle_Histology/


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SMOOTH MUSCLE FIBER MAY

OCCUR:

Singly - in the scrotum (tunica dartos)

In small bundles or fascicles -

associated with hair follicles (arrectorpili muscles)

In well-defined, layered sheets that are

coiled - in muscular arteries.Arranged in two thick layers at right

angles to each other- in the intestines;


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SMOOTH MUSCLE FIBER MAY OCCUR:

With an additional layer in an

irregular pattern - in the stomach,

bladder, and uterus.

Branched smooth muscle fibers -

found in the nipple of the mammary

glands and in the endocardium of the

atrium of the heart.


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Smooth muscles in small

bundles or fascicles -

associated with hair

follicles.

Originate in the papillary

connective tissue and

insert on hair follicles.

Their contraction erects

hairs in animals andproduces goose flesh" in

man.

ARRECTOR PILI MUSCLE


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http://webanatomy.net/histology/muscle_histology.htm


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CM in Cross Section:

Nuclei at the centerofcell

Cells all about thesame size

Proportionally more

nuclei per unit area

than smooth muscle


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MUSCULARISMUCOSAE

Occurs throughout the GI tract fromesophagus to rectum.

A thin layer of smooth muscle at the boundary

between mucosa and submucosa.

It contains both circularand longitudinalfibers.

Thickest in esophagus.

Thinner in the rest of the tract (stomach, small

intestine, colon).


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JEJUNUM

Smooth muscles

are distributed

as:

an outerlongitudinal and

an inner circular

layer in the wall

of the jejunum.


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Because smooth muscle and collagen both share a somewhat

similar appearance (eosinophilic fibers), it may take special care

to notice the muscularis mucosae.


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UTERINEWALLENDOMETRIUM,

MYOMETRIUM,ADVENTITIA

Myometrium is the thick smooth

muscle tunic of the uterus.

This layer thickens during

pregnancy.

At parturition, powerful contraction

is triggered by oxytocin and

prostaglandin.


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Uterus - Smooth muscles with an additional layer

in an irregular pattern.


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ARTERIALWALL : COMPOSEDOF 3 LAYERS

(TUNICAE)

Tunica Intima inner

Tunica Media middle

Tunica Adventitia outer Tunica Intima

Tunica media

Tunica

adventitia

Elastin

membrane


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AORTATHELARGESTARTERY

Elastic Artery

Tunica media - the

spaces between the

elastic tissues are filled

with smooth musclefibers and fibroelastic

tissue.

Help to reduce changes

in blood pressureassociated with

heartbeat.


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MUSCULARARTERIES

Distributing arteries

distributes blood to

various organs.

The thick tunicamedia is composed

of many concentric

layers of smooth

muscle.

activity 4 - muscular tissues

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