muscular systems overview april 22, 2015 sutherlin ast w. crawford adapted from “the anatomy of...

Muscular SystemsOverview

April 22, 2015Sutherlin ASTW. Crawford

Adapted from “The Anatomy of Domesticated Animals” and the Colorado Agriscience Curriculum

The Muscular System

Function:• locomotion or movement• life support– gathering food– reproduction– simple body functions

The Muscular System

Structure of muscles:– consist of mostly protein– found in bundles or sheets– connected to bones by tendons

The Muscular System

Classification of muscles:– Voluntary– Involuntary

The lean portion of animals carcass is what is used for food (muscles)

The Muscular System

• Voluntary– Under control of the animals will– All are straited (striped)– Flexor- decreases the angle between two bones

(biceps)– Extensor- opposite side and increases the angle of

two bones (triceps)

The Muscular System

• Involuntary– Not under the control of the animals free will– Heart– Secretory organs- force out secretions– Digestive system- movement of food– Respiratory system– Smoothed or straited

Let’s go further…

Muscular System Functions

• Body movement• Maintenance of posture• Respiration• Production of body heat• Communication• Constriction of organs and vessels• Heart beat

Properties of Muscle

• Contractility– Ability of a muscle to shorten with force

• Excitability– Capacity of muscle to respond to a stimulus

• Extensibility– Muscle can be stretched to its normal resting length and

beyond to a limited degree

• Elasticity– Ability of muscle to recoil to original resting length after

stretched

Muscle Tissue Types

• Skeletal– Attached to bones– Nuclei multiple and peripherally located– Striated, Voluntary and involuntary (reflexes)

Muscle Tissue Types

• Smooth– Walls of hollow organs, blood vessels, eye, glands, skin– Single nucleus centrally located– Not striated, involuntary, gap junctions in visceral smooth

Muscle Tissue Types

• Cardiac– Heart– Single nucleus centrally located– Striations, involuntary

Skeletal Muscle Structure

• Muscle fibers or cells– Develop from myoblasts– Numbers remain constant

• Connective tissue• Nerve and blood vessels

Embryologic origin

• Muscle cells are the result of the conjoining of embryo cells called myoblasts

• Explains multiple nuclei

Muscle Fibers

• Muscles are attached to bones by tendons– Tendon is the connective tissue– This tissue also encapsules the muscle and forms

the epimysium

Muscle Fibers

• Skeletal muscle is made up of bundles of subunits called fasicles (or fascicles)

• Fascicles are covered by connective tissue call perimysium

• Fascicles are made up of muscle cells– Muscle cells = muscle fibers

Muscle Fibers

• Muscle cells– Ensheathed in endomysium– Made up of long protein molecules call myofibrils– Myofibrils have two types of myofilaments• Thick myofilament• Thin myofilament

Muscle Fiber

Sarcomeres

• The myofibril is divided into chains of sarcomeres

• Sarcomeres are the sections of myofilaments that slide over one another as muscles contract and relax

• This is where the work happens

Organization of myofilaments I:

Sliding Filament Model

• Actin myofilaments sliding over myosin to shorten sarcomeres– Actin and myosin do not change length– Shortening sarcomeres responsible for skeletal

muscle contraction

• During relaxation, sarcomeres lengthen

Sliding filament model II:

Sarcomere Shortening

• Double click the icon to view• OR

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html

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