muscles

3 types of muscles

Skeletal, cardiac smooth

What is the study of muscles?

myology

Skeletal description

striated attached to bones

What type of movement does skeletal have?

Voluntary movements

What part of the nervous system control controls the skeletal the muscles?

somatic division

Cardiac description

striated

Where is cardiac muscle found?

only in heart makes up most of the heart wall

What type of movement is cardiac?

involuntary movement

What can change the heartbeat?

several hormones and neurotransmitters

What is the built-in rhythm of the heart called?

autorhythmicity

What part of the nervous system controls, cardiac and smooth muscles?

Autonomic nervous system and hormones released by endocrine gland

Smooth muscle location

walls of hollow organs and structures

Smooth muscle movement

involuntary

Smooth muscle description

nonstriated

What are the functions of muscle tissue?

producing body movements, stabilizing, body positions, storing and moving substances within your body generating heat

producing body movements

movements of the whole body and localized movements 

Stabilizing body positions

skeletal muscle contract, stabilizing joints, and help maintain body position 

storing and moving substances within your body

prevents outflow of the contents of the hollow organs

What happens when the cardiac muscle contracts

pump blood through the blood vessels of the body,

What happens when the skeletal muscles contracts

promote the flow of lymph plasma and aid the return of blood and veins to the heart

sphincters

ring like bands within the smooth muscles that accomplish storage by sustain contractions

Shivering

involuntary contractions of skeletal muscle that can increase the rate of heat production

Thermogenesis

production of heat to maintain stable body temp

Four types of properties of muscle tissue

electrical excitability, Contractility, extensibility, elasticity

electrical excitability

action potential and muscles are referred to as muscle action potential

What are the two types of stimuli that trigger action potential?

chemical stimuli autorhythmic electrical signals

Chemical stimuli example

neurotransmitter

Contractility

the ability of muscular tissue to contract forcefully when stimulated by nerve impulse

 extensibility

the ability of muscular tissue to stretch within limits without being damaged

What is responsible for limiting the range of extensibility while keeping it within the contractile range of the muscle cell?

the connective tissue within the muscle

elasticity

the ability of muscle tissue to return to its original length and shape after contraction or extension

What has the greatest amount of stretch ability?

smooth muscle

Structure of skeletal muscle tissue

a separate organ composed of muscle fibers  or myocytes

Myocytes/ muscle fibers

Hundreds to thousands of cells, elongated shape

What surrounds muscle fibers, blood vessels, and nerves.

connective tissue

 What does the connective tissue do?

surrounds and protects muscular tissue

What does the hypodermis do?

separates muscle from skin and is a passageway for nerves blood vessels, and lymphatic vessels to enter an exit the muscle

What does the adipose tissue do?

serve as an insulating layer reduces heat loss and protects muscle from physical trauma, while storing most of the bodies triglycerides

What is a fascia?

dense sheet or broadband of a regular connective tissue

Where are fascia found?

Lining of body walls and limbs

Fascia function

supports and surrounds muscles and other organs of the body, free movement, carries nerves, blood vessels, lymphatic vessels, and fill spaces between muscles

what strengthens and protects the skeletal muscles

three layers of connective tissue that extend from the fascia

What are the three layers of connective tissue that extent from the fascia?

epimysium, perimysium, and endomysium

epimysium

the outer layer encircling the entire muscle consist of dense irregular connective tissue

perimysium

layer of dense regular connective tissue surrounding groups of 10 - 100+ muscle fiber

Muscle fascicles

Bundles of muscle fibers

 Endomysium

penetrate the interior of muscle fascicles, separates individual muscle fibers from one another mostly reticular fibers

aponeurosis 

connective tissue extends as a broad flat sheet

Nerve blood supply

well supply with nerves and blood vessels generally 1 artery and one or two veins in each nerve that penetrate the skeletal muscle

What are the neurons that trigger the contraction for skeletal muscles

somatic motor neurons

What does each somatic motor neuron have?

has a threat like action that extends from the brain or spinal cord

What is in close contact with one or more blood capillary

muscle fibers

blood capillaries function

bring in oxygen and nutrients and remove heat in the waste products of muscle metabolism

What is needed when muscles can contract synthesis ATP

oxygen glucose fatty acids, and other substances delivered to the muscle fiber and the blood 

What is the most important component of a skeletal muscle?

muscle fibers

When are the muscle fibers formed?

during embryonic development

How are muscle fibers created?

the fusion of 100 + myoblasts

What happens once fusion has occurred

the muscle fiber loses its ability to undergo cell division

What happens once fusion has occurred

the matured, skeletal muscle fiber has 100+ nuclei

Where are the multiple nuclei of the skeletal muscle fiber found? 

located just beneath the sarcolemma

sarcolemma

the plasma membrane of a muscle fiber

 T tubules

thousands of tiny tube shaped invagenations of the sarcolemma

why do the tunnels of the tubles face inward from the surface towards the center of each muscle fiber

because t tubules are open to the outside of the fiber and filled with intersexual fluid

how does action potential travel

along the sarcolemma, and through the T tube quickly spreading throughout the muscle fibers

The action potential traveling this way ensures what

That it excites all parts of the muscle fibers at basically the same time

sarcoplasm

the cytoplasm of a muscle fiber it includes a substantial amount of glycogen

What can the sarcoplasm be used for?

synthesis of ATP

globin

red colored protein found only in a muscle

What does globin bind too

oxygen molecules

What happens once oxygen molecules bind to globin

they diffuse into muscle fibers from interstitial fluid

when does myoglobin releases oxygen

needed by the mitochondria for ATP production

Why is the mitochondria so close to the contractile muscle proteins

ATP can be produced quickly as needed 

myofibril

small structures that extend the entire length of a muscle fiber

Make skeletal muscles striated

the prominent striations of myofibrils

sarcoplasmic reticulum (SR)

membrane-bound structure of a network of tubules and sacs that stores and releases calcium ions in muscle cells

sacs of the SR are called

terminal cisterns

what is a triad?

T tube and the two terminal systems on either side of it

What is stored in a relaxed muscle fiber within the SR

calcium ions

What triggers muscle contractions

the release of calcium ions from the terminal systems within the SR

 filaments/myofilaments

smaller protein structures

thin filaments

composed of a protein called actin

Thick filaments

composed of the protein myosin

sarcomeres

the basic functional units of a myofibril

 Z disc

narrow plate shape, regions of dense material materials that separate one sarcomere from the next

a sarcomere extend from what

one z disk to the next z disk 

A band

 the darker middle part of the sarcomere that extends the entire length of the thick filament and includes those parts of thin filaments that overlap thick filaments

zone of overlap

where the thick and thin filaments lie side-by-side

I band

a lighter less dense area of sarcomere that contains the rest of the thin filaments, but no thick filaments a z disk passes through the center of each I  band

H line

 narrow  regions and center of each a band that contains thick filaments, but no thin filaments

M line

region and center of each h zone that contains proteins that hold thick filaments together at center of sarcomere

3 kinds of myofiber proteins

contractile proteins, regulatory proteins, structural proteins

contractile proteins

generate force during contractions

regulatory proteins

which helps switch the contraction process on and off

structural proteins

keep the thick and thin filaments in the proper alignment, give the myofibril elasticity and extensibility and link the fibers to the sarcolemma and extracellular matrix 

 how do motor proteins achieve movements

by converting the chemical energy and ATP to the mechanical energy of motion that is the production of force

how many molecules of myosin are needed to form a single thick filament

300 molecules of myosin form a single thick filament 

shape of myosin

shaped like two golf clubs twisted together

the myosin tail points which way

point towards the M line in the center of the sarcomere 

tales of neighboring myosin molecules lay?

parallel to one another forming the shaft of the thick filament