BSC Chapter 10 muscle systems

Myology

The study of muscles

Myofibers

Striated, voluntary, and multi-nucleated, muscle cells

Involuntary and striated muscle called myocytes or cardiocytes

Cardiac muscle

What are the functions of muscles

Movement, stability (posture), communication, control of body openings (sphincter muscles), heat production

What kind of muscle tissue has no striations in the the tissue, involuntary, and cells are called myocytes

Smooth muscle

What are the properties of muscles

Excitability, conductivity, contractility, extensibility, and elasticity

What is the greatest property of elasticity in muscle tissue.

The ability to recoil and return to its shape

What are the types of tissue a skeletal tissue can contain

Connective tissue, nervous tissues, blood vessels, and skeletal muscle.

what does endomysium do in skeletal muscle

Surrounds each muscle fiber

What does is a fascicle in skeletal tissue

the wrapped bundle of individual muscle fibers in skeletal tissue

What is perimysium in skeletal tissue

A layer that wraps muscle fibers together in bundles called fascicles

What is epimysium in skeletal tissue

Tissue that wraps all fascicles of the skeletal tissue and all other contents into a muscle bundle

What does a tendon do in skeletal tissue

Connects muscle to bone

What is deep fascia in skeletal muscle

Fibrous connective tissue that separates neighboring muscles from each other

What is superficial fascia in skeletal muscle

A layer of connective tissue that separates the muscles from the overlying skin

What can the striating tell you about the direction of muscle movement

The direction of the muscle in the way it goes during movement

What can the striating tell you about the direction of muscle movement

The direction of the muscle in the way it goes during movement

What does the term “insertion” refer to in muscle attachment

The moving end (the tendon and bone the muscles are pulling)

What does the term “origin” refer to in muscle attachment

The stationary end (anchor)

What does the term “belly” refer to in muscle attachment

The middle region of a muscle attachment

What does the term “aponeuroses” refer to in muscle attachment

Broad sheet like tendons (example: covering the abdominal muscles)

In terms of muscle movements what does the term “action” refer to

Movement produced by a muscle

In terms of muscle movements what does the term “primer mover” refer to

Muscle that produces most of the force

In terms of muscle movements what does the term “synergist” refer to

Muscle that aids the prime mover by adding power, stabilizing a joint, or modifying the direction of joint movement

In terms of muscle movements what does the term “antagonist” refer to

A muscle that opposes the prime mover (such as an extensor that opposes a flexor)

In terms of muscle movements what does the term “fixator” refer to

Muscle that holds a bone still

What are intrinsic muscles

Muscles that have both their origin and insertion within a specified region such as the head or hand

what are extrinsic muscles

Muscles that have their origin outside of a specified region, and they or their tendons extend into a region, such as muscles of the forearm whose tendons extend into the hand

What do somatic motor neurons do in relationship to skeletal muscle

They are sent signals from the brain to stimulate muscle contraction.

What is a motor unit in relation to somatic nerves and muscle fibers

It relates to the system of one nerve fiber and all the muscle fibers that it branches too and stimulates

How is blood supplied to muscles

Through blood capillaries that penetrate into the endometrium to reach every muscle fiber

What develops in muscles as to strengthen them when well exercised

Mitochondria, myoglobin, glycogen, and blood capillaries

What are the three types of muscle atrophy and their associated causes

Denervation atrophy - the nerve connection to the muscle is severed

Disuse atrophy - muscle is not exercised

Senescence atrophy - aging

Can muscles grow from notice production or repair?

No, only through resistance training

How are muscles named?

Shape, number of heads, location, action of a muscle, orientation, and size

What does the muscular system refer to

Only the skeletal muscles of the body

What two ways can muscle connect to bone

Direct (fleshy) attachment - muscle attaches directly to the bone

Direct attachment - a tendon is used to connect muscle to bone

What is sacroplasm

The specialized type of cytoplasm found in muscle cells

what are myofibrils

A bundle of microfilaments forming a microtubule found In the cells of muscles that generate force and cause contraction on the microscopic level

what are myofibrils

A bundle of microfilaments forming a microtubule found In the cells of muscles that generate force and cause contraction on the microscopic level

What is myoglobin in relation to muscle cells

A molecule rich with oxygen used as storage in muscle cells to be used in the production of ATP

What is myoglobin in relation to muscle cells

A molecule rich with oxygen used as storage in muscle cells to be used in the production of ATP

What are terminal cisternae in the sacroplasmic reticulum of a muscle cell

Enlarged tube-like structures forming from the sarcoplasmic reticulum and connecting to the transverse tubules that receive signals to begin muscle contraction

what types of myofilaments are there

Thick filaments

Thin filaments

Elastic filaments

What is the key to muscle contraction

Myofilaments

What protein are thick myofilaments comprised of

Myosin

What proteins are thin filaments comprised of and what are their functions

Fibrous (F) actin - a chain of (G) actin

Globular (G) actin - contains an active site that can bind to a myosin molecule

Tropomysin - prevents the active sites of actin binding to the myosin of thick filaments

Tropoinin - acts as a switch controlled by calcium to regulate contraction and relaxation

What proteins are elastic filaments comprised and what do they do

Titus - run through the core of a thick filament to give the filaments structure and aid in regulation of overstretching and general recoilness of muscle contraction in the microscopic layer

What are myoblasts

An embryonic unspecialized cell used to produce each muscle fiber and after maturation of the fiber remain as satellite cells for muscle repair.

What is the sacrolemma of a muscle cell

A specialized plasma membrane that contains tunnels called transverse (T) tubules that penetrate into the cell and allow signals from the surface of the cell to enter the muscle fiber

What proteins are called the contractile proteins within the myofilaments

Myosin and actin

What proteins of the micro filaments are called the regulatory proteins

tropomyosin and troponin

In a myofibril what is an A band

The section of the myofibril that consists of thick filaments lying side by side with thin filaments and is responsible for muscle fiber contraction

The (dArk) band

in a myofibril what is an I band

A section of the myofibril in between two A bands that are bisected with a Z disk in the middle comprised of titin and thin filaments

the (LIght) band

What is the Z disk in a myofibril

A base layer of elastic filament comprised of titin proteins used to anchor the connecting filaments

What is a sacromere in a myofibril

The section between two Z disks

What are the striations of a muscle fiber

The polarizing effect of light between the thick and thin filaments or the A and I bands

What is a synapse

The functional connection between a nerve fiber and any target cell that it stimulates

what is a neuromuscular junction

It is a specific synapse where a nerve fiber meets a muscle cell

What is a synaptic knob

The bulbous end of a neuromuscular junction which is nestled in a depression on the sarcoma called stage motor end plate

What is the synaptic cleft

The tiny gap between the synaptic knob and the muscle fiber the synaptic knob is nestled next to

What is a synaptic vessicle

Spheroid organelles within the synaptic knob that are filled with acetylcholine used when a signal arrives to diffuse the chemical and initiate the start of muscle contraction

What are ACh receptors

Receptors in the sarcoma that respond to the exocytosis of the acetylcholine from the synaptic vessicle in which causes the response to contract the muscle fiber

What is acetylcholinesterase

A chemical that breaks down ACh after it has been used to signal a contraction response of the muscle fiber

How much blood does the muscular system recieve per minute at rest

1.25 L or one quarter of the body’s blood supply

Why do blood capillaries coil around muscles

To keep them from breaking during muscle lengthening

What does motor units working “in shifts” mean

When one muscle group tires and becomes fatigued a smaller motor unit will pick up the work to let the muscles of the larger motor unit rest

What is excitation in muscle contraction

The period in which a signal in a nerve fiber triggers the release of ACh

What is excitation-contraction coupling

The period in which the transverse microtubules signal the sacroplasmic reticulum to release its calcium stores

What is contraction in microscopic muscle fibers

The period when a myosin head is activated by ATP and swings forward into a “cocked” position and binds to an active site of actin

what is relaxation in microscopic muscle tissue

The period when a nerve fiber stops signaling the neuromuscular junction to release ACh

What are slow-twitch muscle fibers

Muscle fibers that have an abundance of mitochondria, myoglobin, and blood capillaries and have been well adapted to aerobic respiration which does not produce lactic acid in turn slowing overall muscle fatigue

What are fast twitch muscle fibers

Muscle fibers more fit for fast response but in turn are easily fatigued due to the build up of lactic acid

Why are “red muscles” called as such

They contain more slow twitch muscle fibers

Why are “white muscles” called as such

They contain more fast twitch muscle fibers

What is an intercalated dick in a cardiocyte

A steplike region containing electrical gap junctions that allow the cells to communicate with each other and various mechanical junctions that prevent the cells from pulling apart when they contract

What are the most prolific properties of a cardiocyte.

One nucleus

Nucleus is surrounded by glycogen

Large mitochondria

Adapted to aerobic respiration

Resistance to fatigue

Repairs mainly through fibrosis (scarring)

What are dense bodies in smooth muscle cells

Little masses of proteins scattered throughout the sarcoplsm and on the inner face of the sarcolemma used to connect micro filaments instead of the Z disk

What are the two types of smooth cells

Multi unit

Single unit

What is a multi-unit smooth cell

Smooth muscle that contains synaptic junctions and are connected to adjacent smooth muscle by means of synaptic fibers and move as one unit when triggered by automatic action.

What is a single-unit smooth cell

A cell not connected directly by a nerve fiber but instead reacts to the release of neurotransmitters by way of varisocities which affect a vicinity of these types of cells instead of individually as if they were “one cell”

What are variscosities in smooth single-unit cells

The swellings in a nerve fiber moving through a group of single-unit cells which emits neurotransmitters to instill a reaction

What are the most prolific properties of smooth muscle cells

They can regenerate through mitosis

They lack transverse tubule and in place use masses of proteins called dense bodies to connect myofilaments

There are two types of smooth cells based off of how they react by nerve fibers

Can maintain a state of continual contraction called smooth muscle tone