muscle tissue worksheet exam 3

What 3 criteria are used to classify muscle tissue?

1. Striated or not striated 2. Voluntary or involuntary 3. Multinucleate or uninucleate

What does striated mean?

Muscle tissue has visible stripes or bands.

What does voluntary mean?

Muscle activity is under conscious control.

What does involuntary mean?

Muscle activity occurs without conscious control.

What does multinucleate mean?

A cell contains multiple nuclei.

What does uninucleate mean?

A cell contains one nucleus.

Which type of muscle is multinucleate?

Skeletal muscle is the only muscle type that is multinucleate.

Is skeletal muscle striated or nonstriated?

Striated.

Is skeletal muscle voluntary or involuntary?

Voluntary.

How many nuclei do skeletal muscle cells have?

Multiple nuclei.

Is cardiac muscle striated or nonstriated?

Striated.

Is cardiac muscle voluntary or involuntary?

Involuntary.

How many nuclei does cardiac muscle typically have according to the worksheet?

One nucleus (uninucleate).

Is smooth muscle striated or nonstriated?

Nonstriated.

Is smooth muscle voluntary or involuntary?

Involuntary.

How many nuclei does smooth muscle have according to the worksheet?

One nucleus (uninucleate).

Which muscle type is more heavily striated: skeletal or cardiac?

Skeletal muscle.

What are intercalated discs?

Communicating junctions found in cardiac muscle that allow cardiac muscle cells to be excited as a group.

What are the four properties shared by all types of muscle?

Excitability, contractility, extensibility, and elasticity.

What is excitability?

The ability of muscle tissue to respond to a stimulus.

What stimulus tells a muscle to contract?

A nervous impulse.

Will a muscle contract without stimulation?

No. Muscle must be stimulated to contract.

What is contractility?

the response to the stimulus

What happens to a muscle during contraction?

It shortens and thickens.

What is extensibility?

The ability of a muscle to be stretched beyond its regular position.

what is an example of extensibility

triceps

• when we contract our biceps, our triceps must extend/stretch

What is elasticity?

The ability of a muscle to return to its original shape after being stretched or contracted.

What is an antagonistic muscle pair?

Two muscles that work oppositely: one contracts while the other stretches.

which muscle works in antagonistic pairs

skeletal muscles

What are the four main functions of muscles

Motion, maintaining posture, stabilizing joints, and producing heat.

motion results when a muscle ____

contracts

How does skeletal muscle produce motion?

Contraction causes bones to move.

What is locomotion?

a Skeletal movement that results from contraction causing the bones to move

How does cardiac muscle produce motion?

Contraction causes the heart to change shape, increases circulation, and pumps blood through the body.

How does smooth muscle produce motion in the digestive tract?

Contraction helps move food through the digestive tract and supports waste elimination.

What is peristalsis?

Wave-like contractions of smooth muscle that move food through the digestive tract.

How do skeletal muscles maintain posture?

Their contractions keep the body upright and help it defy gravity.

How do muscles stabilize joints?

Muscles surround joints and maintain muscle tone.

What is muscle tone?

Partial muscle contraction that helps stabilize joints and prevent unwanted movement.

What happens whenever a muscle contracts?

Heat is produced.

How does the arrector pili muscle relate to heat production?

Its contraction produces heat that is trapped by the hair above the skin

What is shivering?

Involuntary skeletal muscle contraction when the body is cold, producing additional heat.

Why does shivering help warm the body?

Rapid, involuntary skeletal muscle contractions produce heat.

What four components make up skeletal muscle?

• Muscle fibers/tissue

• connective tissue (wrapper that surrounds everything else)

• blood vessels

• nerve fibers.

What is gross anatomy?

Anatomy involving structures that can be seen with the naked eye.

Why is a skeletal muscle considered an organ?

It contains both skeletal muscle tissue and connective tissue.

What is direct muscle attachment?

The muscle fuses directly to the periosteum (around bone) or the perichondrium around cartilage of the skeletal system

What is indirect muscle attachment?

Extra connective tissue connects the muscle to the skeletal system.

What is a tendon?

A rope-like extension of connective tissue that attaches the end of a muscle to bone.

What is an example of a tendon?

The Achilles tendon

• largest tendon.

What is an aponeurosis?

A sheet of connective tissue that attaches muscle to bones.

Where is an example of an aponeurosis given in the worksheet?

The palm of the hand.

What is the function of the palm aponeurosis example?

It allows all the fingers to contract at once.

What is the epimysium?

The outermost layer of dense irregular connective tissue surrounding the entire muscle.

• “wrapper”

What does the epimysium surround?

The entire muscle.

What is the relationship between the epimysium and periosteum?

it’s an extension of the periosteum.

What is a fascicle?

A bundle of muscle fibers (cells) separated from one another by connective tissue wrappers (perimysium)

What connective tissue surrounds each fascicle?

Perimysium.

What is the perimysium?

Dense irregular connective tissue surrounding each individual fascicle.

What does the prefix peri- mean in perimysium?

Around.

What is a muscle fiber?

each individual muscle cell contained within a fascicle that are separated from one another by connective tissue wrappers (endomysium)

What are two other names for a muscle fiber?

Myofiber and muscle cell.

What connective tissue surrounds each individual muscle fiber?

Endomysium.

What is the endomysium?

Reticular connective tissue surrounding each individual muscle fiber.

Why is the endomysium made of reticular connective tissue and not dense irregular ct

It needs to move during contraction; dense irregular connective tissue does not have that ability.

What are the three muscle connective tissue wrappers in order from outermost to innermost?

Epimysium surrounds the muscle; perimysium surrounds each fascicle; endomysium surrounds each muscle fiber.

Which connective tissue wrapper surrounds the whole skeletal muscle?

Epimysium.

How many attachment points does a muscle have at minimum?

At least two.

What is the origin of a muscle?

The attachment on the immovable bone.

What is the insertion of a muscle?

The attachment on the movable bone.

Where is the origin usually located relative to the insertion?

The origin is usually proximal to the insertion.

What is the belly (gaster) of a muscle?

everything between the origin and insertion

What is another name for the muscle belly?

Gaster.

What are myofibers?

Individual muscle fibers / cells that run the entire length of the muscle.

How do skeletal muscle fibers develop

Multiple smaller embryonic muscle fibers run along the muscle and eventually fuse to form long muscle fibers.

What two basic cellular structures does a myofiber contain?

A cytoskeleton and a plasma membrane.

What is the sarcolemma?

The plasma membrane of a muscle cell.

What is the sarcoplasm?

The cytoplasm of a muscle cell.

What is one important function of the sarcoplasm?

It stores 2 cytoplasmic inclusions used to help muscle cells contract.

What are the two cytoplasmic inclusions that the sarcoplasm contains

Myoglobin and glycosomes.

What is myoglobin?

A substance that stores oxygen to allow ATP production.

Why does a muscle need ATP?

ATP provides energy needed for muscle contraction.

what are glycosomes

stores glucose as glycogen that muscles use for energy to contract

What is glycogen?

The storage form of glucose.

why are their multiple nuclei in skeletal muscle cells

because of the smaller embryonic fibers fusing together

What are myofibrils?

Contractile units within of muscles

How many myofibrils are found in a muscle cell

Thousands.

What are myofibrils made of?

Chains of sarcomeres.

What is the sarcoplasmic reticulum?

Smooth endoplasmic reticulum that surrounds each myofibril and runs along its length.

Why is the sarcoplasmic reticulum called smooth?

It has no ribosomes.

What is the function of the sarcoplasmic reticulum?

It stores calcium inside the muscle cell.

Why is calcium stored in the sarcoplasmic reticulum important?

Calcium is released from it to cause muscle contraction.

How are the channels of the sarcoplasmic reticulum arranged?

Parallel channels run along the muscle cell and are periodically interrupted by perpendicular channels.

What are terminal cisternae?

Perpendicular channels

What is a T tubule?

A hollow, internal projection of the sarcolemma plasma membrane.

Where does a T tubule run in relation to the terminal cisternae?

runs between two terminal cisternae, like a hot dog between two buns.

What is a triad in skeletal muscle?

One T tubule between two terminal cisternae.

What three structures make up a muscle triad?

Two terminal cisternae and one T tubule.

What are sarcomeres?

Segments or compartments of a myofibril.

Where does muscle contraction occur

Within each sarcomere.