Ch. 10 - Muscle Tissue and Organization pt. 1

Arrange the following structures from smallest to largest.

1. myofilaments 2. myofibrils 3. muscle fiber 4. muscle fascicle

Each myosin protein molecule in a thick filament consists of ______ strands.

2

*Which are possible functions of skeletal muscles?

Body movement: skeletal muscles pull on bones to move the body Maintain posture: continual contraction of specific muscles to maintain body position Protect and support: E.g., layers of muscle tissue protect abdominal organs and support their position Regulate elimination of materials: E.g., sphincters control passage of materials through digestive tract Produce heat: Help maintain body temperature as heat given off from muscle contraction

What tissue types are present in each skeletal muscle?

Connective Muscle Epithelial Nervous

*Which describes what happens during skeletal muscle contraction?

Contracting muscles pull on tendons to produce movement To pull, muscles develop tensions as their sarcomeres shorten For sarcomeres to shorten, thick filaments attach to thin filaments and pull them toward the centers of the sarcomeres NOT: The Z discs of a sarcomere move farther apart.

A-band

Dark band containing both actin and myosin

*Which is the correct order of the connective tissue layers of a skeletal muscle, beginning with the most superficial?

Epimysium: surrounds entire muscle Perimysium: surrounds fascicles Endomysium: surrounds and electrically insulates each muscle fiber

*In a sarcomere, which letter is associated with a region within the A band that contains only thick filaments ( i.e., no thin filaments are present)?

H

H-zone, M-line, Z-disc, I-band

H-zone - Lighter region in the middle of an A band M-line - Appears as a dark protein disc in center of H zone Z-disc - Made of dark proteins called connectins I-band - Light band containing thin filaments only

*In a sarcomere, which letter is associated with the light band immediately surrounding a Z disc?

I bands

In skeletal muscles, fast oxidative (intermediate) fibers are characterized as type ______, and they typically produce ATP through ______ cellular respiration.

IIa, aerobic

I-band

Light band containing thin filaments only

Which of the following is an example of a parallel muscle that has high endurance but is not very strong?

Rectus abdominis

The myosin heads point ______ the edges of the filament and project outward toward the surrounding thin filaments.

toward

In a skeletal muscle cell, two terminal cisternae and the centrally placed T-tubule form a structure called a

triad

Another name for deep fascia is ______.

visceral fascia

Fast anaerobic fibers are also called ______ fibers because they are pale in color due to their lack of ______.

white, myoglobin

*A tropomyosin molecule is a short, thin, twisted filament that covers small sections of the ___________ strands.

actin

*Structurally, troponin attaches to __________ to anchor itself in place.

actin

*A tendon is usually cordlike in appearance, but some appear as a flat sheet, termed an ____________.

aponeurosis

The endomysium is composed of what type of connective tissue?

areolar

A multipennate muscle has ______ of the tendon within the muscle.

branches

*The sarcoplasmic reticulum stores __________ needed to initiate muscle contraction.

calcium ions

The myosin molecules in a thick filament are arranged in a manner that the long tails point toward the ______ of the filament.

center

The expansive sheet of dense irregular connective tissue that separates individual muscles is called the ______.

deep fascia

An example of a multipennate muscle is ______.

deltoid

The epimysium of a muscle is composed of ______ connective tissue.

dense irregular

When the fibers in a convergent muscle all contract at once, they ______ pull as hard on the tendon as a parallel muscle of the same size.

do not

True or false: In muscles moving the appendicular skeleton, the distal attachment is less mobile than the proximal attachment.

false

The majority of skeletal muscle fibers in the body are ______ fibers.

fast glycolytic

Intermediate fibers have a high resistance to ______.

fatigue

Pennate muscles are so named because their tendons and muscle fibers resemble a large ______.

feather

The superior attachment of a muscle ______.

is a term used for muscles moving the axial skeleton

*In general, a skeletal muscle is composed of

muscle fibers, connective tissue sheaths, nerves, arteries, veins

Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______.

myofilaments

There are many successive groupings of ______ that run the entire length of a myofibril.

myofilaments

*Which protein makes up the thick filaments?

myosin

Where a motor neuron axon terminal and a muscle cell meet is called a _____________ junction.

neuromuscular or synaptic

The perimysium of a muscle contains extensive arrays of blood vessels and nerves that supply muscle fascicles. These arrays are called ______.

neurovascular bundles

The cytoplasm of a skeletal muscle cell is referred to a ______.

sarcoplasm

If a skeletal muscle is injured, surrounding ______________ cells may be stimulated to differentiate and assist in its repair and regeneration.

satellite or stem

A parallel muscle ______ when it contracts, and its body ______ in diameter.

shortens, increases

A raphe is a ______.

slender band of collagen fibers

An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she has a greater percentage of _____ fibers in specific muscles.

slow

There are no ______ fibers in the muscles of the eye and hand, where ______ but brief contractions are required.

slow, swift

Over longer distances, runners who have higher proportions of ____ muscle fibers in their leg muscles are able to outperform runners who have a greater number of ______ muscle fibers in their leg muscles.

slow/fast

Type I muscle fibers contract more ______ than type IIa and IIb muscle fibers.

slowly

*Because origin and insertion are not always consistent terminology to describe muscle attachments the terminology according to the textbook now used for the AXIAL skeleton is ____________attachment and an ___________attachment.

superior attachment and an inferior attachment

*At the ends of muscles, the connective tissues merge to form a __________, which attaches the muscle to other structures.

tendon

*The structure responsible for attaching muscle to bone is a

tendon

*Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called

terminal cisternae

The reservoirs and specific sites for calcium ion release to initiate muscle contraction are called ______.

terminal cisternae

The M-line serves as an attachment site for the ______ filaments and keeps them ______ during contraction and relaxation.

thick, aligned

In cross section of the lateral part of an A-band, each ______ filament is sandwiched by three ______ filaments that form a triangle at its periphery.

thin, thick

Match the name of the muscle cell component with its function.

Myofibrils Thick and thin filaments Sarcolemma Regulates entry and exit of materials Sarcoplasm Site of metabolic processes for normal muscle fiber activities Sarcoplasmic reticulum Stores calcium ions needed for muscle contraction T-tubule Transports a muscle impulse from the sarcolemma throughout the entire muscle fiber

*In a sarcomere, which letter is associated with the thin dark line in the middle of an I band?

Z

*A sarcomere is defined as the distance from one _____ to the next.

Z disc

*Which is not a protein found in thin filaments?

Sacromyosin (actin is found in thin filaments)

In the axial skeleton, which muscle attachment site is often more mobile?

Superior

*Which are considered specific characteristics of all muscle cells?

1. Excitability: ability to respond to stimuli 2. Conductivity: ability to transmit electrical events along the cell membrane 3. Contractility: ability to generate tension and shorten cell length 4. Elasticity: ability to return to resting length after shortening or lengthening 5. Extensibility: ability to be stretched beyond resting length

Thin filaments are about ______ nanometers in diameter.

5-6

*A light micrograph of cardiac muscle shows alternating light bands and dark bands. In this example, which component of a sarcomere is observed as the dark bands?

A bands

Each filament composed of a strand of G-actin molecules is called ______.

F-actin

Fast glycolytic fibers are type ______ fibers.

IIx

When you bend your arm at the elbow, the biceps brachii muscle in the upper arm contracts and the bones of the forearm move. Where is the insertion site of the biceps brachii?

In the forearm

Differentiate: muscle, fascicle, muscle fiber, myofibril, myofilament

Muscle Multiple bundles housing many muscle fibers Fascicle A bundle of muscle fibers Muscle fiber Elongated, multinucleated, cylindrical cell Myofibril Long, cylindrical contractile element within muscle cell Myofilament Short contractile proteins of two types: thick and thin

Match the muscle fiber component with its function.

Myofibrils - Contain myofilaments that are responsible for muscle contraction Thick filament - Bind to thin filaments and cause contraction Thin filament - Bind to thick filaments and cause contraction Actin - Binding site for myosin to shorten a sarcomere Tropomyosin - Covers the active sites on actin when muscle cell is at rest

*The component of a muscle fiber that quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber is called the

Transverse tubules (T-tubules)

Myofibrils contain multiple ______; thus, there are numerous ______ in each myofibril.

Z-discs, sarcomeres

*Which is a correct listing of the hierarchy of a skeletal muscle's components, beginning with the smallest?

a: Myofibrils b: Muscle fiber c: Fascicle d: Skeletal muscle

In skeletal muscles, fast fibers are characterized as fast fo fibers____________ or fast oxidative.

glycolytic

The motor neuron axon travels through the epimysium and perimysium, and enters the ______, where it delivers a nerve impulse to an individual ______.

endomysium, muscle fiber

In each helical strand of actin, many small spherical molecules are connected to form a long filament resembling a string of beads. Each spherical molecule is called ______.

g-actin

Each myosin strand has a free ______ head and an attached ______ tail.

globular, elongated

The less mobile attachment of a muscle is called its ______.

origin

Slow _________ fibers are also known as type I fibers.

oxidative

Each ______ shortens as the muscle fiber contracts.

sarcomere

Myofilaments within myofibrils are arranged in repeating microscopic cylindrical units called ______.

sarcomeres

*The neurons that stimulate muscle contraction are called _____ neurons.

somatic motor neurons

In a relaxed muscle, myosin is blocked from binding to actin because strands of ____________ cover the myosin binding sites on the actin.

tropomyosin

Thick filaments are about ______ the diameter of thin filaments.

two times

*Two regulatory proteins are part of the thin filaments. These regulatory proteins are

•Tropomyosin: threadlike protein covering part of actin •Troponin: attaches to actin to anchor itself and also attaches to tropomyosin and can bind calcium

*According to the sliding filament theory, during contraction the length of the _________ remains constant, but the __________ disappears

•Widths of A bands remain constant •H zones disappear •I bands narrow •Z discs in one sarcomere move closer together •The sarcomere shortens in length