Chapter 10 Muscles

What are the characteristics of skeletal muscle

excitability, conductivity, contractility, elasticity, extensibility

The majority of muscle fibers in the body are

fast glycolytic

Intermediate fibers have a high resistance to ____

fatigue

What are some examples of isometric contractions

holding a yoga pose pushing on a locked door sitting up very straight

What percentage of body weight is muscle tissue in an adult

40% to 50%

What is a fasicle

A bundle of muscle fibers

What houses muscle fibers

A fascicle Muscle fibers are bundled within a fascicle Many fascicles are bundled within the whole skeletal muscle

What is a single muscle made of

A single muscle is composed of thousands of muscle cells

What causes a local change in the resting membrane potential

A stimulus

What type of connective tissue is a tendon made of

A tendon is made of dense regular connective tissue

What is contractility

Enables muscle cells to cause body movement and to perform the other functions of muscles Is exhibited when contractile proteins within skeletal muscle cells slide past one another.

What is a tendon

A thick cordlike structure that attaches muscle to bone

When muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction

A-band

What is the order of events once ACh diffuses across the synaptic cleft of a NMJ

ACh binds to receptors on the motor end plate The resulting action potential moves down the sarcolemma The action potential moves down the t-tubules The action potential reaches the terminal cisternae of the sarcoplamic reticulum Calcium ions are released into the sarcoplasm

What is excitability?

Ability of a cell to respond to a stimulus

What is acetylcholine?

Acetylcholine is a neurotransmitter that enables the communication between muscles and motor neurons

What is the double stranded contractile protein

Actin

Which of the following proteins ae found within a sarcomere

Actin and connectin

What is the name of the connective tissue that separates muscle from skin

Adipose connective tissue

What is an aponeurosis?

An aponeurosis is a thin, flattened sheet of dense regular connective tissue. It attaches muscle to either a skeletal component (bone or ligament) or to fascia

What is the function of satellite cells

Assist in repair of muscles

Why is skeletal muscle considered voluntary

Because the muscle fibers can be consciously controlled by the nervous system

What are the functions of skeletal muscle?

Body movement, maintenance of posture, protection and support, regulating elimination of materials, heat production

in a muscle there are concentric layer of connective tissue. from deep to superficial these connective tissue layers are the ______, the ______, and the _______

Endomysium, perimysium, Epimysium

What are the stages of cross-bridge cycling in order:

Calcium binds troponin; myosin binding site uncovered Cross bridge formation Power stroke Release of myosin head by ATP Reset of myosin head

What happens in the capillaries of skeletal muscles

Capillaries are the site of oxygen exchange, glucose exchange, and removal of wast products. Exchange occurs between blood and skeletal muscle fibers

The enzyme acetylcholinesterase resides in the synaptic ____

Cleft

What structures do the epimysium, perimysium, and endomysium form collectively

Collectively they extend past the muscle fibers to form either a tendon or an aponeurosis

What are myofibrils

Cylindrical organelles specialized for contraction

What type of connective tissue is the epimysium made of

Dense irregular connective tissue and is fibrous tissue

What contributes to the eventual total number of nuclei in the fiber

Each myoblast nucleus

What is elasticity

Elasticity is the ability of a muscle cell to return to its original length following either shortening or lengthening of the muscle

What is the elasticity of muscle cells dependent upon?

Elasticity of muscle cells is dependent upon the release of tension in the springlike connectin protein associated with contractile proteins

What is muscle fiber

Elongated, multinucleated cylindrical cell

What are the 3 layers of connective tissue within muscles

Epimysium-surrounds muscle Perimysium-surrounds the fascicle Endomysium-surrounds the muscle cell

When is extensibility exhibited

Extensibility is exhibited when we stretch our muscles before exercising

Slow muscle fibers are about ____ the diameter of fast muscle fibers.

Half

If a muscle cell is stimulated to contract, allowd to partially relax, then stimulated again, its force of contraction the second time will be ____

Higher

Why is a skeletal muscle an organ?

It is an organ because it is made of two or more types of tissue that work together to perform a specific function

What is the location of the deep fascia in relation to the superficial fascia

It is deep or internal to the superficial fascia

What is superficial fascia made of?

It is made of areolar connective tissue and adipose connective tissue

What is an axon?

Is also called a nerve fiber

What is the function of the epimysium

It's function is to protect and support the muscle to protect and support it like a tough leather sleeve

In order to predict how much tension a muscle can produce when contracting, it is important to consider the ____ relationship of thick and thin filaments

Length-tension relationship

Myofibril

Long cylindrical contractile element within muscle cell

What are the characteristics of glycolytic fibers

Low concentration of myoglobin White

although muscle fibers obey the all-or-none principle, the force of muscle contraction can be varied depending on how many ______ units are used

Motor

What controls skeletal muscle contraction

Motor neurons control skeletal muscle contraction

What nerves innervate skeletal muscles

Motor neurons of the somatic nervous system Somatic motor neurons extend from the brain and spinal cord to skeletal muscle fibers

What is a muscle

Multiple bundles housing many muscle fibers

Events of a nerve impule arriving at synaptic knob

Nerve impulse arrives at synaptic knob Ca2+ enters and binds synaptic vesicles ACh is released into synaptic cleft ACh bind receptors on the motor end plate

What is the name of the junction between the axon and the muscle fiber

Neuromuscular junction

What is the organization of a muscle

Muscle fibers Muscle fibers bundled within a fascicle Multiple fascicles Within fascicles each muscle fiber is surrounded by an endomysium Each fascicle is wrapped in perimysium Entire muscle is covered in epimysium

What is the function of the 3 layers of connective tissue within muscles

Protection and support attachment of the muscle to the skeleton or other structures within the body sites for distribution of blood vessels and nerves

As you struggle to twist open a jar, more motor units are called into action until you finally generate enough force to open it. This is an example of

Recruitment

The plasma membrane of a skeletal muscle fiber is called the ____

Sarcolemma

What law of thermodynamics is demonstrated when muscle tissue produces heat

Second law of thermodynamics

When does skeletal muscle cell respond

Skeletal muscle cell responds when its receptors bind neurotransmitter acetylcholine

Describe the gross anatomy of skeletal muscles

Skeletal muscle fibers, connective tissue layers, blood vessels

What are the circular muscle bands that contract and relax to regulate passage of material

Sphincters

The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function

Support, contraction, protection

The enzyme acetylcholine is found in the _____

Synaptic knob

What does the adipose connective tissue in superficial fascia do

The adipose connective tissue in superficial fascia separates muscle from skin

What connective tissue layers do the blood vessels of skeletal muscles extend through

The blood vessels extend through the epimysium, the perimysium to reach the endomysium

What is the function of the endomysium

The endomysium functions to electrically insulate the muscle fibers

What type of connective tissue is the endomysium made of

The endomysium is made of areolar connective tissue

Where is the epimysium

The epimysium covers the entire skeletal muscle

What is extensibility?

The lengthening of a muscle cell Lengthening is possible because the contractile proteins slide past one another to decrease their degree of overlap

What type of connective tissue is the perimysium made of

The perimysium is a layer of dense irregular connective tissue and is fibrous connective tissue

Where is the perimysium

The perimysium is found around each fascicle

What is the function of the perimysium

The perimysium provides protection and support to each bundle of muscle fibers

What are the smallest blood vessels of muscle tissue and where are they found?

The smallest blood vessels are capillaries an are found in the endomysium

What does the stimulus trigger

The stimulus triggers the movement of ions across the plasma membrane of the excitable cell

What is the thin filament composed of?

This is composed of actin, tropomyosin, and troponin

How does a skeletal muscle fiber reach it's length

To reach it's length groups of embryonic muscle cells called myoblasts fuse to form single skeletal muscle fibers during development

Skeletal muscle has an extensive network of blood vessels which means it is what?

Vascularized

Isometric contraction means

a muscle contracts and Does Change length

Isotonic contraction means

a muscle contracts but Does Not Change length

What is fascia

a thin sheath of fibrous tissue enclosing a muscle or other organ

What is conductivity

ability to transmit an impulse involves an electrical signal that is propagated along the plasma membrane as voltage-gated channels open sequentially during an action potential

What are the causes of muscle fatigue

build up of intracellular Pi insufficient Ca2+ Na+ or K+ imbalances

What are the 2 types of isotonic contractions

concentric and eccentric

What are the organelle of skeletal muscle fibers

cytoplasm golgi apparatus ribosomes vesicles cytoplasm is the sarcoplasm multinucleated-many nuclei

What is deep fascia?

dense irregular connective tissue around muscle, also called visceral fascia or muscular fascia

If you strain to push on a wall that does not move, your muscles are in what type of contraction

isometric

What are the types of muscle contraction

isotonic and isometric

What is another name for muscle cells

muscle fibers

What is another name for muscle fibers

myofibers

What is the thick filament composed of

myosin

Thick and thin filaments maintain their ____ whether the muscle is relaxed or contracted

same length

What is the function of fascia

separates individual muscles, binds muscles together with similar functions,fills spaces between muscles, contains nerves, blood vessels, and lymph vessels

Myofilament

short contractile proteins of 2 types, thick and thin

What type of muscle forms the majority of the walls of the digestive tract

smooth

Where is the endomysium

surrounds each individual muscle fiber

A cord-like structure that attaches muscle to bone is a ___

tendon

What is an isometric contraction?

tension develops, but there is no change in the length of the muscle

What is the function of an axon

the axon conducts nerve impulses away from the cell body

What is an isotonic contraction?

the muscle shortens or lengthens while resisting a constant load

What is the double stranded regulatory protein

tropomyosin

What type of muscle is skeletal muscle?

voluntary muscle