Chapter 6. Integumentary System

True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

True

True or false: Skeletal muscle is usually attached to the skeleton, but it is also found at the opening between the digestive tract and the external environment and the urinary tract and the opening to the external environment.

True

Fascicle

A bundle or muscle fibers.

True

A byproduct of anaerobic respiration is lactic acid.

What muscle types would you expect to find in the cardiovascular system?

Cardiac and Smooth

True or false: After diffusing across the synaptic cleft, ACh binds to receptors on the synapatic knob.

False

Myofibril

Long, cylindrical contractile element within muscle cell

Which are characteristics of glycolytic fibers?

Low concentration of myoglobin, white

Match each protein with its function:

MLCK - Phosphorylates myosin Calmodulin - Binds calcium MLCP - Dephosphorylate myosin

Muscle

Multiple bundles housing many muscle fibers.

When calcium ions bind to troponin, which of the following then occurs?

The myosin binding sites on actin are exposed.

After being generated, the muscle impulse continues to spread throughout the muscle fibers as long as _ keeps the motor end plate receptors open.

acetylcholine

Slow and intermediate fibers require oxygen to produce ATP so, so the metabolic reactions within these fibers are termed _.

aerobic

Ten minutes into a marathon, your body is relying on_ cellular respiration for ATP.

aerobic

Each motor unit consists of _.

all the fibers a single motor neuron is innervating in one muscle.

The connective tissue layers in muscle provide: protection, distribution sites for blood vessels and nerves, and a means of _ to the skeleton.

attachment

The rate of rhythmic contraction of cardiac muscle is controlled by the _ nervous system.

autonomic

The sarcoplasmic reticulum stores _____ ions need to initiate muscle contraction.

calcium

The wall of the heart is composed of _ muscle.

cardiac

The invagination of the sarcolemma on the smooth muscle cells pictured are?

caveolae

The enzyme acetylcholinesterase resides in the synaptic ______.

cleft

As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.

closer together

In _ tetany, a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli.

complete

There are two types of isotonic contractions: eccentric and _.

concentric

The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen ____.

debt

When a skeletal muscle is fully contracting for a while, as in arm-wrestling or lifting up a heavy weight, the force of contraction will _.

decrease

When a skeletal muscle is fully contracting for a while, as in arm-wrestling or lifting up a heavy weight, the force of contraction will_.

decrease

Acetylcholine moves across the synaptic cleft by _.

diffusion

A sarcomere is defined as the distance from one Z _ to the next.

disc

After contraction, a muscle fiber returns to its original length through:

elasticity

The epimysium of a muscle surrounds

entire skeletal muscle.

The three connective tissue surrounding the individual components of a muscle are the

epimysium, perimysium, endomysium

In a transverse section of a muscle, you can see that each skeletal muscle is actually composed of many _, which are bundles of muscle fibers.

fascicles

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

fast glycolytic

Intermediate fibers contract _ than slow fibers and _ than fast fibers,

faster/slower

A skeletal muscle's force of contraction weakens during a high demand situation- for example lifting a heavy weight for 30 repetitions. This phenomenon is called muscle _.

fatigue

A skeletal muscle cell is also called a muscle _.

fiber

During aging, the elasticity of skeletal muscle decreases as muscle mass if often replaced by dense regular connective tissue, a process called _.

fibrosis

Smooth muscle is composed of short cells that have a _ shape.

fusiform

In a concentric isotonic contraction, the tension produced is ______ than the resistance.

greater

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

half

If a muscle cell is stimulated to contract, allowed to partially relaxed, then stimulated again, its force of concentration the second time will be _.

higher.

An increase in muscle size is called _.

hypertrophy

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

Eccentric contractions actively _ a muscle.

lengthen

Cardiac muscle cells contain a large number of ______ to generate the ATP required for their unceasing work

mitochondria

Athletes have more defined muscles than non-athletes even while at rest because they have ______ motor units contracting all the time.

more

A motor unit is composed of a single _ and all of the muscle fibers it controls.

motor neuron

Althought 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 we actually record in a EMG is

muscle electricity

During development, many groups of _ fuse to from single skeletal muscle fibers.

myoblasts

After the age of 30, he number of _ in existing muscle fibers decreases.

myofibrils

While observing skeletal muscle tissue under the microscope you note that it appears to be striated due to _.

of the arrangement of myofilaments in each sarcomere

A motor unit is composed of _.

one motor neuron and several muscle fibers.

Slow fibers or type 1 fibers are also called ____ fibers because they contain the pigment myoglobin

oxidative

An extensive network of blood vessels and nerve fiber extends through both the epimysium and the _ of a muscle.

perimysium

The immediate supply of ATP for use in muscle contraction is generated by the _ system.

phosphagen

Contraction of specific skeletal muscles stabilizes joint and helps maintain the body's _ by holding the head and truck erect.

posture

As we age, decreased muscle strength is compounded by a tendency toward _.

rapid fatigue

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

To make a muscle contract more strongly, the nervous system can activate more motor units, This process is called_.

recruitment

An internal membrane complex in skeletal muscle cells that is similar to smooth endoplasmic reticulum of other cells is called the sarcoplasmic ________.

reticulum

After stimulation of ACh receptors, a muscle impulse spreads quickly along the _ and into the muscle fiber along T-Tubules.

sarcolemma

within a myofibril, Z discs separate the functional units known as

sarcomeres.

If skeletal muscle is injured surrounding ______ cells may be stimulated to differentiate and assist in its repair and regeneration

satellite

Myofilament

short contractile proteins of two types: thick and thin

According to the sliding filament theory, when a muscle contracts, thick and thin filaments _ past each other, and the _ shortens.

slide, sarcomere

The _ filament theory explains how muscle fibers shorten during contraction.

sliding

Sarcoplasmic Reticulum

smooth endoplasmic reticulum in a muscle fiber

In addition to skeletal muscle, two other types of muscle are found in the body: ____ muscle and ____ muscle.

smooth, cardiac

The attachment of Ach to the receptor on the motor end plate causes the receptor to open, allowing _ ions to enter the muscle fiber.

sodium

Skeletal muscle contraction is controlled by _ neurons.

somatic

Although smooth muscle cells have both thick and thin filaments, they are not precisely aligned, so no visible _ are present.

striations

A "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called _.

summation

A nerve impulse travels through an axon to its _.

synaptic knob

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

tendon.

The force generated when a skeletal muscle is stimulated to contract is muscle _.

tension

An action potential travels down the sarcolemma, through the t-tubules, to the _.

terminal cisternae

T-tubules are located adjacent to _ which are reservoir storing the calcium ions required for muscle contraction.

terminal cisternae

The H-band is more lightly shaded because only _____ filaments are present

thick

The striated appearance in skeletal muscle cells is due to size and density differences between _ and _ filaments.

thick/thin

Single unit muscle cell contract _.

together

When a muscle fiber is in a relaxed state, the __________ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments sarcolemma

tropomyosin

After release from the terminal cisternae, calcium ions bind to _, causing tropomyosin to move and expose active sites on actin.

troponin

A single contraction and relaxation of a muscle fiber is referred to as a muscle ______

twitch

Within a synaptic knob, synaptic _ contains the neurotransmitter ACh.

vesicles

Sarcoplasm

Cytoplasm of a muscle fiber

Place the following events in the correct order of occurrence once ACh diffuses across the synaptic cleft of a NMJ:

1. ACh binds to receptors on the motor end plate 2. The resulting action potential moves down the sarcolemma 3. The action potential moves down the t- tubules 4. The action potential reaches the terminal cistern of the SR 5. Calcium ions are releases into sarcoplasm

Correctly arrange the following events in the order they would occur at a neuromuscular junction.

1. An action potential reaches the axon endings of the motor neuron. 2. Acetylcholine is released. 3. Acetylcholine binds to receptors on muscle fibers. 4. Sodium gates open and an action potential is generated on the surface of the muscle fiber traveling into the inside of the muscle fiber. 5. The action potential arrives inside the muscle fiber and opens calcium gates. The calcium enables actin-myosin interaction. 6. As long as sufficient ATP is present, these muscle fibers now contract.

place the events at a neuromuscular junction in order

1. Arrival of nerve signal at synaptic knob. 2. Calcium entry into synaptic knob 3. Exocytosis of ACh into synaptic cleft 4. Binding of ACh to motor end plate

Place the events in the diagram in order.

1. Nerve impulse arrives at synaptic knob. 2. Ca2+ enters and binds synaptic vesicles. 3. ACh is released into synaptic cleft. 4. ACh binds receptors on the morot end plate.

place the stages of cross-bridge cycling in order

1. calcium binds troponin; myosin binding site uncovered 2. cross-bridge formation 3. power stroke 4. release of myosin head by ATP 5. reset of myosin head

Place the following events found in cross bridge cycling in the correct sequence:

1. myosin heads bind to actin 2. myosin heads pivot towards the M line 3. atp releases the myosin heads 4. ATPase re-cocks the myosin heads

Each myosin protein molecule in a thick filament consists of ____ strands

2

Muscle fiber

A muscle cell

The abbreviation for acetylcholine is

ACh

In a neuromuscular junction, what enzymes break down acetylcholinne?

AChE

Energy to drive the myosin movement in the sliding filament process is provided in the form of ____.

ATP

While the presence of calcium ions inside the sarcoplasm is a necessary condition for contraction, it is not sufficient. Once Ca2+ has been released and enables actin-myosin cross bridge building _ is needed for muscle action.

ATP

For longer contractions, muscle cells obtain ATP by which process?

Aerobic respiration

Smooth muscle is found in which of the following areas?

Around blood vessels, In the wall of he small intestine, In wall of the Uterus

After breaking your arm, you have a cast on it for three months. when the cast is removed, your arm looks much smaller than it did before. what process caused this to happen?

Atrophy

Which of the following proteins are found within a sarcomere?

Connectin, Actin

In a muscle, the perimysium is composed of what type of connective tissue?

Dense irregular

Muscle Fibers

Enlonged, mulinucleated, cylindrical cell

An EMG records electrical activity produced by skeletal, cardiac, and smooth muscles.

False

Which are characteristics of oxidative fibers?

High concentration of myoglobin, red, good for endurance, use aerobic respiration

Match the duration of a single muscle contraction with the source of ATP:

Immediate- Creatine Phosphate Short term- Anaerobic respiration Long term- Aerobic respiration

Multiunit smooth muscle is found in which of the following locations?

Iris of the eyes, Arrector pili muscles in the skin

Thick myofilaments are composed of bundles of what protein molecule?

Myosin

Sarcolemma

Plasma membrane of a muscle fiber

Which can cause muscle fatigue?

Sodium or potassium imbalancesInsufficient calciumBuild up of intracellular phosphate

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, and Protection

The motor end plate has folds and indentations to increase the membrane surface area adjacent to the _.

Synaptic Knob

An action potential is carried along the sarcolemma, the down _ tubules to the terminal cisternae of the sarcoplasmic reticulum.

T

Thin filaments in smooth muscle cells contain which proteins?

Tropomyosin, actin

An EMG can detect problems with your muscles during activity, as it measures muscle contraction or electrical activity in response to a nerve's stimulation of a muscle.

True

Recruitment increases the number of muscle fibers contracting.

True

Cardiac muscle cells form Y-shaped branches and join to adjacent muscle cells at a junctions called _ disc.

intercalated

Smooth muscle contraction is _ control.

involuntary

The two types of muscle contractions: are _ contraction (when a muscle contracts but does not change length and b. _ contraction (when a muscle contracts and does change length).

isotonic, isometric

The motor neuron transmit the effects of a nerve impulse to the muscle fiber at a neuromusclar _.

junction

Myofibrils are made up of _.

myofilaments

Muscle cell store oxygen bound to what molecule?

myoglobin

Muscle fibers that rely on aerobic respiration for ATP synthesis contain a high concentration of _ which gives them a reddish appearance.

myoglobin

After the cross bridges are formed, ATP is required to detach the _ and complete the sequence of cyclic events.

myosin heads

T-Tubule

narrow, tubular extensions of the sarcolemma into the sarcoplasm