Chapter 12 - Muscular System: Exam 3

What are the 3 types of muscle tissue?

Smooth, cardiac, and skeletal

Smooth Muscle

Involuntary muscle found in hollow organs and vessels; has spindle-shaped cells, each with a single nucleus, cells have no striations, functions in movement of substances in lumen of body

Cardiac Muscle

Involuntary muscle found in the heart; has branching, striated cells, each with a single nucleus, functions in the pumping of blood

Skeletal Muscle

Voluntary muscle that is attached to the skeleton; has striated cells with multiple nuclei

What are the functions of skeletal muscles?

Support the body allowing us to stay upright, allow for movement by attaching to skeleton, help maintain a constant body temperature, assist in movement in the cardiovascular and lymphatic vessels, and protect internal organs and stabilize joints

How are skeletal muscles attached?

Tendon, origin, and insertion

Tendon

Connective tissue that connects muscle to bone

Origin

Attachment of a muscle on a stationary bone

Insertion

Attachment of a muscle on a bone that moves

How do skeletal muscles work?

Antagonistic and synergistic

Antagonistic

Muscles that work in opposite pairs

Synergistic

Muscles working in groups for a common action

What are some examples of how skeletal muscles are named?

Size, shape, location, direction of muscle fiber, attachment, number of attachments, and action

What is an example in size of how skeletal muscles are named?

The gluteus maximus is the largest buttock muscle

What is an example in shape of how skeletal muscles are named?

The deltoid is triangular (Greek letter delta is a triangle

What is an example in location of how skeletal muscles are named?

The frontalis overlies the frontal bone

What is an example in direction of muscle fiber of how skeletal muscles are named?

The rectus abdominis is longitudinal (rectus means straight)

What is an example in attachment of how skeletal muscles are named?

The brachioradialis is attached to the brachium and radius

What is an example in number of attachments of how skeletal muscles are named?

The biceps brachii has 2 attachments

What is an example in action of how skeletal muscles are named?

The extensor digitorum extends the digits

What is the terminology for muscle cell structure?

Sarcolemma, sarcoplasm, and sarcoplasmic reticulum

Sarcolemma

The plasma membrane of a muscle cell

Sarcoplasm

The cytoplasm of a muscle cell

Sarcoplasmic Reticulum

The SER of a muscle cell which stores calcium

What is the terminology for structure with a whole muscle?

Fascicles, myofibrils, myofilaments, and sarcomeres

Fascicles

Muscle fibers arranged in bundles

Myofibrils

Bundles of myofilaments that run the length of a fiber

Myofilaments

Proteins like actin and myosin that are arranged in repeating units

Sarcomeres

The repeating units of actin and myosin found along a myofibril

How many protein myofilaments is the sarcomere made of?

2

What does a thick filament in the sarcomere composed of?

Several hundred molecules of the protein myosin which is shaped like a golf club

What does a thin filament in the sarcomere composed of?

2 intertwining strands of the protein actin

Actin and myosin filament slide over one another during muscle _____

Contraction

What is the beginning of muscle contraction also known as?

The sliding filament model

What is the first step of muscle contraction?

Nerve impulses travel down a motor neuron to a neuromuscular junction

What is the second step of muscle contraction?

Acetylcholine (ACh) is released from the neuron and binds to the muscle fiber

What is the third step of muscle contraction?

The binding of ACh to a muscle fiber stimulates the fiber causing calcium to be released from the sarcoplasmic reticulum

What is the fourth step in muscle contraction?

Released calcium from the sarcoplasmic reticulum combines with troponin, a molecule associated with actin

What is the fifth step in muscle contraction?

Calcium combining with troponin causes the tropomyosin threads around actin shift and expose myosin binding sites

What is the sixth step in muscle contraction?

Myosin heads bind to binding sites forming cross bridges

What is the seventh step in muscle contraction?

ATP binds to the myosin heads and is used for energy to pull the actin filaments towards the center of the sarcomere: contraction now occurs

What is needed to attach and detach the myosin heads from actin?

ATP

What happens to muscle cells after death?

Muscle cells continue to produce ATP through fermentation and muscle cells can continue to contract

What happens when ATP runs out?

Some myosin heads are still attached and cannot detach causing rigor mortis

What may be used to estimate a person’s time of death?

Rigor mortis and body temperature

Motor Unit

A nerve fiber and all of the muscle fibers it stimulates

Muscle Twitch

A single contraction lasting a fraction of a second

Summation

An increase in muscle contraction until the maximal sustained contraction is reached

Tetanus

Maximal sustained contraction

Muscle Tone

A continuous, partial contraction of alternate muscle fibers causing the muscle to look firm

What fuel sources are stored in the muscle?

Glycogen and fat

What fuel sources are stored in the blood?

Glucose and fatty acids

There are ____ amounts of ATP stored in muscle fibers

Limited

Creatine Phosphate Pathway (CP)

Fastest way to acquire ATP but only sustains a cell for seconds; builds up when a muscle is resting

Fermentation

Fast-acting but results in lactate build up

Cellular Respiration (Aerobic)

Not an immediate source of ATP but the best long-term source

How much of our body weight is muscle?

40%

When muscles contract, what do they release?

Heat

What is the average body temperature?

98.6

Ligaments

Connects bone to bone

How many forms do muscle fibers come in?

2

What is considered the sarcomere in a sliding filament diagram?

Z-line to Z-line

Where is the neuromuscular junction located?

Synapse

When a muscle cell is activated, what can it also be called?

Depolarized

What are thin filaments made of (all components)

Actin, troponin, and tropomyosin

What is oxidized for ATP in the muscle?

Fat

What does the creatine phosphate pathway look like chemically?

ATP → ADP + P → CP → C + P → P + ADP → ATP

Fermentation can also be called what?

Glycolysis/Anaerobic Respiration

Aerobic = _____

Oxidative Phosphorylation

What is aerobic respiration good for?

Sustained contractions

Why are fast twitch fibers light in color?

Fewer capillaries and lots of glycogen

What does it mean that slow-twitch fibers are good for endurance?

They are fatigue resistant

What type of meat are slow-twitch fibers?

Red meats

What do fast-twitch fibers rely on?

CP and fermentation

What do slow-twitch fibers rely on?

Aerobic respiration

What are fast-twitch fibers adapted for?

Strength

What are slow-twitch fibers adapted for?

Endurance

Are fast-twitch fibers light or dark?

Light

Are slow-twitch fibers light or dark?

Dark

Do fast-twitch fibers have few or many mitochondria?

Few

Do slow-twitch fibers have few or many mitochondria?

Many

Do fast-twitch fibers have little or a lot of myoglobin?

Little to no

Do slow-twitch fibers have little or a lot of myoglobin?

Many

Fast-twitch fibers have ____ blood vessels than slow-twitch

Fewer

Spasms

Sudden, involuntary muscle contractions that are usually painful

Convulsions (Seizures)

Multiple spasms of skeletal muscles

Cramps

Strong, painful spasms often of the leg and foot

Strain

Stretching or tearing of a muscle

Sprain

Twisting of a joint involving muscles, ligaments, tendons, blood vessels, and nerves