A&P muscular system exam 3

In an isometric contraction, the muscle ______ body movement.

does not produce

Muscle tissue demonstrates the property of _____ when it is done contracting and returns to its resting length.

elasticity

The connective tissue layer that surrounds an entire muscle is called ______.

epimysium

You make a New Year's resolution to work out more and by March notice your muscles are getting bigger. This is a result of muscle ______.

hypertrophy

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

intercalated

smooth muscle tissue

involuntary, non-striated, mononucleated

cardiac muscle tissue

involuntary, striated, 1 or 2 nuclei, intercalated discs

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

isometric or Isometric

Effects of Exercise on Muscle: Resistance

•Forceful contractions, strength training •↑ myosin, actin → ↑ muscle size (hypertrophy) •Small ↑ # of muscle fibers (hyperplasia)

Excitation-contraction coupling

•ACh binding → action potential along sarcolemma + T-tubules → sarcoplasmic reticulum (releases Ca2+)

Anabolic Steroids

•Build myosin/actin •Side effects: •Heart disease •Kidney/liver damage •Testicular atrophy, reduced sperm •Uterine atrophy, menstrual irregularities •Aggression

cardiac muscle

•Cells arranged in thick bundles (branching) •Intercalated discs (desmosomes + gap junctions) •Striated (sarcomeres) •MANY mitochondria (ATP)

Sarcomere

•Contractile unit (repeating, cylindrical units of myofilaments) •Striations •Dark: mainly thick filaments •Light: thin filaments

Sliding Filament Hypothesis

•Contraction of muscle due to sliding of filaments •Thick pull thin closer •Sarcomeres shorten

Gross Anatomy of Skeletal Muscle: Fascia

•Deep fascia: sheet of dense irreg. CT external to epimysium •Separates individual muscles •Superficial fascia: areolar CT + adipose •Separates muscle from skin

Isometric vs. Isotonic Contractions

•Factors: •Force generated by muscle •Resistance (load)

Isometric Contractions

•Force < load •Muscle length = same •Ex. Trying to shovel snow that is too heavy, holding baby in 1 position

Isotonic Contractions

•Force > load •Muscle length = changes •Concentric: shortening •Ex. Biceps brachii shortens when lifting baby •Eccentric: lengthening •Ex. Biceps brachii lengthens when placing baby in crib

Variations in Muscle Fiber Types

•Genes, training •Distance runners: many SO fibers •Sprinters/weight lifters: many FG fibers

Production of ATP: Glycolysis

•Glucose (from blood or glycogen in muscle) → pyruvate (2 ATP) •Cytosol •Oxygen NOT required

Fast Oxidative (FO) Fibers

•Intermediate diameter •Fast myosin ATPase •Fast, powerful contractions •ATP through aerobic cellular respiration → long contractions (little fatigue) •Moderate movement

Resting Muscle Tone

•Involuntary nervous stimulation → random contractions (motor units) → tension (not enough for movement) •Stabilizes bone/joints •Primes muscle for contraction

Effects of Exercise on Muscle: Atrophy

•Lack of exercise •↓ muscle fiber size, tone, power •Physical therapy

Skeletal Muscle Attachments: Axial

Superior A more moveable than inferior A • Superior portion pulled toward inferior portion • Ex. "Crunches" (rectus abdominis contraction)

As the troponin changes shape (due to binding calcium), it moves the ______ molecule to which it is attached, thus exposing the active sites on the G-actin molecules. Multiple choice question. tropomyosin

Tropomyosin

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 openings between the digestive tract and the external environment and the urinary tract and the opening to the external environment.

True Skeletal muscle makes up the sphincters that guard the openings to the urinary and digestive system.

Storage and movement of materials

Voluntary sphincter muscles of the gastrointestinal and urinary tracts can be kept closed or opened

Select all that apply Smooth muscle is found in which of the following locations? Multiple select question. In the wall of the uterus In the wall of the small intestine In the heart wall Around blood vessels in the spinal cord

___In the wall of the uterus ___In the wall of the small intestine ___Around blood vessels

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

aerobic

An increase in the number of mitochondria can be observed in ______.

hypertrophy

What is the force generated when a skeletal muscle is stimulated to contract called?

muscle tension

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

myofibrils

Termination of the nerve impulse at an NMJ results in the passive sliding of ______ back to their original state.

myofilaments

After stimulation of ACh receptors, a muscle impulse spreads quickly along the ____________and into the muscle fiber along T-tubules.

sarcolemma

A contracting skeletal muscle fiber typically shortens as all of its ______ shorten in length.

sarcomeres

The cytoplasm of a skeletal muscle cell has a specific name and is known as

sarcoplasm

As a result of ACh stimulation, calcium ions are released from the

sarcoplasmic reticulum

Cardiac muscle cells are Blank______ and thinner than skeletal muscle cells, and they have only Blank______ nuclei.

shorter; 1-2

Approximately 40-50% of your body weight is _____ muscle.

skeletal

Attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of ______ muscle.

skeletal

The ___________filament theory explains how muscle fibers shorten during contraction.

sliding

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

summation

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

summation

What attachments are axial muscles?

superior/inferior attachments

Upon release from the terminal cisternae, some calcium ions bind to ______ causing it to change shape.

troponin

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

twitch

Skeletal muscle tissue

voluntary, striated, multinucleated

Agonist

• AKA prime mover • Contracts to produce movement • Ex. Triceps brachii = agonist when extending forearm

Antagonist

• Actions oppose agonist • Ex. Triceps brachii = agonist when extending forearm, biceps brachii = antagonist (flexes opposite side of forearm)

Actions of Skeletal Muscles

• Agonist • Antagonist • Synergist

Synergist

• Assists agonist in performing its action • Ex. Biceps brachii = synergist to brachialis(agonist) when work together to flex elbow

Gross Anatomy of Skeletal Muscle: CT

• CT layers form: • Tendon • Attach muscle to bone, ligament, or fascia • Fascia separates individual muscles and muscles from skin

Patterns of Fascicular Arrangement

• Circular • Parallel • Convergent • Pennate

Circular Muscles

• Concentric fascicles around opening • Ex. Orbicularis oris,oculi

Skeletal Muscle Attachments: Appendicular

• Distal A more moveable than proximal A • Ex. Biceps brachii contraction

Gross Anatomy of Skeletal Muscle: CT Layers

• Epimysium: dense irreg. CT,surrounds muscle • Perimysium: dense irreg.CT, surrounds fascicle • Endomysium: areolar CT,surrounds each myofiber

Characteristics of Skeletal Muscle

• Excitability: response to stimulus • Conductivity: electrical signal • Contractility: contractile proteins slide • Extensibility: lengthening of cell (stretching) • Elasticity: returns to original length

Pennate Muscles

• Fascicles have same angle → "feather"• Tendon extends through body

Parallel Muscles

• Fascicles run parallel to long axis • Ex. Rectus abdominis,biceps brachii

Muscles of Respiration

• Inspiration: contraction to ↑ thoracic volume to fill lungs with air • Expiration: contraction/relaxation to ↓ thoracic volume to force air from lungs • Diaphragm • Inspiration: contracts,moves ↓ • Expiration: relaxes,moves ↑ • External intercostals• Elevate ribs- inspiration • Internal intercostals• Depress ribs- expiration

What do appendicular muscles do?

• Move upper/lower limbs • Stabilize/move pectoral and pelvic girdles

Functions of Skeletal Muscle

• Movement • Posture • Protection/support • Elimination: sphincters (GI and urinary tracts) • Heat production

Microscopic Anatomy of Skeletal Muscle

• Sarcoplasm: cytoplasm• Nuclei (many) • Sarcolemma: plasma membrane • T-tubules: invagination of sarcolemma • Sarcoplasmic reticulum: ER, sequesters Ca • Mitochondria

Gross Anatomy of Skeletal Muscle: Myofibers

• Skeletal muscle fibers(myofibers) = cell • Long (10-30 cm), threadlike • Myofibers bundled within fascicle

What do axial muscles do?

• Support/move head and vertebral column • Move facial features • Move mandible (chewing) • Food processing/swallowing • Breathing • Support abdominal/pelvic organs

Convergent Muscles

• Widespread fascicles in broad area,converge on A site • Triangular • Ex. Pectoralis major

Smooth Muscle

•2% b.w. •Fusiform cells •Organs (BV, bronchioles, digestive, ureters, uterus) •Other (Iris, arrector pili muscles) •Non-striated (no sarcomere)

Skeletal Muscle

•40-50% b.w. •Attached to skeleton, openings of GI and urinary tracts

Sarcomere crossbridge cycling

Ca2+ binds to troponin → thin filaments slide past thick filaments •Sarcomere shortens → contracts

A muscle fiber is what level of organization in the body?

Cellular

Posture

Contraction of specific skeletal muscles stabilizes joints.

Muscle Tension

Force generated by muscle contraction

Temperature regulation

Heat is produced as a waste product of energy usage.

The act of shivering is an example of skeletal muscle performing what function?

Heat production

Motor Unit

Motor neuron + myofibers it controls •Inverse relationship between size of motor unit and degree of control

Excitability

Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system? Multiple choice question. Contractility

Body movement

Muscles contract and pull on the tendons that attach the muscles to the bones.

Exercise + Muscle Pain

NOT due to lactate accumulation! •Tears in muscle fibers → fluid, inflammation

Select all that apply Which can cause muscle fatigue? Multiple select question. Na+ or K+ imbalances build up of intracellular Pi insufficient acetylcholinesterase insufficient Ca2+ insufficient ATP

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

Select all that apply In which activities are muscles in an isometric contraction? Multiple select question. doing push ups pushing on a locked door sitting up very straight holding a yoga pose abdominal crunches jumping jacks

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

Place the events that occur at a neuromuscular junction in order.

1- Nerve signal arrives at synaptic knob 2- Calcium enters and binds synaptic vesicle 3- ACh is released via exocytosis into the synaptic cleft 4- ACh binds receptors on the motor end plate

Sarcomere Crossbridge Cycling

1. Ca2+ binds to troponin •Myosin binding site on actin exposed 2. Crossbridge forms (attach) •Myosin heads bind to actin → crossbridge 3. Power stroke (pull) •Myosin head pulls actin toward center of sarcomere → power stroke •Release ADP and P 4. Release of myosin head •ATP binds to myosin head → releases myosin head from actin 5. Reset myosin head •ATP split into ADP and P → energy to reset myosin head

Skeletal Muscle Relaxation

1. Termination of signals in motor neuron → no Ach released 2. Ca2+ bound in sarcoplasmic reticulum (by ATP) 3. Troponin retains original shape, tropomyosin covers myosin binding sites on actin (prevents crossbridging)

Skeletal Muscle Contraction requires?

ATP and Ca2+

Skeletal Muscle Relaxation requires?

ATP and REMOVAL of Ca2+

Smooth muscle is found where in the respiratory system?

Around the bronchioles

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. The process called ______ caused this to happen.

atrophy

Appendicular muscles

attached to appendicular skeleton

Axial muscle

attached to axial skeleton

The sarcoplasm of a skeletal muscle fiber is the cellular component known in other cells as

cytoplasm

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

dense irregular

A piano player uses her hands for brief quick movements. Which muscle fiber type would you therefore predict to be predominant in these muscles?

fast glycolytic

In a normally functioning muscle, the inability to contract and produce tension is called ____ muscle .

fatigue

Overall, as aging progresses, muscle strength and endurance are impaired, and the individual has a tendency to ______quickly.

fatigue or tire

A skeletal muscle cell is also called a muscle

fiber or fibers

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

higher

The diameter of a muscle fiber will predict ______.

how much power it will produce

Slow fibers have a relatively large number of ______. This permits slow muscle fibers to produce a greater amount of ______ than fast muscle fibers while contractions are underway.

mitochondria; ATP

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

more

What attachments are appendicular muscles?

proximal/distal attachments

As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more motor units. This phenomenon, which increases the strength of the contraction, is referred to as .

recruitment

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 ______. Multiple choice question. recruitment

recruitment

CT layers merge to form?

tendon

relaxation period

tension decreases

contraction period

tension increases

The epimysium of a muscle surrounds

the entire skeletal muscle

Slow-twitch and fast-twitch muscle fibers differ primarily in ______.

their ATPase which splits ATP

latent period

there is no tension

As you sit there reading this your muscles, even your relaxed ones are not completely relaxed and soft. This is because they have some background tension called resting muscle ______.

tone

Fast Glycolytic (FG) Fibers

•Large diameter •Fast myosin ATPase •Fast, most powerful contractions •ATP through glycolysis → short contraction bursts (high fatigue) •Intense movement

Effects of Aging on Muscle

•Muscle mass loss: begins mid-30s, age 50 = prominent •↓ # muscle fibers and motor neurons •↓ ATP production (higher fatigue) •Fibrosis

Excitation of myofiber by motor neuron

•Nueromuscular junction •Acetylcholine (Ach) = neurotransmitter •Binds receptors → excitation

Production of ATP: Aerobic Cellular Respiration

•Nutrient + oxygen (from blood or myoglobin) → pyruvate (MANY ATP) •Mitochondria •Oxygen required

Rigor Mortis

•PM muscle stiffening •ATP exhausted → Ca2+ floods sarcomere •ATP exhausted → myosin head cannot detach (crossbridge stays) •Increased exercise just prior to death (ex. struggle) → faster onset of rigor mortis

what are the three Classification of Muscle Fiber Types?

•Slow oxidative (SO) •Fast oxidative (FO) •Fast glycolytic (FG)

Slow Oxidative (SO) Fibers

•Small diameter •Slow myosin ATPase •Slow, less powerful contractions •ATP through aerobic cellular respiration → long contractions (little fatigue) •Endurance!

Cardiac Muscle: Autorhythmic Pacemaker

•Stimulates cells → heartbeat •Controlled by autonomic NS

Effects of Exercise on Muscle: Endurance

•Sustained, moderate activity, ↑ HR •↑ mitochondria •↑ ATP (aerobic cellular respiration) •Delays fatigue

Myofilaments: contractile proteins

•Thick: myosin •Thin: actin

Classification of Muscle Fiber Types

•Type of contraction •ATP supply

Sarcomere

•Z disc: thin filaments anchored •M line: thick filaments anchored •A band: thick and thin filaments •H zone: thick filaments only •I band: thin filaments only