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Flashcards in Muscles Deck (110):
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4 functions of muscle

1. Produces movement
2. Maintains posture
3. Stabilizes Joints
4. Generates heat

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Special characteristics of muscle tissue

1.excitability
2. Contractility
3. Extensibility
4. Elasticity

2

Excitability

Also called responsiveness, ability to receive and respond to stimulus

3

Contractility

Ability to shorten forcibly, sets muscle apart from other tissue types

4

Extensibility

Ability to extend or stretch

5

Elasticity

Ability of muscle cell to recoil and resume it's resting length after stretching

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3 types of muscle tissues and there similarities and differences

1. Skeletal muscle: cells called muscle fibers, have striations, voluntary

2. Cardiac muscle: striated, involuntary

3. Smooth muscle: no striations, visceral, involuntary

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Name of the plasma membrane of a muscle cell

Sarcolemma (muscle husk)

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Muscle cell cytoplasm

Sarcoplasm

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Connective tissue sheaths of a muscle

1. Epimysium
2. Perimysium and fascicles
3. Endomysium

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Epimysium

Overcoat of DICT surrounding the whole muscle

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Perimysium

Surrounds each fascicle, made of fibrous connective tissue

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Endomysium

CT that surrounds each muscle fiber

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Parts of a muscle

1.epimysium
2. Perimysium
3. Endomysium
4. Tendons
5. Fascicles
6. Nerves and blood vessels in the muscle

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When a muscle contracts, the movable bone

The insertion moves towards the orgin

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Insertion

Movable part of the muscle

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Origin

Less movable part of the muscle

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Direct attachment

(Fleshy attachment) the epimysium of the muscle is fused with a periosteum or perichondrium

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Indirect attachment

Extends bruin muscle as a tendon or aponeurosis

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Aponeurosis

Sheet like ct that connects muscles to a bone, cartilage or other muscles

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Why are muscle fibers multinucleate?

The muscle cells fuse together

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Myofibrils

Individual fiber in the muscle cell made up of sarcomeres

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A bands

A dark band on a myofibril

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I band

Light band on a myofibril

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Saracomere

The smallest contractile unit of a muscle, myofibril a are made up of sarcomeres. A sarcomere is a section of a myofibril

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Organizational and structure level of a muscle from organ to molecular structure

1. Muscle
2. Fascicle
3. Muscle Fiber (cell)
4. Myofibril
5. Sarcomere
6. Myofilament

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Myofibril

Organelle of the muscle fiber made up of sarcomeres which contract; an organelle

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Types of filaments in a sarcomere

1. Myosin (thick filaments)
2. Actin (thin filaments)
3. Titin (elastic filaments)

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Sarcolemma

Plasma membrane of a muscle fiber

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Sarcoplasm

Cytoplasm of a muscle cell

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Difference between fibers, myofibrils, and filaments

Fibers= cells, myofibrils= organelle, filaments= extended macromolecular structure

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Z disc

Boundary of each sarcomere

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A band

Width of myosin

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I band

Area with NO myosin, overlaps 2 neighboring sarcomeres

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H zone

Middle of the band that doesn't have actin

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M line

Very center of the myosin

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Titin

Helps muscle cell to spring back to shape after stretching. Stiffens as it uncoils to prevent the sarcomeres from being pulled apart

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Two sets of intracellular tubules

Sarcoplasmic reticulum and T tubules

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Sarcoplasmic reticulum

Modified smooth endoplasmic reticulum that stores calcium ions and releases them on demand when the muscle fiber is stimulated to contract

39

Muscle contraction

1. Nerve impulse travels down neuron
2. Axon terminal releases a neurotransmitter
3.NT diffuses through synaptic cleft (little gap) and binds to sarcolemma
4. Sarcoplasmic reticulum releases calcium ions which causes the myosin heads to to bind to the actin, ATP is then used to bend the myosin heads inwards

- these two things cause actin to get pulled towards the center of the sarcomere

- A band has not changed
- I band shrinks to the size of Z disc
- Hzone disappears

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Sliding filament mechanism/ theory

Myosin and actin do not get shorter, they are just sliding over each other. Shortening the sarcomere

41

Muscle extension

Muscles do not forcibly lengthen. Gravity can pull a muscle back to its original length
- contracting a muscle on the opposite side of a joint can pull a muscle back to its original length

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Motor unit

A neuron and all the muscle fibers that it innervates

-a muscle produces more or less force by using more or fewer motor units

- an individual motor unit can be very large (lots of muscle fibers per neuron) or very small (vice versa) nuance movements of facial muscles

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Large motor units

Produce big movement and lots of force

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Small motor units

Produce small, subtle movement/ little force

45

Muscular dystrophy

A group of inherited muscle destroying diseases that generally appear during childhood. The muscle cells enlarge initially then atrophy and disintegrate. Most common form is Duchenne muscular distrophy common in males

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Duchenne muscular distrophy

A type of MD caused by a recessive gene in mostly male children which produces a defective cytoplasmic protein (dystrophin). Starts at 2-7 in healthy children, disease progresses from extremities upward to face, chest and heart muscles.Victims rarely live beyond 20s dying of respiratory failure

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Fibromytosis

Fibromyalgia, a group of of conditions involving chronic inflammation of a muscle it's connective tissue coverings and tendons and capsules of nearby joints. Symptoms: tenderness, fatigue and frequent awakening from sleep

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Hernia

Protrusion of an organ through its body cavity wall. Can be congenital or caused by heavy lifting, obesity and muscle weakening

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Myalgia

Muscle pain

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Myofascial pain syndrome

Pain caused by tightened band of muscle fibers, which twitch when the skin over them is touched. Overused or strained postural muscles

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Myopathy

Any disease of the muscle

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Myotonic dystrophy

Less common form of MD. Not sex specific. Gradual reduction in muscle mass and control if muscles.abnormal heart rhythm and diabetes. Worse in subsequent generations because gene repeats more

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RICE

Rest, ice, compression and elevation. Standard treatment for a pulled muscle or extensively at reached tendons and ligaments

54

Strain

Commonly called a pulled muscle.excessive stretching of the muscle causes it to tear. Due to over use and abuse. Injured muscle becomes inflamed adjacent joints are immobilized

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Spasm

A sudden involuntary twitch in smooth or skeletal muscle ranging from merely irritating to very painful. Facial an eyelid spasms are called tics and could possibly indicate a psychological factor. A cramp is a prolonged spasm

56

Tetanus

A state of sustained contraction of a muscle that is a normal aspect of skeletal muscle functioning. A disease cause by a bacteria resulting in painful spasms of certain skeletal muscles, which then turns into fixed rigidity of the jaw (lockjaw) and spasms of the trunk and limb muscles. Fatal due to respiratory failure

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What happens when a muscle shortens

The insertion (attachment to the movable bone) moves towards its origin (fixed immovable point of attachment)

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4 functional groups of muscles

1. Prime movers
2. Antagonists
3. Synergists
4. Fixators

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Prime mover

Or agonist(leader) has responsibility for producing a specific movement ex. Pectoralis major a prime mover of arm flexion

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Antagonist

(Against the leader) serves to stretch or remain relaxed. Helps to regulate action of prime mover by providing resistance and helps to not overshoot the mark and helps to slow down or stop a movement
Ex. Latissimus dorsi

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Prime movers and antagonists are located

On opposite sides of the joint across which they act on

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Synergist

Help prime movers

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Synergists help prime movers in what 2 ways?

1. Adding a little extra force to the same movement
2. Reducing undesirable or unnecessary movements that might occur as the prime mover contracts

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Fixators

When a Synergist immobilized a bone or a muscle's origin so that the prime mover has a stable base on which to act, they are called fixators

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A muscle may

Serve as a antagonist or Synergist or prime mover in different movements

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Types of fascicle arrangement (muscle pattern)

1. Parallel
2. Convergent
3. Pennate
3. Circular

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Parallel fascicle arrangement:

Strap like or fusiform. Ex. Sartorius (strap like) biceps brachii (fusiform)

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Fusiform

Wider in the middle and tapered at the ends

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Convergent fascicle arrangement:

Fascicles come together at insertion ex. Pectoralis major

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Pennate fascicle arrangement

"Feather-like"

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3 forms of pennate muscles

1. Unipennate; extensor digitorum long us
2. Bipennate; rectus femorus
3. Multipennate; deltoid

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Circular fascicle arrangement

When fascicles are arranged in concentric rings. Surround external body openings. Sphincters (squeezers) ex. Orbicularis muscles

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Skeletal muscles are named by what 7 ways

1. Location
2. Shape
3. Relative size; Maximus, minimums, longus, brevis
4. Direction/arrangement of fascicles; rectus(straight), transverse, oblique(angle)
5. Location and attachments (origin and insertion)
6. The number or orgins (-ceps, biceps, triceps, ect.)
7. Action

74

Charley horse

A muscle contusion. Tearing of the muscle followed by hematoma and pain

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Electromyography

A recording and interpretation of graphic records of the electrical activity of contracting muscles. Best way of determining functions of muscles and muscle groups

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Hernia

Abnormal protrusion of abdominal contents. Goes through weak spot in muscle

77

Quadriceps and hamstring strain

Also called pulls. Tearing these muscles at the tendons. Common athletes who do not warm up properly and fully extend their hip or knee quickly or forcefully

78

Ruptured calcaneal tendon

Common injury to Achilles' tendon. Happens mostly in older people or young sprinters. Exaggerate dorseflexion and plantar flexion almost impossible. Calf bulges. Repaired surgically.

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Shin splints

Pain in the anterior compartment of the leg, caused by irritation of the tibialis anterior muscle. Follows extreme or unusual exercise without adequate prior conditioning

80

Tennis elbow

Tenderness due to trauma or overuse of the tendon of origin of the fore arm extensor muscles at the lateral Epicondyle of the humerus

81

Torticollis

(Tort= twisted) a twisting of the neck in which there is chronic rotation and tiltin of the head to one side. Due to injury of the sternocleidomastoid on one side; also called wryneck

82

Overall Function of the nervous system

The master controlling and communicating system of the body

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3 functions of the nervous system

1. Sensory input
2. Integration
3. Motor output

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Sensory input

Receptor monitor change inside and outside the body.

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Integration

Processing and interpreting sensory input, making decisions; dictates the response

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Motor output

Response (control muscle, glands, etc)

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Divisions if the nervous system

1. Central Nervous system
2. Peripheral nervous system

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Central nervous system

-consists of brain and spinal chord
-performs integration

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Peripheral nervous system

- consists of nerves, ganglia, receptors etc
- involved in sensory and motor

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Afferent

(Sensory)
Involves somatic sensory and visceral sensory

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Efferent

(motor) somatic motor and visceral motor

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Autonomic nervous system

Consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles and glands; involuntary nervous system

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Somatic nervous system

Composed of somatic motor nerve fibers that conduct impulses from CNS to skeletal muscles; voluntary nervous system

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Somatic sensory fibers

Fibers convey impulses from the skin, skeletal muscles and joints (soma= body)

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Visceral sensory fibers

Transmit impulses from guts within ventral body cavity

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Neurons

Nervous system cells that transmit electrical signals

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Neuroglia

Support and protect neurons

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Special characteristics of neurons

- conduct electrical impulses down the length of a cell
- longevity: can live and function for entire life time
- do not divide: can not be replaced
-high metabolic rate: uses a lot of o2 and glucose

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Parts of a neuron

1. Cell body; contains organelles
2. Chromataphilic bodies; rough ER
3. Dendrites; numerous and branched, receptor sites
4. Axon; only one, has terminal branches at its end, generates and conducts impulses, releases neurotransmitters

100

What do dendrites, the cell body and axons do?

Dendrites and cell body receive info and and axons send info

101

How are neurons classified?

1. Structure
2. Function

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Functional classification of a neuron

1. Sensory neurons (afferent)
2. Interneurons
3. Motor neurons (efferent)

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Sensory (afferent) neurons

Send messages toward CNS; located in PNS

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Interneurons

Involved in integration; found in CNS

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Motor (efferent) neurons

Send messages away from CNS; located in PNS

106

Structural classification of neurons (# of processes)

1. Multipolar
2. Bipolar
3. Unipolar

107

Multipolar neurons

Have many dendrites and one axon; can be motor or Interneurons

108

Bipolar neurons

One dendrite, one axon only found in special sense organs

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Unipolar neurons

One axon typically sensory neurons