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The Muscular System
Muscle System Functions
 Provides voluntary
movement of body
 Enables breathing,
blinking, and smiling
 Allows you to hop,
skip, jump, or do
push-ups
 Maintains posture
 Produces heat
Functions Continued
 Provides movement of
internal organs
 Moves food through
digestive tract
 Enables bladder control
 Causes involuntary actions
 Reflex actions
 Adjusts opening of pupils
 Causes hair to stand on
end ( )
Properties of Muscles
 Excitability: capacity of muscle to respond to
a stimulus
 Contractility: ability of a muscle to shorten
and generate pulling force
 Extensibility: muscle can be stretched back to
its original length
 Elasticity: ability of muscle to recoil to original
resting length after stretched
Muscle Tissue
Characteristics
 Is made up of
contractile fibers
 Provides movement
 Controlled by the
nervous system
 Voluntary-
consciously
controlled
 Involuntary- not
under conscious
control
Cardiac
Skeletal
Smooth
Red vs white muscle fibers
 a.Red (slow) fibers- greater number of mitochondria
- contain high concentration of myoglobin
-react at a slow rate; do not undergo fatigue even with
sustained contraction
- ex. Postural muscles which are opposed to gravity
 b. White (fast) fibers-contain little myoglobin/mitochon
- react rapidly and undergo anaerobic respiration
-generate force quickly but not for long durations
-ex. Fingers and eye movements ( darting motions)
 c. Intermediate fibers- postural muscles that are capable of
rapid contraction at times
- ex. Calf muscle-supports leg but also capable of running,
walking, jumping
Red vs white muscle fiber
Nerve and Blood Vessel
Supply
 Motor neurons
 stimulate muscle fibers to contract
 Neuron axons branch so that each muscle fiber (muscle
cell) is innervated
 Form a neuromuscular junction (= myoneural junction)
 Capillary beds surround muscle fibers
 Muscles require large amts of energy
 Extensive vascular network delivers necessary oxygen
and nutrients and carries away metabolic waste
produced by muscle fibers
Nerve and Blood Vessel Supply
Types of Muscle Tissue
 There are
three main
types of
muscle tissue
 Skeletal
(striated)
 Cardiac
(heart)
 Smooth
(visceral)
Types of Muscle cont.
Skeletal
 Attached to bones
 Makes up 40% of body weight
 Responsible for locomotion, facial
expressions, posture, respiratory movements,
other types of body movement
 Voluntary in action; controlled by somatic
motor neurons
Skeletal
Smooth Muscle
 In the walls of hollow organs, blood vessels,
eye, glands, uterus, skin
 Some functions: propel urine, mix food in
digestive tract, dilating/constricting pupils,
regulating blood flow,
 In some locations, autorhythmic
 Controlled involuntarily by
endocrine and autonomic
nervous systems
Smooth
 Heart: major source of movement of
blood
 Autorhythmic
 Controlled involuntarily by endocrine
and autonomic nervous systems
Cardiac Muscle
Cardiac
Comparison of Muscle Types
Muscle Type Cardiac
Function
Movement of
bone
Walls of internal
organs + in skinLocation
Attached to
bone
Heart
SmoothSkeletal
Striated- light
and dark bands
Many nuclei
Striated
One or two
nuclei
Characteristics
Non-striated
One nucleus
(visceral)
Long + slender Branching
Shape Spindle shape
Control Mode
Beating of heart
Involuntary Involuntary
Movement of
internal organs
Voluntary
Sarcomere
Myofibril
 Contain two
types of protein
filaments
 Actin and
Myosin
 Z disc- point of
anchor of actin
 Sarcomere-
functional unit
of a myofibril,
region
between Z
discs
Thin Filaments
Actin
Molecule
Thick Filaments
Myosin Molecule
Z Disc
Sarcomere
Contractile Proteins: Actin and
Myosin
Myosin (Thick) Myofilament
 Many elongated myosin molecules shaped like golf clubs.
 Single filament contains roughly 300 myosin molecules
 Molecule consists of two heavy myosin molecules wound
together to form a rod portion lying parallel to the myosin
myofilament and two heads that extend laterally.
Myosin Filaments cont
 Myosin heads
1. Can bind to active sites on the actin molecules
to form cross-bridges. (Actin binding site)
2. Attached to the rod portion by a hinge region
that can bend and straighten during
contraction.
3. Have ATPase activity: activity that breaks down
adenosine triphosphate (ATP), releasing
energy. Part of the energy is used to bend the
hinge region of the myosin molecule during
contraction
Actin (Thin) Myofilaments
1. F (fibrous) actin
2. Tropomyosin
3. Troponin
 Two strands of fibrous (F)
actin form a double helix
elongating the myofilament;
attached at either end at
sarcomere.
 Composed of G actin
monomers each of which
has a myosin-binding site
 Actin site can bind
myosin during muscle
contraction.
• composed of 3 major proteins
Actin Filaments cont
 Tropomyosin: an elongated protein
winds along the groove of the F
actin double helix.
 Troponin is composed of three
subunits:
 Tn-A : binds to actin
 Tn-T :binds to tropomyosin,
 Tn-C :binds to calcium ions.
Motor Unit: The Nerve-
Muscle Functional Unit
Mechanics of a Muscle
Contraction
 What stimulates a muscle to
contract?
 Your nervous system
 What cells are involved?
 Muscle cells and a motor neuron
 Motor neuron sends
impulse to muscle cells
 One neuron will form
synapses with many
muscle cells
 What is this called?
 A motor unit
 Let’s take a look under
the microscope.…A motor unit
 A motor unit is a motor neuron and all
the muscle fibers it supplies
 The number of muscle fibers per motor
unit can vary from a few (4-6) to
hundreds (1200-1500)
 Muscles that control fine movements
(fingers, eyes) have small motor units
 Large weight-bearing muscles (thighs,
hips) have large motor units
Neuromuscular Junction
Figure 9.7 (a-c)
5. muscular physiology
5. muscular physiology
5. muscular physiology
Sarcoplasmic Reticulum
(SR)
 SR is an elaborate, smooth endoplasmic reticulum
 runs longitudinally and surrounds each myofibril
 Form chambers called terminal cisternae on either side
of the T-tubules
 A single T-tubule and the 2 terminal cisternae form
a triad
 SR stores Ca++ when muscle not is contracting
 When stimulated, calcium released into sarcoplasm
 SR membrane has Ca++ pumps that function to pump
Ca++ out of the sarcoplasm back into the SR after
contraction
5. muscular physiology
Mechanics of a Muscle
Contraction
 Where does stimulation occur?
 Neuromuscular junction
 How do motor neurons
communicate with
muscle cells?
 Neurotransmitters (typically
acetylcholine) carry
impulse signal across the gap
 What happens when a
muscle cell is stimulated?
 Calcium ions are released into the muscle cell
Myofibrils are
surrounded by
calcium-
containing
sarcoplasmic
reticulum.
Neurotransmitters
Mechanics of a Muscle
Contraction
 What do calcium ions do?
 Cause interaction between actin and myosin
 How do actin and myosin interact?
 Actin filaments slide over the myosin filaments.
 What model explains this?
 Sliding Filament Model
 What causes actin to slide over
myosin?
 The head of myosin connects
to actin and pivots.
 What is this connection called?
 cross-bridge
 The binding of the myosin heads
throughout the sarcomere occurs
asynchronously…
 some myosin heads are
binding while other heads are
releasing the actin filaments.
 Role of Calcium Ions in Contraction
 When muscle is relaxed, attachment sites for
myosin heads are physically blocked by
tropomyosin.
 In order to contract a muscle, troponin
must move tropomyosin.
 Complex regulated calcium ion
concentration.
 Muscle fibers store Ca++ in
sarcoplasmic reticulum.
Sliding Filament theory
Mechanics of a Muscle
Contraction
 What provides the energy to swivel the head of
myosin? _____
 How exactly does the sliding filament model work?
 In the sliding filament model of muscle contraction, the
(thin) actin filaments
[red] (that are attached
to the Z-line) slide (are
actually pulled) inward
along the (thick)
myosin filaments
[blue], and the
sarcomere (measured
from one Z line to the
next) is shortened.
ATP
Mechanics of a Muscle
Contraction
 When each sarcomere becomes shorter it
causes each myofibril to become shorter.
 When each
myofibril becomes
shorter it causes
the muscle fibers
to become shorter
 When each
muscle fiber
shortens the
overall muscle
contracts.
Sarcomere
5. muscular physiology
5. muscular physiology
5. muscular physiology
5. muscular physiology
Myofibril in a state of
contraction
Electrical changes during
muscular contraction
•Depolarization- Na+ moves inside (+)
•Repolarization- (-) charge
•Absolute refractory period- depolarized
membrane, a 2nd stimulus is ineffective ( no
response)
•Relative refractory period- during repolarization,
stronger stimulus can cause a response
5. muscular physiology
Mechanical changes- tension
develops when filaments attempt to slide
past each other
 Isotonic contraction- ‘same tension’
- results in shortening of muscle but tension
remains the same
- filaments are successful in sliding
- moved through a distance
-ex. Walking, lifting an object, bending knee,
smiling
Types of Muscle Contraction
 Isometric contraction- ‘same length’
- contraction without shortening
-increased tension due to exertion against an
immovable object
-not successful in sliding
-Ex. Posture, holding an object, standing
still, opposing gravity
The kymograph
Mechanical changes cont
 Muscle twitch- response after application of
threshold stimulus
-single, brief, jerky contraction
 Summation- stimuli applied in succession
-cells do not get chance to relax between stimuli
-can be summed up
 Tetanus- application of stimuli in rapid
succession
-no period of relation between them
-contraction bec sustained and prolonged
-may dev tension 4x as during a single twitch
 Treppe( staircase effect)- stimuli applied at
slower rate than tetanus
-increased fusion of twitches
-individual contraction gradually becomes
stronger for a short time though stimulus
strength is unchanged
5. muscular physiology
5. muscular physiology
Mechanical Changes
5. muscular physiology
Flow of events during muscular
contraction
Sources of energy for
muscular contraction
 Ca2++ and myosin cause ATP breakdown
 Creatine phosphate- from excess ATP
-stored in muscles
 Glycogen breakdown through anaerobic
respiration
-only for short-term energy
production
Tone- state of partial contraction which gives
muscles a certain firmness
Plasticity- in smooth muscles only
-ability to stretch w/o developing
lasting increase in tension
- dev resistance to stretching at first
-later tension decreases and muscle
adjusts to new length
-in hollow visceral organs like urinary
bladder, stomach, small intestines
Control of a Muscle
Contraction
 How long does a muscle cell
remain contracted?
 Until the release of acetylcholine
stops.
 How strongly does a muscle fiber contract?
 To it’s fullest extent.
 All-or-none response
 So what controls the
strength of a contraction?
 Number of muscle cells recruited
 To get a stronger contraction, more
cells are stimulated
 A single cell can’t contract harder
Muscle Disorders
 A strain is an injury to a muscle or
tendon, and is often caused by
overuse, force, or stretching.
 Injured area
experiences:
 pain and
soreness
 swelling
 warmth, bruising,
or redness
 difficulty using or
moving the
injured area in a
normal manner
Strain
Muscle Disorders
 R.I.C.E.
 Rest: Stop all activities which
cause pain.
 Ice: Helps reduce swelling.
Never ice more than 10-15 min.
at a time. Protect the skin.
 Compression: Wrap the strained
area to reduce swelling.
 Elevation: Keep the strained area as
close to the level of the heart as is
conveniently possible to keep blood
from pooling in the injured area.
Treatment for Muscle Injuries
Muscle Disorders
 Muscle spasm- when A muscle (or even a few
fibers of a muscle) involuntarily contract
 Muscle cramp- involuntarily + forcibly
contracted muscle that does not relax
 A forceful + sustained spasm
CrampsSpasms
 Can last anywhere from a few
seconds to a quarter of an hour
 Caused by strain or injury
 Muscle feels tied up in knots
Muscle Disorders
 Tetanus is a preventable disease through vaccination
 Caused by bacteria that enters the body
through the skin
 Found in soil, dust and manure
 Toxin bacteria produces interferes with nerve
transmission to your muscles and causes
them to seize up in painful spasms.
 Tetanus typically starts in the jaw and muscles
of the face, quickly spreading to the arms and legs.
 “Lockjaw”
 Difficulty swallowing
 Intestines often seize up
 Bladder fails to empty
 Asphyxiation
 Cardiac arrest
Tetanus
Muscle Disorders
 Produced naturally by the body to support such functions as
fighting stress and promoting growth and development
 Referred to as roids, juice, hype, weight trainers, gym candy,
arnolds, stackers, or pumpers
 People use steroid pills, gels, creams, or injections to improve their
sports performance or the way they look.
 Anabolic steroids cause many different types of problems
 types of problems
 premature balding or hair loss
 dizziness
 mood swings
 problems sleeping
 nausea and vomiting
 high blood pressure
 aching joints
 urinary problems
 shortening of final adult height
 increased risk of heart disease,
stroke, and some cancers
Anabolic Steroids
Muscle Disorders
 People with cerebral palsy
may have difficulty walking. They may
also have trouble with tasks such as
writing or using scissors.
 Some people with cerebral palsy have
other medical conditions, including
seizure disorders or mental
impairment.
 Cerebral palsy happens when the
areas of the brain that control
movement and posture do not develop
correctly or get damaged.
Cerebral Palsy
Muscle Disorders
 A genetic condition that describes over 20
genetic and hereditary muscle diseases.
 Characterized by progressive skeletal muscle
weakness, defects in muscle proteins, and the
death of muscle cells and tissue.
 In some cases, cardiac and smooth muscles
are affected.
 Progressive Muscular Wasting (weakness)
 Poor Balance and Frequent Falls
 Walking Difficulty + Waddling Gait
 Limited Range of Movement
 Scoliosis (curvature of the spine)
 Inability to Walk
 Muscle Atrophy and Drooping Eyelids
Muscular Dystrophy
Principal symptoms:
 chronic autoimmune neuromuscular disease characterized
by varying degrees of weakness of the skeletal muscles
 Caused by a defect in the transmission of nerve impulses
at the neuromuscular junction
 Antibodies (produced by the body's own immune system)
block, alter, or destroy the receptors for acetylcholine at the
neuromuscular junction which prevents the muscle
contraction from occurring.
Myasthenia
Gravis
 Certain muscles such as those that control
eye and eyelid movement, facial expression,
chewing, talking, and swallowing are often
involved. The muscles that control
breathing and neck and limb movements
may also be affected.
 Patients initially complain of drooping eye
lids that get worse as the day goes on; they
develop double vision, difficulty talking, and
difficulty chewing.
Rigor mortis- stiffness of skeletal
muscles after death
 Myosin-actin crossbridges are still intact or in
a state of midcontraction at the time of death
 Crossbridges left attached due to depletion of
ATP
 Bonds not broken-rigid muscles
 Rigor mortis disappears as the body
decomposes

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5. muscular physiology

  • 2. Muscle System Functions  Provides voluntary movement of body  Enables breathing, blinking, and smiling  Allows you to hop, skip, jump, or do push-ups  Maintains posture  Produces heat
  • 3. Functions Continued  Provides movement of internal organs  Moves food through digestive tract  Enables bladder control  Causes involuntary actions  Reflex actions  Adjusts opening of pupils  Causes hair to stand on end ( )
  • 4. Properties of Muscles  Excitability: capacity of muscle to respond to a stimulus  Contractility: ability of a muscle to shorten and generate pulling force  Extensibility: muscle can be stretched back to its original length  Elasticity: ability of muscle to recoil to original resting length after stretched
  • 5. Muscle Tissue Characteristics  Is made up of contractile fibers  Provides movement  Controlled by the nervous system  Voluntary- consciously controlled  Involuntary- not under conscious control Cardiac Skeletal Smooth
  • 6. Red vs white muscle fibers  a.Red (slow) fibers- greater number of mitochondria - contain high concentration of myoglobin -react at a slow rate; do not undergo fatigue even with sustained contraction - ex. Postural muscles which are opposed to gravity  b. White (fast) fibers-contain little myoglobin/mitochon - react rapidly and undergo anaerobic respiration -generate force quickly but not for long durations -ex. Fingers and eye movements ( darting motions)  c. Intermediate fibers- postural muscles that are capable of rapid contraction at times - ex. Calf muscle-supports leg but also capable of running, walking, jumping
  • 7. Red vs white muscle fiber
  • 8. Nerve and Blood Vessel Supply  Motor neurons  stimulate muscle fibers to contract  Neuron axons branch so that each muscle fiber (muscle cell) is innervated  Form a neuromuscular junction (= myoneural junction)  Capillary beds surround muscle fibers  Muscles require large amts of energy  Extensive vascular network delivers necessary oxygen and nutrients and carries away metabolic waste produced by muscle fibers
  • 9. Nerve and Blood Vessel Supply
  • 10. Types of Muscle Tissue  There are three main types of muscle tissue  Skeletal (striated)  Cardiac (heart)  Smooth (visceral)
  • 11. Types of Muscle cont. Skeletal  Attached to bones  Makes up 40% of body weight  Responsible for locomotion, facial expressions, posture, respiratory movements, other types of body movement  Voluntary in action; controlled by somatic motor neurons Skeletal
  • 12. Smooth Muscle  In the walls of hollow organs, blood vessels, eye, glands, uterus, skin  Some functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regulating blood flow,  In some locations, autorhythmic  Controlled involuntarily by endocrine and autonomic nervous systems Smooth
  • 13.  Heart: major source of movement of blood  Autorhythmic  Controlled involuntarily by endocrine and autonomic nervous systems Cardiac Muscle Cardiac
  • 14. Comparison of Muscle Types Muscle Type Cardiac Function Movement of bone Walls of internal organs + in skinLocation Attached to bone Heart SmoothSkeletal Striated- light and dark bands Many nuclei Striated One or two nuclei Characteristics Non-striated One nucleus (visceral) Long + slender Branching Shape Spindle shape Control Mode Beating of heart Involuntary Involuntary Movement of internal organs Voluntary
  • 15. Sarcomere Myofibril  Contain two types of protein filaments  Actin and Myosin  Z disc- point of anchor of actin  Sarcomere- functional unit of a myofibril, region between Z discs Thin Filaments Actin Molecule Thick Filaments Myosin Molecule Z Disc Sarcomere
  • 17. Myosin (Thick) Myofilament  Many elongated myosin molecules shaped like golf clubs.  Single filament contains roughly 300 myosin molecules  Molecule consists of two heavy myosin molecules wound together to form a rod portion lying parallel to the myosin myofilament and two heads that extend laterally.
  • 18. Myosin Filaments cont  Myosin heads 1. Can bind to active sites on the actin molecules to form cross-bridges. (Actin binding site) 2. Attached to the rod portion by a hinge region that can bend and straighten during contraction. 3. Have ATPase activity: activity that breaks down adenosine triphosphate (ATP), releasing energy. Part of the energy is used to bend the hinge region of the myosin molecule during contraction
  • 19. Actin (Thin) Myofilaments 1. F (fibrous) actin 2. Tropomyosin 3. Troponin  Two strands of fibrous (F) actin form a double helix elongating the myofilament; attached at either end at sarcomere.  Composed of G actin monomers each of which has a myosin-binding site  Actin site can bind myosin during muscle contraction. • composed of 3 major proteins
  • 20. Actin Filaments cont  Tropomyosin: an elongated protein winds along the groove of the F actin double helix.  Troponin is composed of three subunits:  Tn-A : binds to actin  Tn-T :binds to tropomyosin,  Tn-C :binds to calcium ions.
  • 21. Motor Unit: The Nerve- Muscle Functional Unit
  • 22. Mechanics of a Muscle Contraction  What stimulates a muscle to contract?  Your nervous system  What cells are involved?  Muscle cells and a motor neuron  Motor neuron sends impulse to muscle cells  One neuron will form synapses with many muscle cells  What is this called?  A motor unit  Let’s take a look under the microscope.…A motor unit
  • 23.  A motor unit is a motor neuron and all the muscle fibers it supplies  The number of muscle fibers per motor unit can vary from a few (4-6) to hundreds (1200-1500)  Muscles that control fine movements (fingers, eyes) have small motor units  Large weight-bearing muscles (thighs, hips) have large motor units
  • 28. Sarcoplasmic Reticulum (SR)  SR is an elaborate, smooth endoplasmic reticulum  runs longitudinally and surrounds each myofibril  Form chambers called terminal cisternae on either side of the T-tubules  A single T-tubule and the 2 terminal cisternae form a triad  SR stores Ca++ when muscle not is contracting  When stimulated, calcium released into sarcoplasm  SR membrane has Ca++ pumps that function to pump Ca++ out of the sarcoplasm back into the SR after contraction
  • 30. Mechanics of a Muscle Contraction  Where does stimulation occur?  Neuromuscular junction  How do motor neurons communicate with muscle cells?  Neurotransmitters (typically acetylcholine) carry impulse signal across the gap  What happens when a muscle cell is stimulated?  Calcium ions are released into the muscle cell Myofibrils are surrounded by calcium- containing sarcoplasmic reticulum. Neurotransmitters
  • 31. Mechanics of a Muscle Contraction  What do calcium ions do?  Cause interaction between actin and myosin  How do actin and myosin interact?  Actin filaments slide over the myosin filaments.  What model explains this?  Sliding Filament Model
  • 32.  What causes actin to slide over myosin?  The head of myosin connects to actin and pivots.  What is this connection called?  cross-bridge  The binding of the myosin heads throughout the sarcomere occurs asynchronously…  some myosin heads are binding while other heads are releasing the actin filaments.
  • 33.  Role of Calcium Ions in Contraction  When muscle is relaxed, attachment sites for myosin heads are physically blocked by tropomyosin.  In order to contract a muscle, troponin must move tropomyosin.  Complex regulated calcium ion concentration.  Muscle fibers store Ca++ in sarcoplasmic reticulum.
  • 35. Mechanics of a Muscle Contraction  What provides the energy to swivel the head of myosin? _____  How exactly does the sliding filament model work?  In the sliding filament model of muscle contraction, the (thin) actin filaments [red] (that are attached to the Z-line) slide (are actually pulled) inward along the (thick) myosin filaments [blue], and the sarcomere (measured from one Z line to the next) is shortened. ATP
  • 36. Mechanics of a Muscle Contraction  When each sarcomere becomes shorter it causes each myofibril to become shorter.  When each myofibril becomes shorter it causes the muscle fibers to become shorter  When each muscle fiber shortens the overall muscle contracts. Sarcomere
  • 41. Myofibril in a state of contraction
  • 42. Electrical changes during muscular contraction •Depolarization- Na+ moves inside (+) •Repolarization- (-) charge •Absolute refractory period- depolarized membrane, a 2nd stimulus is ineffective ( no response) •Relative refractory period- during repolarization, stronger stimulus can cause a response
  • 44. Mechanical changes- tension develops when filaments attempt to slide past each other  Isotonic contraction- ‘same tension’ - results in shortening of muscle but tension remains the same - filaments are successful in sliding - moved through a distance -ex. Walking, lifting an object, bending knee, smiling Types of Muscle Contraction
  • 45.  Isometric contraction- ‘same length’ - contraction without shortening -increased tension due to exertion against an immovable object -not successful in sliding -Ex. Posture, holding an object, standing still, opposing gravity
  • 47. Mechanical changes cont  Muscle twitch- response after application of threshold stimulus -single, brief, jerky contraction  Summation- stimuli applied in succession -cells do not get chance to relax between stimuli -can be summed up
  • 48.  Tetanus- application of stimuli in rapid succession -no period of relation between them -contraction bec sustained and prolonged -may dev tension 4x as during a single twitch  Treppe( staircase effect)- stimuli applied at slower rate than tetanus -increased fusion of twitches -individual contraction gradually becomes stronger for a short time though stimulus strength is unchanged
  • 53. Flow of events during muscular contraction
  • 54. Sources of energy for muscular contraction  Ca2++ and myosin cause ATP breakdown  Creatine phosphate- from excess ATP -stored in muscles  Glycogen breakdown through anaerobic respiration -only for short-term energy production
  • 55. Tone- state of partial contraction which gives muscles a certain firmness Plasticity- in smooth muscles only -ability to stretch w/o developing lasting increase in tension - dev resistance to stretching at first -later tension decreases and muscle adjusts to new length -in hollow visceral organs like urinary bladder, stomach, small intestines
  • 56. Control of a Muscle Contraction  How long does a muscle cell remain contracted?  Until the release of acetylcholine stops.  How strongly does a muscle fiber contract?  To it’s fullest extent.  All-or-none response  So what controls the strength of a contraction?  Number of muscle cells recruited  To get a stronger contraction, more cells are stimulated  A single cell can’t contract harder
  • 57. Muscle Disorders  A strain is an injury to a muscle or tendon, and is often caused by overuse, force, or stretching.  Injured area experiences:  pain and soreness  swelling  warmth, bruising, or redness  difficulty using or moving the injured area in a normal manner Strain
  • 58. Muscle Disorders  R.I.C.E.  Rest: Stop all activities which cause pain.  Ice: Helps reduce swelling. Never ice more than 10-15 min. at a time. Protect the skin.  Compression: Wrap the strained area to reduce swelling.  Elevation: Keep the strained area as close to the level of the heart as is conveniently possible to keep blood from pooling in the injured area. Treatment for Muscle Injuries
  • 59. Muscle Disorders  Muscle spasm- when A muscle (or even a few fibers of a muscle) involuntarily contract  Muscle cramp- involuntarily + forcibly contracted muscle that does not relax  A forceful + sustained spasm CrampsSpasms  Can last anywhere from a few seconds to a quarter of an hour  Caused by strain or injury  Muscle feels tied up in knots
  • 60. Muscle Disorders  Tetanus is a preventable disease through vaccination  Caused by bacteria that enters the body through the skin  Found in soil, dust and manure  Toxin bacteria produces interferes with nerve transmission to your muscles and causes them to seize up in painful spasms.  Tetanus typically starts in the jaw and muscles of the face, quickly spreading to the arms and legs.  “Lockjaw”  Difficulty swallowing  Intestines often seize up  Bladder fails to empty  Asphyxiation  Cardiac arrest Tetanus
  • 61. Muscle Disorders  Produced naturally by the body to support such functions as fighting stress and promoting growth and development  Referred to as roids, juice, hype, weight trainers, gym candy, arnolds, stackers, or pumpers  People use steroid pills, gels, creams, or injections to improve their sports performance or the way they look.  Anabolic steroids cause many different types of problems  types of problems  premature balding or hair loss  dizziness  mood swings  problems sleeping  nausea and vomiting  high blood pressure  aching joints  urinary problems  shortening of final adult height  increased risk of heart disease, stroke, and some cancers Anabolic Steroids
  • 62. Muscle Disorders  People with cerebral palsy may have difficulty walking. They may also have trouble with tasks such as writing or using scissors.  Some people with cerebral palsy have other medical conditions, including seizure disorders or mental impairment.  Cerebral palsy happens when the areas of the brain that control movement and posture do not develop correctly or get damaged. Cerebral Palsy
  • 63. Muscle Disorders  A genetic condition that describes over 20 genetic and hereditary muscle diseases.  Characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue.  In some cases, cardiac and smooth muscles are affected.  Progressive Muscular Wasting (weakness)  Poor Balance and Frequent Falls  Walking Difficulty + Waddling Gait  Limited Range of Movement  Scoliosis (curvature of the spine)  Inability to Walk  Muscle Atrophy and Drooping Eyelids Muscular Dystrophy Principal symptoms:
  • 64.  chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles  Caused by a defect in the transmission of nerve impulses at the neuromuscular junction  Antibodies (produced by the body's own immune system) block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction which prevents the muscle contraction from occurring. Myasthenia Gravis
  • 65.  Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often involved. The muscles that control breathing and neck and limb movements may also be affected.  Patients initially complain of drooping eye lids that get worse as the day goes on; they develop double vision, difficulty talking, and difficulty chewing.
  • 66. Rigor mortis- stiffness of skeletal muscles after death  Myosin-actin crossbridges are still intact or in a state of midcontraction at the time of death  Crossbridges left attached due to depletion of ATP  Bonds not broken-rigid muscles  Rigor mortis disappears as the body decomposes