THE MUSCULAR SYSTEM

1
THE MUSCULAR SYSTEM

• A P
• CHAPTER 7

2
TYPES OF MUSCLE

• SMOOTH MUSCLE - involuntary
• CARDIAC MUSCLE - involuntary
• SKELETAL MUSCLE voluntary

3
Organ Systems That Help With Movement

• Muscular system moves the bones/skeleton
• Nervous system transmits impulses to muscles to
  cause contraction

• Respiratory system exchanges oxygen and carbon
  dioxide between the air blood
• Circulatory system transports oxygen to muscles
  removes the carbon dioxide

4
Skeletal Muscle Functions

• Movement of the skeleton
• Maintenance of posture ( muscle tone)
• Generation of heat via muscle contractions

5
MUSCLE STRUCTURE

• Muscle cells are specialized for contraction
  when the muscle cell contract it shortens, thus
  pulling/moving the bone it is attached to
• Muscles are anchored to bone by tendons, usually
  at by at least 2 attached to different bones
• ORIGIN the more immobile or stationary
  attachment
• INSERTION the more movable attachment

6
Muscle Arrangements

• Antagonistic
• opposite function/movements if the biceps
  contract the triceps must relax
• pulls with contraction
• exerts no force with relaxation
• cannot push
• another muscle needed to pull the bone in
  another direction
• See table 7-2 fig 7-1

• Synergistic
• these types of muscles have the same function
• one is the prime mover the muscle that does
  most of the work
• joint stabilization

7
THE BRAINS ROLE

• MOVEMENT
• Nerve impulses come from the frontal lobes of the
  cerebrum
• Movement takes a conscious effort

• COORDINATION
• Regulated by the cerebellum located below the
  occipital lobes of the cerebrum
• Coordination takes place below the level of
  conscious thought

8
Muscle Tone

• The state of slight contraction present in
  muscles
• During contraction alternate fibers contract to
  prevent muscle fatigue
• Good tone helps maintain posture, produces 25 of
  body heat and improves coordination
• Regulated by the cerebellum we dont have to
  think about it

• Isotonic exercises these types of exercises
  involve contraction of the muscle with movement
  uses more oxygen, aerobic, improves the
  cardiovascular system respiratory system
  jogging swimming
• Isometric exercises the muscles contract, but
  do not move the skeleton, not aerobic, does not
  affect the cardiovascular or respiratory system,
  does improve tone kegel exercises

9
Muscle Sense

• The brains ability to know where our muscles are
  what they are doing, without our having the
  stop consciously look at them

• Stretch receptors in the muscles respond to
  stretching generate impulses to the brain that
  is interpreted as a mental picture

10
MUSCLES ENERGY

• ATP- direct source of energy not stored in
  large amts in the muscle
• Secondary energy sources
• Creatine phosphate
• Glycogen- most abundant
• O2 needed to release energy from glucose

• See pg 142 cellular respiration
• Myoglobin in muscle fibers stores some O2
• CV Resp systems supply more O2 with increased
  respirations heart rate
• If O2 not present in sufficient amounts will
  create O2 debt

11
OXYGEN DEBT

• LACTIC ACID- A WASTE PRODUCT OF METABOLISM THAT
  DEVELOPS WHEN O2 IS INSUFFICIENT
• LACTIC ACID CAUSES MUSCLE FATIGUE
• SORENESS IN MUSCLES IS THE RESULT OF LACTIC ACID
  BUILDUP
• OXYGEN DEBT- DEVELOPES AS LACTIC ACID
  ACCUMULATES. THERE IS NOT ENOUGH O2 DELIVERED TO
  THE MUSCLE CELLS

12
EFFECTS OF EXERCISE

• VASODILATION-BLOOD VESSELS INCREASE IN DIAMETER
• HEART PUMPS MORE BLOOD
• CIRCULATION IMPROVES
• GAS EXCHANGE IMPROVES

13
MUSCLE FIBER STRUCTURE

• Neuromuscular junction where the motor neuron
  meets the muscle fiber-fig 7-2
• Axon terminal the tip of the motor neuron
• Acetylcholine a neurotransmitter at the end of
  the axon terminal which helps in the transmission
  of nerve impulses

• cholinesterase an inactivator of the
  neurotransmitter, acetylcholine
• Sarcolemma the membrane of the muscle fiber
• Synapse the small space between the axon
  terminal the sarcolemma

14
Muscle Contraction

• Resting Potential
• Polarization is when the muscles fiber is relaxed
• Outside of the cell positive () charge
• Inside of the cell neg (-) charge
• Na ions more abundant outside the cell
• K and neg ions more abundant inside the cell
• The Na K pumps keep these in balance
• See fig 7-4

• Action Potential
• Depolarization begins due to a nerve impulse it
  starts the contraction process in the muscle
  known as the
• Sliding Filament Theory
• See fig 7-5
• Repolarization continues the process and restores
  the muscle fiber to the resting state or
  polarized

15
ACTIONS OF MUSCLES

• SEE FIG 7-7, TABLE 7-2
• FLEXION
• EXTENSION
• ADDUCTION
• ABDUCTION
• PRONATION

• SUPINATION
• DORSIFLEXION
• PLANTAR FLEXION
• ROTATION

16
MUSCLES OF THE HEAD NECK

• STERNOCLEIDOMASTOID
• MASSETER
• TRAPEZIUS

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SHOULDER, FOREARM AND HAND

• DELTOID
• BICEPS BRACHII
• TRICEPS BRACHII
• PECTORALIS MAJOR seen on muscles of the trunk
  fig 7-10

18
MUSCLES OF THE TRUNK

• EXTERNAL AND INTERNAL ABDOMINAL OB LIQUE
• RECTUS ABDOMINIS
• DIAPHRAGM

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THE PELVIC FLOOR

• LEVATOR ANI
• COCCYGEUS
• EXTERNAL ANAL SPHINCTER

20
LOWER EXTREMITIES

• GLUTEUS MAXIMUS
• GLUTEUS MEDIUS
• HAMSTRING GROUP

21
EFFECTS OF AGING

• WITH AGE, MUSCLE CELLS DIE ARE REPLACED BY FAT
  OR FIBROUS CONNECTIVE TISSUE, BUT.
• REGULAR EXERCISE AND ACTIVITY DELAY THESE EFFECTS