The Muscular System

1
The Muscular System
2
Muscle Function

• produce movement
• maintain posture
• stabilize joints
• generate heat

3
Functional Characteristics

• Excitability- respond to a stimulus
• Contractility- ability to shorten forcibly when
  adequately stimulated
• Extensibility- the ability to be stretched
• Elasticity- the ability of a muscle fiber to
  resume its resting length after being stretched

4
Skeletal Muscle

• Striated
• Multinucleate
• Voluntary

5
Cardiac Muscle

• Striated
• Uninucleate
• Involuntary
• Branching
• Intercalated discs

6
Cardiac Muscle Tissue
7
Smooth Muscle

• Unstriated
• Uninucleate
• Involuntary
• Hollow walled organs and blood vessels

8
Smooth Muscle Tissue
9
Gross Anatomy Skeletal Muscle
10
Gross Anatomy Skeletal Muscle
11
Muscle Anatomy
myofibril

muscle fiber (cell)
sarcomere
12
Muscle Cell
Sarcoplasmic reticulum

13
Myofibril
14
Myosin (Thick) Filament
15
Actin (Thin) Filament
16
Cross Bridges
17
Sliding Filament Hypothesis
18
troponin
actin
No Calcium Ion
tropomyosin
Calcium Ion Present
myosin binding sites
19
Actin Myosin Interaction
20
Motor Unit
Biology 100 Human Biology
spinal cord
21
(No Transcript)
22
Stimulation of Skeletal Muscle
23
Muscle Twitch
24
Contraction Response
25
Origin- fixed point of attachment for biceps
brachii O clavicle and humerus Insertion-
moveable, usually crosses a joint O
radius Prime mover- - muscle group responsible
for producing particular movement Antagonist-
works opposite of prime mover Synergist-reduces
undesirable or unnecessary movement Contraction
of a muscle crossing 2 or more joints would
cause movement of all if synergists werent
there to stabilize it Ex. make a fist without
bending wrist Fixator- specialized synergist-
helps maintain posture ex. muscles of the back
fix scapula
26
Antagonistic Muscles
27
Naming skeletal muscles

• Direction of muscle fibers- straight, transverse
• Size of muscles- maximus, minimus, longus, brevis
• Location- frontalis, temporalis, occipitalis
• of origins- biceps, triceps, quadriceps
• location of muscles origin and insertion-
  sternoclediomastoid- O sternum and clavicle,
  I mastoid process of temporal bone
• shape of muscle- deltoid- triangle shape,
  trapezius- trapezoid shape
• action of muscle- adductor muscle (adducts,
  brings in thigh)

28
aponerosa
Frontalis
Orbicularis oculi
temporalis
zygomaticus
Masseter
Orbicularis oris
sternocledeomastoid
29
Frontal
Obicularis oculi
Temporalis
Obicularis oris
Masseter
Sternoclediomastoid
Deltoid
Pectoralis major
Biceps
Rectus abdominus
External oblique
sartorius
quadriceps
Tibialis anterior
30
aponerosa
occipitalis
Trapezius
Deltoid
triceps
Lattisimus dorsi
Gluteus maximus
hamstrings
gastrocnemus
Achilles tendon
31
Energy for muscle contraction
ATP is the only energy source ATP?(ATPase H2O)
?ADP Pi

• ATP is Generated by
• creatine phosphate
• ADP creatine phosphate?creatine ATP
• 2. lactic acid fermentation
• From stored glycogen via anaerobic glycolysis
• glucose?pyruvic acid (no O2) ?lactic acid
• ?O2
• 3. aerobic respiration
• Glucose ? pyruvate ? acetyl CoA ?Krebs?CO2 H2O
  ATP

32
Slow-Twitch Versus Fast-TwitchMuscle Fibers
33

• Muscle Fiber Types
• Fast glycolitic
• Slow oxidative
• Fast oxidative-glycolytic
• Ratio- redwhite (all 3 types in body)

34
Fast glycolitic

• white muscle fibers
• low myoglobin
• anaerobic glycolysis
• few mitochondria
• fast twitch fibers
• high glycogen stores
• short bursts
• fatigues easily

35
Slow oxidative

• red muscle
• aerobic
• high myoglobin
• low glycogen stores
• lots mitochondria
• slow
• long distance

36
Fast glycolitic-oxidative

• red ? pink
• aerobic
• fast
• high myoglobin
• intermediate amt. of mitochondria
• intermediate glycogen
• intermediate fatigue resistance

37
Red vs White Muscle

• long distance blue fin tuna- mostly red meat
• quick bursts- yellow tail- more white meat

38
Long distance Runner- aerobic respiration
Sprinter- anaerobic respiration
39
Effects of Exercise

• Disuse- atrophy
• Muscles must be physically active if they are to
  remain healthy
• Cast- muscle strength can decrease at a rate of
  5/ day can use e- stimulus
• Avoid muscle injuries
• warm up muscles- walk fast 5 minutes
• then stretch- avoids pulls and tares

40
Muscle Injuries

• cramp- sustained spasm or tetanic contraction
  may be due to low blood sugar levels, electrolyte
  depletion, dehydration
• strain- muscle pull
• spasm- tics

• hernia- protrusion of organ through body cavity
  wall? may be due to heavy wts.

41
Isotonic and Isometric Contractions

• Isotonic contraction
• Contraction with a change in length
• The muscle shortens and movement occurs.
• Isometric contraction
• Contraction without any change in length
• The muscle does not shorten and there is no
  movement produced even though the muscle
  contracts.

42
Isotonic and Isometric Contractions
Isometric
Isotonic