Download 1 - Lone Star College

Chapter 07
Lecture Outline
See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
7.1 Functions and Types of Muscles
2
A. Smooth Muscle
1.
2.
3.
4.
5.
6.
7.
Located in the walls of hollow organs and
blood vessels
Involuntary contraction
Moves materials through organs and
regulates blood flow
Cylindrical cells with pointed ends
Each cell is uninucleated
No striations
Not easily fatigued
3
B. Cardiac Muscle
1.
2.
3.
4.
5.
Forms the heart wall
Fibers are uninucleated, striated, tubular,
and branched
Fibers interlock at intercalated disks, which
permit contractions to spread quickly
throughout the heart
Contraction does not require outside
nervous stimulation
Nerves do affect heart rate and strength of
contraction
4
C. Skeletal Muscle
1.
2.
3.
Fibers are cylindrical, multinucleated, and
striated
Make up muscles attached to the skeleton
Contraction is voluntary and controlled by
the nervous system
5
Types of Muscles
6
D. Connective tissue coverings of
skeletal muscle
1.
Endomysium
a. Thin layer of areolar connective tissue
b. Surrounds each skeletal muscle fiber
2. Perimysium – surrounds bundles of muscle
fibers (fascicles)
3. Epimysium
a. Layer that surrounds the entire muscle
b. Becomes part of the fascia (separates
muscles from each other)
c. Collagen fibers extend from epimysium
to form tendons that attach muscles to
the periosteum of bone
7
Connective Tissue of Skeletal Muscle
8
E. Functions of Skeletal Muscles
1.
2.
3.
4.
5.
Support the body to allow us to be upright
Make bones and other body parts move
Help maintain a constant body temperature
by generating heat
Assists fluid movement in cardiovascular
and lymphatic vessels
Help protect bones and internal organs,
and stabilize joints
9
7.2 Microscopic Anatomy and
Contraction of Skeletal Muscle
10
A. Muscle fiber components
1.
2.
Sarcolemma – plasma membrane
Sarcoplasm – cytoplasm
a. Contains glycogen that provides energy
for muscle contraction
b. Contains myoglobin which binds oxygen
until needed
3. Sarcoplasmic reticulum (SR) – endoplasmic
reticulum
4. T (transverse) tubules
a. Formed by the sarcolemma penetrating
into the cell
b. Come into contact with expanded
portions of the sarcoplasmic reticulum
11
5. Myofibrils and sarcomeres
a.
b.
Myofibrils run the length of the muscle fiber
Composed of numerous sarcomeres
1) Extends between two vertical Z lines
2) Contains two types of protein myofilaments
a) Thick filaments – made up of myosin
b) Thin filaments – made up of actin,
tropomyosin, and troponin
3) I band contains only thin filaments
4) A band in the center of the sarcomere contains
thick and thin filaments
5) H zone in the center of the A band has only
myosin filaments
12
Anatomy of a Muscle Fiber
13
6. Myofilaments
a.
Thick filaments
1) Composed of several hundred of
molecules of myosin
2) Myosin molecules end in a double
globular head that will form a crossbridge
b. Thin filaments
1) Two intertwining strands of actin
2) Double strands of tropomyosin coil over
each actin strand
3) Troponin occurs at intervals on the
tropomyosin strand
14
7. Sliding Filament Theory
a. Occurs when sarcomeres shorten (during
muscle contraction)
b. Myosin heads break down ATP and form a
temporary link with actin called a crossbridge
c. Cross-bridges bend and pull the actin
filaments past the myosin filaments
d. Thick and thin filaments remain the same
length
e. I band shortens
f. H zone disappears
15
Anatomy of a Muscle Fiber
16
B. Skeletal Muscle Contraction
1.
Neuromuscular junction
a. Axon terminals
1) Come into close proximity to the
sarcolemma
2) Have vesicles that contain the
neurotransmitter acetylcholine (ACh)
b. Synaptic cleft – a small gap that
separates the axon from the sarcolemma
17
Neuromuscular Junction
18
2. Steps involved in skeletal muscle
contraction
a.
b.
c.
d.
e.
f.
Nerve signal arrives at the axon terminal
The synaptic vesicles release ACh
ACh binds to receptors on the sarcolemma
The sarcolemma generates an electrical
signal that travels down the T tubules to
the SR
The SR releases calcium
Calcium from the SR allows the filaments
to slide past one another
19
C. The role of actin and myosin
1.
Myosin binding sites on actin molecules
a. Covered by tropomyosin when muscle is
relaxed
b. Released calcium combines with
troponin, moving the tropomyosin, and
exposes myosin binding sites
2. Heads of myosin have two binding sites
a. One site binds to ATP and splits it into
ADP and P
b. Second binding site binds to actin
20
Role of actin and myosin in muscle
contraction
21
3. Relaxation of the muscle
a.
b.
c.
Nerve signal stops
SR uses ATP to pump the calcium back into
the SR
Myosin heads detach from actin and the
sacromere lengthens
22
D. Contraction of Smooth Muscle
1.
Smooth muscle fibers contain thick and
thin filaments
a. Filaments are not arranged into
myofibrils that create striations
b. Thin filaments are anchored to the
sarcolemma or dense bodies
2. When contracted, the elongated cells
become shorter and wider
3. Contraction occurs very slowly
4. Contractions can last for long periods of
time without fatigue
23
E. Energy for muscle contraction
1.
Stored ATP present before strenuous
exercise only lasts a few seconds
2. Muscles acquire new ATP in three ways
a. Creatine phosphate breakdown
b. Cellular respiration
c. Fermentation
24
Energy sources for muscle contraction
25
3. Creatine phosphate breakdown
a. Does not require oxygen (anaerobic)
b. Regenerates ATP by transferring its
phosphate to ADP
c. Fastest way to make ATP available to
muscles
d. ATP produced only lasts about 8 seconds
e. CP + ADP  ATP + C
26
4. Cellular respiration
a.
b.
c.
d.
e.
f.
g.
Usually provides most of a muscle’s ATP
Uses glucose from stored glycogen and
fatty acids from stored fats
Requires oxygen
Myoglobin can make oxygen available to
muscle mitochondria
Carbon dioxide and water are end
products
Heat is a by-product
Glucose + O2  CO2 + H2O + ATP
27
5. Fermentation
a.
b.
c.
d.
e.
Anaerobic process
Produces ATP for short bursts of exercise
Glucose is broken down to lactate (lactic
acid)
Muscle will cramp and fatigue due to lack
of ATP
Glucose  Lactate + 2 ATP
28
F. Oxygen debt
1.
2.
3.
4.
Occurs when muscles use fermentation to
supply ATP
Causes heavy breathing after exercise
Training causes the number of
mitochondria to increase and a greater
reliance on cellular respiration, so there is
less oxygen debt
Requires replenishing creatine phosphate
supplies and disposing of lactic acid
29
7.3 Muscle Responses
30
A. Muscle Responses in the Laboratory
1.
All-or-none law – a muscle fiber contracts
completely or not at all
2.
A whole muscle shows degrees of contraction
a. Muscle twitch – a single contraction that lasts
only a fraction of a second
1) Latent period
2) Contraction period
3) Relaxation period
b. Summation – increased muscle contraction
without relaxing completely
c. Tetanic contraction – maximal sustained
contraction; fused twitches, no relaxation
31
Myogram showing a single muscle twitch
32
Myograms
33
Muscle Responses in the Laboratory, cont
3.
Fatigue
a. Muscle relaxes even though stimulation
continues
b. Reasons for fatigue
1) ATP is depleted
2) Accumulation of lactic acid in the
sarcoplasm inhibits muscle function
3) ACh may become depleted
4) Brain may signal a person to stop
exercising
34
B. Muscle Responses in the Body
1.
Motor unit
a. A nerve fiber together with all of the muscle
fibers it innervates
b. Obeys the all-or-none law
2.
Recruitment
a. As the intensity of nervous stimulation
increases, more motor units are activated
b. Results in stronger muscle contractions and less
fatigue
3.
Tone
a. Some muscle fibers are always contracting
b. Important in maintaining posture
35
4. Athletics and muscle contraction
a.
Size of muscles
1) Atrophy – a decrease in muscle size
2) Hypertrophy – an increase in muscle size
b. Slow-twitch fibers (Type I fibers)
1) Tend to be aerobic
2) Have more endurance
3) Have many mitochondria
4) Dark in color because they contain
myoglobin
5) Highly resistant to fatigue
6) Good for endurance activities
36
Athletics and muscle contraction, cont
c. Intermediate-twitch fibers (Type IIa fibers)
1) All the same features as slow-twitch
fibers, but much faster.
2) Better blood supply
3) Moderate strength for short periods of
time
4) Called fast aerobic fibers.
5) Used in moderate activity
37
Athletics and muscle contraction, cont
d. Fast-twitch fibers (Type IIb fibers)
1) Tend to be anaerobic
2) Designed for strength
3) Light in color
4) Have fewer mitochondria, little or no
myoglobin, and fewer blood vessels than
fast-twitch fibers
5) Vulnerable to accumulation of lactic acid
and can fatigue easily
6) Good for short, explosions of energy
38
7.4 Skeletal Muscles of the Body
39
A. Basic principles
1.
2.
3.
4.
5.
Origin – attachment of a muscle to the
immovable bone
Insertion – attachment of a muscle to the
bone that moves
Prime mover – muscle that does most of
the work in a movement
Synergist – muscles that assist the prime
mover
Antagonists – muscles that work opposite
one another to bring about movement in
opposite directions
40
Origin and Insertion
41
B. Naming muscles
1.
2.
3.
4.
5.
6.
7.
Size – maximus, medius, minimus, longus,
brevis, vastus
Shape – deltoid, trapezius, latissimus,
teres
Direction of fibers – rectus, orbicularis,
transverse, oblique
Location – frontalis, femoris, brachii
Attachment – origin and insertion
Number of attachments – biceps, triceps,
quadriceps
Action – flexor, extensor, adductor, levator
42
Superficial skeletal muscles
43
C. Muscles of the head
1. Muscles of Facial Expression
a. Frontalis
b. Orbicularis oculi
c. Orbicularis oris
d. Buccinator
e. Zygomaticus
f. Levator anguli oris
g. Levator labii superioris
h. Depressor anguli oris
i. Depressor labii inferioris
44
Muscles of the head, cont
2.
Muscles of Mastication
a. Masseter muscles
b. Temporalis muscles
45
Muscles of the head and neck
46
47
D. Muscles of the neck
1.
Swallowing
a. Tongue and buccinators
b. Suprahyoid and infrahyoid muscles
c. Palatini muscles
d. Pharyngeal constrictor muscles
2. Muscles that move the head
a. Sternocleidomastoid
b. Trapezius muscles
48
Muscle of the head and neck
49
E. Muscles of the trunk (anterior)
1.
Muscles of the thoracic wall
a. External intercostal muscles
b. Diaphragm
c. Internal intercostal muscles
2. Muscles of the abdominal wall
a. External and internal obliques
b. Transversus abdominis
c. Rectus abdominis
50
Muscles of the anterior shoulder and trunk
51
Muscles of the trunk
52
F. Muscles of the shoulder and upper limb
1.
Muscles of the Shoulder
a. Muscles that move the scapula
1) Trapezius
2) Serratus anterior
b. Muscles that move the arm
1) Deltoid
2) Pectoralis major
3) Latissimus dorsi
4) Rotator cuff muscles
a) Supraspinatus
b) Infraspinatus
c) Teres minor
d) Subscapularis
53
Muscles of the posterior shoulder
54
Muscles of the upper limb
55
Muscles of the shoulder and upper limb, cont
2.
Muscles of the Arm (humeral area)
a. Biceps brachii
b. Brachialis
c. Triceps brachii
3. Muscles of the Forearm (ulna/radius area)
a. Flexor carpi and extensor carpi
b. Flexor digitorum and extensor digitorum
56
Muscles of the forearm
57
Muscles of shoulder and upper limb
58
G. Muscles of the hip and lower limb
1.
Muscles that move the thigh (femoral area)
a. Iliopsoas
b. Gluteus maximus
c. Gluteus medius
d. Adductor group muscles
1) Pectineus
2) Adductor longus
3) Adductor magnus
4) Gracilis
59
2. Muscles that move the leg (tibia/fibula
area)
a. Quadriceps femoris group
1) Rectus femoris
2) Vastus lateralis
3) Vastus medialis
4) Vastus intermedius
b. Sartorius
c. Hamstring group
1) Biceps femoris
2) Semimembranosus
3) Semitendinosus
60
Muscles of the hip and thigh
61
3. Muscles that move the ankle and foot
a.
b.
c.
d.
e.
Gastrocnemius
Tibialis anterior
Fibularis longus
Fibularis brevis
Flexor and extensor digitorum longus
62
Muscles of the leg
63
Muscles of the hip and lower limb
64
7.5 Effects of Aging
65
Effects of Aging
A.
B.
C.
D.
Muscle mass and strength tend to decrease
Endurance decreases
Changes in nervous and cardiovascular
systems adversely affect muscles
Exercise at any age can stimulate muscle
buildup and reduce risk of diabetes and
glycation
66
7.6 Homeostasis
67
A. Smooth muscles
1.
2.
3.
Smooth muscle in arteries and arterioles
help maintain blood pressure
Smooth muscle contraction moves food
along the digestive tract and assists in the
voiding of urine
Smooth muscle sphincters can divert blood
flow to where it is needed
68
B. Cardiac muscle
1.
2.
Cardiac muscle contraction forces blood
into the arteries and arterioles
Creates blood pressure
69
C. Skeletal muscle
1.
2.
3.
4.
5.
Skeletal muscles protect internal organs
and stabilizes joints
Skeletal muscles are active during
breathing
Heat produced by skeletal muscle
contraction helps maintain normal body
temperature
Skeletal muscle contraction allows us to
relocate our bodies
Contraction creates pressure to move fluids
through vessels
70
Systems Work Together
71