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Skeletal Muscles
Myology
My = muscle
ology = study of
Muscles
650
Males : 42% of body is muscle
weight
Females : 35% muscle weight in the
body
Voluntary - skeletal
Involuntary – cardiac & smooth
Cardiac muscle
Heart
Involuntary
1-2 nuclei
Basket weave
Striated
Not regenerated
Smooth muscles
Involuntary
Visceral
1 nuclei
Spindle shaped
Not striated
Nerves – needed or not?
regenerated
Skeletal muscles
Striated
Needs a lot of ATP
Moves skeleton
Attached to bone
Some regeneration occurs
Muscle slides
Use the slides to view these –
discuss with your partner the
differences
Print out & label a picture of skeletal,
cardiac and smooth muscle
Cardiac Muscle
Figure 7-10(a)
Smooth Muscle Tissue
Figure 7-10(b)
Striated muscle
Functions of skeletal muscles
Movement
Posture / body position
Support of soft tissues
Protection
Homeostasis - temperature
Characteristics of muscles
Tissue types
Connective
Epithelial
Muscle
Neural
Muscle connections
Origin – muscle’s connection to the
non-moveable bone
Insertion – muscle’s connection to
the moveable bone
Action - joint movement
Muscles work in pairs
Flexor – contracted muscle (agonist)
Extensor – relaxed muscle
(antagonist)
Ex. Biceps & triceps
What would happen if muscles
worked alone?
Helper muscles = synergist
ex: brachioradialis- helps to flex
the elbow
Origins, Insertions, and Actions
– Origin
Muscle attachment that remains fixed
– Insertion
Muscle attachment that moves
– Action
What joint movement a muscle produces
Anatomy of Skeletal Muscles
The Organization of a Skeletal Muscle
Figure 7-1
Neuromuscular Junction page 191
Figure 7-4(a)
Figure 7.2a
Essentials of Anatomy & Physiology, 4th Edition
Martini / Bartholomew
7
The Muscular
System
PowerPoint® Lecture Outlines
prepared by Alan Magid, Duke University
Microanatomy page 188
– Sarcolemma
Muscle cell membrane
– Sarcoplasm
Muscle cell cytoplasm
– Sarcoplasmic reticulum (SR)
Like smooth ER
– Transverse tubules (T
tubules)
– Myofibrils (contraction
organelle)
– Sarcomeres
Movement due to
Filaments:
Actin
Myosin
Energy – will need ATP
Sarcomere- smallest part of a
muscle that contracts
Relaxed muscle
Page 189
Figure 7-3 (2 of 2)
Resting sarcomere
ADP
+
P
Myosin head
Active-site exposure
ADP
+ P
Sarcoplasm
Troponin
Actin
ADP
+
Ca2+
Tropomyosin
Cross-bridge formation
Ca2+
Active site
ADP
P +
Myosin reactivation
P
Ca2+
ADP Ca2+
P +
ADP
P +
Cross bridge detachment
Pivoting of myosin head
ATP
ADP
+ P
ADP + P
Ca2+
Ca2+
Ca2+
ADP
P +
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Ca2+
Ca2+
ATP
Ca2+
ADP + P
Figure 7-5
1 of 7
Muscle Contraction
1. NeurotransmitterAcetylcholine (ACh) released
from the motor neuron
ACh binds to receptors on the
sarcolemma
Na ions enter cell
ACTION POTENTIAL generated
2. Action potential travels through the
cell via the T-TUBULES
3. Ca ions released from the cisternae
and bind to troponin
troponin change shape (twist) to
expose the active site on the actin
4. Crossbridge forms as actin and
myosin bind together using ATP
As actin slides toward center of each
sarcomere – CONTRACTION occurs
5. Acetylcholinesterase (AChase)is
released - ACh is broken down, Ca
crossbridges break, Ca goes back to
the cisternae, actin returns to resting
position
Rephosphorylation occurs
from ADP
- ATP
Resting sarcomere
ADP
+
P
Myosin head
Active-site exposure
ADP
+ P
Sarcoplasm
Troponin
Actin
ADP
+
Ca2+
Tropomyosin
Cross-bridge formation
Ca2+
Active site
ADP
P +
Myosin reactivation
P
Ca2+
ADP Ca2+
P +
ADP
P +
Cross bridge detachment
Pivoting of myosin head
ATP
ADP
+ P
ADP + P
Ca2+
Ca2+
Ca2+
ADP
P +
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Ca2+
Ca2+
ATP
Ca2+
ADP + P
Figure 7-5
1 of 7
Table 7.1
Essentials of Anatomy & Physiology, 4th Edition
Martini / Bartholomew
7
The Muscular
System
PowerPoint® Lecture Outlines
prepared by Alan Magid, Duke University
Contractions need
Calcium
Calcium is absorbed with the help of
vitamin D
How do you get vitamin D?
Vitamin D
Sunlight- used by body to make D
Lack of vitamin D = ricketts
Which system takes in the sunlight
and helps muscles have a supply of
Ca?
homeostasis
What does the body do if it is cold?
Muscle contraction and heat is
released
Exercises
Stretching – to prevent injury
Resistance – to build muscle
Aerobic - needing oxygen, efficient,
more ATP available through respiration
(which organelle?)
Anaerobic – without oxygen, less
oxygen – lactic acid buildup
Lack of oxygen - muscle becomes
sore
Lack of ATP – muscle can cramp
Types of Contractions
Isotonic contraction
constant tension
(iso = same, tonic = tension)
ex.
Isometric contraction
The length of a muscle stays constant
(iso = same, metric = length)
ex.
ATP
Light activity
Aerobic metabolism of fatty acids
Storage of glucose as glycogen
Moderate activity
Breakdown of glycogen to glucose
Glycolysis of glucose
Peak activity
Anerobic breakdown of glucose
Production of lactic acid
Physical Conditioning
– Anaerobic endurance
Time over which a muscle can contract
effectively under anerobic conditions.
– Hypertrophy
Increase in muscle bulk. Can result from
anerobic training.
– Aerobic endurance
Time over which a muscle can contract
supported by mitochondria.
steroids
Synthetic hormones
Anabolic- builds muscle mass
Androgen
Estrogen
Side effects
Aging
Reduce
– Muscle size
– Muscle elasticity
– Muscle strength
– Exercise tolerance
– Injury recovery ability
Disorders
Muscular dystrophy
Sprains
Case study
Which organelle stores ATP
Which releases more ATP- aerobic or
anaerobic respiration?
Which is the backup for the other?
Rigor mortis – ATP is decreased so
Ca permeability is increased, muscle
can’t move
The Appendicular Muscles
2 groups
Muscles of the shoulder and upper
limbs
Muscles of the pelvic girdle and lower
limbs
Names of muscle- based on
Size
Shape
Location
Action
Origin
insertion
Shoulder Muscles
– Trapezius
– Rhomboid
– Levator scapulae
– Serratus anterior
– Pectoralis minor
Muscles of the Shoulder
Figure 7-17(a)
Anatomy of the Muscular
Muscles
of the Shoulder
System
Figure 7-17(b)
Muscles That Move the Leg
Figure 7-21
The Integumentary System
Removes excess body heat;
synthesizes vitamin D3 for
calcium and phosphate
absorption; protects
underlying muscles
Skeletal muscles pulling on
skin of face produce facial
expressions
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
2 of 11
The Skeletal System
Maintains normal calcium and
phosphate levels in body fluids;
supports skeletal muscles;
provides sites of attachment
Provides movement and
support; stresses exerted by
tendons maintain bone mass;
stabilizes bones and joints
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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The Nervous System
Controls skeletal muscle
contractions; adjusts
activities of respiratory and
cardiovascular systems
during periods of muscular
activity
Muscle spindles monitor
body position; facial
muscles express emotion;
muscles of the larynx,
tongue, lips and cheeks
permit speech
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
4 of 11
The Endocrine System
Hormones adjust muscle
metabolism and growth;
parathyroid hormone and
calcitonin regulate calcium
and phosphate ion
concentrations
Skeletal muscles provide
protection for some
endocrine organs
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
5 of 11
The Cardiovascular System
Delivers oxygen and
nutrients; removes carbon
dioxide, lactic acid, and
heat
Skeletal muscle
contractions assist in
moving blood through
veins; protects deep blood
vessels
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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The Lymphatic System
Defends skeletal muscles
against infection and
assists in tissue repairs
after injury
Protects superficial lymph
nodes and the lymphatic
vessels in the
abdominopelvic cavity
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
7 of 11
The Respiratory System
Provides oxygen and
eliminates carbon dioxide
Muscles generate carbon
dioxide; control entrances
to respiratory tract, fill and
empty lungs, control
airflow through larynx, and
produce sounds
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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The Digestive System
Provides nutrients; liver
regulates blood glucose
and fatty acid levels and
removes lactic acid from
circulation
Protects and supports soft
tissues in abdominal
cavity; controls entrances
to and exits from digestive
tract
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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The Urinary System
Removes waste products
of protein metabolism;
assists in regulation of
calcium and phosphate
concentrations
External sphincter controls
urination by constricting
urethra
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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The Reproductive System
Reproductive hormones
accelerate skeletal muscle
growth
Contractions of skeletal
muscles eject semen from
male reproductive tract;
muscle contractions
during sex act produce
pleasurable sensations
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-23
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