perfomance enhancing drugs 2 Would you consider supplements such as Creatine to be a performance enhancing drug Why or why not The Muscular System AampP Fall 2016 I Overview of Muscle Tissues ID: 752952
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Slide1
Bell Ringer
1. What is the best way to build muscle WITHOUT using
perfomance
enhancing drugs?
2. Would
you consider supplements such as
Creatine
to be a performance enhancing drug? Why or why not?Slide2
The Muscular System
A&P Fall 2016Slide3
I. Overview of Muscle Tissues
Muscle Types
Skeletal Muscle
Muscle fibers are packaged together to form whole muscles
Muscles are striated (have stripes)
Controlled voluntarilySlide4
2. Smooth Muscle
a. Found in walls of hollow organs
i. Ex. Stomach, bladder, etc b. Has no striations c. Involuntary controlSlide5
3. Cardiac Muscle
a. Found only in the heart
b. Has striations
c. Involuntary controlSlide6
B. Skeletal Muscle Functions
1. Producing Movement
a. mobility of the body as a whole
2. Maintaining posture and body position a. continual tiny adjustments to maintain standing or sitting postureSlide7
3. Stabilizing Joints
a. muscle tendons reinforce joints where bones don’t fit together well
i. Ex. Shoulder joint 4. Generating Heat a. energy used for muscle activity creates heat 5. Protection
a. covers internal organsSlide8
II. Microscopic Anatomy of Skeletal Muscle
Myofibrils
Ribbon-like organellesSlide9
2. Made of chains of
sarcomeres
Myofilaments
are substructures that produce light and dark banding patterns
i
. Thick filaments made of myosin proteinii. Thin filaments made of actin
proteinSlide10
3. Broken into many parts
Z disc
i
. Where
sarcomeres
join togetherLight I bandSpace where no myosin protein is present
Dark A band
Space where myosin protein is presentSlide11
d. H zone
Space where
mysoin
IS present, but
Actin
is absente. M lineLocated within the H zoneProtein rods that hold adjacent myosin filaments togetherSlide12Slide13
B. Muscle Fibers (Cells)
Have many oval nuclei
Contain special organelles
Myofibrils
Many in each cell
Take up most of the space in the cytoplasm
Sarcoplasmic
reticulum
Special ER that surrounds every myofibrilSlide14
3. Plasma membrane is called the
sarcolemma
Means “Muscle Husk”
4. Each cell enclosed in
Endomysium
a. A delicate connective tissue sheathSlide15
C. Fascicle
Formed by many muscle fibers bundled together
Surrounded by the
Perimysium
Another fibrous membrane
Coarser and stronger than the EndomysiumSlide16
D. Muscle Organ
Formed by many Fascicles bundled together
Surrounded by the
Epimysium
Toughest membrane of all
Also form tendons at the end of musclesSlide17Slide18
III. Skeletal Muscle Activity
Stimulation & Contraction of a Single Muscle Cell
The Nerve Stimulus and the Action Potential
Motor Unit
Made of one neuron and multiple muscle cells
The nerve fiber branches into multiple axon terminalsSlide19Slide20
b. Structure of Neuromuscular Junctions
Space between a neuron and muscle cell
Filled with vesicles that contain acetylcholine (
ACh
)
Acetylcholine is a neurotransmitterSlide21Slide22
c. Action of neuromuscular junctions
i
. Impulse (action potential) causes
ACh
vesicles to travel from the nerve to the muscle fiber ii. ACh triggers the release of calcium within the fiber
iii. Calcium allows myosin to bind with
actin
iv. Myosin pushes
actin
toward the H zone causing contractionSlide23Slide24
2. The Sliding Filament Theory
a.
Actin
is pushed closer together to cause contraction within each
Sarcomere
b. Myosin does NOT shorten during this process c. Filaments simply slide past each otherSlide25
B. Contraction of Skeletal Muscle as a whole
1. Graded Responses
a. The “all-or-none” rule applies to fibers
i
. means a fiber will always contract to its fullest extent when stimulated ii. Does NOT apply to the whole muscleSlide26Slide27
b. Whole muscle can react with different degrees of shortening in 2 ways
i
. change the frequency of muscle stimulation
ii. Change the number of fibers being stimulated at one timeSlide28
2. Muscle Response to rapid stimulation
a. Complete Tetanus
i. muscle contractions are completely smooth and sustained ii. No evidence of relaxation Slide29
b
. Multiple nerve impulses are sent rapidly
i
. muscle has no time to relax between
ii. Effects cause a “summed” contraction that is stronger Slide30
3. Muscle Fatigue and Oxygen Deficit
a. Muscle fatigue occurs when muscles are exercised strenuously
i. Muscles are still being stimulated but are unable to contract Slide31
b
. Oxygen deficit most likely cause
i
. body is unable to take oxygen in
fast enough ii. Muscles do not get the amount needed to contract iii. Lactic acid builds up as a resultSlide32
4. Types of Muscle Contraction
a. Isotonic
i. the muscle shortens during contraction ii. Ex. Bending your knee b. Isometric
i
. the muscle does NOT shorten
ii. Ex. Straining to lift a heavy objectSlide33Slide34
5. Muscle Tone
a. Some muscle fibers are still contracting at all times
i. allows muscle to remain firm and healthy ii. Exercise can increase muscle tone Slide35
b. Endurance exercises
i
. results in stronger, more flexible
muscles
that resist fatigue ii. Ex. Jogging or biking c. Resistance exercises i. increases muscle strength and size ii. Ex. Forcing a muscle to contract