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38 terms

chapter 10-Muscle Tissue

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Muscle Function
-produce movement
-generate heat
-maintain posture
-move substances in body
-regulate organ volume
Muscle properties
-Excitability
-Contractibility
-Extensibility
-Elasticity
Excitability
ability to respond to stimuli by producing action potential
Contractibility
ability to shorten/thicken generating force
Extensibility
ability to stretch without damaging tissue
Elasticity
ability to return to original size/shape after contraction/stretching
Fascia
fibrous CT that surrounds the muscle tissue
Superficial fascia
separates muscle from skin
-protects muscle from trauma
-protects against shock (insulates)
-stores fat
-carries blood vessels/nerves
Deep Fascia
it groups muscles with similar functions together
-it fills spaces b/w muscles
-it carries nerves/blood vessels/lymphatic vessels
Epimysium
CT membrane that covers entire muscle
Perimysium
CT membrane covers individual fasicle
endomysium
CT covers individual muscle fiber and fills space in between.
sarcolemma
plasma membrane
sarcoplasmic reticulum
resembles ER. encircles each myofibril
-stores/ release Ca++
T. Tubules
to rapidly propagate nerve impulse along muscle fiber
Sarcoplasma
resembles cytoplasm.
-glycogen=ATP
-myoglobin--reddish pigment. stores and releases 02 in aerobic reaction.
sacromere
area between 2 Z discs. most important basic functional unit in muscle tissue
Actin
the thin filament protein
Myosin
thick filament protein
-a motor protein=spreads ATP
Sacromere Anatomy
-H Zone: only myosin
-A Band: both actin and myosin
-I band: only actin
-M line: marks center of the H-Zone
-Z discs: mark center of I-Band
-----anchors thin filaments
-----connect myofibrils
Muscle proteins
-contractile, regulatory, and structural
Contractile proteins
for contraction
-actin
-myosin
regulatory proteins
to switch contraction on/off
troponin
holds tropomyosin in place
tropomyosin
when is held in place, it blocks myosin from reaching actin
structural proteins
titin: responsible for elasticity
Myomesine: form M-line
Nebulin: ensures alignment of thin filaments
Dystrohin: carries tension from sacromere to tendon.
Muscle contraction
1.) Ca++ is released from sarcoplasmic reticulum
2.) Ca++ binds to troponin and changes its shape
3.) Tropomyosin moves out of the way
4.) Myosin can now reach actin
5.) myosin heads use ATP and move actin (contraction)
synapse
area of communication b/w two neurons, or a neuron/target cell.
Neurotransmitter
a protein released from neuron to switch a muscle contraction on.
neurotransmitter junction
synapse b/w a neuron and a muscle
Muscle Energy source
1.) Creatine Phosphate: 1 ATP---15 seconds
2.) Anaerobic cellular respiration: 2 ATP---30-60 seconds
3.) aerobic respiration: 36-38 ATP hours--need O2
Twitch contraction
a brief contraction of all muscle fibers in a motor unit in response to single action potential
latent period
A brief delay between the stimulus and muscular contraction
contraction period
-Ca++ binds to troponin
-Cross-bridges form
wave stimulation
the increased strength of contraction resulting from the application of second stimulus before the muscle has completely relaxed after a previous stimulus. (fused/complete or unfused/imcomplete)
Skeletal fiber types
1.) Based on content of Myoglobin
a. increased myoglobin = dark meat fibers
b. decreased myoglobin = white meat fibers
2.) Based on structural function
a. Aerobic--oxidative fiber (fast/slow)
b. Anaerobic--Glycolytic fibers (fast)
Cardiac Muscles
-in the walls of the heart
-fibers branch
-fibers have intercalated discs (desmosomes & gap junction)
-contractions are longer than skeletal
-involuntary; striated
smooth muscle
1.) visceral (single unit)
-----in organs/large blood vessels
-----all muscle fibers contract as a single unit
2.) Multi unit
-----iris/arrector pili muscle
----- each muscle fiber contract singly
-slowest, non-striated, involuntary