1. “The beginning of wisdom is to call things by their right names.”
11/14/2018
Title: Anat & Phys 11/28/06
Objectives:
To learn about the physiology of muscles.
Class Topics
Muscle physiology
Connective Tissue Coverings
All or none principle
Neuromuscular junction
Innervation
Myofibril
Contraction
“The beginning of wisdom is to call things by their right names.”
Chinese proverb
Wednesday, November 14, :07 PM

2. Class Assignments Lab - Reaction Time 11/28/06 Read 197-212 12/4/06
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Class Assignments
What
By When
Lab - Reaction Time 11/28/06
Read /4/06
Due this class period
Due next class period
Due in the future

3. Connective Tissue Coverings
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Connective Tissue Coverings
Fascia - broad band of collagen-based connective tissue
Tendons - connective tissue connecting muscle to bone
connects in the periosteum for strength
Aponeurosis - fascia of one muscle attaching to that of another muscle

4. Connective Tissue Coverings
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Connective Tissue Coverings
Epimysium - surrounding each muscle closely
Perimysium - divides the muscle into fascicles
around each bundle of muscle fibers
Endomysium - surrounding each muscle fiber

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From:
From:
/muscle/musc-img/fasicle.jpg

6. Skeletal Muscle striated all or none response
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Skeletal Muscle
striated
all or none response
if a muscle fiber is exposed to a stimulus (electrical or nervous) it will contract to its full extent
How can we have smooth movements?

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8. Neuromuscular Junction
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Neuromuscular Junction
Each muscle fiber is connected to a nerve fiber - motor neuron
Where they join is called the neuromuscular junction
one nerve cell may have several junctions with one muscle cell and even several muscle cells
nerve cells send messages to muscle cells by releasing neurotransmitters
chemicals that have receptors in muscle cells that stimulate contraction - acetylcholine
Wisconsin Online - Animation

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From:

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Innervation
1:10
Eye muscles
1:1000
Leg muscles

13. Muscle fibers each fiber represents 1 muscle cell some organelles
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Muscle fibers
each fiber represents 1 muscle cell
some organelles
Nuclei, sarcoplasmic reticulum, sarcolemma, ribosomes, mitochondria
mostly myofibrils
filaments that contain myosin and actin proteins and the location of contraction
Myosin - thick filament
Actin - thin filament

14. Contraction Terminology
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Contraction Terminology
A band - myosin filaments - dark area of myofibril
I band - actin filaments - light area of myofibril
Z line - Where actin filaments connect together (middle of I band)
H zone - non overlap area
Sarcomere - area from Z line to Z line

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16. From: http://www.biology.eku.edu/RITCHISO/301notes3.htm
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From:

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Contraction Overview
Filaments on myosin and actin merge causing muscle fibers to converge
Myosin - 2 protein strands with globular proteins (heads) sticking out that can react with active sites of actin to form cross bridges
Actin/troponin/tropomyosin
Actin – contains active site used to bond with myosin
Tropomyosin – resting position for myosin heads
Together with troponin
Troponin – bond to calcium ions
Changes shape to expose actin active sites
Together with tropomyosin

19. Contraction step by step
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Contraction step by step
Stimulation - acetylcholine released from motor neuron
Muscle fiber stimulation by acetylcholine & calcium ions are released from the sarcoplasmic reticulum
Calcium ions bind to troponin molecule
Troponin molecules change shape causing tropomyosin to rotate and expose active sites on the actin molecule

20. Contraction step by step
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Contraction step by step
Cross bridges form between actin (active sites) and myosin filaments (globular proteins)
Actin filaments slide along myosin filaments (ATP used) due to a swivel action of myosin globular protein
Muscle fiber shortens as contraction occurs
Wisconsin Online - animation
Texas A&M University - animation

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