Download Muscle Structure

PSE4U EXERCISE SCIENCE
MUSCULAR SYSTEM CAROUSEL ACTIVITY
Student Resource (Assignment)
Instructions:
In groups of 2, students use resources provided (e.g., software, video, internet sites,
textbooks) to complete worksheets describing the features of neuromuscular principles
and theories. Each group is assigned a topic to research and will present its findings to
the class in a carousel format.
Students will have some class time to research their topic. The organizational structure
for the carousel is dependent on the number of students in the class (e.g., sixteen
students equal eight stations equal eight pairs).
Assuming an eight-station carousel format, student "A" becomes the expert and
presents his or her findings to his/her peers for four rotations. Students record the
information presented as they move from station to station.
After four rotations, student "B" becomes the expert and presents his or her findings for
the rest of the rotations (5-8).
During rotations, peers check for correctness using an observation checklist. Teacher
assesses each presenter using a communication rubric.
At the completion of the carousel, students return to their pair to share information
gathered on the features of neuromuscular principle and theories presented
Some neuromuscular principles and theories that could be considered:
 The Sliding Filament Theory
 The Motor Unit
 The Neuromuscular Junction
 Muscular Structure
 The Role of Calcium / ATP
 The “All or Nothing” Principle (Law)
 The Proprioceptor System (e.g., golgi tendon organ, muscle spindles)
 The Reflex Arc
There will be a library research period on Wednesday, 23 February, 2011..
A GRAPHIC ORGANIZER (attached) will be presented to the teacher during next
class (Thursday, February 24); next class will be a computer lab period in Lab 106.
Monday, February 28, 2011 will be an in-class work period in Period 2.
Carousel activity will take place on Tuesday March 1, 2011. (St. David’s Day)
PSE4U EXERCISE SCIENCE
COMMUNICATION RUBRIC FOR MUSCLE CAROUSEL ACTIVITY
The following assessment tool will be used to assess communication skills throughout
the Exercise Science Course.
Achievement Chart Category: Communication
Communication
Level One
Level Two
Criteria
(50%-59%)
(60%-69%)
1. Communication - communicates
- communicates
of information
information with
information with
about function of
limited clarity
some clarity
muscular system.
-demonstrates
-demonstrates
limited
some
understanding of
understanding of
facts, concepts,
facts, concepts,
theories.
theories.
-provides few
-provides some
supportive details supportive details
and answers to
and answers to
audience
audience
questions
questions
2. Communication
of information
based on
research suitable
for an oral
presentation to
the carousel
activity
Look fors:
Sending Verbal
Messages
(oral report)
Presentation Skills
- communicates
with a limited
sense of
audience and
purpose
-
PSE4U SCORING TOOL:
- communicates
with a some
sense of audience
and purpose
Level Three
(70%-79%)
- communicates
information with
considerable
clarity
-demonstrates
good
understanding of
facts, concepts,
theories.
-provides
supportive details
and answers to
audience
questions
- communicates
with a clear sense
of audience and
purpose
Level Four
(80%-100%)
- communicates
information with a
high degree of
clarity and with
confidence
-demonstrates
extensive
understanding of
facts, concepts,
theories.
-provides many
supportive details
and answers to
audience
questions
- communicates
with a strong
sense of audience
and purpose
clear articulate
interesting diction
effective voice volume/inflection
eye contact with the audience
appropriate facial expression, body language and gestures
effective pacing
projects energy and interest
logical progression or linked thoughts
presentation skills (e.g., controlled use of voice, body language,
presentation style, effective use of media/technology)
organization (e.g., effective opening/closing, appropriate development
of parts of the presentation, thoughtful sequencing of ideas)
creativity (e.g., audience involvement, effective use of
props/visuals)
provokes thoughtful audience responses
GRAPHIC ORGANIZER
Student’s Name: ________________________________
Topic: _________________________________________
Evaluator: Teacher: ___________ Peer: ______________
Type of Graphic Organizer:
______________
Word Web Flow Chart Timeline
Suitable Title?
Yes
Criteria
Knowledge/
Understanding
Visual
communication
of information
and ideas
Written
communication
of information
and ideas
Overall
Achievement
Level:
No
Self: ____________
Other:
_____/1
Mark
Assigned
Level 1
Level 2
Level 3
Level 4
Organizer
demonstrated
limited
knowledge of
facts and
terms
Organizer
demonstrated
some
knowledge of
facts and
terms
Organizer
demonstrated
considerable
knowledge of
facts and terms
Organizer
demonstrated
thorough
knowledge of
facts and terms
_____/3
Information
and ideas
communicated
with limited
clarity
Information
and ideas
communicated
with some
clarity
Information and
ideas
communicated
with
considerable
clarity
Information and
ideas
communicated
with thorough
clarity
_____/3
Information
and ideas
communicated
with limited
clarity
Information
and ideas
communicated
with some
clarity
Information and
ideas
communicated
with
considerable
clarity
Information and
ideas
communicated
with thorough
clarity
_____/3
Total
Mark:
_____/10
TEACHER NOTES:
Neuromuscular principles and theories background information:
Muscle Structure
 Skeletal muscle is an organ that contains muscle tissue, connective tissue, nerves
and blood vessels
 Muscle cells, often called muscle fibres, are long, sometimes running the entire
length of the muscle. They are the largest cells in our bodies. They are cylindrical
cells about the diameter of a human hair and have many nuclei situated on the
periphery of the cell which give them a striated appearance under low magnification
 The epimysium covers the body’s 430 (or more) skeletal muscles. The tendons
attach to the bone on its connective tissue known as the periosteum
 Under the epimysium, the muscle fibres are grouped in bundled called fasciculi, that
may consist of up to 150 fibres, which the bundles surrounded by connective tissue
(epimysium) which encircles and is continuous with the fibre’s membrane the
sarcolemma
 All of the tissues are continuous with the tendon, so tension that develops in one
muscle cell can develop tension in the tendon
Neuromuscular Junction
 The junction between a motor neuron (nerve cell) and the muscle fibres it innervates
is called the motor end plate, or more often, the neuromuscular junction
 Each muscle cell has only one neuromuscular junction, although a single motor
neuron innervates many muscle fibres, sometimes as many as several hundred
 A motor neuron and the muscle it innervates is called a motor unit; when stimulated
all the muscle fibres of a motor unit contract together
 The sarcoplasm is the interior structure of the muscle fibre. The sarcoplasm
contains contractile components which consists of protein filaments; other proteins;
stored glycogen and fat particles; enzymes, and specialized structures such as
mitochondria and the sarcoplasmic reticulum
 Hundreds of thousands of myofibrils each about the diameter of 1/100th the diameter
of a human hair, dominate the sarcoplasm. Myofibrils contain the apparatus that
contacts the muscle cell, which consists primarily of two types of myofilaments:
myosin and actin. Myosin is referred to as thin filaments and the action is referred to
as thick filaments.
 Globular heads called cross bridges protrude away from the myosin filament at
regular intervals. The actin filaments consist of two strands arranged in a double
helix. Two other proteins tropnin and tropomyolsin, are in-between the actin
filament. Myosin and actin filaments are the smallest contractile unit of skeletal
muscle known as the sarcomere. Sarcomeres run longitudinally along the entire
muscle fibre
Motor Unit
 The smallest independent unit controlled by the central nervous system is the motor
unit
 Several motor units comprise the muscle body (the number depends on the
individual muscle – small muscles in the eye may contain 6 to 7 motor units within
the muscle body – larger skeletal muscles may have 200 motor units making up the
muscle body)


A motor unit is composed of a number of muscle fibres (the number depends on the
individual muscle – small muscles in the eye may contain a few muscle fibres within
the motor unit – large skeletal muscle may contain several hundred and its efferent
motor nerve which innervates it
When a motor unit is activated – all fibres within the motor unit are activated
Sliding Filament Theory
REST:
 At rest, the cross bridges extend toward action. The actin and myosin are now in a
coupled position. The level of Calcium (Ca) concentration is low.
STIMULATION:
 Myosin cross bridges form a type of bond with selected sites on the actin filaments.
Actomyosin formation takes place. There is an immediate increase of intracellular
Ca. This is brought about by the arrival of the action potential at the transverse
tubules, which causes Ca to be released by the sarcoplasmic reticulum. The
inhibitory action of troponin that prevents actin-myosin interaction is released when
Ca ions bind rapidly with troponin in the actin filaments. Now the muscle is “turnedon”.
CONTRACTION:
 Cross bridges swivel or collapse. The muscle shortens and the actin slides over the
myosin. Tension develops. The ATP is broken down to ADP plus Pi plus energy.
Contraction will continue as long as Ca ions remain at a level that inhibits the
troponin-tropomyosin system
RELAXATION:
 At the relaxation state, when the nerve stimulus to the muscle is removed, Ca ions
move back into the sarcoplasmic reticulum (SR). The retrieval of Ca from the
troponin-tropomyosin proteins “turns off” the active sites on the actin filaments. This
deactivation accomplishes two things:
1) It prevents any mechanical link between the myosin cross-bridges and the actin
filaments,
2) It reduces the activity of myosin ATPase so there is no more ATP splitting.
Muscle now returns
to resting state.
Role of Calcium
 Following the depolarizing of the fibre’s membrane, the electrical impulse travels
through the fibre’s network of tubules of the interior of the cell
 The arrival of an electrical charge causes the SR to release large qualities of stored
calcium ions into the sarcoplasm
 In the resting state, tropomyosin is believed to lie on top of the active sites on the
actin filaments, preventing binding of the myosin heads
 Once calcium ions are released from the sarcoplasmic reticulum, they bind with the
troponin on the actin filaments
 Troponin, with its strong affinity from calcium ions, is believed to then initiate the
actin process by lifting the tropomyosin molecules off of the active sites on the actin
filaments
Role of ATP
 Energizes the power stroke
 Disconnects actomyosin coupling
 Escorts calcium back into the sarcoplasmic reticulum
The “All or None” Principle (Law)
 Muscular fibre or neuron responding completely when exposed to a threshold
stimulus
 A skeletal muscular fibre exposed to a stimulus of threshold strength responds to its
fullest extent
 Increasing the strength of the stimulus does not affect the fibre’s degree of
contraction
 Therefore, a skeletal muscle fibre normally does not contract partially; if it contracts
at all, it contracts completely, even though in some instances, it may not shorten
completely
The Proprioceptor System (e.g., Golgi Tendon Organ, Muscle Spindles)







The term kinesthesia means conscious recognition of the position of the body parts
with respect to on another as well as recognition of limb movement rates
These functions are accomplished by extensive sensory devices in and around joints
There are three principal types of proprioceptors: (1) free nerve endings, (2) Golgitype receptors, (3) pacinian corpuscles
The most abundant of these are free nerve endings, which are sensitive to touch and
pressure (these receptors are stimulated strongly at the beginning of movement; they
adapt slightly at first, but then transmit a steady signal until the movement is
complete.
Golgi-type receptors are found in ligaments around joints and although they are not
as abundant as free nerve endings, but they work in a similar manner
Pacinian corpuscles are found in the tissues around joints and adapt rapidly following
the initiation of movement
Joint receptors work together to provide the body with a conscious means of
recognition of the orientation of body parts as well as feedback about the rates of
limb movement
Reflex Arc
 A reflex arc is the nerve pathway from the receptor to the Central Nervous System
and from the Central Nervous System along a motor pathway back to the effector
organ
 Reflex contraction of skeletal muscles can occur in response to sensory input and
not dependent on the activation of higher brain centres
 One purpose of a reflex is to provide a rapid means of removing a limb from a source
of pain
Note to Teachers
Teachers need to create an observation checklist for the students’ presentations in the
carousel activity. Criteria for the checklist could include:
Knowledge/understanding
- description of principle/theory, role/function of the principle/theory and its
relevance to movement
- appropriate supportive details
- relevant and accurate information/ideas
- answers questions and/or extends audience responses
For more details, refer to the Communication Rubric in Teaching/learning Strategy #8 for
this unit.
Neuromuscular principles and theories background information adapted from the
following resources:
O.A.C. Physical and Health Education Core Concept A: Human Performance. The
Halton District School Board
Behnke, R. Kinetic Anatomy. Human Kinetics: Windsor, CA ISBN 0-7360-0016-X
Kapit, W. and Elson, L. (2001). The Anatomy Colouring Book (3rd Edition). Benjamin
Cummings: Toronto, CA 2001. ISBN 0-8053-5086-1
Powers, Scott K. Edward T. Howley. Exercise Physiology: Theory and Application to
Fitness and Performance (4th Edition). New York, New York: McGraw-Hill Higher
Educaton. 2001. ISBN: 0-07-235551-4
Robertson, T. & Glover, S. Senior Physical Education (Revised Edition). Coghill
Publishing: Malvern, Australia ISBN 9491687-71-8
Shier, D., Bulter, J & Lweis, R. Hole's Essentials of Anatomy and Physiology. McGrawHill: Toronto, CA. 2000. ISBN 0-07-290775-4
Thompson, C. & Floyd, R. Manual of Structural Kinesiology (14th Edition). McGraw- Hill:
Toronto, CA. 2001. ISBN 0-07-232917-3