Ch. 6
The MuscularSystem
You are selected for an internship at the National Space BiomedicalResearch Institute in Houston, Texas. Part of your job is to monitor thehealth of the astronauts for the National Aeronautics and SpaceAdministration (NASA) before, during, and after a space mission. Bychance, your time in the lab corresponds with the return of an Americanastronaut from the International Space Station. She just spent 171 daysin the space station and is now getting back to her research studies onearth. Unfortunately, it was discovered that she would
have to go through at least 3 weeks of physical therapy.
You learned from reading her physical health report
that she lost ____of her skeletal muscle mass. Most of
it occurred within the last 2 months of the mission in
space. The normal muscle loss during a space mission
is less than 20%. A majority of muscle atrophy results from disuse, yetshe followed all the exercise programs NASA requires. Your job is toassist the research team in investigating her problem.
Determine the most likely cause of her accelerated loss of muscle mass.
Case Study Investigation
Muscle cells are composed ofspecialized__________________that allowthem to change shape and shortenor ____________________
Over half the body’s mass iscomposed of muscle tissue, and over90% of this muscle tissue is involvedin skeletal movement.
Muscles require glucose, oxygen,calcium and electrolytes andrelease metabolic wastes.
Overview
Chapter 6 – The Muscular System
Three types of muscle are found in the human body:
a) __________________muscle
(slightly striated
& involuntary;
b) ____________
muscle
(striated &
voluntary)
c)_____________________muscle
(non-striated &
involuntary)
Muscle
1._______________: stationarybone the muscle attaches to
(i.e. zygomatic arch)
2. ___________: rest ofthe muscle (i.e. masseter)
3. ________________:moveable bone the muscleattaches to
(i.e. mandible)
Musculature:Gross Anatomy
Origin:
Scapula /
Humerus
Body
Biceps
Brachii
Insertion:
Radius
_________________
attachs muscle
to bone
Sacs of synovial fluid btwn
tendon & bone for lubrication
raises eyebrow
closes eyes
smile muscle
closes lips
yes/no muscle
closes jaw
extends head / neck
closes jaw
adducts
upperarm
deltoid
abducts
arm
Muscles of the Trunk
flex trunk
adducts
arm
flexes forearm
pronates & supinates
flexeselbow
extends
elbow
MUSCLES of the
ARM
flexes thigh +
lower leg
(middle quadricep)
(lateral quadricep)
(medial quadricep)
Vastus intermedius
(inner quadricep)
plantar-flexes
ankles
dorsi-flexes ankles
plantar-flexes ankles
Quadriceps
extend the leg
extends thigh
(lateral
hamstring
(middle hamstring)
Hamstrings
flex the leg
adducts thigh
(medial hamistring)
____________ = muscles that
help the prime mover
____________ = muscle that produces the opposite movement as prime mover
_____________________=muscle
responsible for the movement
Basic Skeletal Muscle Function
1. Skeletal Movements = _______ on bone (relaxation / contraction)
2. Posture / Muscle Tone: ______________weightdistribution and hold muscles in position
a. tonic contraction:
only a few muscles
contract at a time;
NO shortening and
NO movement
3.Regulate ____________________________
a. ______________________: bands of smooth muscle that preventoutflow of fluids from hollow organs
4.Move substances within the body:
a. cardiac muscle – ________________________________
b. smooth muscle –moves food through digestive sys.(__________________)
5.___________ Production: when muscles contract theyproduce heat
a.________thermia – decrease in
body temp below normal
b. ______thermia – increase in
body temp above normal
Concept Check #1
1.What are muscles composed of that allow them to do their jobs?
2. What are 5 functions of the muscular system.
3. If I were to flex my elbow which muscle would be the primemover, synergist, and antagonist?
4. Give an example of how cardiac and smooth muscle movesubstances within the body.
5. How does the origin and insertion of a muscle differ?
6. Research the origin and insertion for the following muscles:
Concept Check #2
Skeletal Muscle Structure
surrounds fassicles
surrounds each
surrounds entire
muscle
bundle of muscle cells
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13904 Muscle Structure Animation
Microcopic Muscle Cell Structure
skeletal muscle cells are long, cylindrical cells covered with anexcitable (can transmit) membrane called the ________________
proteins in sarcolemma _______________________________infoto muscle cells causing them to contract
cytoskeleton of
muscle cells contain
myofilaments made
up of protein
a) thick: myosin
b) thin:
1) __________
2) ___________
3) _______________________
contractile unit of muscle is called a ____________________(thousands/muscle cell) which is surrounded by a sarcoplasmic reticulum(stores/transports __________for contraction)
Thick & thin
myofilaments
overlap within
sarcomere
gives muscle its
______________
appearance &
carries out
contraction
chains of
sarcomeres form
_______________
________________________ Chain Structure
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter42/animations.html# - Sarcomere shortening bio book animation
1 sarcomere
How Do Muscles Contract
contraction occurs when sarcomeres shorten simultaneously
1.Nerve Stimulation at the neuromuscular junction (motorneuron meets muscle fiber)
Nerve cells release neurotransmitter __________________ whichbinds to sarcolemma and allows ___________to cross membrane
Flow of ions causes _______ to be released from SR; travels tosarcomere and initiates contraction phase
(basic neuromuscularjunction animation)
2.Muscle Contraction – takes place inside muscle cell
Ca binds to _______________; moves it off the actin-bindingsite on tropomyosin so myosin can ______________ to actin
________________ provides energy for myosin head to pullthick m.f across thin m.f. (shortening Z-lines of sarcomere)
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html - action potential andmuscle contraction
3. Muscle Relaxation
starts when neural
stimulation _________
Na+ and K+
ion levels
completely recover
SR retrieves
most of its Ca
Myosin headsrelease actin
Troponin ________actin-binding
site on
tropomyosin
________________ muscle stiffness caused by ___________________ outof SR into sarcomere after death
Creatine phosphate, glycogen, & myoglobin (red chemical) all serve as______________________________reserves for muscle contraction
unique muscle composition is genetically determined
Types of Skeletal Muscle Fibers
Feature
Slow Red Twitch Fibers
(Type I)
Fast White Twitch Fibers
(Type IIb)
Size
Smallest
largest
Mitochondria
large amount
(get ATP through aerobicprocesses)
small amount
(get ATP through anaerobicprocesses)
Color
red
(high myoglobin content)
white
(low myoglobin content)
Speed ofContractions
Slow
Fast
Resistance toFatigue
High (very fatigue resistant)
Low (not fatigue resistant)
Activities
Maintaining posture,endurance activities (i.e.marathon runners)
Muscle: soleus
Rapid, intense movements of shortduraction (i.e. sprinters, throwing aball or weight lifting)
Muscle: gastrocnemius / vastus lateralis
Concept Check #3
7. List the three membranes of muscle in order from superficial todeep then explain how they each differ.
8. What is the name given to the membrane that surrounds a musclecell and why is it important?
9. Why is the sarcoplasmic reticulum that surrounds the sarcolemmaso important?
Concept Check #4
10. Draw a picture of a sarcomere and label the two differentmyofilaments and explain how it relates to the sliding filament theory.
11. Why is Ca necessary for starting a muscle contraction.
Skeletal Muscle Action
skeletal muscle structure responds to the amount of work it must do
1. irregular use or lack of ________________________________________causes
a loss of sarcomere proteins
decrease in muscle strength
decrease in muscle size = _________________________
2. regular use & increased ________________________causes
increase in muscle strength
increase in muscle size = _________________________
Increased blood flow = enlarges muscle diameter = muscle strength
Heavy muscle use = sarcomere density = muscle diameter
Some ppl can increase sarcomere density and strength w/o a significant increase indiameter……genetic differences and variations in blood flow
Skeletal Muscle Action
shortening of the muscle brings the insertion closer to the origin
___________________________- minimal level of stimulusrequired to cause a fiber to contract
muscle cells are controlled by different motor units with differentthreshold levels so not all muscles contract at the same time
____________________________– a fiber contracts completely ornot at all; It’s the difference in picking up 1 textbook or 25textbooks.
http://study.com/academy/lesson/how-motor-unit-summation-develops-muscle-tension.html - study. Com (partial)
Skeletal Muscle Action
muscles can be categorized by the effect it has on jointmotion
• abductor – muscles that move a bone ________ from
the midline (deltoid, gluteus maximus)
• adductor – muscles that move a bone ____________
to the midline (gracilis, pectoralis major)
• ________________ – muscles that increase the angle
of a joint (tricep, quadriceps)
• _________________– muscles that decrease the
angle of a joint (bicep, hamstrings)
• sphincter – muscles that _____________ the size of
an opening (esophogeal sphincter, rectal spincter)
Skeletal Muscle Action
isotonic contractions: when a muscle is ________________shortening or lengthening ex. lifting weights
isometric contractions: ____________________but muscleis contracted and ________________is building ex. pushingagainst an
immovable object
Fatigue
during muscular exercise:
b.v. in muscles _____________ & blood flow and O2delivery ____________________
muscle ______________occurs after extended orstrong muscle contractions and _______________can’tsupply muscle fibers fast enough
oxygen _____________ – amount of O2 taken in to“pay back” resting metabolic conditions
if O2 is unavailable, _____________is converted into______which helps break down glucose for energy
production of lactic acid in the body causes soreness
Aging and Pathology of the Skeletal System
• many disorders of the musculature are due to interactions with theskeletal and nervous systems
Strains vs. Sprains
strains – _______________ the muscle’s force on joints and tendons
pain and swelling of fascia, joints, ligaments, and tendons
nerves signal pain when stretched or swollen (stiff)
sprains – more severe; sudden or violent ________
on a joint/muscle
tearing of ligament, muscle, or tendon and
damage to nearby blood vessels
requires time for tissue and protein replacement
To keep swelling down apply _______1st
followed by continuous _____________ to
speed healing
• ___________________ – related to sprains; direct hit(s) to amuscle
Myopathy / Neuromuscular disorders
inability of the nervous system to communicate properly to muscles
1. ________________________ myopathies – group of neuromusculardiseases caused by genetic abnormalities of the mitochondria; muscles can’tproduce ________________ from food; muscles become easily cramped
2. __________________________(2 types – 1st non-hereditary;2nd hereditary) – caused by damage to soft tissues @ muscle;bone growing within muscle tissue; pain during contraction
3. muscular __________________- involves ______________weakness in the voluntary muscles; inability of nervous systemto stimulate muscle action; results in atrophy and wasting
Affect of _____________________on Muscles
______________ body’s ability to produce muscle
prevent muscle breakdown &
________________________time
resemble chemical structure of
___________________________
{T} directs the body to produce
more or ________________ male
characteristics (like increased
muscle mass, etc)
Aging of the Muscular System
___________________ (natural muscle loss due to aging process)
_____________________(muscle loss usually associated with AIDS, cancer,starvation, anorexia, bulimia); slower form reduces bodies ability to rebuildmuscle structure
decrease in neural stimulation -> ____________________
malnutrition / undernutrition decrease in carbs and proteins _______________________and nutrients for repair and maintenance
decline in _____________________and insulin-like growth factor–1 (IGF-1); needed for muscle cell growth, maintenance, & repair
physical therapies
1)artificial up-regulation with electrical ____________causesmuscles to retain protein)
2)muscle ________________________
Concept Check #5
12. List 2 things that can happen when muscles are used irregularly.Regularly?
13. How do hypertrophy and hypotrophy (atrophy) differ?
14. Do all the muscle fibers (cells) in my arm contract when I pick upa pencil? Use the terms threshold stimulus and all or none theoryin your explanation.
Concept Check #8
15. How do strains, sprains, and contusions differ?
16. Name and describe 2 different types of myopathies.
17. What is cachexia in terms of muscle aging.
18. Describe 4 factors that contribute to muscle aging.
Case Study Investigation
Selected for an internship at National Space Biomedical Research Ins.
Required to monitor astronauts for NASA before, during, and after aspace mission.
American astronaut spent 171 days in the space stations has to gothrough 3 weeks of physical therapy.
She lost 30% of her skeletal muscle even after following all theexercise programs NASA required. The average is less than 20%.
Questions:
1.Why did the American lose 30% of her skeletal muscle after hermission to space? Be specific.
2. She lost 10% more than the average astronaut. What else associatedwith her mission could have contributed to the American’s muscleloss?