Download Outline

MUSCLE PHYSIOLOGY
Interactions of Skeletal Muscles in the Body
- muscles work together or in opposition to achieve a variety of movements
- for every muscle, there is an opposing muscle doing the opposite
- muscles PULL (
)
– immovable point of attachment
– movable point of attachment
example – Pectoralis major -
Deltoid
-
– sternal end of clavicle
- sternum
- ribs 1-6
– intertubercular groove on humerus
– clavicle
- acromion process and spine of scapula
– deltoid tuberosity
Biceps Brachii –
-
– coracoid process on scapula
- supraglenoid tubercle
– radial tuberosity
4 Functional Groups of Muscles
1.
– leader, major muscle
- example biceps
2.
– opposing prime mover
- example triceps
3.
– help prime mover
- more force or stabilizes joint
4.
– stabilize bones like scapula
- posture
Naming Skeletal Muscles
The following hints will help you to name skeletal muscles
1.
– bones, regions
example- temporalis muscle, intercostals muscles
2.
– deltoid, trapezius
3.
– maximus –
- minimus –
- longus –
- brevis –
- major –
- minor –
example: gluteus maximus, gluteus minimus
pectoralis major, pectoralis minor
4.
- rectus – straight (erect)
- transverses – 90 degrees
- oblique – 45 degrees
example: rectus femoris
5.
- biceps – 2 origins or heads
- triceps – 3 origins or heads
6.
- origin first in name, insertion second
example: sternocleidomastoid
- origin – sternum clavicle
- insertion – mastoid process of temporal bone
7.
– flex, extend, abduct, adduct, etc
example: -adductor longus
- supinator
8.
example: extensor carpi radialis longus
I. Muscle functions
A.
- get shorter, pull on bones
B.
- continuously fighting gravity
C.
- strengthening joint
D.
- byproduct of ATP (energy) production
II. Characteristics of muscle
A.
- from nervous system
B.
- ability to shorten
C.
- recoil
D.
- stretch, opposite of contract
III. Organization of Skeletal Muscle
- muscle to bone
- organ with different tissues:
- muscle, connective, epithelial, nerves
- muscle covering
- bundle of muscle cells
- fascicle covering
- equal to muscle fiber
- muscle cell covering
- muscle cell membrane
- long, round, subunit of a
muscle cell
microfilaments
or
or
or
2 types
actin myosin-
IV. Microscopic structure of a Skeletal Muscle Cell
- one contractile unit
- one section of a myofibril
- located from Z-line to Z-line
- thick protein filament
- attaches to actin
- pivots
l- main part of molecule
- thin protein filament
- globular
- twisted pearl necklace
- blocks actin’s
“active” site
- binding site for calcium
- place were actin (active site)
and myosin (head) attach.
- length of myosin
- dark band
- space between myosin
- light band
- space between actin
- myosin only
- ends of sarcomere
- anchors actin
V. Microscopic structure of a sarcomere
– muscle cytoplasm
lots stored glycogen and myoglobin (O2 attaches)
= S.R. - like E.R. – surrounds myofibril
–
ends of S.R. and runs parallel to T-tubules
- stores calcium
– extend deep into myofibril
– 2 terminal cisternae and T-tubule
– makes ATP
– cells large and many per cell
VI. Microscopic structure of a Skeletal Cell (neuromuscular junction)
VII. Muscle Physiology (Sliding Filament theory)
1.
- travels along sarcolemma and down T-tubules
2.
- A.P. in terminal cisternae cause it to release Ca++ to
sacroplasm
3.
- binds to troponin (on actin) causing it to change shape
4.
- moves tropomyosin so it’s not blocking active site on actin
5.
- myosin heads attracted to active site
6.
– myosin head binds and pivots pulling Z-lines closer
7.
- ATP (energy) needed to break head of myosin
- crossbridge detachment
8.
- Resetting myosin head, ATP (energy) returns head to
original position
9.
- steps 4-7 like a ratchet tool
10.
- get closer together, I and H disappear
11.
- stops
12.
- returns Ca+ to S.R.
13.
- blocks active site on actin and contraction stops
VIII. Contraction of a Skeletal Muscle
– 1 nerve and all muscle fibers it attaches to
– single brief stimulus
– combined twitches
– constant stimulus over period of time
– whole muscle cell contracts. Not part of a cell
– summation of motor units
– minimal stimulus needed to start muscle contraction
– muscle graph
– after stimulation, before contraction
– crossbridges active
– initiated by Ca++ uptake back into S.R.
tension
Time
IX. Exercise
– increase tension, muscle length stays same
– increase tension, muscle length changes
concentric – muscle shortens
eccentric – muscle lengthens
- 90° about strongest
- why?
– inability to contract, not enough energy
– stiffening of body – lack of ATP to break bonds
– continuous contraction (living)
– lack of O2 after and during exercise
energy for contraction
1.
– 4 to 6 seconds
2.
– 0 to 15 seconds
3.
– 30 to 40 seconds
4.
– 60 to ? seconds
Then reverse until exhaustion
adaptations to exercise – improves physical and psychological wellbeing
increases capillaries
increases mitochondria
COMPARISON OF MUSCLE TYPES
Characteristic Skeletal
Body Location
Cell shape and
appearance
Connective tissue
components
Presence of
myofibrils
composed as
sarcomeres
Presence of gap
junctions
Neuromuscular
junction
Regulation of
contraction
Source of Ca++
Presence of
pacemaker(s)
Effect of nervous
system
Speed of
contraction
Rhythmic
Respiration
Cardiac
Smooth