Types of Muscles

Topics: Action potential, Neuron, Nervous system Pages: 26 (4297 words) Published: April 19, 2013
I. Types of Muscles
a. Skeletal
i. Striated
ii. Uses intracellular calcium to contact
iii. Big cylindrical cells
iv. Multi-nucleated
v. Voluntary
vi. Location: attached to the bone
vii. Used for locomotion
b. Cardiac
i. Involuntary
ii. Uni-nucleated
iii. Striated
iv. Location: walls of heart
v. Used to propel blood
vi. Uses extracellular calcium
c. Smooth
i. Involuntary
ii. Location: Walls of hallow organs
iii. Non-striated
iv. Uses extracellular calcium
v. Spindle shaped cells
vi. Uni-nucleated
vii. Used to propel things through internal passageways

II. Types of Muscles
a. Locomotion- Moving your body in space
i. Skeletal muscle
b. Move substances within body; food and water
i. Smooth Muscle
c. Stability- hold bones in position around joint
i. Skeletal Muscle
d Regulate Organ Volume- food storage, blood vessels
i. Smooth Muscle
e. Heat Production- 85% of body heat is bi-product of muscle contraction; shivering
i. Skeletal muscle
f Maintain Posture- hold body up-right
i. Skeletal Muscle

III. Characteristics of Muscles
a. Excitability
i. Can receive and respond to stimuli
ii. Chemical stimulus: food
iii. Electrical stimulus: nerve
b. Contractibility

i. Muscle can shorten and thicken
c. Extensibility
i. Muscle can lengthen and stretch
ii. Smooth has the most
d. Elasticity
i. Can recoil to original shape

IV. Skeletal Muscle Structure
A. Background
CT Components
a. Fascia: Sheet of broad band of fibrous CT beneath skin or around muscle
b. Superficial Fascia: Right under skin (hypodermis)
c. Deep Fascia: made of dense irregular- surrounds skeletal muscle cartilage

B. Layers of CT in Skeletal Muscle
a. Epimysium: dense irregular- surrounds entire outer surface of muscle- where blood vessels come in- protection
i. Fascicle: bundles of cells
b. Perimysium: surrounds each fascicle (bundle)
c. Endomysium: surrounds each individual cell (fibers)

*All three layers extend to form tendon
*All layers help reinforce muscle
*All contribute to elasticity
*All provide entry/exit pathogens for blood vessels and nerves

V. Blood and Nervous Supply
a. Blood supply
a. Very good
b. Needs 0xygen and glucose for ATP
c. Needed for waste removal
d. Each muscle has an artery- blood to; vein- blood away
e. Capillaries in endomysium- where things are exchanged
between blood & tissue
f. Each skeletal muscle cell in control with 1 or 2 capillary help feed muscle cell
b. Nervous Supply
a. Branches through muscle layers
b. Somatic nervous system controls muscles
c. Skeletal muscle- needs electrical stimulation
d. Action Potential- signal sent to skeletal muscle
e. Motor Neuron- control skeletal muscle (carry Action

VI. Microanatomy of Skeletal Muscle cell (fiber)
a. Background
1. Very large 10x the size of average cell
2. Up to 30cm in length cell goes whole length of muscle
i. Sarcolemma: cell membrane
ii. Sarcomere: cytoplasm
iii. Sarcoplasmic Reticulum: ER (Smooth ER) used to store and release Ca+ for muscle contraction
iv. Myofibril: rod like structures run in parallel length of cell used for contraction
v.Syncytium: joining together 100’s of embryonic cells fuse together to make a muscle cell
vi. Glycosome: vesicles of glycogen (storage polysaccharides) vii. Myoglobin: protein/pigment bind to and stores oxygen for ATP production
*Skeletal muscle has lots of mitochondria (ATP)

b. Myofibrils
i. Cylindrical rod shaped, tightly packed
ii. 100’s to 1000’s in a single cell
iii. ≈ 80% of cell volumes
iv. Contractile element – used for shortening
v.Contain 3 types of myofilaments
1. Thick myofilaments
2. Thin myofilaments
3. Elastic myofilaments
c. Sarcomere
i. Anatomy
1. Smallest unit of contraction
2. Functional unit
3. Where start and end Z disc
4. A-band: dark area makes most of sarcomere (middle)

5. I-band: Part that looks light (each side) cut in ½ by z-disc 6. Myosin {Thick} filament: located in A Band [darker/blocks...
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