GOALS Ch 9
What do all muscle cells have in common?
What are some common terms used to describe muscle cells?
What are major muscle functions?
How do muscle cells differ? (p. 310-11, 9th ed) Compare the three types of muscle tissue: location, voluntariness, rhythmicity, etc
MUSCLE SIMILARITIES (Cardiac, smooth & skeletal)
1. Skeletal and smooth cells elongated
2. Contraction dependent on myofilaments
Actin and myosin
3. Terminology: myo- and sarco- = muscle
Sarcolemma = cell membrane
Sarcoplasm = cell cytoplasm
Sarcoplasmic reticulum (SR)= endoplasmic reticulum
*
Special characteristics of muscle
Exhibit excitability/irritability = ability to receive & respond to stimulus
Contractility = ability to shorten forcibly w. Stimulation
Elasticity= ability of muscle to recoil & resume resting length after being stretched
Extensibility= ability to be stretched
General Muscle Functions
Produces movement by contraction [all]
Actin slides into myosin
Maintains posture [skeletal
Stabilizes joints [skeletal]
Generates heat [skeletal]
Forms valves in internal organs [ smooth]
Pumps blood [cardiac]
Moves urine [smooth]
MUSCLE DIFFERENCES (in 3 types). Make a table to describe these:
Location
Structure of cells
Function
Means by which activated to contract
Aerobic
Source of calcium
Number of nuclei, etc… .
1. Skeletal Muscle Characteristics
Skeletal description
Longest muscle cell
Attached to skeleton
Voluntary control
Striations
Multinucleated
Tires easily
Calcium from SR
Skeletal muscle: striations
1. Skeletal muscle Characteristics
Aerobic & anaerobic
[with and without oxygen]
T-Tubules
[new organelle in muscle]
Can display tetany
locked contraction
No pacemaker
[ no contracting by itself]
2. Cardiac Muscle
in heart wall = myocardium
Involuntary; self-exciting (has pacemaker)
Striations; single nucleus per cell
Rhythmic (75 bpm) ; Slow contraction
Aerobic only!
Cardiac Muscle
Two sources of Calcium/Ca++: from SR [inside] and from ECF [outside]
FYI:
100 bpm = tachycardia;
<60 bpm = bradycardia
3. Smooth muscle
Walls of hollow visceral organs
No striations; single nucleus per cell
Involuntary; self exciting & rhythmic
3. Smooth muscle
Slow, sustained contraction = peristalsis [of food, urine, etc]
Has pacemakers
Mainly aerobic
Calcium from SR and ECF
GOALS: Detail Skeletal Muscle
Describe the layers of connective tissue coverings.
Describe nerve and blood supply to skeletal muscle.
What is the difference between direct and indirect attachments?
Of origin and insertion?
1. Connective tissue wrappings of skeletal muscle
Endomysium =surrounds each muscle fiber
Perimysium = collagen sheath around fascicle = bundle of muscle cells
Epimysium = outer coat around perimysium of dense connective tissue; can bind to
Deep fascia = outermost layer that binds muscle into groups
Fascia
All connective tissues continuous
with each other and
with tendons
Reinforce muscle
Provide entry/exit routes for blood vessels
*
2. Nerve & blood supply of skeletal muscle
Muscle:
Supplied with nerve ending to contract
Needs rich blood supply for:
oxygen and glucose delivery (artery) &
waste [CO2, ..] pick up (veins)
Blood vessel (artery) and nerve enters center of muscle and branches into connective tissue
3. ATTACHMENTS:
Most muscles span joints & have at least 2 attachments to bone
1. INSERTION = End that moves
2. ORIGIN = End that is stationary; usually proximal
DIRECT ATTACHMENTS
= Epimysium fused to periosteum of skeleton
INDIRECT ATTACHMENTS= Epimysium extends beyond muscle as
1. tendon
2. Aponeurosis = broad connective tissue sheet
GOALS: Skeletal Muscle Cell
Describe the detailed parts of a skeletal muscle cell.
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