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.