Musclular System Flashcards
Location of Skeletal Muscle
Attached to bones
Location of Cardiac Muscle
Heart only
Location of Smooth Muscle
forms part of the structure of blood vessels, surrounds many hollow organs
Function of Skeletal Muscle
movement of the body
Function of Cardiac Muscle
pumping of blood
Function of Smooth Muscle
constriction of blood vessels, movement of contents in hollow organs
Basic Anatomy of Skeletal Muscle
very large, cylindrical, multinucleate cells arranged in parallel bundles
Basic Anatomy of Cardiac Muscle
quadrangular cells with occasional branching points, jointed to other cells by intercalated disks
Basic Anatomy of Smooth Muscle
Small, spindle-shaped cells with the long axis generally oriented in the same direction
Striated Muscle Tissues
Skeletal and Cardiac
Muscle Tissues with Gap Junctions
Cardiac and Smooth
Initiation of Action Potential in Skeletal Muscle
Neurons only
Initiation of Action Potential in Cardiac Muscle
spontaneous(pacemaker cells), or from another cardiac muscle cell
Initiation of Action Potential in Smooth Muscle
spontaneous, whenever slow-wave potentials exceed the threshold
Role of Nerve Stimulation in Skeletal Muscle
required for initiation of a twitch contraction,
summation and tetanus are possible
Role of Nerve Stimulation in Cardiac Muscle
stimulatory and inhibitory nerves modulate the heart rate and force of contraction, not required for cardiac muscle to function
Role of Nerve Stimulation in Smooth Muscle
stimulatory and inhibitory nerves can modulate a degree of tension developed, not required for smooth muscle to function
Duration of Electrical Activity in Skeletal Muscle
short-duration action potentials (1-2 msec)
Duration of Electrical Activity in Cardiac Muscle
long-duration action potentials (200 msec)
Duration of Electrical Activity in Smooth Muscle
very long slow waves at roughly 10 second intervals,
occasional superimposed long-duration action potentials (300 msec)
Energy Source for ATP Generation in Skeletal Muscle
phosphocreatine, stored glycogen, aerobic metabolism
Energy Source for ATP Generation in Cardiac Muscle
aerobic metabolism
Energy Source for ATP Generation in Smooth Muscle
aerobic metabolism
Energy Efficiency in Skeletal Muscle
low
Energy Efficiency in Cardiac Muscle
moderate
Energy Efficiency in Smooth Muscle
high
Likelihood of Fatigue in Skeletal Muscle
low-very high, depends on energy source and work load, in extreme conditions may fatigue in second
Likelihood of Fatigue in Cardiac Muscle
low as long as blood supply is adequate
Likelihood of Fatigue in Smooth Muscle
very low
Rate of Muscle Shortening in Skeletal Muscle
fast compared to other muscle types, type 2 fibers are faster than type 1
Rate of Muscle Shortening in Cardiac Muscle
moderate
Rate of Muscle Shortening in Smooth Muscle
very slow
Duration of Contraction in Skeletal Muscle
as short as 100 msec for a single twitch, tetanus may be prolonged
Duration of Contraction in Cardiac Muscle
short, about 300 msec, summation and tetanus not possible
Duration of Contraction in Smooth Muscle
very long, may be sustained indefinitely
Stored ATP Quantities in Muscle
stored only in small quantities
Phosphocreatine Quantities in Muscle
three to five times the amount of stored ATP
Glycogen Quantities in Muscle
variable, some muscle types store large quantities of glycogen
Stored ATP Time Course of Use
~10 second
Phosphocreatine Time Course of Use
~30 seconds
Glycogen Time Course of Use
Primarily used during heavy exercise within the first 3-5 minutes
Aerobic Metabolism Time Course of Use
always present
increases dramatically within several minutes of onset of exercise, when blood flow and resipiration increase
Stored ATP Fun Fact
ATP is the only direct energy source
it must be replenished by other energy sources
Phosphocreatine Fun Fact
converted quickly to ATP
Glycogen Fun Fact
glucose can be metabolized to ATP without Oxygen
yields two ATP molecules per glucose molecule
Aerobic Metabolism Fun Fact
high yield
complete metabolism of one gluocose molecule yeilds 38 ATP molecules
Functions of Muscluar System
- Motion - reflex, voluntary, homeostatic
- Posture
- Heat Production - up to 85% bosy heat
Characteristics of Muscle Tissue
- Excitability
- Contractility
- Extensibility
- Elasticity
Excitablility of Muscle Tissue
receives and responds to stimuli
Contractility of Muscle Tissue
shortens with stimuli
contraction is active
Extensibility of Muscle Tissue
Extension is passive
Elasticity of Muscle Tissue
can return to original shape after Extension or Contraction
Muscle Tissue Types
- Skeletal
- Cardiac
- Smooth
Skeletal Muscle
striated, voluntary (most), True Syncytium,
syncytium - multinucleate cells
Types of Skeletal Muscle
- Type 1 Fibers
- Type 2 A Fibers
- Type 2 B Fibers
Type 1 Fibers
slow twitch, fatigue resistant,
Uses Oxidative Phosphorylation for Energy
Red Fiber (myoglobin), Posture Muscles