PER510- Physiology
Ch. 6, 7, and 8 outline
Types of Muscle Tissue
Skeletal muscle- move bones (some skin)
Voluntary control- some have involuntary override = diaphragm, muscles for posture
Striated
Ca++ needed for contraction stored internally (sarcoplasmic reticulum)
Cardiac muscle- wall of the heart
Involuntary control- autorhythmic- resting rate due to Na+ leak channels
Rate influenced by autonomic stimulation- sympathetic ↑, parasympathetic ↓
Intercalated disks- area of gap junctions and desmosomes = allow ionic disturbance to move between
adjacent cells (action potential)
Striated
Ca++ needed for contraction- 75% internally, 25% externally
Smooth muscle- walls of blood vessels, respiratory airways, digestive system, urinary system
Involuntary control- some autorhythmic, some influence of autonomic NS or hormonal signals
No striations
Nearly 100% Ca++ needed for contraction comes from ECM
2 types = unitary- bundles or sheets of cells- ex. blood vessel walls
Multiunit- separate fibers- ex. Ciliary muscles and iris of the eye, piloerector muscles of skin
Muscle Function and Unique Features
Movement- of body or body parts as well as materials within the body
Stabilization of body or body parts and posture
Thermogenesis- heat production
Storage and movement control- sphincters
Excitability- similar to neurons, they are able to respond to action potentials by altering cellular activity
Contractility- ability to shorten with force
Extensibility- able to stretch beyond resting length
Elasticity- able to recoil to resting length without injury or impaired function
Muscle Terminology
Motor unit- single neuron and muscle fibers it innervates
, Twitch- contraction of a motor unit in response to nervous stimulation
Summation (treppe)- multiple stimuli from a neuron causes contraction to continue, increasing force until
full isotonic tension is reached
Tetanus- state of sustained partial or full contraction
Incomplete (unfused)- 20 – 30 stimuli per min, allowing partial relaxation between twitches
Complete (fused)- 80 – 100 stimuli per min, total contraction without relaxation
Hypertrophy- increase in size (length / diameter) and strength
Most commonly a result of increasing myofilaments (actin and myosin)
May also involve increasing the number of myofibrils within the muscle fibers
Lastly, may involve adding additional sarcomeres to the ends of the myofibrils
*↑ mitochondria #, sarcoplasmic reticulum (Ca++ storage), enzymes for energy prod.
**Also requires an increase in vascular supply and nerve innervation
Example- A.I.= eccentric hypertrophy → enlargement of the left ventricular chamber
A.S. = concentric hypertrophy → enlargement of the muscular walls
Hyperplasia- increasing the number of fibers (cells) within the muscle
Atrophy- decrease in size and strength which occurs with prolonged inactivity
Results of decreasing the number of myofilaments, myofibrils, sarcomeres and or fibers
Involves the ATP dependent ubiquitin proteosome pathway (apoptosis- ch.2)
Loss of nerve innervation → w/in 2 months myofilament breakdown begins – fully reversible
3 months – 2 years → recovery still possible, but some permanent loss of function
Greater than 2 years → muscle fibers are replaced with fibrous and fatty tissue
Permanent loss of function = contracture or fibrous shortening
Skeletal Muscle Anatomy
Tendons (aponeurosis)- connective tissue attaching skeletal muscles to bones (some skin)
Epimysium- connective tissue covering an entire skeletal muscle
Fascicles- bundles of skeletal muscle fibers (cells)
Perimysium- connective tissue covering and separating the fascicles
Fibers- muscle cells
Endomysium- connective tissue covering individual fibers
Sarcoplasm- cytoplasm of muscle cells
Ch. 6, 7, and 8 outline
Types of Muscle Tissue
Skeletal muscle- move bones (some skin)
Voluntary control- some have involuntary override = diaphragm, muscles for posture
Striated
Ca++ needed for contraction stored internally (sarcoplasmic reticulum)
Cardiac muscle- wall of the heart
Involuntary control- autorhythmic- resting rate due to Na+ leak channels
Rate influenced by autonomic stimulation- sympathetic ↑, parasympathetic ↓
Intercalated disks- area of gap junctions and desmosomes = allow ionic disturbance to move between
adjacent cells (action potential)
Striated
Ca++ needed for contraction- 75% internally, 25% externally
Smooth muscle- walls of blood vessels, respiratory airways, digestive system, urinary system
Involuntary control- some autorhythmic, some influence of autonomic NS or hormonal signals
No striations
Nearly 100% Ca++ needed for contraction comes from ECM
2 types = unitary- bundles or sheets of cells- ex. blood vessel walls
Multiunit- separate fibers- ex. Ciliary muscles and iris of the eye, piloerector muscles of skin
Muscle Function and Unique Features
Movement- of body or body parts as well as materials within the body
Stabilization of body or body parts and posture
Thermogenesis- heat production
Storage and movement control- sphincters
Excitability- similar to neurons, they are able to respond to action potentials by altering cellular activity
Contractility- ability to shorten with force
Extensibility- able to stretch beyond resting length
Elasticity- able to recoil to resting length without injury or impaired function
Muscle Terminology
Motor unit- single neuron and muscle fibers it innervates
, Twitch- contraction of a motor unit in response to nervous stimulation
Summation (treppe)- multiple stimuli from a neuron causes contraction to continue, increasing force until
full isotonic tension is reached
Tetanus- state of sustained partial or full contraction
Incomplete (unfused)- 20 – 30 stimuli per min, allowing partial relaxation between twitches
Complete (fused)- 80 – 100 stimuli per min, total contraction without relaxation
Hypertrophy- increase in size (length / diameter) and strength
Most commonly a result of increasing myofilaments (actin and myosin)
May also involve increasing the number of myofibrils within the muscle fibers
Lastly, may involve adding additional sarcomeres to the ends of the myofibrils
*↑ mitochondria #, sarcoplasmic reticulum (Ca++ storage), enzymes for energy prod.
**Also requires an increase in vascular supply and nerve innervation
Example- A.I.= eccentric hypertrophy → enlargement of the left ventricular chamber
A.S. = concentric hypertrophy → enlargement of the muscular walls
Hyperplasia- increasing the number of fibers (cells) within the muscle
Atrophy- decrease in size and strength which occurs with prolonged inactivity
Results of decreasing the number of myofilaments, myofibrils, sarcomeres and or fibers
Involves the ATP dependent ubiquitin proteosome pathway (apoptosis- ch.2)
Loss of nerve innervation → w/in 2 months myofilament breakdown begins – fully reversible
3 months – 2 years → recovery still possible, but some permanent loss of function
Greater than 2 years → muscle fibers are replaced with fibrous and fatty tissue
Permanent loss of function = contracture or fibrous shortening
Skeletal Muscle Anatomy
Tendons (aponeurosis)- connective tissue attaching skeletal muscles to bones (some skin)
Epimysium- connective tissue covering an entire skeletal muscle
Fascicles- bundles of skeletal muscle fibers (cells)
Perimysium- connective tissue covering and separating the fascicles
Fibers- muscle cells
Endomysium- connective tissue covering individual fibers
Sarcoplasm- cytoplasm of muscle cells
