Chapter 10 Muscle tissue
Sarcoma
muscle plasma membrane
Skeletal muscle function
moves bones
skeletal muscle appearance
multi-nucleated, longitudinal, striated
Skeletal muscle control
voluntary
Cardiac Muscle appearance
one nuclei, striated, branched, intercalated
Cardia Muscle function
pump blood
Cardia Muscle control
involuntary
Visceral Muscle function
various functions ex: peristalsis
Visceral muscle location
various organs ex: GI tract
Visceral Muscle appearance
one nuclei, spindled-shaped, no striations
Visceral muscle control
involuntary
Electrical excitability
ability to respond to certain stimuli by producing electrical signals called action potentials
Contractility
ability to control and shorten in length when stimulated by an action potential
Extensibility
ability to stretch without damage
Elasticity
ability to return to its original shape and resting length after contraction or extension
Fascia
dense sheet of C.T. that lines the body wall and limbs
supports and surrounds muscle and other organs
fascia
allows free movement of muscle and contains blood vessels, nerves, and lymphatic vessels
fascia
holds muscles with similar functions together
fascia
Endomysium
fine sheath of C.T. composed of reticular fibers surround each muscle fiber that extends from fascia to protect ans strengthen skeletal muscle
Perimysium
dense irregular C.T. that surrounds groups of muscle fibers called fascicles that extends from fascia to support and strengthen skeletal muscle
Epimysium
overcoat of dense irregular C.T. that surrounds the entire muscles and extends from fascia to protect and strengthen skeletal muscle
Tendon
a rope-like band of tissue that connects muscle to bone
Aponeurosis
a broad flat sheet that atttaches sheet-like muscles needing a wide area of attachment
Myoblasts
fusion of mesodernmal cells-once fused the muscle fibers cannot undergo cell division
Terminal Cisternae
dilated end sacs of the sarcoplasmic reticulum that butt against the T-tubules from both sides
where large amounts of calcium is stored
terminal cisternae
Triad
a tranverse tubule and two terminal cisternae on either side
Myoglobin
protein in sarcoplasm that contains oxygen used by mitochondria for ATP production
Sarcomeres
filaments inside a myofibril that are arranged in functional units
extends from one Z disc to another
Sarcomere
separated from one another by Z discs
Sarcomeres
Z discs
narrow plated-shaped regions of dense protein material
separates one sarcomere from the next one
Z discs
"A" band
dark, middle part of sacromere that extends entire length of thick filaments, contains thin filament that overlap thick filaments
"I" bands
lighter, less dense area of sarcomere, contains remainder of thin filaments
Z discs pass through center
"I" bands
contains no thick filaments
"I" bands
"H" zone
narrow region in center of "A" bands, contains thick filaments
has no thin filaments
"H" zone
"M" line
hold thick filaments together at center of sarcomere
center of "H" zone that contains proteins
"M" line
Actin
main protein component of thin filaments
a thin molecule join and twist into helix to form an action filament
actin
has myosin binding sites
actin
Contractile proteins
actin and myosin
Myosin
main component of thick myofilament and acts like a motor protein
forms shaft of filament and shaped like golf clubs
myosin
has two binding sites: actin and ATP
mysosin
blocked by tropomyosin in relaxed muscle and held in place by troponin molecules
myosin
Tropomyosin
regulatory protein that blocks myosin binding sites in relaxed muscles
Troponin molecules
hold myosin in place during relaxed muscles
Tropomyosin
changes shape when calcium ions attaches which pulls tropomysosin away so myosin can attach to actin
myosin pulls on actin causing thin filaments to slide inward and the Z discs move towards each other and sacromere shortens
sliding filament theory
Contracted Sarcomere
thin filament move inward, "H" and "I" narrow and dissappear in max contracted muscle
Contracted Sarcomere
width of "A" band and length on myofillaments dont change
Contracted Sarcomere
Z discs come together and makes sarcomere shorten
what the myosin is called when it attached to the actin
cross bridge
Excitation
a muscle's action protential
Contraction
sliding of the filaments
sequence of events that links excitation and contraction
Excitation-Contraction coupling
Synapse
communication between 2 neurons or between a neuron and a target cell
Neuromuscular Juntion (NMJ)
a synapse between a somatic motor neuron and muscle fiber
Motor End Plate
region if the sarcolemma opposite the synaptic end bulbs which contains acetylcholine
always the neurotransmitter in somatic neurons that innervate skeletal muscles
Acetycholine
Acetycholine
molecules of a neurotransmitter found in synaotiv vesicles that are in synaptic end bulbs
Calcium (NMJ)
causes exocytosis of a neurotransmitter into the synaptic cleft which diffuse across the synaptic cleft
Central fatigue
happens before muscle fatigue, when a person may feel tired and has desire to stop activity
occurs due to change in the central nervous system
Central fatigue
protective mechanism to stop exercise before structutal muscle damage occurs
Central fatigue
process where glucose gives rise to lactic acid when oxygen is absent or low in concentration
Anaerobic Glycolysis
Oxygen Debt
the extra oxygen over and above the resting oxygen consumption that is taken into the body after exercise
Extra O2 from O2 debt
replenishes CP stores, converts lactate into pyruvate ATP production in the heart, liver, kindeys, skeletal muscles, reloads O2 onto myoglobins
Motor unit
Consists of a somatic motor neuron and all skeletal muscle fibers in innervates, all fibers contract in unison
what determines the strength of contraction?
on the size of the motor units and number of activated at one time
Motor Unit Recruitment
process in which the number of active motor units increase, weakest recruited first followed by stronger motor units
Twitch Contraction
brief contractionof all muscle fibers in a motor unit in response to a single action potential
Wave summation
situation where stimuli arriving at different times causing larger contraction
comes after twitch contraction and refractory period
Wave Summation
Unfused (incomplete) tetanus
when a skeletal can only partially relax between stimuli at a rate 20 to 30 times per second
Fused (complete) tetanus
when the fibers is stimulated at 80 to 100 times per second, does not relax at all
Muscle Tone
skeletal muscle at rest exibiting a small amount of tension
established by weak alternating, involuntary activation of small groups of motor units in muscle
Muscle tone
keeps muscles firm but doesnt create a force strong enough to produce movement
Muscle tone
Isotonic Contraction
tension is constant while muscle length changes and movement occurs
Isotonic Contraction (Concentric)
muscle shortens and creates movement to reduce the angle to a joint
Isotonic Contraction (Eccentric)
muscle tension resists the load and muscle length increases
Isometric Contraction
Muscle contracts, does not change length and no movement occurs
important in maintaing posture and supporting objects in a fixed position
Isometric Contraction
important for stabilizing some joints while others move
Isometric contraction
Intercalated disc
irregular transverse thickening of the sarcolemma that connect cardiac muscle fibers to one another
found in cardiac muscles
intercalated discs
contains desmomes to hold fibers together and gap junctions that allow muscle action potentials to spread from one muscle fiber to another
intercalated discs
by the gap junctions connecting , an autorythmic signal can be transmitted to connecting fibers so that all can contract at on time
Smooth muscle
Peristalsis
the act of visceral smooth muscle that squeezes substances through the organs by alternating contracting and relaxing
does NOT have T tubules
smooth muscle
has invaginations of plasma memebrane called caveolae containg Ca++
Smooth muscles
has thin filaments that attach to dense bodies, similar to Z discs
Smooth muscles
calmodulin is the regulatory protein
Smooth muscle
hypertrophy
growth of skeletal tissues after birth is due to increase in the size of cells
hyperplasia
increase in number of cells in skeletal and cardiac muscles
Pericytes
produces new smooth muscle fibers
stem cells found in association with blood capillaries and small capillaries
Pericytes
Spasms
sudden involuntary contraction of a single muscle within a large group of muscles
usually painless
Spasms
Cramp
involuntary muscle contractions
often painful
cramps
caused by inadequate blood flow to muscles such as dehydration, overuse and injury, and abnormal blood electrolyte levels
cramps