Anatomy and Physiology Chapter 10 Muscle Tissue

Muscle functions
Movement, stablizing, storing and moving substances throughout body, heat generation
Properties of muscle tissue
Electrical excitability, Contractility, extensibility, elasticty
3 Types of Muscle tissue
Skeletal, Cardiac, Smooth
Skeletal muscle
Striated, multinucleated, voluntary
Cardiac muscle
Striated, Uninucleated, involuntary
Smooth muscle
Nonstriated, uninucleated, involuntary
Epimysium
Epimysium
Surrounds entire muscle
Perimysium
Perimysium
surrounds fascicles.
Fascicles
Bundles of muscle cells
Endomysium
Endomysium
Surrounds individual muscle fibers
Sarcolemma
Cell memebrane. Has transverse tubules
Sarcoplasm
Cytoplasm containing glycogyn and myoglobin
Myofibrils
rod like unit of a muscle
Sarcoplasm reticulum
Stores calcium, terminal cisterns
Terminal cisterns
Calcium abundance near transverse tubules
Triad
2 terminal cisterns and 1 transverse tubules
Sarcomeres
Functional unit of a skeletal muscles
Myofilament
Thin and thick
z Disc
the ends of one sarcomere
I Band
Place where you can only see thin filament
A Band
Length of thick filament
H zone
Only see thick filament
M Line
Middle of sarcomere, holds thick filament in place
Myosin
Binding site for ATP and actin. Looks like two golf clubs wrapped around each other
Actin
Myosin bonding site, in thin myofilaments
Muscle regulatory proteins
Tropomyosin and troponin
Tropomyosin
Covers myosin binding sites
Troponin
Tnl(Actin), TnT(Tropomyosin), ThC(Calcium)
Neuromuscular junction
Synapse between a somaticmotor neauron and a skeletal muscle fiber
Neurotransmitter
Chemical message, stored in synaptic vesicles, released across synaptic cleft and binds to receptors on motor end plate.
Acetylcholine (ACh)
Stored in synaptic vesicles, released across synaptic cleft, binds to ACh receptors on motor end plate. ACH binds to a receptor to open ion channels and the sodium around the synapse rushes in through the channels down the electro chemical gradient.
Action potential
Calcium released from sarcoplasmic reticulum into sarcoplasm. Calcium binds to TnC
Sliding filament Mechanism
Thin filaments slide over thick filaments, by the z discs pulling together. The I band and H zone shorten, and the A band remains the same length
Atp hydrolysis
Reorients and energizes myosin head
Contraction cycle
Atp Hydrolysis, Cross bridge, Power stroke, detachment of myosin from actin
Attachment of myosin on Actin
Phosphate released, ADP attaches to myosin head
Power stroke
ADP released, rotate toward center of sacromere
Detachment
ATP attaches to myosin causing detachment of myosin from actin
Terminating muscle contraction
Acetylcholinesterase breaks down ACh in cleft
Muscle metabolism energy source
ATP
the methods to metabolize
PHosphorylation of ADP, Anaerobic cellular respiration, Aerobic cellular respiration
Phosphorylation of ADP
Catalyzed by creatine kinase and provides energy for short bursts of activites (15 seconds)
Anaerobic Cellular Respiration
Glycolysis, oxygen is not required, provides energy for around 30-40 seconds
Glycolysis
Net atp gain=2; Glucose->Pyruvic acid, if Oxygen->Lactic Acid
Aerobic Cellular Respiration
Requires oxygen, which diffuses into muscle fibers. Prolonged activities where endurance is important.
Muscle fatigue
Inability to contract after prolonged activity
Reasons for muscle fatigue
Inadequate release of calcium, depletion of creatine phosphate, insufficient oxygen, depletion of glycogen, multiple reason
Oxygen Debt
Extra oxygen that body takes in after exercise to restore metabolic conditions to resting level. Converts lactic acid to glycogen, synthesizes atp and creatine phosphate, replaces oxygen that was before removed.
Control of muscle tension
Motor unit, muscle twitch, frequency of stimulation, strength stimulus
Motor unit
A somatic motor neuron and all the skeletal muscle fibers it innervates. Measured on a myogram
Myogram
Shows latent period, contraction period, relaxation period and refractory period
Refractory period
period of lost excitability after stimulus is applied
Tetanus
unfused (incomplete), Fused (Complete)
Strength of stimulus
Frequency of action potentials, recruitment of motor units
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