Chapter 10 Flashcards
Authorythmicity
Build in rhythm
Natural pacemaker of heart
Functions of muscular tissue
Producing movement
Stabilizing body positions
Storing/moving substances in body
Generating heat
Thermogenesis
Muscle tissue contracts producing heat
Electrical excitability
Ability to respond to stimuli by producing action potentials
Stimulated by electrical signals (auto rhythmic) or chemical stimuli (neurotransmitter/hormones/pH changes)
Muscle fibers also called
Myocytes
Subcutaneous layer/hypodermis
Aereolar/adipose separate in skin from muscle
Fascia
Dense sheet/broad band or ICT
Lines body wall, supports/surrounds muscles/organs
Layer of connective tissue extending from fascia
Epimysium
Perimysium
Endomysium
Epimysium
Outer later around entire muscle
DITC
Perimysium
DICT
Surrounds 10-100+ muscle fibers separating into fascicles
Fasicles
Bundles of 10-100+ muscle fibers
Can be seen with naked eye
Meat rips at these
Endomysium
Penetrates interior of each radicle and separating individual fibers
Mostly reticular fibers
Tendon
All three connective layers extend rope like from muscle and attach to periosteum
Aponeurosis
Tendon but Broad flat sheet
Neurons that stimulate skeletal muscle
Somatic motor neurons
Bloody supply of muscles
Capillaries
Sarcolemma
Llamas membrane of muscle cell
Transverse tubules
Invaginations of sarcolemma
Filled with interstitial fluid
How do muscle action potentials travel
Along sacrolemma through T tubules throughout muscle fiber
Sarcoplasm
Cytoplasm of muscle cell
Large amount of glycogen
Myoglobin
Myoglobin
Red protein only in muscle
Binds o2 and releases it for ATP production
Myofibrils
Tiny threads in sarcoplasm
Contractile organelles of skeletal muscle
2um diameter
Sarcoplasmic reticulum
Fluid filled membranous sacs encircling myofibril
Stores Ca2+
Terminal cisterns
Dilated end sacs of SR
Butt against t tubules
Releases Ca2+
Triad
T tubules and 2 terminal cisterns
Where are filaments found
In myofibrils
Thin filaments
Actin
8nm diameter
Contractile protein
Thick filaments
Myosin
16nm diameter
Contractile protein
Sarcomeres
Basic functional units of myofibril
Have filaments inside
Z disc
Seperate one sarcomere from bect
A band
Entire length of thick
Zone of overlap
Where thin/thick are
In A band
I band
Rest of thin filaments
Z disc in center
H zone
Thick not thin in A band
M line
Hold thick filaments at center of H zone
Contractile proteins
Myosin (thick)
Actin (thin)
Binding sites on myosin
Actin binding site
ATP binding site
Binding sites on actin
Myosin binding site
Regulatory proteins
Tropomyosin: blocks myosin binding sites in actin
Troponin: troponin moves tropomyosin away uncovering binding sites
Titan
Structural protein
Third most plentiful protein
Huge (50x larger than normal protein)
Z disc to M line stabilizing thick filament
Very elastic
Sliding filament mechanism
Thin slide inwards
I band and H zone narrow then disappear (max contraction)
What happens before Contraction cyle
SR release Ca ions into sarcoplams
Ca binds to troponin which moves tropomyosin away from binding sites
Contraction cycle steps
1.ATP hydrolysis: myosin head is energized and orientated (90°)
- Attachment of myosin to actin: cross bridge formed, P group released
- Power stroke: myosin head picots pulls thin past thick (45°), ADP released
- Detachment of myosin from actin: myosin binds ATP detaching cross bridge
cross bridges in thick filament
600
Attached/detaches 5/sec
Excitation contraction coupling
Sequence of events linking excitation (muscle action potential) to contraction (sliding of filaments)
Occurs at triad
Voltage gated Ca2+ channels
In t tubule membrane arrange as tetrads
Voltage sensors triggering opening of ca2+ release channels