Muscular System Flashcards
Muscles
Distinguished by their ability to transform chemical energy (ATP) into directed mechanical energy. In so doing become capable of exerting force
Covered by externally by the epimysium
What are the types of muscle tissue?
Skeletal
Muscle
Cardiac
What are skeletal and smooth muscle cells but not cardiac?
Elongated and called muscle fibres
Skeletal muscle
Longest of all muscle have stripes
Attached to bone
Voluntary muscle
Contract rapidly, tire easily, powerful
Cardiac muscle
Found only in heart
Stripes
Involuntary
Contracts at steady rate due to hearts own pacemaker
Smooth muscle
Found in walls of hollow organs- stomach, urinary bladder
Involuntary
Can contract on its own without nervous system stimulation
Characteristics of muscle tissue
Excitability- ability to receive and respond to a stimuli
Contractibility- ability to shorten forcibly when stimulated
Extensibility- ability to be stretched
Elasticity- ability to recoil to resting length
Muscle function
Produce movement
Maintain posture and body position
Stabilise joints
Generate heat as they contract
Protect organs
Skeletal muscle anatomy
Made up of different tissues with 3 features:
Nerve and blood supply
Connective tissue sheaths
Attachments
What is a nerve and blood supply
Each muscle receives a nerve, artery and veins
Contracting muscle fibres require huge amounts of oxygen and nutrients
Fascicle
A discrete bundle of muscle cells
Serrated from the rest of the muscle by a connective tissue sheath
Surrounded by perimysium
Muscle fiber
Elongated multi nuclear cell
Striated
Surrounded by endomysium
Sarcolemma
Muscle fiber plasma membrane
Sarcoplasm
Muscle fiber cytoplasm
Myofibrils
Densely packed
Consists of sarcomeres
Sarcomere
Smallest contractile unit of muscle fiber
Consisted of area between z discs
Thick filament
each thick filament consists of many myosin molecules
whose heads protrude at opposite ends of the filament
Thin filament
consists of 2 strands of actin subunits twisted into a helix plus two types of regulatory proteins (troponin + tropomyosin)
Tropomyosin
blocks myosin binding sites on actin molecules
preventing cross-bridge binding
it is held in place by troponin
Troponin
bound to both tropomyosin and actin
regulates the availability of myosin binding sites on actin
calcium ions
binds to troponin
sarcoplasmic reticulum
network of smooth endoplasmic reticulum tubules surrounding each myofibril
what are the functions of sarcoplasmic reticulum
run longitudinally
functions in regulation of intracellular Ca 2+ levels
stores and releases Ca 2+
T tubules
formed by protrusion of sarcolemma deep into cell interior
what do t tubules allow to do
allow electrical nerve transmissions to reach deep into interior of each muscle fibre
