Chapter 1 Flashcards
What is a motor unit?
A single nerve(/neuron) and the collection of muscle fibers it innervates
What is a fascicle?
A group of muscle fibers that are bundled together by fiber type. (e.g. Type 1 slow twitch, type 2a/2x fast twitch).
What type of tissue is the perimysium and what does it surround?
It is a thin layer (middle layer) of connective tissue that surrounds the fascicle aka groups of muscle fibers.
What is the Epimysium?
The outer most layer of connective tissue/fascia that engulfs the entire muscle & extends beyond the muscle to connect our tendons to bone.
What is the Endomysium?
The (i)nner most connective tissue that surrounds each individual muscle fiber.
Strains apply to what?
Muscle
Sprains are associated with what?
Liagments
What bones make up the axial skeleton?
Skull, rib cage, sternum, and vertebrae
What bones make up the appendicular skeleton?
Scapula, Arm, Wrist, and Hand Bones, Leg, Ankle, and Feet Bones, Hips (Illium (large fan shape), Ischium (posteriorinferior portion), and Pubisn (anteromedial portion), Sacrum, and Cocyx.
What are muscle cells/fibers made up of? And what do they contain?
Muscle fibers are made of myofibrils and they contain sacromeres - the smallest contractile unit of muscle.\ which is made up of actin ^ myosin.
Between the Z-disc, I-band, H-zone, and A-band (of a sarcomere) which can shorten and which stays the same and never changes in length?
The Z-disc, I-band (which connects to actin), and H-Zone can shorten/contract, but the A-band, which is the length of the mysoin never changes in length.
When myosin pulls on actin like a row boat to shorten the muscle for contraction this action is referred to as what? How is this contraction relinquished or reset?
Power Stroke
Through ATP Hydrolysis
(Combined the process is what allows us to produce force)
When an action potential is sent from the brain and down the nerve to the neuromuscular junction, what is released?
Hint: This neurotransmitter causes excitation of the sarcolemma and hence causes muscle contraction.
Acetylcholine (ACH)
What 7 Steps are involved in Activating a Muscle Fiber?
- The creation of an action potential
- The AP moving down the nerve to the neuromuscular junction
- The consequent release and crossing of acetylcholine thru the neuromuscular junction which excites the sarcolemma
- This signal continues down the t-tubles and causes calcium to be released FROM the sarcoplasmic
reticulum (where it is stored) - Ca+ then binds with troponin which binds to tropomyosin (the “rope” around actin”) which allows that binding site of actin to be exposed.
- Myosin then binds to actin to allow crossbridging at the gubular head.
- The Sliding Filament Theory can now occur - i.e. continuous power strokes and crossbridging. This will last as long as Ca++ is available to bind with troponin OR until relaxation occurs.
Are type 2a muscle fibers, fast twitch, slow twitch, or mixed?
Explain why?
Type IIa are mixed and often referred to as “fast oxidative glycolytic fibers” because they have both oxidative (i.e. aerobic) and glycolytic (i.e. CHO reliant) properties.
(They are also surrounded by more capillaries hence, the greater capacity for aerobic metabolism)
