Basic Characteristics

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Question

Answer

What is the function of Skeletal Muscle?

Movement and Stability of Skeleton

What is a Motor Unit/Muscle Fiber?

collection of 10-2000 Cells innervated by branches of ONE Motor Nerve

When do Motor Units respond to a Stimulus?

when Depolarized

What are Myofibrils?

bundles of Myofilaments

What are Myofilaments?

Contractile Proteins - Myosin, Actin

What are z-Lines?

Protein anchoring discs for Actin

How does a Sarcomere shorten?

Myosin over Actin

What are 4 characteristics of Skeletal Muscle?

1. resting Potential (like Neurons); 2. Voluntary, quick Contraction; 3. All-or-None contraction; 4. Biochemical Specialization

what is meant bu All-or-None Contraction?

ALL Cells of a given Motor Unit contract FULLY, Simultaneously, or not at all

What are the 2 types of Biochemical Specialization?

SLOW-Oxidative "Red" Fibers, FAST-Glycolytic "White" Fibers

What are some characteristics of SLOW-Oxidative Fibers?

1. slow, Sustained contractions; 2. HIGH Myoglobin; 3. MANY Mitochondria, LITTLE Glycogen; 4. NUMEROUS Capillaries; 5. SMALL Motor Units; 6. DIFFICULT to Fatigue

What are some characteristics of FAST-Glycolytic Fibers?

quick, Brief contractions; 2. LITTLE Myoglobin; 3. FEW Mitochondria, LOTS Glycolytic Enzymes; 4. FEW Capillaries; 5. HUGE SR; 6. HIGH Glycogen; 7. LARGE Motor Unit; 8 .LARGE Diameter; 9. EASILY Fatigued

Name 2 Glycolytic Enzymes.

Pyruvic & Lactic Acids

Why do "White Fibers" have a lot of Glycogen?

need because Anaerobic --> less ATP

How does exercise change or not change Skeletal Muscle?

INCREASES Vascularity, Mitochondria, and amount of Myosin & Actin