KINE 433 EXAM 2

Skeletal Muscle

Muscle that is voluntary and regulated by the central nervous system (CNS).

Cardiac Muscle

Involuntary muscle that is regulated by the autonomic nervous system (ANS).

Smooth Muscle

Involuntary muscle found in blood vessels and bronchioles, regulated by the autonomic nervous system (ANS).

Sarcomere

The contractile unit of a muscle fiber.

Actin

A protein that forms thin filaments in muscle fibers.

Myosin

A protein that forms thick filaments in muscle fibers

Troponin

A protein that binds calcium ions and helps regulate muscle contraction by moving tropomyosin.

Excitation-Contraction Coupling

The process by which an electrical signal (action potential) triggers muscle contraction.

Alpha Motor Neuron (a-MN)

A type of neuron that carries action potentials from the CNS to muscle fibers.

Motor Unit (MU)

An alpha motor neuron and all the muscle fibers it innervates.

ATP (Adenosine Triphosphate)

The primary energy carrying molecule in cells.

Aerobic and Anaerobic Systems

Aerobic systems use oxygen to produce energy, while anaerobic systems do not.

Creatine Kinase

An enzyme that catalyzes the conversion of phosphocreatine (PCr) to creatine and phosphate in the cytoplasm

Lactate

A byproduct of anaerobic metabolism that can inhibit fat metabolism.

Glucose Regulation

Maintaining blood glucose levels within a target range, primarily through insulin and glucagon.

Antidiuretic Hormone (ADH)

A hormone that helps to retain water in the kidneys and regulate fluid balance.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormone system that regulates blood pressure and fluid balance.

Respiratory Exchange Ratio (RER)

A ratio used to estimate the composition of fuels being used for energy.

Excess Post Exercise Oxygen Consumption (EPOC)

The amount of oxygen consumed after exercise to restore the body to its resting state.

Type I Muscle Fibers

Slow twitch fibers with a high oxidative capacity, suitable for endurance activities.

50% of fibers in muscle

Type II Muscle Fibers

Fast twitch fibers, subdivided into IIa (moderate oxidative capacity) and IIx (low oxidative capacity), suited for power activities.

Muscles are composed of

muscle fibers that vary in contractile and metabolic properties

Muscle fibers are multinucleated

true

Actin and Myosin

interact with each other to cause muscle contraction.

Thin filaments are composed of

Actin, Myosin, and Troponin

First Step of Excitation-Contraction Coupling

The Control Center, AP starts in the brain

Second Step of Excitation-Contraction Coupling

In the Neuromuscular Junction, a-MN releases ACh

Third Step of Excitation-Contraction Coupling

The Nicotinic Receptors, ACh binds to Nicotinic Receptors

Fourth Step of Excitation-Contraction Coupling

T-Tubules, AP travels down the tubules

Fifth Step of Excitation-Contraction Coupling

Sarcoplasmic Reticulum releases Ca²+

Sixth Step of Excitation-Contraction Coupling

Troponin, Ca²+ binds troponin & pulls tropomyosin off active sites

Seventh Step of Excitation-Contraction Coupling

Myosin Heads bind actin and tilts

Relaxed Muscle

Active sites are blocked & ATP bound to myosin

No force generated

Contracting Muscle

Active Sites are exposed & ATP is hydrolyzed

Myosin Head is attached

Fully Contracted Muscle

Pi Released (power stroke) & ADP released

New ATP binds and Myosin head detaches

How does contraction stop?

CC is removed, ACh gets degraded & Ca²+ is pumped out

Type IIa Muscle Fiber

Moderate oxidative capacity with intermediate mitochondrial and capillary density

45% of fibers in muscle

Type IIx Muscle Fiber

Low oxidated capacity with loc mitochondrial and capillary density

5% of fibers in muscle

Gel Electrophoresis

gel substance used to pull out proteins with an electrical current

Force and Velocity is high in

Type II MU

Preferred Fuel of the Muscle

Fats; yield more kcal/g (9.4 kcal/g)

Crossover Effect

the shift from Fat to CHO metabolism

occurs around 70% VO2 max

Why does Crossover Effect Happen

Fat metabolism is slow and Recruits Type II Fibers

What happens with Recruitment of Type II Fibers

increase in lactate production

Lactate inhibits fat metabolism called lipolysis

During low intensity exercise

Lactate does not increase / no LA to inhibit fat metab

Adenosine

Combination of Adenine and Ribose

What is essential to Cross-Bridge Cycling

Myosin ATPase

What splits phosphate off ATP molecules

ATPases

ATP-PCr System

Immediate energy system that is dominant in 1-15 seconds

Glycolytic System

Short-Term energy system dominant in 15-120 seconds

Oxidative System

Long-term energy system dominant beyond 2 minutes

Creatine Supplements

increase PCr storage and increases total work

Glycolysis

breakdown of glucose to produce Pyruvate in the cytoplasm

Energy Investment Phase EIP

2 ATP used to phosphorylate Glucose

Energy Payoff Phase EPP

4 ATP & 2 NADH produced

The fate of Pyruvate

Determined by O2

Pyruvate with O2 Deficient

PA is converted to LA by Lactate Dehydrogenase

Pyruvate with O2 Sufficient

PA & NADH enters the mitochondria