Physiology module 2 async flashcards

These flashcards cover key concepts in nerve and muscle physiology, including membrane potentials, action potentials, muscle contraction mechanisms, and muscle fiber types.

What is the difference between diffusion potential and equilibrium potential?

Diffusion potential is the potential difference generated when an ion moves down its concentration gradient, while equilibrium potential is the potential difference measured when the ion reaches electrochemical equilibrium.

How is equilibrium potential calculated for an ion?

Equilibrium potential is calculated using the Nernst equation, which considers the permeability of the membrane to that ion and the concentration of the ion across the membrane.

What role does potassium play in generating resting membrane potential?

Potassium ions diffuse out of the cell, losing positive charge and making the inside of the cell negative relative to the outside, contributing to the resting membrane potential.

What effect does the sodium-potassium pump have on membrane potential?

The sodium-potassium ATPase pumps three sodium ions out of the cell and two potassium ions into the cell, creating a net loss of positive charge and thus contributing to a negative membrane potential.

What is the significance of the Goldman equation?

The Goldman equation accounts for the permeabilities of multiple ions to calculate the resting membrane potential, providing a more realistic view of membrane behavior in physiological conditions.

What are action potentials and how are they generated?

Action potentials are regenerating depolarizations of membrane potential that propagate along excitable membranes, initiated by depolarization and involving changes in ion permeability, primarily sodium ions.

What is depolarization?

Depolarization is when the membrane potential becomes less negative, moving towards zero.

What is the all-or-none principle in action potentials?

The all-or-none principle states that if a threshold potential is reached, an action potential will be generated fully; if not, no action potential occurs.

What is meant by the term 'excitation-contraction coupling'?

Excitation-contraction coupling refers to the physiological process by which a nerve impulse leads to muscle contraction, involving calcium release and interaction with troponin and tropomyosin.

What are the roles of calcium in muscle contraction?

Calcium binds to troponin C, causing it to change shape and move tropomyosin away from myosin-binding sites on actin filaments, allowing muscle contraction to occur.

What is a motor unit?

A motor unit consists of a motor neuron and all the muscle fibers it innervates, which allows for coordinated muscle contractions.

What is muscle atrophy and what causes it?

Muscle atrophy is the decrease in muscle mass and strength due to disuse or lack of neural stimulation, which can occur in situations like immobilization or in response to certain diseases.

How does muscle hypertrophy occur?

Muscle hypertrophy occurs through an increase in the protein content in muscle fibers, primarily in the amount of actin and myosin, resulting from resistance training.

What is the difference between slow oxidative fibers and fast glycolytic fibers?

Slow oxidative fibers are fatigue-resistant and suited for endurance, while fast glycolytic fibers have a higher glycolytic enzyme content, allowing for quick energy production but prone to fatigue.

What is tetanization and how does it occur?

Tetanization is the increase in contraction strength due to the additive effect of individual twitch contractions, resulting from high-frequency stimulation.

What does the size principle refer to in muscle activation?

The size principle states that smaller motor units are recruited first for precise control, followed by larger motor units for stronger contractions.

What is the role of tropomyosin in muscle contraction?

Tropomyosin binds to actin filaments and blocks myosin-binding sites, preventing contraction until calcium binds to troponin and causes tropomyosin to shift.