Resting Membrane Potential, Action Potentials, and Muscle Physiology

These flashcards cover the key concepts regarding resting membrane potentials, action potentials, nervous system functions, and muscle physiology as outlined in the lecture notes.

What is the primary function of the Na+/K+ pump in resting membrane potential?

It helps maintain the negative charge inside the cell by moving 3 Na+ out and 2 K+ in.

What are the four phases of an action potential after reaching threshold?

Depolarization, peak, repolarization, and hyperpolarization.

What initiates the release of neurotransmitters at synaptic terminals?

The action potential causes voltage-gated Ca2+ channels to open, leading to the release of vesicles containing neurotransmitters.

What is the difference between EPSP and IPSP?

EPSP (excitatory postsynaptic potential) causes depolarization due to Na+, Ca2+, Mg2+ entering, while IPSP (inhibitory postsynaptic potential) causes hyperpolarization due to Cl- entering or more K+ leaving.

What is the role of the Nodes of Ranvier in action potential propagation?

They are gaps in the myelin sheath that contain voltage-gated channels, allowing for faster conduction of action potentials via saltatory conduction.

What are glial cells and name a few types?

Glial cells support neurons; types include astrocytes, oligodendrocytes, and ependymal cells.

What causes Multiple Sclerosis and what are its effects?

It is caused by autoimmune destruction of myelin, leading to slower impulses and reflexes, affecting senses and potentially resulting in death.

Describe the neuromuscular junction's role in muscle contraction.

At the neuromuscular junction, alpha motor nerves release acetylcholine (ACH), which activates ACH-gated channels, leading to depolarization and action potential initiation in the muscle.

What does the crossbridge cycle require to continue?

It requires ATP and calcium ions (Ca2+).

How does muscle fiber recruitment work?

Recruitment occurs when more motor neurons activate to increase the number of muscle fibers contracting until 100% of the muscle is engaged.

Explain length-tension relationship in muscles.

Muscle force varies with joint motion; optimal force occurs with optimal overlap of sarcomeres, which decreases when muscles are too long or too short.

What are the three types of muscle fibers?

Red, intermediate, and white muscle fibers differ in myosin types, myoglobin content, and energy usage (aerobic vs anaerobic).

How can training affect muscle fiber characteristics?

Training can increase muscle size and influence the muscle's speed; aerobic training can make muscles slower, while resistance training can enhance speed.