Recording-2026-10-26T20_47_31.810Z

Acetylcholine (ACh) role at the neuromuscular junction

The neurotransmitter released from motor neurons that crosses the synaptic cleft and binds to receptors on muscle fibers to trigger contraction.

Selective serotonin reuptake inhibitors (SSRIs) mechanism

Medications that elevate mood by blocking the reabsorption of serotonin into the presynaptic neuron, increasing its availability in the synaptic cleft.

Substantia nigra dopamine deficiency

The underlying neurological cause of Parkinson's disease, impairing fine motor control.

Nitric oxide vascular function

A chemical messenger that acts as a potent vasodilator to widen blood vessels and increase blood flow.

Gamma-aminobutyric acid (GABA)

The primary inhibitory neurotransmitter in the central nervous system that calms neural activity and is enhanced by benzodiazepines.

Histamine physiological actions

An inflammatory chemical mediator that produces vasodilation (causing hives) and bronchoconstriction (narrowing airways) during allergic reactions.

Autonomic blood diversion: Sympathetic vs. Parasympathetic

The sympathetic system directs blood toward skeletal muscle and the brain for rapid response, whereas the parasympathetic system diverts blood to the gastrointestinal tract for digestion.

Saltatory conduction

The rapid transmission of nerve impulses along a myelinated axon as action potentials skip between the Nodes of Ranvier.

Resting membrane potential ion distribution

High concentration of $Na^+$ outside the cell and high concentration of $K^+$ inside the cell, producing a resting charge of approximately $-70\,mV$.

Depolarization phase of an action potential

The influx of $Na^+$ down its concentration gradient through open voltage-gated channels, raising membrane potential to approximately $+30\,mV$.

Repolarization phase of an action potential

The outward flow of $K^+$ through voltage-gated channels, driving the membrane potential back down toward negative values.

Sodium-potassium pump ($Na^+/K^+$ ATPase)

An active transport pump fueled by ATP that restores resting ion gradients by pumping $Na^+$ out of the cell and $K^+$ back in.

Sarcoplasmic reticulum function in muscle contraction

The intracellular organelle that stores and releases calcium ($Ca^{2+}$) into the sarcoplasm following an action potential traveling down T-tubules.

Troponin vs. Tropomyosin roles in sarcomere activation

Calcium ($Ca^{2+}$) binds to troponin, which shifts tropomyosin away from the active sites on actin so myosin heads can bind.

Functional joint classifications: Synarthrotic, Amphiarthrotic, Diarthrotic

Synarthrotic joints are immovable (fibrous), amphiarthrotic joints are slightly movable (cartilaginous), and diarthrotic joints are freely movable (synovial).

Structural comparison: Shoulder vs. Hip joint

The glenohumeral joint has a shallow glenoid fossa providing high mobility but low stability; the acetabulofemoral joint has a deep acetabulum providing high stability but less mobility.

Primary stabilizer of synovial joints

Skeletal muscles surrounding the joint, followed by reinforcing ligaments and joint capsule architecture.

Cruciate ligaments of the knee (ACL and PCL)

Intracapsular knee ligaments that cross each other to stabilize the connection between the femur and tibia.

Iliopsoas

The primary muscle group responsible for hip flexion.

Teres major rotator cuff classification

A shoulder muscle that is explicitly excluded from the rotator cuff group.