Untitled Flashcards Set

Action Potential

The change in electrical potential that occurs when a neuron fires.

All-or-nothing principle

A neuron either fires at full strength or not at all.

Resting potential

The state of a neuron when it is not firing an impulse.

Depolarization

Phase in action potential characterized by Na+ influx, making the inside of the cell more positive.

Repolarization

Phase in action potential characterized by K+ efflux, restoring the negative internal charge.

Refractory period

The time following an action potential during which a neuron is unable to fire again.

CNS

Central Nervous System; includes the brain and spinal cord.

PNS

Peripheral Nervous System; nerves outside the CNS involved in sensory and motor pathways.

Multipolar neuron

Most common neuron type, typically involved in motor functions.

Dendrites

Branching extensions of a neuron that receive signals.

Axon

Long part of a neuron that transmits signals to other neurons or muscles.

Myelin sheath

Insulation around axons that speeds up signal transmission.

Sensory neuron

Afferent neuron that carries signals toward the CNS.

Motor neuron

Efferent neuron that carries signals away from the CNS to effectors.

Interneuron

Neuron that connects sensory and motor neurons within the CNS.

Reflex Arc

Pathway that mediates a reflex action.

Fovea centralis

Part of the retina responsible for sharp central vision, rich in cones.

Accommodation

The process by which the lens of the eye changes shape to focus light.

Myopia

Nearsightedness, a vision disorder where distant objects appear blurry.

Hyperopia

Farsightedness, a vision disorder where close objects appear blurry.

Cataracts

Clouding of the lens of the eye, affecting vision.

Erythrocytes

Red blood cells that carry oxygen and carbon dioxide.

Leukocytes

White blood cells involved in immune response.

Platelets

Cell fragments that play a critical role in blood clotting.

Plasma

Liquid component of blood that carries cells, proteins, and nutrients.

Normal blood pH

The slightly alkaline pH range for blood, which is 7.35–7.45.

Arteries

Blood vessels that carry oxygenated blood away from the heart.

Veins

Blood vessels that return deoxygenated blood to the heart.

Capillaries

Small blood vessels where gas and nutrient exchange occurs.

Pacemaker

The SA node that initiates the heartbeat.

Heart sounds

Sounds made by heart valves closing, notably 'Lub-dub'.

Layers of Heart

Includes pericardium (outer), myocardium (muscle), and endocardium (lining).

Inspiration

Process of inhalation where the diaphragm contracts, increasing volume and decreasing pressure.

Expiration

Process of exhalation where the diaphragm relaxes, decreasing volume and increasing pressure.

Epiglottis

Flap that covers the trachea during swallowing to prevent food from entering the airway.

Larynx

Voice box containing vocal cords.

Pleural membrane

Membrane that reduces friction around the lungs.

Tidal volume

Volume of air inhaled or exhaled in a normal breath, approximately 500 mL.

Vital capacity

The maximum volume of air that can be inhaled or exhaled.

CO₂ role in blood

Regulates blood pH by being converted to bicarbonate.

Path of food

Mouth → Esophagus → Stomach → Small intestine → Large intestine → Anus.

Liver

Organ that produces bile and detoxifies blood.

Gallbladder

Organ that stores bile produced by the liver.

Pancreas

Organ that releases digestive enzymes and insulin.

Villi

Finger-like projections in the small intestine that increase surface area for absorption.

Bolus

Chewed food mixed with saliva before swallowing.

Chyme

Partially digested food that leaves the stomach.

Adult tooth count

32 teeth in a typical adult.

Tooth structure

Includes enamel (hard shell), dentin (supporting base), and pulp (nerves/vessels).