Nervous and Endocrine Systems Diploma Review

A comprehensive set of vocabulary flashcards covering the nervous system structure, action potentials, brain anatomy, sensory organs, and the endocrine system based on the lecture transcript.

Neuron

A nerve cell specialized for conducting nerve signals over long distances.

Dendrites

Long cell extensions that receive electrochemical impulses from other neurons.

Neurolemma

A membrane that helps the neuron repair itself after an injury.

Myelin sheath

A white fatty insulating covering over the axon composed of individual Schwann cells.

Nodes of Ranvier

The spaces between Schwann cells where the axon is exposed.

Sensory neurons

Neurons that carry signals from the sensory organs to the central nervous system.

Motor neurons

Neurons that carry signals from the central nervous system to muscles.

Interneurons

Neurons that allow signals to travel within the central nervous system.

Resting membrane potential

The small electrical potential of a neuron at rest, measuring $-70\,mV$ from the perspective of the ICF.

Depolarization

The process where the membrane becomes permeable to sodium ions, causing the ICF to reach an electrical potential of $+30\,mV$.

Repolarization

The process of returning the membrane to its original resting polarity by closing sodium channels and actively transporting positive ions out of the axon.

Action potential

A spike seen on a voltage graph during depolarization, also known as a nerve impulse.

Conduction

The process by which an impulse travels down the axon because increased sodium permeability at one point causes increased permeability at an adjacent point.

All-or-none principle

The principle that an action potential will only occur if the threshold for excitation is reached; otherwise, the impulse will simply fade out.

Synapse

The place between the synaptic knob of a presynaptic neuron and the dendrite of a postsynaptic neuron.

Acetylcholine

The most common neurotransmitter, which is a protein produced by neurons.

Cholinesterase

The enzyme that breaks down Acetylcholine

Central Nervous System (CNS)

The part of the nervous system composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

The part of the nervous system composed of spinal nerves extending from the spinal cord, subdivided into somatic and autonomic systems.

Autonomic nervous system

A part of the PNS that regulates smooth muscle, glands, and organs without conscious control.

Sympathetic system

The component of the autonomic system that prepares the body for 'fight or flight' by diverting blood to skeletal muscles and increasing heart rate.

Parasympathetic system

The component of the autonomic system stimulated by acetylcholine that acts once a perceived threat has passed.

Cerebrum

The top portion of the brain, highly convoluted and divided into right and left hemispheres.

Frontal lobe

A lobe of the cerebrum that controls personality and contains the motor cortex for voluntary motion.

Parietal lobe

A lobe of the cerebrum containing the sensory cortex that processes sensation.

Occipital lobe

The lobe at the back of the cerebrum containing the visual cortex.

Temporal lobe

The lobe of the cerebrum responsible for hearing.

Corpus callosum

A band of myelinated fibers that transmits information between the two hemispheres of the brain.

Cerebellum

A structure consisting of two hemispheres that sits at the top of the brainstem and coordinates muscular movements.

Medulla oblongata

A brain structure that controls autonomic functions including breathing, heart rate, and blood shunting.

Hypothalamus

A brain structure that controls temperature, hunger, and thirst while monitoring the endocrine system.

Reflex

The simplest neural pathway connecting a specific sensory stimulus with a response without involving the brain.

Sclera

The rigid, white outer protective layer of the eyeball.

Choroid

The middle layer of the eye containing blood vessels that nourish the retina.

Retina

The inner layer of the eye containing photoreceptors like rods and cones.

Rods

Photoreceptors that perceive black and white images in low light levels.

Cones

Photoreceptors that absorb colors and function at high light levels, with the highest concentration at the fovea.

Accommodation

The process of ciliary muscles changing the shape of the lens to focus on near or distant objects.

Nearsightedness

A condition caused by an eyeball that is too long, resulting in images focusing in front of the retina.

Astigmatism

A condition where the cornea or lens lacks a smooth curvature, causing parts of the visual field to be out of focus.

Glaucoma

Damage to the retina caused by excessive pressure from the buildup of aqueous humor.

Eustachian tube

A tube that allows air to pass between the ear to keep air pressure inside the middle ear equal to the auditory canal.

Organ of Corti

A membrane within the cochlea covered in hair cells that function as hearing receptors.

Semicircular canals

Three fluid-filled canals with hair cell receptors that respond to motion to help the body keep its balance.

Peptide hormones

Hormones made of proteins that act by binding to receptors on the surface of target cells.

Steroid hormones

Hormones that pass through cell and nuclear membranes to bind with receptors in the nucleus and change gene expression.

ADH (Antidiuretic Hormone)

Hormone produced by the hypothalamus that increases reabsorption of water from urine into the bloodstream.

TSH (Thyroid Stimulating Hormone)

Hormone from the anterior pituitary that stimulates the thyroid to release thyroxine.

ACTH (Adrenocorticotropic Hormone)

Hormone that stimulates the adrenal cortex to release cortisol, aldosterone, and androgens in response to stress.

Thyroxine

A thyroid hormone that increases the rate of metabolic activity, producing ATP and heat.

Calcitonin

A thyroid hormone that decreases blood calcium by depositing it into bones and teeth.

Insulin

A pancreatic hormone that decreases blood glucose by increasing cell permeability to glucose.

Glucagon

A pancreatic hormone that increases blood glucose by converting stored glycogen into glucose.

Aldosterone

A hormone from the adrenal cortex that increases blood volume by increasing reabsorption of sodium and water.

Homeostasis

The process by which a stable internal condition is maintained, often through negative feedback loops.

Hyperthyroidism

A condition resulting in a higher metabolic rate, weight loss, and irritability, associated with Graves' disease.

Goiter

A swelling of the thyroid gland often caused by a lack of iodine.