Unit 2 Study Guide

Acetylcholine

A neurotransmitter involved in muscle contraction and various functions in the nervous system.

ACTH

Adrenocorticotropic hormone, a hormone that stimulates the adrenal cortex.

Actin

A protein that forms the contractile filaments of muscle cells.

Action Potential

A temporary reversal of the membrane potential along the neuron.

Adenylate Cyclase

An enzyme that converts ATP to cyclic AMP in response to a chemical signal.

Adrenal Cortex

The outer portion of the adrenal glands that produces corticosteroids.

Amplifier Enzyme

An enzyme that amplifies the strength of a signal within a cell's signaling pathway.

Anterior Pituitary

The front part of the pituitary gland that releases hormones such as ACTH and growth hormone.

Astrocyte

A type of glial cell in the brain that supports neurons and maintains the blood-brain barrier.

Autocrine Signals

Chemical signals secreted by cells that act on themselves.

Axon Hillock

The part of a neuron where the axon begins and where action potentials are initiated.

Axon Terminal

The endpoint of a neuron where neurotransmitters are released.

Ca2+

Calcium ions, which play a critical role in muscle contraction and neurotransmitter release.

Contact-Dependent Signals

Signals that require direct contact between cells.

CRH

Corticotropin-releasing hormone, which stimulates the release of ACTH.

Cyclic AMP

A second messenger important in many biological processes, derived from ATP.

Dendrite

The branch-like extensions of a neuron that receive signals from other neurons.

Depolarization

The process of reducing the membrane potential, making it less negative/more positive.

Endocrine Cell

A cell that secretes hormones directly into the bloodstream.

Epinephrine

A hormone also known as adrenaline, involved in the fight-or-flight response.

Gap Junction

A specialized intercellular connection that allows for direct communication between adjacent cells.

Glucagon

A hormone that raises blood glucose levels by promoting the conversion of glycogen to glucose.

G-Protein Coupled Receptors

A large family of receptors that, when activated, initiate a cascade of intracellular signaling effects.

Graded Potential

Changes in membrane potential that vary in size, unlike action potentials.

Gray Matter

Region of the brain and spinal cord rich in neuronal cell bodies.

Hormone

A chemical messenger produced by glands that regulates various physiological functions.

Hyperpolarization

The process of increasing the membrane potential, making it more negative/less positive.

Hypothalamus

A brain region controlling many autonomic functions and hormone release from the pituitary gland.

Inositol triphosphate

A second messenger that plays a role in intracellular calcium signaling.

Insulin

A hormone that lowers blood glucose levels by facilitating cellular glucose uptake.

Lens

A transparent structure in the eye that helps focus light on the retina.

Ligand-Gated Ion Channels

Ion channels that open in response to the binding of a chemical messenger.

Microglia

Immune cells in the central nervous system that respond to injury or infection.

Muscle fiber

The basic building block of skeletal muscle tissue.

Myosin

A protein that, along with actin, is responsible for muscle contraction.

Negative Feedback

A regulatory mechanism where a change in a system causes an action that counteracts the initial change.

Neurohormone

A hormone produced by neurons that acts on distant target cells.

Neuron

A nerve cell that transmits electrical impulses.

Neurotransmitter

A chemical messenger that transmits signals across a synapse between neurons.

Nociceptors

Sensory receptors that detect harmful stimuli and signal pain.

Nodes of Ranvier

Gaps in the myelin sheath of axons that facilitate rapid conduction of impulses.

Norepinephrine

A neurotransmitter and hormone involved in the body's fight-or-flight response.

Odorant Receptors

Receptors in the olfactory system that detect airborne chemical stimuli.

Oligodendrocytes

Glial cells in the central nervous system that produce myelin.

Paracrine Signals

Chemical signals that act on nearby cells.

Phospholipase C

An enzyme involved in the signaling pathway of some G-protein coupled receptors.

Phosphorylation

The addition of a phosphate group to a molecule, often regulating activity.

Photoreceptor

A specialized neuron in the retina that responds to light.

Posterior Pituitary

The back part of the pituitary gland, which stores and releases oxytocin and vasopressin.

Prohormone

An inactive precursor that must be converted into an active hormone.

Protein kinase

An enzyme that modifies proteins by adding phosphate groups.

Pupil

The opening in the center of the iris that regulates the amount of light entering the eye.

Receptor

A protein molecule that receives chemical signals from outside a cell.

Receptor Channels

Channels that open in response to the binding of ligands.

Repolarization

The process of returning the membrane potential back to a resting state following depolarization.

Retina

The light-sensitive layer at the back of the eye where photoreceptors are located.

Sarcomere

The basic unit of muscle contraction in striated muscle.

Sarcoplasm

The cytoplasm of muscle cells.

Sarcoplasmic reticulum

A specialized endoplasmic reticulum in muscle cells that stores calcium.

Schwann Cells

Glial cells that myelinate peripheral nerve fibers.

Second Messenger

Molecules that relay signals received at receptors to target molecules in the cell.

Sensory Receptors

Specialized neurons that detect and respond to specific sensory stimuli.

Sodium Pump

A membrane protein that transports sodium ions out of cells, helping maintain cellular homeostasis.

Synapse

The junction between two neurons where communication occurs.

Synaptic Vesicle

Small membrane-bound structures that store neurotransmitters.

Target Cell

A cell that possesses receptors for specific hormones or neurotransmitters.

Taste Buds

Sensory organs on the tongue that detect taste.

Thalamus

A brain structure that relays sensory information to the cerebral cortex.

Thyroid Gland

An endocrine gland that regulates metabolism through hormone production.

Tropomyosin

A protein involved in muscle contraction that regulates the interaction of actin and myosin.

Troponin

A protein complex involved in muscle contraction that responds to calcium.

Vestibular Apparatus

The structure in the inner ear that provides balance and spatial orientation.

White Matter

Region of the brain and spinal cord rich in myelinated axons.

Afferent vs Efferent Pathways

Afferent pathways carry signals to the central nervous system, while efferent pathways carry signals away from it.

Anterior vs. Posterior Pituitary

The anterior pituitary produces hormones that regulate growth and metabolism, while the posterior pituitary stores and releases hormones like oxytocin.

Autocrine vs. Paracrine vs. Endocrine

Autocrine signals act on the same cell that secretes them; paracrine signals act on nearby cells; endocrine signals travel through the bloodstream to distant cells.

Basic Physiology of a Muscle Contraction

Muscle contraction occurs when actin and myosin filaments slide past each other, fueled by ATP.

Basic Physiology of Hearing, Smell, Taste, Touch, and Vision

Each sense involves specialized receptors that transduce specific stimuli into neural signals for processing.

Blood-Brain Barrier

A selective permeability barrier that protects the brain from circulating pathogens and toxins.

cAMP vs. Ca2+ signaling

cAMP is a second messenger involved in many signaling pathways, while Ca2+ serves as a critical signaling ion in muscle contraction and neurotransmitter release.

Cellular Anatomy of a Neuron

A neuron consists of a cell body, dendrites, and an axon.

Chemical vs. Electrical Synapse

Chemical synapses transmit signals via neurotransmitters, while electrical synapses transmit signals directly through gap junctions.

Endocrine vs. Exocrine

Endocrine glands release hormones into the bloodstream; exocrine glands release substances like enzymes through ducts.

Function of Myelination

Myelination increases the speed of action potentials along axons.

General Organization of Nervous System

The nervous system is divided into the central and peripheral nervous systems.

Graded Potential vs. Action Potential

Graded potentials are variable in magnitude and can summate, while action potentials are all-or-nothing signals.

HPA and APT Endocrine Axes

The HPA axis involves interactions between the hypothalamus, pituitary gland, and adrenal glands; APT axis refers to anterior pituitary hormone regulation.

Intracellular vs. Membrane Receptors

Intracellular receptors bind lipophilic signaling molecules; membrane receptors bind hydrophilic molecules at the cell surface.

Neuroendocrine Reflex

A reflex involving both neural and endocrine components.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber.

Neurotransmitter vs. Hormone

Neurotransmitters transmit signals across synapses in the nervous system; hormones are released into the bloodstream to target distant cells.

Non-neuronal Cells

Support cells in the nervous system, including glial cells.

Outer vs. Middle vs. Inner Ear

The outer ear collects sound waves, the middle ear amplifies them, and the inner ear transduces them into neural signals.

Pathophysiology of Diabetes Mellitus

Diabetes results from insufficient insulin production or cellular insensitivity to insulin.

Processes of an Action Potential

An action potential involves depolarization, repolarization, and hyperpolarization phases.

Rods vs. Cones

Rods are photoreceptors sensitive to low light; cones are responsible for color vision.

Signal Transduction Pathways

Complex biochemical routes that convert external signals to cellular responses.

Simple Endocrine and Neural Reflex

Endocrine reflexes involve hormones; neural reflexes involve direct neural connections.

Spinal Reflex Arc

A neural pathway that controls reflex actions.

Structure of Hormones

Hormones can be classified into peptide, steroid, and amine categories based on their chemical structure.