Unit 1: Homeostasis, Feedback Control, & Roles of Body Systems

Action Potential

The rapid rise and subsequent fall in membrane potential across a nerve cell membrane, generating a nerve impulse

Antagonistically

Acting in opposition; for example, two muscles that have opposite effects on a joint

Autonomic Nervous System

The part of the nervous system responsible for involuntary functions, including heart rate, digestion, and respiration

Carbonic Acid

A weak acid formed when carbon dioxide dissolves in water (H2CO3)

Cell Specialization

The process by which cells become specialized in structure and function during development

Control Mechanisms

Processes that regulate physiological variables within a narrow range

Effector

A muscle, gland, or organ that responds to signals from the control center to restore homeostasis

Endocrine System

The system of glands that secrete hormones into the bloodstream to regulate various bodily functions

Enzymes

Biological catalysts that speed up chemical reactions in cells

Equilibrium

A state of balance where there is no net change

EvoDevo (evolutionary developmental biology)

The field of biology that compares the developmental processes of different organisms to infer the ancestral relationships between them and to understand how developmental processes evolve

Extracellular (interstitial) fluid

The fluid that surrounds cells in the body

Gaia Hypothesis

The hypothesis that the Earth and its biological systems behave as a self-regulating entity

Gene Expression

The process by which information from a gene is used in the synthesis of a functional gene product (protein or RNA)

Homeostasis

The maintenance of a stable internal environment in the body.

Hormones

Chemical messengers produced by endocrine glands and transported in the bloodstream

Intracellular fluid

The fluid within cells

Negative Feedback Loop

A control mechanism in which the response counteracts the initial stimulus, restoring homeostasis

Nervous System

The system of nerves and nerve tissue that controls and coordinates bodily activities

Organ System

A group of organs that work together to perform a specific function

Oxytocin

A hormone that stimulates uterine contractions during childbirth and milk ejection during breastfeeding

pH

A measure of the acidity or alkalinity of a solution

Positive Feedback Loop

A control mechanism in which the response amplifies the initial stimulus

Protozoans (protists)

Single-celled eukaryotic organisms

Receptors

Structures on cells that bind to specific molecules, such as hormones or neurotransmitters

Set Point

The ideal or normal value for a physiological variable

Sodium-Potassium Pump

A protein in the cell membrane that actively transports sodium ions out of the cell and potassium ions into the cell

Stem Cells

Undifferentiated cells that can differentiate into various specialized cell types

Transposable Elements (jumping genes)

DNA sequences that can change their position within the genome