Properties of Water, Homeostasis, and Human Body Systems

Comprehensive vocabulary flashcards covering the chemical properties of water, homeostasis, feedback mechanisms, neuron physiology, circulatory and respiratory systems, transport across cell membranes, and human excretory and digestive systems.

Sweat

A salty liquid produced by glands in the skin that helps regulate body temperature, composed of water, salt, urea, ammonia, fats, and other trace molecules such as ions.

Atom

A tiny, mostly empty basic unit of matter consisting of a positively charged nucleus (protons and neutrons) surrounded by negatively charged electrons.

Molecule

The smallest unit of a substance that retains its chemical and physical properties, formed by two or more atoms held together by chemical bonds.

Covalent Bond

A strong chemical bond formed by the sharing of electrons between atoms.

Polar Molecule

A molecule with an unequal distribution of electrons, resulting in one side carrying a slight positive charge and the opposite side carrying a slight negative charge.

Hydrogen Bond

A weak bond that forms between the negatively charged oxygen atom and the positively charged hydrogen atom of different water molecules.

Cohesion

The property of water molecules sticking to and pulling other water molecules with them via hydrogen bonds, which also generates surface tension.

Adhesion

The property of water molecules sticking to other polar or charged surfaces, such as glass, plant tissues, or fabrics.

Unusual Density of Water

The characteristic property wherein solid water (ice) is less dense than liquid water, allowing ice to float and preventing aquatic bodies from freezing solid from the bottom up.

High Specific Heat

The capacity of water to absorb a substantial amount of heat energy and retain that heat for an extended period without a drastic change in temperature.

Evaporative Cooling

The cooling process that occurs when liquid water absorbs large amounts of heat and transitions into a gas, carrying heat away from the body or surface.

Homeostasis

Any self-regulating biological process by which an organism tends to maintain internal stability and balance despite changes in the external environment.

Negative Feedback

A regulatory mechanism that decreases or negates a stimulus to return the body to homeostasis, such as sweating when hot or shivering when cold.

Positive Feedback

A regulatory process that amplifies or increases an initial signal or response, such as uterine contractions stimulated by oxytocin during childbirth.

Stimulus

A detectable change in the internal or external environment that triggers a signal sent to the brain for processing.

Neuron

A specialized cell of the nervous system consisting of a cell body, dendrites, an axon, and synapses, responsible for conducting electrical and chemical signals.

Dendrite

The branch-like extension of a neuron that receives and gathers information and impulses from other cells.

Axon

The elongated projection of a neuron that conducts nerve impulses away from the cell body toward other cells or effectors.

Synapse

The microscopic junction between two neurons across which signals are transmitted via chemical messengers called neurotransmitters.

Central Nervous System (CNS)

The core division of the nervous system composed of the brain and spinal cord, responsible for processing incoming information and initiating responses.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of nerves and supporting cells that collect sensory data and transmit signals between the body and the CNS.

Botulinum Toxin (Botox)

A potent neurotoxin produced by the bacterium Clostridium botulinum that paralyzes muscles by blocking signal transmission across synapses between neurons and muscle cells.

Artery

A muscular blood vessel that transports oxygen-rich blood away from the heart to the tissues of the body.

Vein

A blood vessel that carries oxygen-poor and carbon dioxide-rich ($CO_2$) blood back toward the heart.

Capillary

An extremely narrow, microscopic blood vessel connecting arteries and veins where the exchange of gases, nutrients, and waste products occurs.

Alveoli

Tiny air sacs in the lungs surrounded by capillary networks where nonpolar gas exchange ($O_2$ and $CO_2$) takes place by diffusion.

Diffusion

The passive movement of particles from an area of higher concentration to an area of lower concentration, requiring no energy expenditure.

Osmosis

The diffusion of water molecules across a selectively or semi-permeable membrane.

Semi-permeable Membrane

A biological barrier that allows certain substances to pass through while preventing the passage of others based on size, charge, or polarity.

Facilitated Diffusion

The passive movement of large, polar molecules or charged ions across a cell membrane with the assistance of membrane transport proteins, requiring no cellular energy.

Hypertonic Solution

A solution that has a higher concentration of solutes and a lower concentration of water relative to the cell, causing the cell to lose water and shrink.

Hypotonic Solution

A solution that has a lower concentration of solutes and a higher concentration of water relative to the cell, causing the cell to absorb water, swell, and potentially burst.

Isotonic Solution

A solution in which the concentrations of solute and water are equal on both sides of the cell membrane, resulting in no net movement of water.

Plasmolysis

The shrinkage of a cell caused by the osmotic loss of water when placed in a hypertonic environment.

Cytolysis

The bursting of an animal cell caused by excessive intake of water when placed in a hypotonic environment.

Kidney

An excretory organ that filters metabolic wastes from the blood to produce urine and helps maintain water and salt homeostasis.

Ureter

A tube of the excretory system that transports urine from the kidney to the urinary bladder.

Urinary Bladder

A hollow excretory organ that stores urine before it is excreted from the body.

Urethra

The canal through which urine is discharged from the urinary bladder to the exterior of the body.

Ingestion

The initial phase of the digestive process involving the intake of food into the mouth.

Digestion

The mechanical and chemical breakdown of macromolecules and complex foods into smaller molecules and monomers suitable for absorption.

Absorption (Digestive)

The process by which broken-down nutrient molecules cross into body cells and enter the circulatory system for distribution.

Elimination

The final stage of the digestive tract in which undigested and unabsorbed food materials are expelled from the body as waste.