How Homeostasis Keeps Your System in Balance
Homeostasis is a key concept in biology. The concept of homeostasis is the description for when the internal conditions of living organisms remain stable (within a normal range), regardless of what is going on in the external environment. These internal conditions include your body temperature, pH level, and glucose level.
Homeostasis attempts to maintain your system in a normal range; if toxins would build up in your system, homeostasis would be disrupted, and you would become very sick.
Homeostasis and metabolism
Each cell in your body is actively involved in metabolism, which basically is the process of using nutrients from food to provide fuel for cellular processes. Metabolism is like a wood-burning stove that heats a home (your body). Food is like the logs that are thrown on the fire.
When logs burn, ash is created. Ash is the waste created from the using of energy. If the ash is not removed from the fireplace, eventually the fire can no longer burn. When food is broken down, as much of the nutrients as possible are used to fuel the body. After as much energy as possible is extracted from food through digestion and metabolism, the remainder is excreted, or removed.
Suppose that it’s really cold outside — snowing even — and you run out to your mailbox in a short-sleeve shirt. While you’re out there, a neighbor stops by to chat. Your body wants to maintain its body temperature around 98.6°F. Your skin senses the cold conditions outside, and nerve impulses are sent from receptors in your skin to your brain that say, Hey! It’s cold out here!!
In an attempt to stay around 98.6°F, your body makes adjustments automatically. Goose pimples form, which actually are the hair follicles on your body tightening to make your body hair stand up higher to help insulate your body. If that doesn’t help to maintain the normal temperature, you start to shiver. Shivering is an attempt by your body to create heat through movement.
If your chatty neighbor is still rambling on, and shivering doesn’t help keep you warm, your body’s thermostat will begin to drop (if it goes too far, hypothermia begins), and your furnace will kick on to create heat internally so that homeostasis — maintaining relatively normal values — occurs.
Homeostasis and disease
Disease occurs when homeostasis can’t be achieved. Suppose that your chatty neighbor spread the flu virus to you when he sneezed during your conversation. Your body needs to fight off the invading virus, which likes living at your normal body temperature. At 98.6°F, the virus can happily reproduce, making you sicker and sicker.
Your body wants to be in homeostasis, but if it maintained normal body temperature, the virus would take over your entire body. In defense against the virus, your body temperature rises above the normal range (fever), which makes your body an uncomfortable place for the virus to live. The virus slows down in the hotter temperature, which allows your immune system to attack it.
The fact that your body temperature goes above normal (fever) means that homeostasis is disrupted, and that indicates disease (the flu). Once your body has effectively suppressed the viral attack, the fever breaks, and your body temperature returns to normal. The disease state is over, and homeostasis returns.
Remember that fever is a natural, healthy process. If you develop a fever, let it do its job of making your body inhospitable to a virus or bacteria. Don’t quell the fever with aspirin, ibuprofen, or acetaminophen right away. If the fever continues for days, though, you should see the doctor.
A fever caused by a virus usually breaks on its own as your body fights the virus. However, an infection caused by bacteria requires an antibiotic to help your body fight. The fever associated with a bacterial infection usually is higher and lasts longer than a fever caused by a virus.

Biology Glossary
anemia
A low number of red blood cells or low level of hemoglobin; may be caused by dietary deficiencies, metabolic disorders, hereditary conditions, or damaged bone marrow.

Biology Glossary
antigen
A foreign substance in the body that causes an immune response.

Biology Glossary
body mass index
The BMI is the result of a formula that uses your weight and height to determine whether you need to lose weight.

Biology Glossary
carbohydrates
Energy-packed compounds consisting of carbon, hydrogen, and oxygen that provide quick fuel for organisms.

Biology Glossary
cellulose
A form of carbohydrate that has a structural role in living organisms (animals and plants).

Biology Glossary
centrifuge
A machine that is used to separate blood cells and platelets from plasma.

Biology Glossary
chloroplasts
Plant cells that use energy from sunlight to create food.

Biology Glossary
cytoplasm
The fluid contained within animal cells. Also called plasma.

Biology Glossary
disaccharides
Carbohydrate molecules in which 2 monosaccharide molecules are joined together. Disaccharides consist of 6 to 14 carbon atoms.

Biology Glossary
DNA
Stands for deoxyribonucleic acid. Large molecules found in all living things that carry genetic information.

Biology Glossary
electron microscope
A high-powered, expensive device that uses beams of electrons to bring the finest details of cells into focus.

Biology Glossary
endocrine system
A system of glands that secrete different types of hormones that help regulate organisms.

Biology Glossary
endoplasmic reticulum
The ER is a series of canals that connects the nucleus of animal cells to the cytoplasm outside those cells.

Biology Glossary
equilibrium
The state of a chemical reaction in which the amounts on each side of the reaction have stabilized.

Biology Glossary
eukaryotes
Organisms — including plants and animals, as well as fungi, protozoa, and most algae — with cells that contain a nucleus and chromosomes.

Biology Glossary
Golgi apparatus
A component within cells that packages and distributes hormones, enzymes, and other cell products to other organelles or outside the cell.

Biology Glossary
hemoglobin
An iron-containing molecule in red blood cells that carries oxygen around the body.

Biology Glossary
heterotrophs
Animals — including herbivores, carnivores, and omnivores — that feed on other living organisms.

Biology Glossary
homeostasis
The processes used by the body to constantly achieve and maintain balance.

Biology Glossary
integument
The skin or outer surface of an animal. Small animals such as earthworms use integumentary exchange to exchange gases with the environment.

Biology Glossary
Krebs cycle
A method of describing the steps involved in the chemical process of respiration.

Biology Glossary
lipoproteins
Compounds such as HDL and LDL that carry cholesterol through the bloodstream; made from a fat (lipid) and a protein.

Biology Glossary
lysosomes
Specialized cellular organelles formed by the Golgi apparatus that help to clean up the cell by breaking down harmful cell products and removing dead organelles.

Biology Glossary
maceration
A process, such as chewing, that physically breaks down food into pieces.

Biology Glossary
matrix
The extracellular fluid in which animal cells float.

Biology Glossary
mitochondria
An organelle in animal cells that combines food with oxygen to supply energy to cells.

Biology Glossary
monosaccharides
Carbohydrate molecules in which simple sugars consist of three to seven carbon atoms.

Biology Glossary
nuclear membrane
A two-layer structure that separates the nucleus from the cytoplasm in animal cells.

Biology Glossary
organelles
Structures that float inside the fluid of cells; used during metabolic processes.

Biology Glossary
osmosis
A mechanism that moves water and nutrients into and throughout a plant.

Biology Glossary
peristalsis
The action of food being moved down the esophagus and through the entire digestive tract.

Biology Glossary
peroxisomes
Sacs of enzymes within animal cells that help protect the cell by breaking down accumulations of toxic products such as hydrogen peroxide.

Biology Glossary
photosynthesis
The biochemical process that plants use to acquire energy from the sun.

Biology Glossary
plasma membrane
The membrane that holds fluid within animal cells. Also called the cell membrane.

Biology Glossary
polysaccharides
Carbohydrate molecules that are formed by many long chains of monosaccharides.

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prokaryotes
Organisms — such as bacteria and blue-green algae — with cells that do not contain a nucleus.

Biology Glossary
ribosomes
Components within cells that assist in making proteins from amino acids.

Biology Glossary
RNA
Stands for ribonucleic acid. In animals, works with DNA to produce proteins needed throughout the body.

Biology Glossary
ruminants
Mammals — such as cattle, sheep, and goats — that can break down and digest cellulose.