Bio.1.2.1
Explain how homeostasis is maintained in the cell and within
an organism in various environments (including temperature
and pH).
an organism in various environments (including temperature
and pH).
What is homeostasis?
Homeostasis is the process of maintaining stable conditions inside of a cell or in an organism. Homeostasis consists of keeping sugar, salt, nutrients and other substances within a certain and safe range. Levels inside of the cell, or the entire organism, must constantly be adjusting because of changes in conditions inside and outside of the cell. By moving different substances in and out of a cell, it is able to maintain homeostasis. A cell or organism MUST maintain homeostasis to stay alive.
Plasma membrane
The plasma membrane is a phospholipid bilayer that protects the cell. It also regulated what enters and exits the cell. It regulates what can enter and what is allowed to leave like a bouncer at a club, or security at a concert.
Homeostasis within a cell
Homeostasis within a cell is maintained by the transport of substances into and out of the cell. Here's examples of how they are moved.
Cell Transport
Cell transport assists with homeostasis by keeping conditions within normal ranges inside of cells. Passive transport and active transport are used to maintain homeostasis.
Active Transport-
Active transport is when the cell has to use energy to move the substance across the plasma membrane. Energy is needed because the substance would be moving from a lower concentration to a higher concentration. Imagine walking up a hill- that takes much more energy than sledding down it. ATP (Adenosine Triphosphate) is the molecule that provides the energy needed. A Sodium-Potassium Pump is an example of active transport.
Vesicular Transport-
Vesicular Transport is also known as cytosis. Vesicles are small sacks that are made up of phospholipids. This tiny sac transports things into and out of the cell. It is also a kind of active transport because it requires energy. When the vesicles are transporting substances outside of the cell it is called exocytosis because the substance is exiting the cell. Endocytosis is the exact opposite. It instead allows substances to be brought into the cell. There are also different types of endocytosis such as Phagocytosis, Pinocytosis, and Meditated Endocytosis.
Passive Transport
Passive transport also moves substances in and out of the cell but the difference is that it doesn't use energy. No energy is needed because the substances are moving from an area of high concentration to an area of low concentration. It's like sledding back down the hill. It can move by itself without the use of energy. There are several different types of passive transport. There are many different types of passive transport including simple diffusion, osmosis, and facilitated diffusion.
Simple Diffusion
Diffusion is the movement of substances across a membrane. It happens because of a difference in concentration and occurs without help from other molecules
Osmosis
Osmosis is the diffusion of water molecules across a membrane.
Facilitated Diffusion
Facilitated diffusion is diffusion with the help of transport proteins.
Homeostasis within an organism
Homeostasis within an organism is similar to homeostasis in a cell. Things have to be taken in and excreted. The organism used to explain the process of homeostasis that will be used will be the human body. All of the systems of the body help to maintain homeostasis. Here are a few!
Body systems and their jobs in homeostasis
- The Circulatory System- The circulatory system is a system of transportation that contains many important things. White blood cells fight infections, red blood cells transports oxygen and hydrogen, and platelets help with blood clotting. Nutrients needed and waste that have been given off by cells are carried in plasma.
- The Nervous System- The nervous system has to have a continuous flow of blood to it to function. The nervous system sends messages throughout the body. It controls many things and including consciousness, reflex actions, and fight or flight.
- The Respiratory System- This system bring in needed oxygen and excretes carbon dioxide and other gases humans don't need.
- The Digestive System- This system digests food and breaks down nutrients needed for the body to function.
- The Urinary System- This system helps to excrete substances that are no longer needed in the body and its cells such as excess water and salt.
All of these systems work together inside of the body to help humans maintain homeostasis.
Homeostasis in various environments
Temperature Control
The magic number for a healthy persons body temperature is 98.6 degrees Fahrenheit. However, this number can be changed by different outside temperatures. The human body copes with this in different ways and the method for returning to homeostasis changes based on whether or not it is changed because of rising or falling temperatures.
Rising- when the body warms superficial blood vessels dilate, sweat glands activate, and muscles do not shiver.
Falling- when the body cools superficial blood vessels constrict, sweat glands inactivate, and muscles begin to shiver.
Rising- when the body warms superficial blood vessels dilate, sweat glands activate, and muscles do not shiver.
Falling- when the body cools superficial blood vessels constrict, sweat glands inactivate, and muscles begin to shiver.
Those are some examples about how the human body is able to maintain homeostasis in heated or cooled environments. Also, humans assist the regulation of body heat by wearing clothes to compensate for the absence thick body hair.
pH Control
pH control is also very important in the human body. Too much or not enough acidity can be bad for humans. The body has certain ways of maintaining homeostasis, though, in situations like this. The normal pH level of blood is 7.4 and that is about as acidic as distilled water. In order to prevent a rise or fall in acid levels, all fluids in the body-even cytoplasm in cells-are buffered. A buffer is a chemical or a mixture of one or more chemicals that absorb either hydrogen or hydroxide ions. Hemoglobin is an example of a protein buffer in blood.
Other things such as glucose and blood pressure are also monitored and regulated to help the body maintain homeostasis. If a person is unable to maintain homeostasis they can become ill, and possibly die. Homeostasis is important in every living cell. Its important in every living organism as well.