1.5: Homeostasis

homeostasis

maintenance of a relatively constant internal environment within the body

Body variables fluctuate around a….

set point: Ideal normal value

The body therefore maintains a normal range, not one perfectly fixed

Why is homeostasis important for proper body function

cells and body systems function properly only when internal conditions remain within acceptable ranges

3 components of a feedback loop: Receptor

monitors the value of some variable by detecting a stimulus (a change in the variable)

3 components of a feedback loop: Control center

establishes the set point and receives input from the receptor

3 components of a feedback loop: Effector

generates the response which can change the value of the variable

Negative feedback

• counteracts the original change

• its goal is to move the variable back toward the set point

• it regulates most systems in the body

• Ex. Body temp regulation

counteracts

a change in a variable (body temp) by decreasing the change to help maintain homeostasis by returning to the set point

positive feedback

• makes the original deviation/change greater

• instead of returning toward the set point, the response is amplified until the original stimulus is removed

• Ex. Childbirth, lactation, and blood clotting

• Harmful example= severe blood loss/ hemorrhaging

Metabolism

The set of life-sustaining chemical reactions in organisms

chemical reaction

process that leads to the chemical transformation of one set of chemical substances to another

catabolism

reactions that break substances down

ised to form ATP

Anabolism

Reactions that build substances up

often require ATP