Homeostasis

Definition

• Homeostasis: The process of maintaining a stable internal environment in the body.

Components of Homeostasis

1. Receptor: Detects changes in the internal environment.
2. Control Center: Receives information from receptors and sends out signals.
3. Effector: Carries out the response to bring the condition back to homeostasis.

Homeostasis Mechanism

• Variable: A condition that can be changed or regulated (e.g., temperature).
• Set Point: Ideal normal values for variables.
• Deviation: Any change away from the set point.
• Imbalance: When a variable is no longer in homeostasis.

Process of Homeostasis

1. Stimulus: Produces a change in the variable.
2. Receptor: Detects the change.
3. Information Transfer: Receptor sends information to the control center.
4. Control Center Response: Sends signals to activate an effector.
5. Effector Response: Counters the imbalance to return the variable to homeostasis.

Feedback Mechanisms

Negative Feedback Mechanism

• Purpose: Opposes deviation from the set point.
• Commonality: Most common regulation mechanism.
• Example (Body Temperature):
  • Set Point: 98.6 degrees Fahrenheit.
  • Rise in Temperature:
    • Receptors detect increase.
    • Information sent to the hypothalamus.
    • Hypothalamus activates sweat glands.
    • Sweating lowers body temperature.
  • Decrease in Temperature:
    • Receptors detect decrease.
    • Information sent to the hypothalamus.
    • Hypothalamus activates skeletal muscles.
    • Shivering warms the body.

Positive Feedback Mechanism

• Purpose: Amplifies deviation from the set point.
• Commonality: Rare regulatory mechanism.
• Example (Childbirth):
  • Baby's head pushes against the cervix.
  • Nerve impulses sent to the brain.
  • Brain stimulates pituitary gland to release oxytocin.
  • Oxytocin carried to the uterus.
  • Uterus contracts harder, pushing baby.