homeostasis

Positive and Negative Feedback Mechanisms

• Positive Feedback

  • Characterized by a continuous reinforcement of a process.

  • Example: Human Baby Birth

    • Pressure on the cervix triggers hormone release.

    • Hormones cause contractions of the uterus.

    • Increased release of hormones leads to increased glucose for cellular respiration, which is critical for ATP production.

• Negative Feedback

  • Dominant mechanism for maintaining homeostasis.

  • Works to counteract changes to maintain stable internal conditions.

  • Examples:

    • Body Temperature Control

      • Receptors in skin detect temperature increases.

      • Messages are sent to the hypothalamus in the brain.

      • Hypothalamus signals sweat glands to produce sweat for cooling.

      • Blood vessels near the surface dilate to release heat.

    • Blood Glucose Regulation

      • High blood glucose levels trigger mechanisms to lower it.

      • Low levels trigger mechanisms to increase it.

Homeostasis

• Definition: The body's ability to maintain a stable internal environment despite fluctuations.

• Key Structures:

  • Hypothalamus: Regulates thirst, body temperature, and some hormonal responses.

  • Kidneys: Manage water balance, adjusting urine production based on hydration needs.

Examples of Homeostatic Regulation

• Labor and Delivery

  • Uterine contractions stimulate hormone release, which increases contraction intensity.

• Blood Coagulation

  • Platelets accumulate at a tear in a blood vessel, attracting more platelets to facilitate healing.

Disease and Homeostasis

• When homeostasis is disrupted, it can lead to disease states.

• Examples:

  • Diabetes: Inability to maintain blood glucose levels.

  • Body Temperature Disorders: Hypothermia or hyperthermia can be fatal.

  • Osteoporosis: Loss of calcium leading to increased fracture risk.

  • Respiratory Diseases: Impairment in oxygen absorption due to lung issues.

Disease Causes

• Pathogens: Disease-causing agents, including bacteria, viruses, fungi.

  • Common illnesses: COVID-19, hepatitis, pneumonia, malaria.

• Inherited Disorders: Genetic conditions affecting body functions.

  • Examples: Muscular dystrophy, cystic fibrosis, hemochromatosis.

• Nutritional Deficiencies: Lack of essential nutrients can lead to diseases like scurvy or rickets.

• Trauma: Internal injuries from accidents can go unnoticed but impact organ function.

• Heat-related Illnesses: Lack of hydration can lead to heat stroke, particularly in vulnerable populations like the elderly.

Key Terminology

• Iatrogenic: Disease induced by medical treatment.

• Indentulous: Lacking natural teeth.

• Dentate: Having teeth.