NSFN SU 1

Page 1: Homeostasis and Homeostatic Mechanisms

• Homeostasis maintains a stable internal environment despite external changes.

  • Involves various physiological processes and mechanisms.

• Temperature regulation is vital, with mechanisms to keep body temperature within normal ranges.

• Feedback systems are critical for maintaining homeostasis:

  • Negative Feedback: Output reduces effect of stimulus (e.g., body temperature).

  • Positive Feedback: Enhances the initial stimulus (e.g., blood clotting).

• Other mechanisms involve control systems that ensure biological rhythms are maintained.

  • Involves neuroendocrine cells and hormonal responses.

Page 2: Hormonal and Neural Communication

• Different physiological processes rely on hormonal and neural mechanisms.

• Example mechanisms include:

  • Hormonal signals impacting metabolic processes.

  • Neural signals affecting immediate responses in tissues.

• Example of hormonal feedback is the regulation of insulin and glucose levels.

• Endocrine and nervous systems work together for complex homeostatic control.

Page 3: Mechanisms of Temperature Regulation

• Body temperature regulation involves:

  • Sensor (thermoreceptors) detects changes.

  • Integrator (hypothalamus) processes information.

  • Effectors (sweat glands, muscles) enact changes.

• Adaptations to temperature changes help maintain homeostasis, such as vasodilation and vasoconstriction.

Page 4: Color and Temperature

• Identification of temperature-related color changes in the body can indicate homeostatic status.

• Influences from the environment affect the body’s thermoregulation.

• Physiological responses can vary based on temperature exposure.

Page 5: Body Heat and Response Mechanisms

• The body responds to infections by altering temperature (fever).

• Hormonal responses facilitate adaptation to changing temperatures.

• Heat production can be influenced by infection and metabolic rate.

Page 6: Influences on Heart Rate and Blood Pressure

• Heart activity and blood pressure are affected by physiological changes:

  • Factors such as age, sex, exercise, and temperature influence heart rate.

  • Understanding these variations is crucial for assessing cardiovascular health.

Page 7: Respiratory Mechanisms

• Key processes in respiration include:

  • Ventilation: in and out air movement in lungs.

  • Gas Exchange: diffusion of gases in alveoli and blood vessels.

• Four components of respiration: pulmonary ventilation, alveolar gas exchange, gas transport, and systemic diffusion.

Page 8: Blood Pressure Regulation

• Blood pressure (BP) is defined as the force exerted by circulating blood against arterial walls:

  • Systolic Pressure: pressure during cardiac contraction.

  • Diastolic Pressure: pressure during relaxation phase.

• BP is critical for perfusion and overall health.

Page 9: Determinants of Blood Pressure

• BP influenced by various factors:

  • Cardiac output and peripheral vascular resistance.

  • Influenced by blood volume and viscosity.

• Normal BP parameters include systolic < 120 mm Hg and diastolic < 80 mm Hg.

Page 10: Factors Affecting Blood Pressure

• Blood pressure increases with:

  • Age and physical exertion.

  • Hormonal influences (sex differences).

• Hypertension: defined as stage 1 > 140/90 mm Hg, stage 2 > 160/100 mm Hg.