LO: Define homeostasis and describe the homeostatic control of temperature

Homeostasis

• Self-regulating process by which biological systems maintain stability while adjusting to changing external condition
• Receptor sensing
• Afferent pathways
• Central processing
• Efferent pathways
• Output response
• Positive and negative feedback
• Traditional set point theory
• Contemporary integration

Temperature sensing

• Thermoreceptors
• Transient receptor potential (TRP) channels within CNS, preoptic anterior hypothal - warm sensitive, and periphery, skin - cold sensitive
  TRP channels - ion channels that let positive ions flow
• Phasic - respond to changing temperature

Temperature pathway

• Spinothalamic tract
• Three neuron chain
• Cold signal - A$\delta$ fibers
• Warm signal - C fibers
• Synapse at point of entry, immediate decussation

Thermo-effectors

• Hypothal co-ordinates appropriate response
• Preventive effectors
• Corrective effectors

LO: Describe the pathophysiology of fever

Altered regulation

• Non-thermal factors in temperature control - modulation
• Altered onset thresholds or gain/magnitude of response