Lecture 4 Flashcards
Homeostasis
Regulation of the body’s internal environment at a near stable level
Set point?
Homeostasis regulates a physiological variable relative to this
3 homeostatic mechanisms
Negative feedback
Positive feedback
Feedforward
Negative Feedback
Returns variable towards the set point, minimizes the difference between actual level and the set point (body temp regulation)
Homeotherms
Maintain a fairly stable body temp. despite swings in the environmental temp. (rabbit)
Heterotherms
Have a body temperature similar to that of their surroundings. (iguana)
Negative feedback loop
Maintains a balance between heat loss and heat gain
Cooling Physiology
Stimulated; heating physiology inhibited, e.g. increased blood flow to skin, sweating, panting
Heating Physiology
Stimulated; cooling physiology inhibited, e.g. decreased blood flow to skin, shivering, erect hair or feathers
Platyhelminthes
Flatworms
Nematoda
Roundworms
Temp increase/decrease integrated by ____
Hypothalamus
Negative Feedback - Hypothalamus Chart??
Negative Feedback - Endocrine slide 12???
Positive Feedback
Moves variable away from the set point, amplifies difference between actual level and the set point, used to quickly increase/decrease a process, amplification shut off by negative feedback
Positive Feedback - Childbirth slide 16??
Oxytocin
Contraction inducing hormone
The rising phase of the nerve action potential - slide 17??
Feedforward
Future needs are anticipated, physiology is adjusted in advance, often involves learning and complex behaviours, slide 18/19
What happens during a fever? (4)
Temporary increase in body temperature usually due to infection
Foreign bodies signal hypothalamus to increase internal temperature set point
Turns on the immune system to help fight infection (symptomatic)
Mild fever ok, high fever can be deadly
