Homeostasis

An introduction

How well do you know yourself?

• It is interesting to note that though every human has a body, very few people truly understand and respect how amazing it is

• The human body is a self regulated machine, capable of responding to various external and internal stimuli, and initiating appropriate responses to these stimuli

What happens when you exercise?

• Think very carefully about something that more of us should be doing – exercising

• What happens to our bodies?

Your body in balance

• All the things you experience when you exercise are due to your body’s desire to maintain its normal functioning balance

• This is achieved by the cooperation of multiple systems

• These systems work together to sense changes and initiate responses to reverse these changes – or prevent them from worsening

• This normal balance within the body is known as HOMEOSTASIS – from the Greek “similar, still”

Call and answer

• The mechanism of homeostasis requires these basic components:

• What senses the “call” or “change”:

• What gives the “answer” or “tries to respond to the change”

Regulation of body temperature

Controlling the controls

• Homeostasis is usually regulated by feedback loops that act to prevent the initiated changes from running out of control

• The easiest way to understand a feedback loop is to study your thermostat

Your home thermostat• A change in the heat in the

house – for example a decrease, will be sensed by the thermostat

• The thermostat turns the furnace on, creating heat

Not unlike our own thermostat• Ultimately, the

hypothalamus is our thermostat

• The thermostat monitors internal body temperature and kickstarts changes to increase or decrease it

We are warm blooded• Mammals, including ourselves,

• This is very important to human health; you should understand that from your childhood – parents become very concerned when children run a fever because it can cause major problems for the body

• POIKLIOTHERMS or ECTOTHERMS

• Reptiles can be boring to watch sometimes because their excessive sunbathing is needed to keep their body temperature regulated

Positive feedback

• In some cases, a change will initiate a larger response as opposed to shutting it off

• http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter1/animation__positive_and_negative_feedback__quiz_1_.html

Thermoregulation in humans

• Short term thermoregulation in humans makes use of contracting muscles and changing blood flow

• If you think about the basic symptoms you experience when you’re hot or cold, you will get an idea of how the body is trying to dispel heat or retain it: