Homeostasis August 10, 11 2015. The maintenance of relatively stable internal conditions Dynamic...
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Homeostasis August 10, 11 2015
Transcript of Homeostasis August 10, 11 2015. The maintenance of relatively stable internal conditions Dynamic...
Homeostasis
August 10, 11 2015
The maintenance of relatively stable internal conditions
Dynamic process – the body is constantly regulating to keep conditions within acceptable ranges
Homeostasis
Many variables are maintained by homeostasis.
What examples canyou think of?
Examples of Homeostasis
Many variables are maintained by homeostasis. Examples include:
Temperature Blood pH Blood sugar Water balance Blood pressure Ion balance
Examples of Homeostasis
Homeostatic Control Mechanisms
Homeostatic Control Mechanisms
AnalogiesThermostat
Cruise control
others?
What is the ...
Variable?
Stimulus?
Receptor?
Control center?
Effector?
(some may not be listed on chart)
What is the ...
Variable?
Stimulus?
Receptor?
Control center?
Effector?
Receptors aren’t shown on this picture, but there are two sets of thermoreceptors: some in the hypothalamus to measure internal temperature , and some in the skin to measure external temperature
You do: What is the ...
Variable? Stimulus? Receptor? Control center? Effector?
You do: What is the ...
Variable? Stimulus? Receptor? Control center? Effector?
Receptors aren’t shown again, but there are two types of calcium receptors scattered throughout the body
Most homeostatic mechanisms are examples of negative feedback.
In negative feedback, the output acts to change the direction of the stimulus.
Example: If the body is hot, the hypothalamus will activate the sweat glands and dilate the blood vessels (the two outputs) … both of which will act to reduce the body temperature.
Negative Feedback Mechanisms
Some processes in the body are positive feedback mechanisms.
In positive feedback, the output enhances thestimulus
Positive Feedback Mechanisms
Positive or Negative Feedback?
Blood Clotting Blood Pressure
Positive or Negative Feedback?
Blood Clotting Blood Pressure
Positive – The output (platelet adhering) increases the original stimulus (platelet-attracting chemical)
Negative– The output (decreased heart rate / increased diameter) decreases the original stimulus (high blood pressure)
Come up with examples and non-examples of negative and positive feedback.
(For non-examples, I want something that at first glance might seem like positive or negative feedback, but isn’t).
What is it that distinguishes the true examples from the non-examples?
Positive and Negative Feedback
Most disease is caused by a disturbance of homeostatic mechanisms known as homeostatic imbalance.
Homeostatic imbalance can result from Aging Genetic mutations Pathogens Environmental factors
Homeostatic Imbalance
- 10 minutes -
Congo Line review
Chapter 1 outline due next classFirst quiz Aug 14 / 17!
Homework
What are your key takeaways from our objectives?
What was our LP and how did we use it?How does what we did today relate to our
significant concept?
Closure
Study this diagram.
1) What is the stimulus?
2) What are the effectors?
3) Is this + or – feedback, and how can you tell?
Exit Ticket
Identify the body system to which each organ belongs4) Pancreas5) Liver
Ex) Which system cleans and returns body fluids to the blood stream?
Exit Ticket
