Unifying Themes: Homeostasis

All About YouTeacher Education Course

2013-2014

Introducing Michel Siffre!Imagine how your body

would respond if you lived in a camp in an underground cave.

How would you know when to go to sleep without the normal cues of night and day?

Responding to Stimuli For each stimulus, give the expected response:

Why do you think we respond to these stimuli?

Stimuli

You prick your finger with a pin

Waiting for a bus in the winter

Waiting for a bus in the summer

Touch a hot iron

Hear a fire alarm in the same room

Responses

Pull your finger away

Shiver

Sweat

Pull your hand away

Cover your ears

Responding to StimuliLet’s focus on two

examples:• Waiting for a bus in the

winter • Waiting for a bus in the

summer

Why does our body react the way it does?• We need to maintain

homeostasis, or a state of internal balance

Positive Feedback MechanismOur bodies respond to a

stimulus by increasing a process until homeostasis is reached

Example: healing a cut

Negative Feedback Mechanism Our bodies respond to a stimulus by decreasing a process in order

to maintain homeostasis Example: blood sugar levels

Biological Clock and Circadian Rhythm

Circadian rhythm controls sleep Our circadian rhythm controls

many things in our bodies such as • body temperature• hormone secretion• blood pressure• sleep cycles

Although scientists still debate the function of sleep, it is an activity characterized by four main things:• a reduction in physical activity• display a typical body position. In

humans, we usually lay down and close our eyes

• lowered response to external stimuli• easily reverse the state of sleeping to

waking

Suprachiasmatic nuclei (SCN)

Circadian and Homeostatic Drive to SleepThe homeostatic drive to

sleep is independent from the circadian drive to sleep because it is no longer affected by light, it is affected by the history of our sleep

Sleep is important! “Just as nutritional status,

ambient temperature, level of stress, blood oxygenation, and other variables clearly affect the ability to learn, adequate sleep is vital for optimal performance in learning tasks.” –

Jerome M. Siegel of the UCLA Department of Psychiatry and Brain Research and the Center for Sleep Research

The University of Chicago conducted a study of volunteer students who only received four to six hours of sleep a night • The students developed

higher blood pressure and higher levels of stress hormone

• The students also showed some level of slowed metabolism and insulin resistance, which can lead to type 2 diabetes

Activity, Part 1

Are You a Lark or an Owl? Questionnaire ScoresDefinite evening

Moderate evening Intermediate Moderate

morningDefinite morning

16-30 31-41 42-58 59-69 70-86

Activity, Part 2Sleep Journal

Sleep Journal and Sleep Chart Practice

Day Date Activity one hour before bed Time to bed Time

awake

Duration of disruption from sleep

Total time sleeping

How did you feel

when you woke up?

 Sunday

 9/23/12

 Watching T.V.

 11:30 pm

 2:30 am

 10 min

 6 hours and 20 minutes

 Groggy

 2:40 am

 6:00 am

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Wrap UpHow do your sleep patterns demonstrate that

your body is maintaining homeostasis?

Do you think sleep is a positive feedback mechanism or a negative feedback mechanism? Why?