homeostasis. what is homeostasis? the way the body keeps its internal environment constant, in...
TRANSCRIPT
What is Homeostasis?
The way the body keeps its internal environment constant, in other words, how the body “maintains a steady state”
What internal conditions need to be maintained? Temperature Blood Glucose levels Oxygen and Carbon Dioxide levels Water levels Blood pH
Feedback Mechanisms
Feedback mechanisms are the general mechanism of nervous or hormonal regulation in animals.
Feedback occurs when the response to a stimulus has an effect of some kind ( or ) on the original stimulus. The nature of the response determines how the feedback is
'labelled'.
Negative feedback is when the response DIMINISHES the original stimulus
Positive feedback occurs when the response ENHANCES the original stimulus
Positive Feedback
Response that enhances the original stimulus
Less common of the two Most changes to our bodies “steady state” are threatening and
enhancing them is NOT helpful
Examples: During labor, a hormone called Oxytocin is released that intensifies
and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle continues until the baby is born
When a blood vessel is damaged, platelets start to cling to the injured site and release chemical that attract more platelets, where they continue to accumulate until a clot is formed
Negative Feedback
Response diminishes the original stimulus
Most common feedback loop
Examples: When blood sugar rises, receptors in the body sense a change. In
response to this, the pancreas secretes insulin into the blood, effectively lowering blood sugar levels. Once homeostasis is reached, the pancreas stops releasing insulin
Next, we are going to look at one of the bodies most important roles in keeping us alive and healthy, thermoregulation
Thermoregulation
Control of body temperature is known as thermoregulation
The normal human body temperature is 37 degrees Celsius (98.6 degrees Fahrenheit) Too much variation results in our bodies being unable to conduct
the necessary chemical reactions
Body temperature is controlled by the thermoregulatory center in the hypothalamus
Thermoregulation
A body temperature that is too low is known as HYPOTHERMIA, and can lead to death
So, how does your body try to warm you up when you get too cold? Hair’s stand on end Blood vessels near the surface receive less blood Shivering Behavioral responses
Hair stands on end so air currents do not get to the skin, traps an insulating layer of still, warm air next to skin
Blood vessels near the skin constrict (vasoconstriction) so less blood passes through them. This means less heat is lost by radiation.
hair
Bloodvessel
Thermoregulation
Thermoregulation
Shivering: Your muscles contract involuntarily,
generating heat
Behavior: Curl up, huddle, put on more clothes, drink
something warm
Thermoregulation
A body temperature that is too high is known as HYPERTHERMIA and can cause dehydration, heat stroke, and possibly death
So, how does your body try to warm you up when you get too hot? Sweating Blood vessels near the surface receive more blood Hairs lie flat Behavioral responses
Thermoregulation
Sweat is produced by sweat glands. When this evaporates, it cools the skin.
Sweat gland
Hair lies flat so air currents get to the skin. Heat is lost by convection.
Blood vessels near the skin dilate (vasodilation) so more blood passes through them. This means more heat is lost by radiation.
VasodilationHairs lie flatBody sweats
Normal body temperature is
restored
VasoconstrictionHairs stand on endBody doesn’t sweat
Shivering occurs
Normal body temperature
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