1. Homeostasis and Body Systems
Biology

2. Role of the Nervous System
The nervous system is very important in maintaining homeostasis within our bodies.
The nervous system regulates:
Automatic Responses
Ex = shivering when cold
Voluntary Responses
Ex = putting on a sweater

3. The Brain is the Nervous System Control Center
Different parts of the brain control different nervous
system responses:
Receive and transmit information
Regulate physiological processes like
water balance
body temperature
hunger
sleep

4. The Brain also helps to regulate the Endocrine System
The Endocrine System is made of glands and
cells that produce and release chemical
messages in the form of HORMONES.
Hormones stimulate processes that help
maintain homeostasis.

5. Hormones Transported in Blood
Hormones are chemicals
Control balance of sugar absorption by cells, water balance in body, and much more
Moved within blood stream past every part of body
Recognized only by “Target Cells” with special receptor proteins that can interact with the hormones (like a lock & key)

6. Example of Hormone Function
Dehydration:
Sensor cells in brain detect water shortage because body has higher sodium concentration when water concentration is low .
Brain cells signal for production and release of hormones (ex. Vasopressin) which are carried in the blood throughout the body 

7. Example of Hormone Function cont…
Target cells that have certain receptors for this hormone (kidney cells) receive hormone message.
Message signals cell membranes of kidney tubule cells to become more permeable to water.
More water is reabsorbed by circulatory system and kept within body.
Prevents excess water from being released in urine and restores the water balance.

8. Feedback Systems
Groups of body systems that work together to maintain homeostasis in the body.
Regulates body responses to changing conditions outside and inside the body.
Can be POSITIVE or NEGATIVE

9. Negative Feedback Body detects change
Body systems attempt to correct the abnormal situation
Real-World Examples:
Body System Examples:
-Thermostat
-Body temperature maintenance
-Driving in traffic
-Blood pressure regulation

10. Positive Feedback Example

11. -Contractions during childbirth
Positive Feedback
Quick response that amplifies the change (instead of “correcting it” in negative feedback)
Real-World Examples:
Body System Examples:
- Dominos
-Blood clotting
-Crowd cheering/
clapping
-Contractions during childbirth

12. The End