1. Nervous System/ Endocrine System

2. Nervous System
Nervous system: The system of cells, tissues and organs that regulates the body's responses to internal and external stimuli
The nervous system is made up of: nervous tissue, the brain, and the spinal column
Plays a key role in maintaining internal balance

3. Nervous System The brain – control center for the nervous system
Hypothalamus- regulates water balance, body temperature, feeding, sleep and the endocrine system
Endocrine system: made up of glands and cells that release hormones into the blood

4. Endocrine System
Hormones: chemical messengers in the body. They regulate internal balances like water and blood sugar balance
Only certain target cells are able to respond to the hormone. If an organ has a receptor for that hormone than it will respond

5. Endocrine System
Receptors: proteins that fit the shape of a specific hormone molecule. They work in a lock and key fashion
Dehydration example:
hypothalamus detects that the body is short of water (concentration of sodium increases)

6. Endocrine System
Hypothalamus signals the pituitary gland to release vasopressin (a type of hormone) into the bloodstream.
Vasopressin binds to the receptors in the kidney
Vasopressin causes the tubules in kidneys to become more permeable to water

7. Nervous System
Remember: reabsorbing water and losing less in the urine prevents the body from going into dehydration.
Feedback- Body automatically sensing changing conditions

8. Nervous System Feedback is important for maintaining internal balance
Feedback can cause the body to counteract the initial condition or enhance them.

9. Nervous System
Negative feedback: body reacts to internal conditions that need to change by trying to change the balance away from them.
Ex: dehydration, blood pressure
Blood pressure: nervous system sensors in neck detect change. Signal is sent to brain. Brain responds by increasing heart rate. Increased heart rate increases blood pressure.

10. Nervous System
The brain also signals blood vessels to constrict which also increase blood pressure.
Positive feedback: adjusts internal conditions toward the initial. Ex: being cut

11. Review:
Nervous system: fast acting responses such as thirst hunger
Endocrine: slower and longer lasting responses such as secretion of vasopressin

12. Nervous system has two types of cells:
Neurons: produce and send nerve impulses
Glial – protects, supports, and insulates neurons