1. 6.6 – Hormones, homeostasis and reproduction

2. Homeostasis Keeping the body within certain physiological limits
pH, CO2 and glucose concentrations of blood, water balance, and body temperature
Much energy in your body is used to maintain homeostasis
Negative feedback mechanisms – work like a thermostat
a. If certain limit is reached, triggers a response to bring body back within normal range
Nervous and endocrine systems work together to maintain
a. Autonomic nervous system triggers glands to release hormones which travel through blood to target cells

4. Hormones and their functions
A. Thyroxin – amino acid and iodine Thyroid – butterfly shaped gland in neck
2. 2 forms – T3 and T4 (# of iodines)
3. Target cells – most all in body
4. Transcription regulator (stimulates)
5. Increases metabolism in cell -> requires more energy -> requires more O2
6. Also helps regulate body temp (increased activity increases temp)

5. Leptin Produced by adipose tissue More fat -> more leptin produced
Target cells = hypothalamus
Function is to decrease appetite (since there is enough supply in reserves)
Obesity – desensitized to leptin, tend to have higher levels, but does not suppress appetite

6. Melatonin Produced by pineal gland in brain
Regulates circadian rhythms
Produced mostly at night
Production disrupted by exposure to light at irregular times

7. III. Diabetes A. Insulin – produced by beta cells in pancreas – decreases blood sugar 1. Opens protein channels on cell membranes so that glucose goes into the cell (and out of the blood) 2. Stimulates hepatocytes (liver cells) to convert glucose to glycogen B. Glucagon produced by alpha cells in pancreas – increases blood sugar 1. Stimulates liver to break down glycogen into glucose

9. Hyperglycemia (high blood sugar)
Type I – beta cells don’t produce enough insulin, a. Genetic, auto-immune, unknown
b. Controlled with insulin injections
Type II – body cell receptors don’t respond to insulin (insulin-resistance)
a. Genetic, over-consumption of sugar, obesity
b. Treated with diet and various medications

10. Effects
1. Blindness
2. Kidney failure
3. Nerve damage
4. High risk of cardiovascular disease
5. Poor wound healing