Hormones and Homeostasis. Homeostasis Maintaining a stable internal environment despite unstable...
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Transcript of Hormones and Homeostasis. Homeostasis Maintaining a stable internal environment despite unstable...
Hormones and Homeostasis
Homeostasis Maintaining a stable internal environment
despite unstable external conditions Examples of systems with homeostasis
Blood pH Maintained around 7.4 Uses buffers
Carbon dioxide concentration Uses chemoreceptors in the walls of certain blood
vessels Blood glucose level Body temperature Water balance
Endocrine System Consists of endocrine glands that
produce hormones Hormones are put into the blood stream Only cells with special receptors will
accept the hormones Called target cells
Helps maintain homeostasis
Important Hormones Thyroxin
Produced by the thyroid gland Regulates metabolism in the cell Regulates body temperature
Leptin Produced by adipose tissue Increased fat increases leptin secretion Should decrease appetitie
Some people are leptin desensitized Melatonin
Produced by the pineal gland Regulates sleep cycles Melatonin pills can be used to help induce sleep in children and
when jet lagged from travel
Negative Feedback Loop Control of a process by the result or effect of
the process Requires
Sensors to measure the current situation A center in the brain that knows the optimum
value of the situation A way of bringing the situation to the optimum
value When this occurs the center turns off the mechanism
used to bring it to optimum Action changes things so that action is no longer needed
Negative Feedback Loop
Blood glucose regulation Done with hormones located in the islets of langerhans (in the
pancreas) Contain chemoreceptors which are sensitive to the levels of
glucose in the blood Levels rise after a meal Levels drop after exercise
If blood levels are too low The alpha cells will release glucagon Protein hormone that travels to all parts of the body but with the liver
being the target Liver cells respond by converting glycogen into glucose Will also convert amino acids to glucose
If blood levels are too high Beta cells will release insulin Protein hormone released into the blood Makes muscle cells absorb glucose Makes liver cells turn glucose into glycogen In fat tissues glucose is turned into fat
Diabetes A metabolic disorder where the person does not produce enough
insulin or the body does not properly react to insulin Type I
No insulin or an insufficient level is produced by the beta cells Caused by the bodies producing antibodies to the insulin or the beta cells Treatment
Injection of insulin Pancreas transplant
Type II Insufficient levels produced or cells of the body become less sensitive to
it Unknown causes but might be
Obesity Increase in age Family history
Treatment Reduced carbohydrate intake Increased physical activity Weight loss medication
Bozeman