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Each gland has afunction to regulatebodily functions.

The glands worktogether to keepthe body in balance

Diseases can be resultof an imbalance ordeficiency of hormone

Endocrine glands are notphysically connected but arescattered throughout the body .

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Living cells can function only within anarrow range of such conditions as

temperature, pH , ion concentrations, andnutrient availability, yet living organismsmust survive in an environment where

these and other conditions vary from hourto hour, day to day, and season to season

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The human body, for example, maintains bloodpH within the very narrow range of 7.35 to 7.45. A pH below this range is called acidosis and apH above this range is alkalosis. Eithercondition can be life-threatening. One can liveonly a few hours with a blood pH below 7.0 orabove 7.7, and a pH below 6.8 or above 8.0 isquickly fatal. Yet the body's metabolismconstantly produces a variety of acidic wasteproducts that challenge its ability to maintainpH in a safe ran

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Endocrine SystemPrimary Function: To coordinatephysiological responses to maintainhomeostasis(works with the nervous system todo this)

Physiological- changes inside thebody. Such as blood pressure,blood sugar level, heart rate

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Endocrine SystemDefinition:The bodys network of glands that producemore than 50 different known hormonesMaintain and regulate body functions, likeGrowth and DevelopmentImmunity

DigestionReproductionHomeostasis

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Nervous System Endocrine System Quick ResponseElectrical Signal

Carried by neuronsNo diffusion

Slower response, butlonger lastingChemical signal(hormones)Bloodstream to targetorgans (havereceptors)Yes diffusion (thatswhy its slower)

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Location of Endocrine GlandsA. Pineal Gland - melatonin (sexual maturity, biological

circadian rhythms)B. Pituitary Gland - FSH (sperm/egg), LH (sex

hormones)C. Thyroid Gland - thyroxine (growth/metabolism)D. Hypothalamus - ADH (water reabsorption in kidney),

oxytocin (milk release, uterine contract)

E. Thymus - thymosin (white blood cells)F. Adrenal glands- corticoids (metabolism of protein,carb and fats)

G. Pancreas - Insulin, Glucagon

H. Ovaries - estrogen/progesteronI. Testes - testosterone

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Secreting cell: a glandBlue circles: hormone

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Hormones you need to know

1. Epinephrine2. Glucagon3. Insulin4. Oxytocin5. Antidiuretic hormone (ADH)

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Epinephrine (adrenaline)

Made by gland: adrenal glandsTarget tissue: muscle, blood vesselsEffect it has: Initiates response to stress.

Increases metabolic rate, heart rate andblood pressure

dilates blood vesselsraises blood sugar

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Oxytocin

Made by gland: pituitary glandTarget tissue: Uterus, mammary glandEffect it has:

Stimulate uterine contractionRelease of milk

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ADH (antidiuretic hormone)

Made by gland: pituitary glandTarget tissue: KidneysEffect it has:

Stimulates reabsorption of water (keepswater in the body)

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Glucagon

Made by gland: pancreasTarget tissue: liver, fatty tissuesEffect it has:

raises blood sugartells liver to turn its stored glycogen into

glucose and to put it into the bloodstream

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Positive feedback.... the best example of this is

during pregnancy. When a woman goes intolabor the whole process is controlled by apositive feedback system. The uterus sensesincreased pressure and sends a message tothe brain saying "woah.... too much pressure...need to get rid of it." The brain send a message(through a hormone.. oxytocin) back to theuterus which allows it to begin contracting. Thissystem stays in effect until the pressure (baby)is expelled. In short, a positive feedback systemis one where something is sensed somewherein the body and the brain sends messgaes tothat part to increase some action.

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An example of beneficial positive feedbackis seen in childbirth, where stretching of

the uterus triggers the secretion of ahormone , oxytocin, which stimulatesuterine contractions and speeds up labor. Yet another is seen in protein digestion, where the presence of partially digestedprotein in the stomach triggers thesecretion of hydrochloric acid and pepsin,the enzyme that digests protein. Thus, oncedigestion begins, it becomes a self-accelerating process.

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Example of positive feedback1. Damage is done to a

blood vessel2. Clotting fibers accumulate

at the site of damage3. Clot formation triggers

release of chemicals

4. Chemicals stimulate theproduction of moreclotting fibers

5. Goes back to step #2

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Watch animation of bloodclotting

http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/m1/s7/trm1s7

_3.htm

http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htmhttp://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htmhttp://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htmhttp://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htmhttp://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htmhttp://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/ml/s7/trm1s7_3.htm

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QuickTime and aTIFF (Uncompressed) decompressor

are needed to see t his picture.

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Negative Feedback

1. Definition: change away from initialconditions

2. When does this happen? Corrects anabnormal situation

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Example of Negative Feedback

1. Dehydration leads to low blood pressure2. Low blood pressure detected by

baroreceptors on the heart3. Those baroreceptors send message to

brain4. The brain sends a message to both the

blood vessels and the heart5. Arteries constrict and heart rate increases6. Result: Normal blood pressure

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Feedback: Insulin andGlucagon

If sugar gets above 100 mL, the pancreasmakes insulin, which lowers blood sugar

If sugar gets below 100 mL, the pancreasmakes glucagon, which acts to raise theblood sugar

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The usual means of maintaining homeostasis is ageneral mechanism called a negative feedback loop. The body senses an internal change andactivates mechanisms that reverse, or negate, thatchange.An example of negative feedback is bodytemperature regulation. If blood temperature risestoo high, this is sensed by specialized neurons in

the hypothalamus of the brain. They signal othernerve centers, which in turn send signals to the blood vessels of the skin. As these blood vesselsdilate, more blood flows close to the body surface

and excess heat radiates from the body. If this isnot enough to cool the body back to its set point,the brain activates sweating. Evaporation of sweatfrom the skin has a strong cooling effect, as we feel

when we are sweaty and stand in front of a fan

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Body temperature also requires carefulhomeostatic control. On a spring or fall day in atemperate climate, the outdoor Fahrenheittemperature may range from the thirties orforties at night to the eighties in the afternoon(a range of perhaps 4 to 27 degrees Celsius). Inspite of this environmental fluctuation, our core body temperature is normally 37.2 to 37.6degrees Celsius (99.0 to 99.7 degreesFahrenheit) and fluctuates by only 1 degree orso over the course of 24 hours. Indeed, if core

body temperatures goes below 33 degreesCelsius (91 degrees Fahrenheit) a person islikely to die of hypothermia , and if it goesabove 42 degrees Celsius (108 degrees

Fahrenheit) death from hyperthermia is likely