REGULATION Part II CHEMICAL REGULATION The Endocrine System

REGULATION Part II CHEMICAL REGULATION (The Endocrine System)

Regulation - includes the processes by which organisms respond to stimuli within & around them. It results in the coordination and control of life processes. Regulation is achieved by the integration of the NERVOUS SYSTEM & the ENDOCRINE SYSTEM

I. SIMILARITIES between Nervous & Endocrine Systems (Chemical vs. Nervous Regulation) A. both maintain homeostasis B. both secrete chemicals- such as: Nervous System Secretes neurotransmitters Endocrine System Secretes hormones

II. DIFFERENCES between Nervous & Endocrine Systems A. Endocrine System response last longer B. Nervous System response is faster C. Nervous System impulses travel via neurons D. Endocrine System hormones travel via bloodstream

1. Associated with organs and tissues of the body that collectively release substances known as hormones. 2. Known also as ductless glands because their secretions are released directly into the bloodstream. B. Glands- organs specialized for secretion 1. Exocrine glands- discharge secretions into ducts such as digestive tract glands ex. liver, pancreas, salivary, sweat

2. Endocrine glands- "ductless glands" discharge into bloodstream ex. ) Pituitary, thyroid, thymus, pancreas, parathyroid, adrenal glands C. Hormones “chemical messengers” secretions produced by the endocrine system that target specific tissue There are two types 1. Protein-type hormones [ex. insulin, thyomisin] 2. Steroid-type hormones [produced by the adrenals] a. Anabolic Steroids- synthetic version of male hormone testosterone which lead to increased muscle bulk & strength in both males and females. Side effects are: acne, head aches, sterility, stimulated growth, cancer & death.

REGULATION of HORMONE 1. POSITIVE FEEDBACK reinforces original change [ex. poison ivy- first you get a rash, then you scratch. . . then you have a larger rash, then you scratch more. . stop scratching]

2. NEGATIVE FEEDBACK "self-regulation" 1. Mechanism by which hormone secretions are regulated (works like a thermostat) 2. One hormone in the blood stimulates or inhibits the production of another hormone 3. Opposes original change ex. )[Estrogen & FSH] + [Thyroid Stimulating Hormone (TSH) & thyroxin] +[Testosterone and Feedback inhibition]

Negative feedback loops have been compared to a thermostatically controlled temperature in a house, where the internal temperature is monitored by a temperature-sensitive gauge in thermostat. If it is cold outside, eventually the internal temperature of the house drops, as cold air seeps in through the walls. When the temperature drops below the point at which thermostat is set, thermostat turns on the furnace. As the temperature within the house rises, thermostat again senses this change and turns off the furnace when the internal temperature reaches the pre-set point.

When you eat carbohydrates that include sugars (low density), white flour, grains - all types, fruits and vegetables, your body converts these to glucose that goes into your blood stream. The hypothalamus gland senses a rise in blood sugar and sends hormones to your pancreas to release insulin from the beta cells (islets of langerham cells). Each cell in your body contains insulin receptor sites. These receptor sites act like a lock on a door to the cell. When insulin gets to the cell, it acts like a key to open the cell door and allow glucose to enter the cell. The glucose goes into the mitochondria where it goes through a Krebs cycle that produces 2 units of energy for each 1 unit of pyruvic acid that was formed from the glucose. This is how you get energy from the glucose.

Now, when the glucose level in the blood is adequate, the hypothalamus senses this and to stabilize the blood sugar, it sends a hormone to the pancreas to produce glucagon. The glucagon is sent to the liver where the glucose is now converted to glycogen and stored in the liver. If too much sugar is eaten too quickly, the liver sends the glycogen to other parts of the body. This overload of sugar does two other primary things, it causes the insulin receptor sites to become fatigued because they start rejecting the insulin and this is where diabetes type II insulin resistance can happen. The next thing is the excess glucagon being produced drops the blood sugar to a low point, and this triggers the body to think it is in a major stress mode. This triggers the adrenal glands to fire and produce CORTISOL, the stress hormone.

When you don’t get enough iodine your thyroid doesn’t work correctly. This is what can happen:

IV. The Human Endocrine System A. Hypothalamus -controls body temperature, blood pressure, sleep & emotions 1. Produces secretions that stimulates the pituitary B. Pituitary Gland-"master gland" 1. Secretes hormones that control the activity of other endocrine glands and regulate various biological processes. The pituitary gland is influenced both neurally and hormonally by the hypothalamus.

2. Pituitary Secretions include: 1. growth hormone GH (stimulates cellular activity in bone, cartilage, and other structural tissue) disorders for GH include giantism (hypersecretion) & dwarfism (hyposecretion) 2. thyroid stimulating hormone TSH (causes the thyroid to release thyroxin) 3. follicle stimulating hormone FSH (stimulates activity in the ovaries & testes) 4. lutenizing hormone LH (causes the release of egg cells from ovaries & controls sex hormones in males + females) 5. antidiuretic hormone ADH vasopressin (which causes the nephrons of the kidney to excrete less water in the urine) ALCOHOL STOPS THE RELEASE OF ADH; therefore, IT CONTRIBUTES TO A HANGOVER

C. Thyroid Gland produces thyroxin that is made of iodine 1. located in the neck 2. thyroxin regulates the rate of metabolism D. Parathyroid Glands produces parathormone, located within the thyroid 1. parathormone controls metabolism of calcium which is necessary for growth, health of bones & teeth, *BLOOD CLOTTING*, nerve functions + muscle contraction

E. Adrenal Glands - secrete adrenaline causes "Flight or Fight" action adrenaline causes blood vessels to constrict, heartbeat, blood pressure, clotting adrenaline also increases rate of metabolism and release of glucose by liver [example: slows flow of digestive juices] F. Pancreas- ISLETS of LANGERHANS (cells found within pancreas) -is both exocrine & endocrine gland secrete hormones such as glucagon & insulin

Insulincauses absorption of sugar into body cells which results in lowering blood sugar levels. The cells of the body need glucose as a source of energy. This sugar simply doesn't pass into the body cells. INSULIN MUST BE PRESENT. Also, insulin turns glucose into glycogen for storage of energy. Glucagon- cause discharge of sugar from liver into blood which results in raising blood sugar levels glycogen into glucose. (opposite of insulin)

G. Gonads- sex glands (two each) 1. in females OVARIES secrete many hormones one is estrogen which causes development of female REPRODUCTIVE system & sex characteristics 2. TESTES in males secrete testosterone which causes development of male sex characteristics

V. Disorders of the Endocrine System A. Goiter - enlargement of the thyroid gland usually resulting from the gland’s inability to make thyroxin. It is associated with iodine deficiency in diet. B. Diabetic Mellitus -(form of diabetic coma)disorder characterized by an INSULIN deficiency (hypoglycemia) that results in an elevated blood sugar level.

C. Diabetes Insipidus, rare disease caused by deficiency of vasopressin, one of the hormones of the posterior pituitary gland, which controls the amount of urine secreted by the kidneys. The symptoms of diabetes insipidus are marked thirst and the excretion of large quantities of urine, as much as 4 to 10 liters a day. This urine has a low specific gravity and contains no excess sugar. In many cases, injection or nasal inhalation of vasopressin controls the symptoms of the disease. D. Diabetic Shockhypersecretion of insulin. Glucose level in blood drops, leads to death, unconsciousness or convulsions.