Endocrine System

CATEGORY:

•Biology

DEFINITION:

•Control system of ductless glands that secrete hormones within specific organs

-Hormones act as messengers...carried by the bloodstream to different cells in the body, which interpret the messages and act on them

FUNCTION:

•Provides electrochemical connection from hypothalamus of the brain to all the organs that control metabolism, growth & development, and reproduction

-Hormones provide ability to maintain homeostasis and respond to stimuli

—For Hormone functions and associated Glands...see Spreadsheet

ACTION:

•Two types of hormones: Steroidal (lipid based) and Non-Steroidal (protein based)

•Negative feedback...Increases in hormone activity decreases production of that hormone

-Immune System and other factors contribute as control factors maintaining constant levels of hormones

FACTS:

•Hormones chemically classified as...

-Amino Acid derived...modified Amino Acids

-Polypeptide and Proteins...chains of Amino Acids (some Protein Hormones are Glycoproteins, containing Glucose or other Carbohydrate groups)

-Steroids...Lipids synthesized from Cholesterol (characterised by four interlocking carbohydrate rings)

-Eicosanoids...Lipids synthesized from Fatty Acid chains of phospholipids

•Hormones activate target depending on chemical nature of the hormone...

-Lipid-Soluble (Steroid and Hormones of Thyroid Gland) diffuse through cell membranes of target cells...then binds to a receptor protein that activates a DNA segment turning on specific genes

-Water-Soluble (Polypeptide, Protein, most Amino Acid Hormones) bind to a receptor protein on the plasma membrane of the cell. The receptor protein stimulates production of a second messenger

MANIPULATION:

•Hormones are released by different stimuli...

-Hormones from other Endocrine Gland

-Blood chemical characteristics

-Neural stimulation

DIETING:

•Well chosen Macro Nutrient intake and lifestyle choices are the best way the functionality of the Endocrine System can be controlled and primed to function optimally

RELATED TO:

•Hormones

•Digestive System

NOTES:

GLANDS:-

•Hypothalamus...

-Controls the glandular secretion of the Pituitary Gland

-Receives nervous stimuli from receptors throughout the body and monitors chemical and physical characteristics of the blood, including temperature, blood pressure, and nutrient, hormone, and water content

-When deviations in Homeostasis occurs, the Hypothalamus stimulates cellular activity in various parts of the body by directing the release of hormones from the Anterior and Posterior Pituitary glands

-Master Gland as is the main place for everything that happens within the Endocrine System

•Pituitary Gland (Hypophysis)...

-Attached to the bottom of the hypothalamus

-Subdivided into Anterior (adenohypophysis) and Posterior (neurohypophysis)...Anterior Pituitary sends hormones that control all other hormones of the body

-Anterior stimulates other endocrine glands to secrete their hormones...secretes...

—Thyroid-stimulating hormone (TSH)

—Growth hormone (GH)

—Endorphins

—Other hormones

-Posterior is a projection of the hypothalamus and does not produce its own hormones, but stores and releases oxytocin and antidiuretic hormones

•Thyroid...

-Involved in the production of the hormones T3 (Triiodothyronine) and T4 (Thyroxine) which increase metabolic activity of the body‘s cells...also regulates Calcium in the blood by shuttling excess to the bones

-Insufficient amounts of thyroxine (hypothyroidism) stems from a reduction in the rate of oxidative energy-releasing reactions within body cells...resulting in...

—Puffy skin

—Sluggishness

—Lowered vitality

—Weight gain

—Decreased libido

—Inability to tolerate cold

—Muscle pain and spasm

—Brittle nails

-Too much Thyroxine (hyperthyroidism) leads to...

—Abnormally high body temperature

—Profuse sweating

—High blood pressure

—Loss of weight

—Irritability

—Insomnia

—Muscular pain and weakness

-The Production of T3 and T4 are regulated by Thyroid Stimulating Hormone (TSH) released by the pituitary gland

—TSH production is increased when T3 and T4 levels are too low...thyroid hormones are released throughout the body to direct the body's metabolism, stimulating all cells within the body to work at a better metabolic rate

—Release increased under certain situations such as cold temperatures when a higher metabolism is needed to generate heat

-Thyroid Hormone cannot be produced without an abundant source of iodine...from Protein and some vegetables

•Parathyroid...

-Four Parathyroid glands

-Secretes Parathyroid Hormone (PTH) to regulate Calcium

•Adrenal Glands...

-Regulates many essential functions, including biochemical balances that influence athletic training and general stress response

-Glucocorticoids (corticosterone, cortisone, and Cortisol) stimulate the conversion of Amino Acids into Carbohydrates (Gluconeogenesis) and formation of Glycogen by the liver...also stimulate the formation of reserve Glycogen in the tissues (such as in the muscles)

—Glucocorticoids participate in lipid and protein metabolism

-Produce chemicals Adrenalin (Epinephrine), Norepinephrine and Dopamine

-Produces the Mineral Corticoid Aldosterone signalling the kidney to reabsorb Sodium while secreting or eliminating potassium...together with Insulin and Glucagon the ionic environment of internal fluid is regulated

-Epinephrine and Norepinephrine produce the "fight or flight" response (SNS), increasing heart rate, breathing rate, blood flow to most skeletal muscles, and concentration of Glucose in the blood...decreasing blood flow to digestive organs and diminish most digestive processes

•Pancreas...

-Important organ of the Digestive and Circulatory systems in maintaining our Blood Sugar levels

-Produces digestive enzymes released into the small intestine to aid in reducing food particles to basic elements to be absorbed by the intestine and used by the body

-Forms Insulin, Glucagon and other hormones to be sent into the Bloodstream to regulate Blood Sugar levels and other activities throughout the body

•Sex Organs...

-Testes (male) and ovaries (female) produce and secrete hormones that are balanced by the Hypothalamus and Pituitary glands

-Primary hormone productions are...

—Male = Testosterone 

—Female = Oestrogen

•Pineal Gland...

-Small endocrine gland in the brain

-Primary hormone produced and secreted is Melatonin

—Secretion is highest at night and between the ages of 0-5

—Melatonin acts mainly on the Gonads