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Endocrine System

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  1. Endocrine System By: Sarah Shelby & Sierra

  2. Helpful prefixes and suffixes -crin (to secrete) dieuret-(to pass urine) endo-(within) exo-(outside) Hyper-(above) Hypo-(below) Para-(beside) Toc-(birth) Sarah

  3. Function of the System

  4. Endocrine Function • Helps regulate conditions within the body to maintain homeostasis • Secretes hormones in the body’s internal environment • Works with the nervous system so that different parts of the body can communicate with each other and adjust to changing incoming signals

  5. Exocrine Function • Secrete substances outside the body through tubes or ducts; leading to the surface

  6. Endocrine vs. Exocrine endocrine • Secrete within the body • EX: pituitary gland • Secrete to the outside of the body • EX: sweat gland exocrine

  7. Hormones Hormones are substance(s) that are secreted by endocrine glands and transported into the blood Hormones influence their target cells during stimulation A hormone alters the metabolism of the target cells *Paracrine: secretions affect only neighboring cells *Autocrine: secretions affect only secreting cell 1

  8. Control of Hormone Secretion • Hypothalamus regulates anterior pituitary gland’s release of hormones that stimulate other endocrine glands to secrete hormones. • Hypothalamus receives information about the internal environment from neural connections and cerebrospinal fluid • Nervous system stimulates glands directly • A group of glands responds directly to changes in the composition of the internal environment 2

  9. General characteristics Only target cells can respond to a hormone, they have a specific receptor that other cells lack such as proteins or glycoprotein (these can bind with a hormone) • Endocrine and nervous system “oversee” the cell- to-cell communication through chemical signals that bind receptors to molecules • Help maintain metabolic processes • Control rate of reactions • Help transport substances across membranes • Helps with water balance • Helps with electrolyte balance Endocrine glands and hormones

  10. Steroids and Nonsteroids Sierra

  11. Most hormones are steroids or steroid-like substances which are synthesized fromcholesterolaminespeptidesproteinsor glycoprotein which is synthesized from amino acids. Hormones can produce change in the target cell, even at low concentrations. Steroids are carried through the bloodstream and are weakly bound to plasma proteins, so they can be efficiently released to their target cells. 3

  12. Steroid hormones are insoluble in water but soluble in lipids • When a steroid hormone enters a target cell: • The steroid hormone diffuses through the cell membrane • Then binds to a specific protein molecule-the receptor for the hormone • The resulting hormone-receptor complex binds in the nucleus to particular regions of the target cell’s DNA and copies genes into the mRNA molecules • mRNA molecules leave the nucleus and enter cytoplasm • mRNA molecules and the ribosome direct the synthesis of specific proteins

  13. Nonsteroid hormones includeaminespeptidesand proteinswhich usually bind receptors to target cell membranes The receptors are protein molecules that have a binding and activity site Messages are sent to the target cell by joining the binding site of it’s receptor (hormones sending the message) This stimulates the receptor’s activity site to interact with other membrane proteins

  14. Nonsteroid hormones First messenger Receptor binding can alter functions of enzymes or membrane transport mechanisms, which changes concentration of other cellular components The hormone triggering this is

  15. Nonsteroid hormones Biochemicals in cells that produce changes in response to hormone building Second messenger Is called Signal transduction The process of chemical communication from the outside to the inside of the cell Is called

  16. Hormone binds to its receptor The second messenger associated with one group of hormones is cyclic adenosine monophosphate (cyclic AMP) It works like this Resulting hormone-receptor activates a G protein 4 cAMP activates protein kinases enzymes that transfer phosphate groups from ATP to their substrate molecules(specific proteins) G protein activates a membrane protein called adenylate cyclase Adenylate cyclase catalyses the circulation of ATP in cytoplasm into cAMP

  17. prostaglandins 5 • Group of biochemicals that regulate cells • Lipids from a fatty acid in cell membranes called arachidonic acid • Usually only affect the organs where they are produced • Influence movements of sodium ions and water molecules in the kidneys • Helps regulate blood pressure • Produced in many cells

  18. Negative feedback system Hormone level rises in the blood, the hormone does its effect. The negative feedback inhibits the system and the hormone secretion decreases. As the hormone level decreases, the effects of the hormone stop. When inhibition of the system is lifted, secretion of the hormone takes place once again. Negative feedback systems keeps hormone levels in the bloodstream relatively stable. 6

  19. Major endocrine glands!!!! Shelby

  20. Pituitary gland Attached to the base of the brain and has an anterior and posterior lobe. Releases hormones from the hypothalamus, which controls the secretions of the anterior lobe. Posterior lobe releases hormones into the bloodstream in response to nerve impulses from hypothalamus. 7

  21. Anterior Pituitary hormones Growth hormone(GH): stimulates body cells to grow and reproduce, and speeds up rate at which cells use carbohydrates and fats Prolactin(PRL): promotes milk production following the birth of an infant Thyroid-stimulating hormone(TSH): controls secretion of hormones from thyroid gland Thyrotropin-releasing hormone(TRH): from the hypothalamus regulates release of TSH Adrenocorticotropic hormone (ACTH): controls secretion of hormones from adrenal cortex Corticotropin-releasing hormone (CRH): regulates ACTH from the hypothalamus, stress can also increase it’s release Follicle-stimulating hormone (FSH): gonadotropins affecting male and female gonads Luteinizing hormone (LH): gonadotropins affecting male and female gonads 8

  22. Posterior Pituitary Hormones • Neurons in the hypothalamus produce antidiuretic hormone and oxytocin • ADH causes kidneys to conserve water • Hypothalamus regulates ADH secretion based on the amount of water in body fluids • Oxytocin plays a role in childbirth by contracting muscles from uterine wall, and forcing milk into ducts from milk glands • Stretching of the uterus in later stages of pregnancy stimulates the release of oxytocin 9

  23. 10 Thyroid Gland Thyroxin tetraiodothyronine Located below the larynx and consists of 2 lobes Thyroxin triiodothyronine •  These 2 increase the rate at which These hormones are essential for growth and development Hypothalamus and pituitary gland control release of these Cells release energy from carbohydrates, enhance protein synthesis, and stimulate breakdown of lipids

  24. Thyroid continued… This lowers blood levels of calcium and phosphate ions when they are too high Calcitonin increases the rate at which calcium is stored in bones and excreted by urine Extrafollicular cells of thyroid secrete calcitonin Calcitonin secretion is regulated by negative feedback involving blood concentrations of calcium

  25. 11 Parathyroid Gland Parathyroid hormone(PTH) increases blood calcium ion concentration and decreases phosphate ion concentration Located on posterior end of thyroid PTH influences kidneys to conserve calcium PTH stimulates bone reabsorption by osteoclasts, releasing calcium into blood A negative feedback mechanism involving blood calcium levels regulates release of PTH *Calcitonin and PTH exert opposite effects in regulating calcium ion levels in blood

  26. Adrenal glands Adrenal medulla: secretes epinephrine and norepinephrine into the bloodstream(used in times of “fight or flight”) Adrenal cortex: produces over 30 steroids Aldosterone: (mineralocorticoid) causes kidneys to conserve sodium ions and thus water, and excrete potassium ions Cortisol: (glucocorticoid) influences metabolism of glucose, protein, and fat in response to conditions that stress the body Adrenal sex hormones: released by the gonads and may stimulate early development of reproductive organs 12

  27. 13 Pancreas: secretes hormones as an endocrine gland, and digestive juices to digestive tract as an exocrine gland Posterior to stomach Has 2 cell types: Alpha cells: secrete glucagon -glucagon increases the blood levels of glucose by stimulating the breakdown of glycogen and conversion of noncarbohydrates into glucose Beta cells: secrete insulin -insulin decreases the blood levels of glucose by stimulating the liver to form glycogen, increasing protein synthesis, and stimulating adipose cells to store fat *insulin and glucagon coordinate to maintain a relatively stable blood glucose concentration

  28. Other Endocrine Glands Pineal gland: lies near the upper portion of the thalamus, and secretes melatonin which is involved in regulation of circadian rhythms -also linked to the onset of puberty Thymus gland: lies between lungs and sternum, secretes thymosins that affect production of T lymphocytes • ovaries produce estrogen • Placenta produces estrogen, progesterone, and gonadotropin • Testes produce testosterone Produces atrial natriuretic peptide Kidney produces erythropoietin

  29. All pictures from BingAll info from the anatomy book