Hormones PDF

Hormones Hormones are chemical messengers that affect cellular )A metabolism. Metabolism includes:...

Hormones Hormones are chemical messengers that affect cellular )A metabolism. Metabolism includes: Protein synthesis)1 Enzyme activation)2 Changes in membrane permeability)3 Mitotic division)4 Release of enzymes, hormones, or other secretions)5 Endocrine signals are produced by endocrine cells that release )B signaling molecules, which are specific and can travel long distances through the blood to reach all parts of the body. Hormones that target other glands are known as tropins (tropic )C hormones) Types of Hormones Steroid (Lipid) hormone Protein.Steroid (lipid) Can not enter cell  Enter cells directly  activity Not lipid soluble Bind to a nuclear  Proteins are hormone receptor (NHR) large and NHR carries protein into  charged nucleus and binds to (Hydrophilic, ionic) DNA Bind to receptors  Regulates gene  Trigger second  expression messenger activity Control RNA Second messengers:  synthesis Cyclic AMP Function as (cAMP) repressors or Inositol activators TriPhosphate Protein Hormones and Second (1) Cyclic AMP (cAMP) messengers When a protein hormone binds to a receptor it activates a )1 G-protein. Second messengers are molecules that relay  G-proteins are Guanosine Nucleotide Proteins  (GTPase) that interact with GTP, forming GDP and signals from receptors on the cell surface to phosphate target molecules inside the ce l, in the The G-protein will then bind to and activate the )2 cytoplasm, or nucleus. membrane-bound enzyme adenylyl cyclase Adenylyl cyclase reacts with ATP to form cyclic AMP. )3 Since protein hormones cannot enter the cell  The cyclic AMP then goes on the activate specific )4 they must utilize these complex second proteins. messenger molecules. An important protein activated by cyclic AMP is protein )5 kinase A, which goes on the phosphorylate certain cellular proteins. Some ion channels, for example, are gated by cyclic AMP. )6  Protein hormones and second messengers (2)Inositol Tri-phosphate Cyclic AMP When a protein hormone binds to a receptor it activates )1 a G-protein. G-proteins are Guanosine Nucleotide Proteins  (GTPase) that interact with GTP, forming GDP and phosphate The G-protein will then bind to and activate the )2 membrane-bound enzyme phospholipase-C Phospholipase-C produces inositol tri-phosphate (IP3) )3 Inositol Tri-Phosphate diffuses through the cytoplasm )4 to the endoplasmic reticulum The ER releases calcium ions in response to the IP3 )5 binding. The calcium ions activate calcium-sensitive proteins in )6 Protein hormones and second messengers Human glands and hormones Inositol Triphosphate (ip3) Pituitary Gland( 1) Located at the bottom of the brain under the hypothalamus.  Contains two lobes  Anterior (front) Lobe.I Secretes the following hormones: TSH (Thyroid Stimulating Hormone): stimulates thyroid gland.i ACTH (Adreno Corticotropic Hormone): stimulates the cortex of.ii adrenal glands HGH (Human Growth Hormone): stimulates bone/muscle growth.iii LH (Luteinizing Hormone): stimulates ovulation/sperm maturation.iv FSH (Follicle Stimulating Hormone): stimulates egg/sperm.v development Prolactin: stimulates milk ejection.vi Posterior Lobe.II Secretes the following hormones: Oxytocin : labor contractions.I ADH (Anti-diuretic hormone): stimulates kidney tubules to retain.II water in the body  (2)Hypothalamus Located just above the pituitary gland Secretes releasing factors to regulate pituitary Integrates nervous and endocrine systems (3)Thyroid Located in neck Secretes three hormones: a) Thyroxine (T4): increases metabolism and cellular respiration, cell growth, differentiation b) Tr iodothyronine (T3): increases metabolism,ce lular respiration, ce l growth, differentiation c) Calcitonin: lowers blood calcium levels (absorbs calcium into bones). Thyroxine and triiodothyronine contain iodine Iodine is essential for proper thyroid functioning. (5)Pancreas Parathyroid Located under stomach  Endocrine and exocrine gland  (4) to thyroid gland. Located next exocrine: secretes into ducts Contains two sets of cells that secrete hormones  Secretes Parathormone: Raises blood  Islets of Langerhans alpha cells: secrete glucagon to hydrolyze glycogen into glucose.1 calcium levels; releases calcium from bone 2. beta ce ls : secrete insulin to lower blood glucose levels and absorbs from kidneys and intestines. (6)Adrenal Gland (7) Gonads Located on top of each kidney  Testes: secrete testosterone.1 Two parts to each gland  1) Adrenal Cortex – outer part of the gland, secretes: a. Cortisol: reduce inflammation; increase glucose metabolism 2. Ovaries: secrete estrogen and progesterone b. Aldosterone: increase sodium absorption from kidney tubules c. Androgens Estrogen: Female secondary sex characteristics  Regulates menstrual cycle 2) Adrenal Medulla – inner part of the gland, secretes hormones involved in the fight-or-flight response. Occurs at high concentrations near the end of the fo licular phase. a. Epinephrine estrogen becomes a positive inducer of the anterior pituitary. b. Norepinephrine Positive feedback triggers the anterior pituitary to release more FSH Functions: increase heart rate, blood pressure, muscle contraction and LH. more FSH and LH cause the ovary to produce more estrogen. The ensuing LH surge is responsible for ovulation. Progesterone:  Stimulates secretory and vascular activity of the endometrium, (thickens uterine lining). preparing for implantation of an embryo. Secreted by the corpus luteum (empty follicle) after ovulation.  Feedback inhibition Insulin and Glucagon Negative feedback REGULATION OF BLOOD CALCIUM LEVELS BY PTH Changes in signal transduction pathways can alter cellular response. Conditions where signal transduction is blocked or defective can be deleterious, preventative or prophylactic (using medicines to prevent disease). 1. Diabetes Islets cells malfunction Type I: Insulin production stops Treatment: insulin injections to lower blood glucose levels Type II: insulin produced is not effective - ce l receptors do not bind insulin Treatment: medications that make cells more responsive 2. Hypothyroidism Abnormally low thyroxine levels. Symptoms: extreme fatigue, weight gain, cold intolerance, muscle cramps, feeling of not enough sleep.