BIOL 460 1nd Edition Lecture 8Outline of Last Lecture I. Mechanisms of Hormone actiona. Lipophilic b. Steroid hormone familyc. Thyroid hormone family II. Glands Outline of Current Lecture I. Pituitary Glanda. Embryology b. Hormonesi. Adenohypophysis ii. Neurohypophysis II. Adrenal GlandCurrent LecturePituitary Gland Continued1. Embryologya. Notochord- skeletal support for embryob. Also called primary inducer- produces growth factorsc. Very anterior end of notochord secretes GFs or inducers that trigger floor of diencephalon to evaginated. Also evagination in embryonic mouth (stomadeum)→ Rathke’s pouch These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.e. Rathke’s pouch forms adenohypophysis, evagination from hypothalamus forms neurohypophysis 2. Pituitary Hormonesa. Hormones of adenohypophysis i. Trophic hormonesii. Means “to feed”iii. High concentration of trophic hormones cause target glands to hypotrophy iv. Low concentration→ atrophy v. Growth hormone (GH) (somatotrophin)- promotes tissue and organ growth vi. Thyroid stimulation hormone (TSH) (thyrotropin)= produce and secrete thyroid hormonesvii. Adrenocorticotrophic hormone (ACTH) (corticotrophin)1. Triggers adrenal cortex growth 2. Trigger corticosteroid releaseviii. Follicle stimulating hormone (FSH) (Folliculotropin)-1. Stimulate follicles in ovary to mature2. Stimulate seminiferous tubules to produce spermix. Luteinizing hormone (LH) (luteotropin)-1. Stimulate corpus luteum- formed from remnants of follicle after ovulation, endocrine gland producing progesterone2. Causes interstitial cells to secrete testosterone in males x. Prolactin- stimulates milk production after childbirth b. Hormones of neurohypophysisi. Neurohypophysis- storage organ ii. Hormones secreted are produced by nuclei of hypothalamus (paraventricular nucleus and supraoptic nucleus)iii. Hormones are 1. Antidiuretic Hormone a. Diuretic- makes you urinate b. ADH- kidneys reabsorb water, less urine produced2. Oxytocina. Contraction of the uterus in childbirth b. Responsible for milk ejection reflexiv. Neurons produce these hormones in their cell bodiesv. Axons extend into neurohypophysis, causing exocytosis of the hormone vi. ADH and oxytocin have similar structures (2 nucleotides are different)- polypeptide NTM vii. Hypothalamic control of neurohypophysis secretion1. Controlled via a tract 2. Hypothalamic- neurohypophyseal tract 3. Group of parallel axonsviii. Neuroendocrine reflexes 1. Osmoreceptors relay info to nuclei in hypothalamus 2. This relays to neurohypophysis 3. Results in release of ADH ix. Adenohypophyseal control1. Hypothalamus secretes hormones that control adenohypophyseal hormone release 2. Transported via adenohypophyseal portal system3. Hypothalamic hormones→ adenohypophyseal hormonesa. Thyrotropin- RH→ TSHb. Corticotrophin-RH→ ACTHc. Gonadotropin- releasing hormones→ FSH/LHd. GH-RH→ growth hormone (somatotrophin)e. Somatostatin (inhibits GH)→ somatotrophinf. Prolacting inhibiting hormone→ prolactin 4. Works via negative feedback a. More T3 and T4 inhibits hypothalamus from releasing TSH_RH b. Also make adenohypophysis less sensitive to TSH-RH5. Relationship between hypophysis (pituitary) and target organ is called axis Adrenal Glands1. Composed of medulla and cortex2. Medulla- 85% epinephrine, 15% norepinephrine 3. Cortex- corticosteroids a. Formed from
View Full Document
Unlocking...