context: endocrine system
1. Growth hormone 2. thyroid hormone 3. insulin 4. parathyroid hormone 5. calcitriol 6. reproductive hormones
T/FTrue False
false, we wouldn't be having this conversation since the chapter is on endocrine system, but hey, the gonads are pictured outside of the speedo in the illustration.
context: nervous vs endocrine system
1. release neurotransmitters into synaptic cleft containing specific receptors 2. Relays signals. 3. Regulates specific cells or cell groups (muscles, glands) - Rapid, short-term effects -Cannot regulate long-term processes (growth, reproduction)
context: nervous vs endocrine system
1. Release hormones into ECF and bloodstream 2. influence target tissues containing specific receptors. -Slow, long-term effects -can effect entire body -ductless
context: nervous vs endocrine system
how the nervous system regulates/influences the endocrine system
context: intercellular signaling
1. endocrine 2. neurocrine 3. neuroendocrine
context: intercellular signaling
cells that secrete chemical messengers (hormones) into the bloodstream
context: intercellular signaling
neurons releasing chemical messengers that enter the bloodstream
context: intercellular signaling
neuronal action potential results in the release of hormones from endocrine cells
context: endocrine reflexes
aka feedback loops (regulates homeostasis) 1. receptor 2. integration center 3. effector
context: endocrine reflexes- 3 components
sensitive to particular stimuli
context: endocrine reflexes- 3 components
usually CNS. Receives and processes information from receptor and sends out commands
context: endocrine reflexes- 3 components
cell/organ responding to commands (opposes or enhances initial stimuli) -set point changes in living things *most endocrine reflexes are negative feedback loops
context: endocrine reflexes
1. Nervous system reflex 2. Endocrine system reflex 3. Neuroendocrine reflex
context: endocrine reflexes- 3 types of reflexes
withdrawal reflex (ex: pull away from hot pan)
context: endocrine reflexes- 3 types of reflexes
increase blood glucose --> insulin (by Beta cells of pancreas) --> lower BG
context: endocrine reflexes- 3 types of reflexes
neurons of hypothalamus signal endocrine cells of adrenal glands to release EPI --> adequate EPI
context: endocrine reflexes
1. humoral 2. hormonal 3. neural
context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
change in composition of extracellular fluid
context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
hormone binding to receptor
context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
neurotransmitter present at neuroglandular junction
5 features of the endocrine system
1. single endocrine gland may produce more than one hormone 2. one hormone may be produced by several endocrine glands 3. a target cell can be influenced by several different hormones 4. a single chemical can be both a hormone and neurotransmitter 5. some organs only produce hormones, other produce hormones and perform other functions too
context: 5 features of the endocrine system
anterior pituitary produces 7 hormones
context: 5 features of the endocrine system
ovaries and placenta both produce Estrogen
context: 5 features of the endocrine system
multiple populations of receptors
context: 5 features of the endocrine system
NE (in bloodstream and synaptic cleft)
context: 5 features of the endocrine system
ovaries produce hormones and release ovum
How are hormones classified?
by chemical structures
3 classifications of hormones
1. amino acid derivatives 2. peptide hormones 3. lipid derivatives
context: 3 classifications of hormones
1. derivatives of Tyrosine 2. derivatives of Tryptophan
context: 3 classifications of hormones - amino acid derivatives
1. Thyroid hormones (Thyroxine (Thyroid gland)) 2. Catecholamines (Epinephrine (AM), Norepinephrine (AM), Dopamine (H) - END) AM = adrenal medulla H = hypothalamus
context: 3 classifications of hormones - amino acid derivatives
1. Melatonin (Pineal gland)
context: 3 classifications of hormones
1. glycoproteins (>200a.a. + carbs/sugars) 2. short polypeptides and small proteins (<200a.a.)
context: 3 classifications of hormones - peptide hormones
1. pituitary gland - TSH, FSH, LH 2. kidneys - EPO 3. reproductive organs - inhibin
context: 3 classifications of hormones - peptide hormones
1. hypothalamus - ADH, oxytocin, regulatory hormones 2. pituitary gland - ACTH, GH, MSH, PRL 3. heart - ANP, BNP 4. digestive tract - hormones (ch. 24) 5. pancreas - insulin, glucagon 6. parathyroid gland - PTH 7. C cells of thyroid - CT 8. adipose tissue - leptin, resistin 9. lymphatic system - hormones (ch. 22)
context: 3 classifications of hormones
1. eicosanoids - lipid derivatives of arachidonic acid 2. steroid hormones - structurally similar to cholesterol
context: 3 classifications of hormones - lipid derivatives
1. leukotrienes 2. prostaglandins 3. thromboxanes 4. prostacyclins
context: 3 classifications of hormones - lipid derivatives
1. gonads - androgens , estrogens (ex : estradiol), progestins2. adrenal cortex - mineralocorticoids, glucocorticoids, androgens 3. kidneys - calcitriol
context: 3 classification of hormones
1. hydrophilic - cell membrane receptor -ex- GPCR, ion channel-linked, enzyme-linked (phosphorylases) 2. lipophilic - intracellular receptors -ex- steroids
context: hypothalamus and pituitary gland: basic A&P
1. hypothalamus 2. pituitary gland (aka hypophysis) *connected : by infundibulum of hypothalamus
context: hypothalamus and pituitary gland: basic A&P
1. anterior pituitary (adeno hypophysis) : consists of gland ular tissue - produces 7 hormones2. posterior pituitary (neuro hypophysis) : consists of neural tissue - produces 2 hormones
context: hypothalamus and pituitary gland: basic A&P
peptide hormones
context: hypothalamus and pituitary gland: basic A&P
usually released in pulsatile fashion - frequency of pulses and amount of hormone released influence response of target tissue
Portal system
connects 2 capillary beds
pathway of hypophyseal portal system
artery --> hypothalamic capillary bed --> portal vein --> anterior pituitary capillary bed --> vein
context: hypophyseal portal system
portal capillaries are fenestrated (window)
what is the highest level of endocrine control?
hypothalamus
context: hypothalamus
1. release regulatory hormones 2. act as endocrine organ 3. exert direct neural control over endocrine cells
context: hypothalamus - 3 ways of integration
hypothalamic regulatory hormones regulate secretory activity of endocrine cells in the anterior pituitary
context: hypothalamus - 3 ways of integration
hypothalamic nuclei synthesizes hormones and releases into systemic circulation (posterior pituitary)
context: hypothalamus - 3 ways of integration direct neural control over endocrine cells
hypothalamic nuclei directly innervate adrenal medulla and regulate hormone secretion
3 types of neurons in the hypothalamus
1. median eminence 2. supraoptic and paraventricular 3. direct
context: 3 hypothalamic nuclei
synthesis, package, and transport regulatory hormones pathway : released in ECF --> capillary bed --> hypophyseal portal circulation --> capillary bed of anterior pituitary - the hypothalamic regulatory hormone cause the endocrine cells of anterior pituitary to release a hormone into the system circulation
context: 3 hypothalamic nuclei
extend into the posterior pituitary and release hormones into ECFpathway : hormone enters capillaries --> system circulation
context: 3 hypothalamic nuclei
directly regulate endocrine cells of the adrenal medulla to release EPI and NE. pathway : increase in sympathetic output (action potentials) --> hormones (NE and EPI) released by adrenal medulla -sympathetic division of ANS.
2 types of hypothalamic regulatory hormones
1. releasing hormones 2. inhibiting hormones
context: 2 hypothalamic regulatory hormonesreleasing hormones (RH)
stimulates the synthesis and secretion/release of hormone from anterior pituitary (ex: GH-RH)
context: 2 hypothalamic regulatory hormonesinhibiting hormones (IH)
prevents synthesis and secretion of hormone from anterior pituitary (ex: GH-IH)
growth hormone (GH)
aka : somatotropinAnterior pituitary stimulates cell growth/division by increasing protein synthesis. expecially skeletal muscle and cartilage
2 ways to regulate GH release
1. growth hormone-release hormone (GH-RH) aka : somatocrinin2. growth hormone-inhibiting hormone (GH-IH) aka : somatostatin- both 1 and 2 released from hypothalamic nuclei -results in the release or inhibition of GH from somatotrophs in the anterior pituitary (1 of 7 endocrine cell types)
context: 2 types of effects of GH
GH doing the work -important when glucose levels are normal a) muscle : inc. a.a. uptake and protein synthesis and inc. myoblast differentiation and proliferation b) adipose : inc. lipolysis (cells use F.A. for energy) c) liver : inc. IGF, inc. glycogenolysis*IGF = insulin-like growth factor aka : somatomedin -produced by liver in response to GH ("hormone 2")
context: 2 types of effects of GH
IGF doing the work -important when glucose levels are high (post-feed/having a meal) a) muscle : uptake of glucose and a.a.; inc. protein synthesis b) chondrocyte stimulation : linear bone growth
context: regulation of growth hormone secretion
1. GH-RH inhibits its own release from the hypothalamus 2. IGF inhibits release of GH from anterior pituitary 3. GH and IGF stimulates production of Growth Hormone-Inhibiting Hormone (GH-IH) from hypothalamus - decreased release of GH from anterior pituitary inhibitor )
3 growth hormone disorders (clinical interest)
1. dwarfism 2. gigantism 3. acromegaly
context: 3 growth hormone disorders
pituitary; proportionally smaller (<4'10") Hypo secretion of GH in childhood treatment : hormone replacement
context: 3 growth hormone disorders
(>7'6" 310 lbs.) Hyper secretion of GH in childhood treatment : surgery if pituitary tumor (can mess with other hormones in there)Rx : Somavert ; GH antagonist - not very successful
context: 3 growth hormone disorders
more common than gigantism Hyper secretion of GH in adults cartilage and small bones respond enlargement of jaw/skull, extremities treatment : surgery if pituitary tumorRx : Somavert ; GH antagonist - more successful here
9 peptide hormones of the pituitary gland/hypothalamus
1. growth hormone (GH) 2. thyroid stimulating hormone (TSH) 3. adrenocorticotropic hormone (ACTH) 4. prolactin (PRL) 5. follicle stimulating hormone (FSH) 6. luteinizing hormone (LH) 7. melanocyte stimulating hormone (MSH) ---- 8. antidiuretic hormone (ADH) - vasopressin 9. oxytocin
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei : release thyroid releasing hormone (TRH) which stimulates the anterior pituitaryanterior pituitary : thyrotrophs release thyroid stimulating hormone (TSH)function : target: follicle cells of thyroid gland-TSH regulates all aspects of thyroid hormone synthesis and release of hormone 2 (T3 (more of) and T4 ) Negative feedback : T3 and T4 inhibit further release of TSH from thyrotrophs and inhibit TSH release from hypothalamus*no inhibitory thyroid hormone
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei : release of corticotropin releasing hormone (CRH) which stimulates the anterior pituitaryanterior pituitary : corticotrophs release adrenocorticotropic hormone (ACTH)function : target: zona fasciculata of adrenal cortex-release of hormone 2 (corticosteroids- cortisol, glucocorticoids ) Negative feedback : glucocorticoids inhibit further release of ACTH from corticotrophs and CRH release from hypothalamus
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei : release of 1. prolactin releasing factors (PRF) 2. prolactin inhibiting hormone (PIH) - ex. Dopamine - inhibits prolactin release anterior pituitary : mammotrophs release prolactinfunction : target: 1. females - mammary gland development and milk production (not ejection) 2. males - regulates androgen production from testes Negative feedback : prolactin inhibits its own release from mammotrophs and release PRF from the hypothalamus. prolactin also increases release of PIH from hypothalamus.
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei : release gonadotropin releasing hormone (GnRH)anterior pituitary : gonadotrophs release1. follicle stimulating hormone (FSH) 2. luteinizing hormmone (LH) function : target: gonads1. testes- release androgens 2. ovaries- promotes follicle development and releases Estrogens, Progestins Negative feedback : sex hormones inhibit further release of FSH and LH from gonadotrophs and GnRH release from hypothalamus
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei : nothing (?)anterior pituitary : MSH only produced during1. fetal development 2. pregnancy 3. very young children 4. disease states function : target: melanocytes in the skin - melanin production*MSH production in adult humans usually occur locally (skin ) - normally not produced by the anterior pituitary
context: 9 peptide hormones of pituitary/hypothalamus
aka vasopressin Hypothalamic nuclei (supraoptic nuclei) : synthasize antidiuretic hormone (ADH)posterior pituitary : releases antidiuretic hormone (ADH)function : regulates water and electrolyte balance by decreasing urination; inc. in ADH results in H2 O retention in kidney (more aquaporins in collecting duct - keep more water)Stimuli for ADH secretion : 1. Increased plasma osmolarity - detected by osmoreceptors (supraoptic nuclei) in hypothalamus 2. Decreased plasma volume - detected by baroreceptors in aorta, carotid artery Inhibiting ADH secretion : 1. alcohol inhibits ADH causing inc. pee
context: 9 peptide hormones of pituitary/hypothalamus
Hypothalamic nuclei (paraventricular nuclei) : synthesize and release oxytocinposterior pituitary : releases oxytocinfunctions : in reflex loops that are positive feedback loops1. uterine contractions - stimulates smooth muscle of uterus - may be trigger for labor (released also by uterus and fetus) Rx - Pitocin - labor induction, placental delivery 2. milk ejection - sensory endings in breast stimulated by suckling = oxytocin released into circulation from posterior pituitary --> contraction of myoepithelial cells in breast alveoli = milk ejected into breast ducts = happy baby -stimulates prolactin secretion (inc. milk production)
Male fertility and hormones
Hypothlamic nuclei : release gonadotropin releasing hormone (GnRH) - consistant, pulsatile release at pubertyanterior pituitary : gonadotrophs release1. follicle stimulating hormone (FSH) 2. luteinizing hormone (LH) function : target: gonads1. FSH - stimulates spermatogenesis in sertoli cells (testosterone needed too) 2. LH - inc. testosterone production in Leydig cells Negative feedback : 1. Sertoli cells produce inhibin to dec. FSH (and perhaps GnRH) secretion 2. Testosterone inhibits GnRH release *know seminiferous tubule (not shown)
Female fertility and hormones
Hypothalamic nuclei : release gonadotropin releaseing hormone (GnRH) - cyclical/pulsatile release at pubertyanterior pituitary : gonadotrophs release1. follicle stimulating hormone (FSH) 2. luteinizing hormone (LH) function : target: gonads1. FSH - follicale stimulation and egg maturation by stimulating Estrogen which a) proliferation of endometrium b) thins cervical mucus c) inhibits GnRH 2. LH - ovulation stimulation by stimulating Progesterone (and some Estrogen) which a) differentiation/maintenance of endometrium b) thickens cervical mucus c) inhibits GnRH Negative feedback : inc. Estrogen and Progestorone (with some Estrogen) inhibits GnRH and inhibin from mature ovum causes dec. FSH
Precocious Puberty (clinical interest)
Puberty Precocious puberty girls : 10 years < 7 years boys : 12 years < 9 yearssymptoms: only females : 1. breast development 2. menstruation only males: 1. enlargement of genitalia 2. deeper voice both: 1. acne 2. body hair 3. growth spurt results : self esteem issues, teasing by peers, loss of childhood/innocence, emotional trauma, aggressiveness, age-inappropriate sex drive, breast cancer, growth spurt --> short stature (androgens cause closure of epiphyseal plate)Etiology : in the endocrine system. Usually not ovarian or testicular dysfunction. Hypothalamus triggers pituitary to release FSH, LH etc. --> pubertycould it be brain tumor? CNS infection? Head trauma treatment : surgery, antibiotics, LH receptor antagonist
context: Pineal gland
synthesize melatonin from tryptophan
context: Pineal gland
collaterals from visual pathway (suprachiasmatic nucleus ) enter pineal gland and influence melatonin production -lowest during daylight
context: Pineal gland
1. inhibits reproductive functions 2. free radical scavenger 3. establishes circadian rhythms
context: Pineal gland - 3 functions of melatonin
dec. sperm and oocyte (egg) maturation (via dec. GnRH) - melatonin levels decline at puberty (inc. GnRH)
context: Pineal gland - 3 functions of melatonin
acts as antioxidant
context: Pineal gland - 3 functions of melatonin
sleep/wake cycles - low sunlight in winter results in higher melatonin levels and may contribute to seasonal depression (melatonin supplements may help with insomnia and jet lag)