Chapter 16 Endocrine - Part 2

Chapter 16 Endocrine - part 2

Endocrine system

• several separate organs • release hormone into capillaries • hormone transported in blood

• endocrine vs exocrine Endocrine Glands

• Hypothalamus • Pituitary • Pineal gland • Thyroid • Parathyroid • Thymus • Adrenal Cortex • Adrenal Medulla • Pancreas • Ovary • Testes • several others things to know

• endocrine gland • gland + hormone(s) produced • hormone + its action • diseases

types of hormones

• direct hormones target = non-endocrine tissue • tropic hormones target = endocrine glands – releasing hormones from hypothalamus – stimulating hormones from ant. pituitary • prohormone inactive forms

Thyroid gland

• follicular cells • produce thyroid hormone • lumen • stores colloid • parafollicular (C) cells – produce calcitonin

Thyroid hormone

• thyroid hormone thyroxine T4 tri-iodothyronine T3 • effects: – calorigenic stim gene/enzymes of cell respiration uncoupling enzymes increase basal metabolic rate = heat

– metabolic protein synthesis increase heart rate and BP

– growth nervous system development muscle, skeletal development

– see table 16.2 Thyroid hormone synthesis

• thyroglobulin synthesis

• iodination I2 added to tyrosine

• storage colloid = thyroglobin + I2

• cleavage T4 and T3 break from colloid stim by TSH

• secretion exocytosis

• transport TBG thyroxine-binding globulin

control of T4 • stimulus: TSH (thyroid stimulating hormone)

– low blood T4 – low body temp – pregnancy

• inhibited by any inhibition of TSH

– high blood T4 – somatostatin

Diseases of Thyroid hormone

• Grave’s Disease hyperthyroidism –  BMR ;  HR – weight loss ; sweating – exopthalmos • Myxedema hypothyroidism (adult) – fluid accumulation – weakness; lethargy ; mental “sluggishness” –  BMR ; weight gain ; chilled • Cretinism hypothyroidism (congenital) – decreased growth; and mental development • Goiter – thyroid tumor

– decreased I2 increased TSH  increase colloid

Calcitonin

• = thyrocalcitonin • parafollicular (C) cells • effects: decrease blood calcium deposit calcium into bone

• stimulus: high blood Calcium

Parathryroid gland

• Parathyroid hormone – PTH = parathormone

• effects : increase blood calcium increase Ca++ absorption increase Ca++ reabsorption remove Ca++ from bone

• stimulus: low blood calcium

Adrenal gland

• 2 separate glands adrenal cortex outer adrenal medulla inner

Adrenal medulla

• 2 catecholamines epinephrine norepinephrine

• effects: – “adrenaline rush” “fight or flight” increase heart rate , BP bronchodilation increase BMR increase alertness

– increase blood glucose

• stimulus: Sympathetic nervous system

Adrenal cortex hormones

• hormones: corticosteroids – mineralcorticoids aldosterone

– glucocorticoids cortisol

– gonadocorticoids androgens

mineralcorticoids

• aldosterone • effects: • increases Na levels in blood and tissue fluid – stim transcription of Na-K ATPase in kidney + – increases reabsorption Na into blood • increase blood volume • increase BP • stimulus: renin-angiotensin low blood Na ACTH

glucocorticoids

• cortisol “stress hormone” • “ glucose sparing” • increase blood glucose glycogenolysis • fat catabolism gluconeogenesis • protein catabolism more AA for repair • anti-inflammatory limit immune system • affects memory • stimulus: ACTH stress inflammation Gonadocorticoids

• androgens : – males convert to testosterone – female convert to estradiol • effects: puberty sex drive minimal compared to gonad production

Diseases of Adrenal Cortex

• Cushing’s increased Cortisol – ACTH producing tumor ant pituitary , lung – pharmaceutical doses – cushingoid features: moon face : buffalo hump steroid diabetes osteoporosis - fractures low inflammatory response

• Addison’s Disease decreased Aldosterone , Cortisol • low Na ; increase K levels • low BP • hypoglycemia Diseases of Adrenal Medulla

• pheochromocytoma chromaffin cell tumor – increased epinephrine effects

Pancreas

• pancreatic islets = islets of Langerhans – alpha (α) cells glucagon – beta (β) cells insulin • somatostatin Glucagon

• effects: increase blood glucose – liver - glycogenolysis gluconeogenesis lipolysis

• stimulus: low blood glucose sympathetic n.s.

Insulin

• effects: decrease blood glucose – the most anabolic hormone • increase glycogenesis (storage) • increase protein synthesis and lipogenesis – increase membrane transport of glucose • increase carrier proteins GLUT4 – increase cell respiration – decrease gluconeogenesis , lipolysis

• stimulus: high blood glucose parasympathetic n.s. glucagon Insulin production

• glucose enters beta cells GLUT2 channel • increases cell respiration - ATP + • ATP closes K channels - depolarization ++ • depolar opens voltage gated Ca channels ++ • Ca enters beta cell ++ • Ca stim exocytosis of insulin

somatostatin

• same as hypothalamic hormone (GHIH) – inhibits GH (growth hormone) • inhibit TSH (thyroxine) • inhibit gastric activity

glucose related hormones

• decrease blood glucose : – insulin • increase blood glucose : – glucagon for body if low glucose – epinephrine for N.S. if immediate stress – cortisol for N.S. if long term stress – growth hormone for growth – thyroxine for cell respiration, heat Diseases of Pancreas

• hypoglycemia = low blood glucose • hyperglycemia = high blood glucose • glucosuria • Polyuria • Polydipsia • Polyphagia • Diabetes Mellitus hyperglycemia – type 1 Insulin dependent IDDM – congenital (autoimmune) decrease Beta cells – type 2 non Insulin dependent NIDDM – developed – decrease Insulin receptors on target cells Thymus

• thymic hormones • maturation of T lymphocytes

Pineal gland

• = epithalamus • melatonin – circadian rhythms – inhibit RAS • stim by hypothalamus

• estradiol follicle • progesterone corpus luteum

• estradiol follicle – effects: ovum development uterus development mammary duct development

– stimulus: FSH

• progesterone corpus luteum , placenta – effects: uterus development mammary gland development

– stimulus: LH , hCG

• inhibin inhibits FSH, LH Testes

• testosterone interstitial cells – effects: sperm maturation accessory sex glands

– stimulus: ICSH

• inhibin sustentacular cells – effects: inhibits FSH

Hypothalamus

• “master gland” of the endocrine system • direct hormones – ADH = antidiuretic hormone urine concentration decrease blood Osm

– oxytocin uterine contractions milk secretion

• regulatory hormones controls Pituitary gland – RH = releasing hormones (factors) – IH = inhibitory hormones

Pituitary

• = Hypophysis • Posterior Pituitary neurohypophysis • neural connection to hypothalamus • Anterior Pituitary adenohypophysis • blood connection to hypothalamus • Posterior Pituitary

• extension of the Hypothalamus • hypothalamic-hypophyseal tract – axons from Hypothalamus

• hormones made in hypothalamus released from posterior pituitary

Posterior Pituitary

• ADH Antidiuretic hormone (vasopressin) – effects: increase water reabsorption – kidney decrease blood Osm increase blood volume, BP

– stimulus: increase osmolarity

• oxytocin – effects: uterine contractions milk release

– stimulus: stretch of uterus nursing Anterior Pituitary

• = adenohypophysis

• hypophyseal portal system • vascular system betw hypothalamus and ant. pituitary

• direct hormones specific body responses

• stimulating hormones control other endocrine glands Anterior Pituitary – direct hormones

• GH growth hormone = somatotropic hormone – effects: mitosis protein synthesis Insulin-like growth factors increase blood glucose

– stim: GHRH ; low GH ; exercise • PRL prolactin – effect: milk production – stim nursing PRH

• LH luteinizing hormone ovulation Anterior Pituitary – stimulating hormones

• TSH thyroid stimulating hormone thyrotropin • ACTH adrenocorticotropic hormone corticotropin • FSH follicle stimulating hormone folliculotropin • LH luteinizing hormone luteotropin • ICSH interstitial cell stimulating hormone • GH somatotropin

• these stimulate target tissue to release hormone ; grow • controlled by Releasing hormones from hypothalamus

stimulating hormone effect

• ant pituitary other endocrine glands TSH thyroid thyroxine ACTH adrenal cortex cortisol FSH follicle estrogen LH corpus luteum progesterone ICSH interstitial cells testosterone GH liver insulin-like growth factors

hypothalamus – releasing factors

• hypothalamus ant. pituitary growth hormoneRH GHRH GH prolactin RH PRH PRL corticotropicRH CRH ACTH thyrotropicRH TRH TSH gonadotropicRH GnRH (FHRH) FSH “ GnRH (LHRH) LH growth hormoneIH GHIH inhibit GH gonadotropicIH GnIH inhibit FSH, LH

• ** hypothalamus controls all pituitary production - there is a regulating hormone from hypothalamus for every pituitary hormone

Who’s the Boss ?

• master gland? • “private controls the general” • target gland hormones control the hypothalamus and anterior pituitary • negative feedback • positive feedback: estradiol stim LH for ovulation not so during pregnancy

diseases of Growth Hormone

• increased GH: • Gigantism • increased length of long bones • congenital • Acromegaly • increased size of facial bones, hands • pituitary tumor ; adult • decreased GH: • Pituitary Dwarfism • decreased height ; normal proportions • congenital other endocrine structures

• heart atrial natriuretic peptide ANP • kidney renin erythropoietin calcitriol

• brain brain natriuretic peptide BNP • skin cholecalciferol (Vitamin D) • liver angiotensin • digestive tract gastrin secretin cholecystokinin

• adipose estrogens BP hormones

• antidiuretic hormone raise BP • epinephrine raise BP • cortisol raise BP • renin-angiotensin raise BP • thyroxine raise BP • atrial natriuretic peptide lower BP

endocrine reflex path

• control reflex path from stimulus to response • stimulus = change in condition

• afferent signal stimulus - change in condition • receptor endocrine gland • integration endocrine gland • efferent signal hormone • effector organ , tissue response