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

Ovary

* estradiol follicle

* progesterone corpus luteum

Ovary

* 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

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