Chapter 19Chapter 19 ENDOCRINE ENDOCRINE SYSTEMSYSTEM

1.1. Compare the basic organization and function of the Compare the basic organization and function of the ES and the NSES and the NS

2.2. Describe the structural and functional organization of Describe the structural and functional organization of the hypothalamus and the pituitary and explain the hypothalamus and the pituitary and explain their relationshiptheir relationship

3.3. Discuss the locations and structures of the thyroid, Discuss the locations and structures of the thyroid, parathyroid, and adrenal glands as well as the parathyroid, and adrenal glands as well as the thymus and the endocrine part of the pancreas.thymus and the endocrine part of the pancreas.

4.4. List the hormones (and their function) produced by List the hormones (and their function) produced by these glands. these glands.

5.5. Briefly review the results of abnormal hormone Briefly review the results of abnormal hormone productionproduction

Endocrine System OverviewEndocrine System Overview

Ductless glands produce Ductless glands produce hormoneshormones

Gland may be entire Gland may be entire organ or interspersed bits organ or interspersed bits of tissueof tissue

Chemical classification of Chemical classification of hormoneshormones

Target tissues are Target tissues are identified by receptorsidentified by receptors

HypothalamusHypothalamus

Control Center for Control Center for internal environmentinternal environment

Regulates nervous and endocrine systems via 3 mechanisms:

1. ANS centers exert nervous control on adrenal medulla

2. ADH and Oxytocin production

3. Regulatory hormone production (RH and IH) controls pituitary gland directly and all other endocrine glands indirectly

Fig 19-3

Pituitary Gland (= Pituitary Gland (= Hypophysis)Hypophysis)

Structure:Structure: Infundibulum - connection to hypothalamus Infundibulum - connection to hypothalamus In the sella turcica In the sella turcica Two parts with an embryonic double originTwo parts with an embryonic double origin

Posterior Pituitary = neurohypophysisPosterior Pituitary = neurohypophysis Storage Storage shed for ADH and Oxytocin (produced in ?)shed for ADH and Oxytocin (produced in ?)

Anterior Pituitary Anterior Pituitary = adenohypophysis= adenohypophysis production of production of 7 peptide hormones, 7 peptide hormones, see fig 19.5see fig 19.5

Histology

Fig 19-4

Hypophyseal Portal System Hypophyseal Portal System

Portal systems:Portal systems: two capillary networks two capillary networks in serial arrangement in serial arrangement Advantage?Advantage?

Named after their Named after their destination: . . . destination: . . .

Portal veins:Portal veins: blood blood vessels that link two vessels that link two capillary networkscapillary networks

Fig 19-6

Thyroid GlandThyroid Gland Anterior surface of trachea Anterior surface of trachea

just inferior of thyroid just inferior of thyroid cartilage (or Adam’s apple)cartilage (or Adam’s apple)

Two lobes connected by Two lobes connected by isthmusisthmus

MicroscopicMicroscopic thyroid folliclesthyroid follicles produce thyroid hormoneproduce thyroid hormone

C Cells - produce calcitonin C Cells - produce calcitonin ((CaCa2+2+))

Fig 19-7

Thyroid Gland FunctionThyroid Gland Function

Thyroxin (T4) and triiodothyronine (T3) speed up metabolic rate

Calcitonin lowers blood Ca2+ levels

Thyroid pathologies: Hyper- and Hypothyroidism

Goiter

Exophthalmus

HyperthyroidismHypothyroidism

Slowing of mind and body

Four Parathyroid Four Parathyroid GlandsGlands

Parathyroid Parathyroid hormone (PTH; hormone (PTH; sometimes also sometimes also called called parathormone)parathormone)

Function: Function: antagonist to antagonist to CalcitoninCalcitonin

Fig 19-9

4 tiny glands embedded in the back of the 4 tiny glands embedded in the back of the thyroid (superior and inferior)thyroid (superior and inferior)

Thymus GlandThymus Gland Inside thoracic cavity

immediately posterior to sternum above the heart

Most active in infancy and childhood - Largest just before puberty

Thymosin - enhances lymphocyte production and competence. (important for immune system)

Adrenal or Suprarenal Adrenal or Suprarenal GlandGland

Cortex:Cortex: corticosteroid production aldosterone, cortisol, sexhormonealdosterone, cortisol, sexhormone

Medulla: modified sympathetic Medulla: modified sympathetic ganglion produces adrenaline and ganglion produces adrenaline and noradrenaline (noradrenaline (parallels sympathetic parallels sympathetic division of ANS)division of ANS)

HistologyHistology

Fig 19-10

Pancreas Part of endocrine and Part of endocrine and

digestive systems. digestive systems. (99% exocrine)(99% exocrine)

Pancreatic islets Pancreatic islets or islets of Langerhansor islets of Langerhans cells: glucagon cells: glucagon ( blood sugar levels by

stimulating liver to convert glycogen to glucose)

cells: insulin cells: insulin ( blood sugar levels by causing the cells to take up glucose for use by the mitochondria)

cells: somatostatincells: somatostatin