Endocrine System

Cerebralcortex

Hypothalamus

Anterior Pituitary

Adrenalgland Thyroid

Target tissue

Releasing Hormones

ACTH TSH

Cortisol T3/T4

Low Blood Pressure

Aldosterone

Pancreas

Glucose

Insulin

Parathyroid

Low Ca2+

PTH

Pituitary Gland

Anterior Pituitary Posterior Pituitary

Hypothalamus

Pituitary Stalk Hypothalamic Axons

Cluster of hormome-secreting cells

Axon termini release hormones

• Growth Hormone (GH)• Adrenocorticotrophic Hormone

(ACTH)• Thyroid-Stimulating Hormone (TSH)• Prolactin• Leutenizing Hormone (LH)• Follicle-Stimulating Hormone (FSH)

Anterior Pituitary• Oxytocin• Vasopressin

Posterior Pituitary

Anterior Pituitary

Posterior Pituitary

Hypothalamus

Pituitary Stalk

Optic Chiasm

Pituitary

Acidophil

Basophil

Chromophobe

Anterior Pituitary

Reticulin Fibers

Capillary

• Growth Hormone Releasing Hormone (GHRH) -> GH

• Corticotropin Releasing Hormone (CRH) -> ACTH

• Thryotropin Releasing Hormone (TRH) -> TSH

• Gonadotropin Releasing Hormone -> FSH and LH

Hypothalamus hormones that regulate release of pituitary hormones

Hypothalamus

Anterior Pituitary

Portal Vein

1. Neurons synthesize hormone-releasing hormones

3. Hormone-releasing hormones diffuse out of secondary plexus to stimulate acidophils and basophils.

4. Hormones from acidophils and basophils diffuse into secondary plexus and distribute throughout the body.

2. Neurons release hormone-releasing hormones into primary capillary plexus.

Fenestrated Endothelium

Somatotroph

Secretory Granule

Anterior Pituitary

Anterior Pituitary Posterior Pituitary

Hypothalamus

Pituitary Stalk Hypothalamic Axons

Cluster of hormome-secreting cells

Axon termini release hormones

Herring Body

PituicyteBlood Vessel

Posterior Pituitary

Capillary Lumen

Fenestrated Endothelium

Axon Terminus

Posterior Pituitary

Adrenal Glands

GlomerulosaFasciculataReticularis

CortexMedulla

Adrenal Gland

Glomerulosa CapsuleFasciculata

Trabecula

Zona Glomerulosa

Fasciculata

Glomerulosa

Zona Fasciculata

CRH TRH

TSHACTH

AdrenalGlands

Cortisol T4/T3

ThyrotrophCorticotroph

Hypothalamus

Pituitary Cell

Target Cell

Hormone

Throphic Hormone Nega

tive

Feed

back

Nega

tive

Feed

back

Cortisol Pathway T4/T3 Pathway

Thyroid

O

CH3

HOCH3

C O

CH2OH

O

CH3

HOC

C O

CH2OH

O

H

O

CH3

HOCH3

C O

CH2OH

OH

O

CH3

OCH3

C O

CH2OH

OH

AldosteroneCorticosterone

Cortisol

Cortisone

GlomerulosaCells

17 α-Hydroxylase

11 β-Hydroxysteroid dehydrogenase (HSD)

Cholesterol

Reticularis

Fasciculata

Zona Reticularis

Medulla

Reticularis

Adrenal Medulla

Thyroid

C-cell

Colloid

Principle Cell

Thyroid

Na+ I-

I-I0

CH2

OH

CH2

OH

CH2

OH

CH2

OH

CH2

OH

CH2

OH

CH2

OH

CH2

OHCH2

O

OH

CH2

O

OH

CH2

O

OH

CH2

O

OH

Thyroglobulin secretion

Iodination

EndocyticVesicle

Lysosome

Conjugation

Cl-

T3 T4

TPO

T4T3

Colloid

Principle Cell

Interstitium

CRH TRH

TSHACTH

AdrenalGlands

Cortisol T4/T3

ThyrotrophCorticotroph

Hypothalamus

Pituitary Cell

Target Cell

Hormone

Throphic Hormone Nega

tive

Feed

back

Nega

tive

Feed

back

Cortisol Pathway T4/T3 Pathway

Thyroid

Parathyroid

Chief Cells

Oxyphil Cell

Parathyroid

Endocrine Pancreas

Exocrine Pancreas

Islet of Langerhans

Endocrine Pancreas

Cytosol

Interstitium

PO3

Glycolysis TCA Cycle

ATP

CO2 H2O

K+

Ca+

ATP-binding closes channel

Membrane depolarization open channel

Calcium-binding triggers fusion Insulin

Glucose

Glucokinase