Endocrine

ENDOCRINE SYSTEM

Function

• Help regulate internal functions

• Use chemical messengers

• Recall: Endocrine vs. Exocrine glands

• Nervous System vs Endocrine System

Target Specificity

• Lock ‘n Key action

• Hormone-Receptor Complex

Hormone

Receptor

Glands

ENDOCRINE GLANDS & HORMONES

Hypothalamus

• Functions both as an Endocrine Gland and nervous tissue.

• Location

• Hormones

– Tropic Hormones

Pituitary Gland

• Two Parts: Anterior and Posterior

• Anterior Pituitary Gland (APG)

– Growth Hormone (GH)

– Prolactin

– Thyroid Stimulating Hormone (TSH)

– Adrenocorticotropic Hormone (ACTH)

– Follicle-Stimulating Hormone (FSH)

– Luteinizing Hormone (LH)

Pituitary Cont’d

• Posterior Pituitary (PPG)

– Oxytocin (OT)

– Antidiuretic Hormone (ADH)

• Hypothalamic control:

– APG: stimulated by hormones from hypothalamus

– PPG: modified axons

Fig. 17.4

Third ventricle of brain

Median eminence

Hypothalamo–hypophyseal tract

Stalk (infundibulum)

Neurohypophysis:

Posterior lobe

Pars tuberalis

Anterior lobe

Adenohypophysis:

(a)

Optic chiasm

Nuclei of hypothalamus:

Paraventricular nucleus

Supraoptic nucleus

Oxytocin

Antidiuretic hormone

(b)

Portal venules

Posterior lobe

Anterior lobe

Hypothalamic hormones

Anterior lobe hormones

Pineal gland

Cerebral aqueduct

Mammillary body

Anterior Posterior

Primary capillaries

Neuron

cell body

Axons to

primary

capillaries

Floor of

hypothalamus

Gonadotropin-releasing hormone

Thyrotropin-releasing hormone

Corticotropin-releasing hormone

Prolactin-inhibiting hormone

Growth hormone–releasing hormone

Somatostatin

Follicle-stimulating hormone

Luteinizing hormone

Thyroid-stimulating hormone (thyrotropin)

Adrenocorticotropic hormone

Prolactin

Growth hormone

Superior hypophyseal

artery

Secondary

capillaries

Hypophyseal

portal system:

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Thyroid

Follicles: Produce Hormones

• Hormones

▫ Thyroxine (T4)

▫ Triiodothryonine (T3)

▫ Both used iodine and have nonspecific target cells

▫ Calorigenic effect

• Colloid: Stores Hormones, jelly-like structure

• Parafollicular Cells: Cells found between follicles produce Calcitonin

▫ Calcitonin

Fig. 17.9

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Follicle

TracheaInferior thyroid vein

(b)

Isthmus

(a)

Superior thyroid

artery and veinThyroid

cartilage

Thyroid

gland

Follicular

cells

Colloid of

thyroglobulin

C (parafollicular)

cells

b: © Robert Calentine/Visuals Unlimited

Fig. 17.7

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

TRH

TSH

Target organs

Thyroid hormone

Stimulatory effect

Inhibitory effect

2

3

4

1

5

6

+

+

+

+

Negative feedback

inhibition

–

-

-

• Location

• Parathyroid Hormone (PTH)

Parathyroid Gland

Adrenal Glands

• Sits on top of each Kidney

• Receives a lot of Blood from Renal Artery

• 2 sections:

– Medulla: Inner layer

– Cortex: Outer layer, has sub-layers or zones.

Adrenal Cortex

• Aldosterone

– Produced in outer zone

– Regulates Electrolytes

• Cortisol

– Produced in middle zone

– Regulates metabolism and glucose

• Androgens

– Produced in inner zone

– Sex steroids

Adrenal medulla

• Produces and releases epinephrine and noreprinephrine.

• Functions:

– Gluconeogenesis

– Glycogenolysis

– Increased cardiac function

– Increased blood flow to muscles

– Increased pulmonary ventilation

Pancreas

• Exocrine and Endocrine Gland

• Acinar Cells produce pancreatic juices

• Islet cells produce hormones

– Beta Cells

• Produce insulin

• Lowers Blood Glucose levels and stores glucose in cells

– Alpha Cells

• Produce glucagon

• Increase Blood Glucose levels by releasing glucose into blood stream

– Antagonistic Effect