The endocrine system consists of glands that secrete hormones directly into the bloodstream, which then travel to target organs. The pituitary gland is located near the hypothalamus and is divided into the anterior and posterior lobes. The anterior lobe secretes trophic hormones that stimulate other glands, while the posterior lobe secretes ADH and oxytocin. Other glands discussed include the thyroid, adrenal glands, pancreas, and pineal gland. The lab will examine the structures and functions of these glands.

1. Lab 3
ENDOCRINE SYSTEM

2. Overview of Endocrine System

3. Endocrine Glands and Hormones
 Endocrine glands produce hormones and secrete them
into the bloodstream.
 Ductless glands
 Hormones then travel through the bloodstream until they
reach their target organ, which they affect in a highly
specific manner.
 Hormones only affect the organ(s) that contain a specific
receptor for that hormone; resulting in this highly specific
response once a hormone binds to its target tissue.

5. Feedback Control Mechanisms

6. Pituitary Gland
 Attached to the
hypothalamus by the
infundibulum
 Divided into two lobes:
 Anterior Lobe
 Glandular tissue
 Posterior Lobe
 Neural tissue

7. Anterior Pituitary
1 Hypothalamic neurons secrete
releasing and inhibiting hormones
into primary capillary plexus.
2 Hypothalamic hormones travel
though hypophyseal portal veins to
the anterior pituitary; where they
stimulate or inhibit release of
hormones from the anterior
pituitary.
3 Anterior pituitary hormones are
secreted into secondary
capillaries.

8. Hypothalamic Control of Anterior
Pituitary

9. Anterior Pituitary Hormones
 Trophic hormones stimulate
hormone secretion in other glands:
 Growth Hormone (GH)
 Thyroid-stimulating hormones
(TSH)
 Adrenocorticotropic hormone
(ACTH)
 Follicle-stimlulating hormone (FSH)
 Luteinizing hormone(LH)
 Prolactin (PRL)
 Can cause hypertrophy of target
organ at high concentrations.

11. Posterior Pituitary

12. Posterior Pituitary Hormones
 Anti-diuretic Hormone (ADH)
 Also known as vasopressin
 Acts upon kidney to promote water re-absorption
 Urine volume is decreased
 Oxytocin
 Stimulates smooth muscle contraction, especially during
parturition (birthing process)
 Promotes milk let-down (milk ejection reflex) in females.

13. Adrenal Gland
Adrenal Cortex
 Regulated by hormones
 Release hormones called corticosteroids
 Zona glomerulosa – secretes mineralcorticoids
 Regulate Na+ and K+ balance
 Aldosterone: Sodium and water retention; while excreting
potassium
 Zona fasciculata – secretes glucocorticoids
 Regulate glucose metabolism and that of other organic
molecules.
 Cortisol: stimulate glucose formation and inhibit utilization of
glucose.
 Zona reticularis – secrete sex steroids
 Weak androgens like Dehydropepiandrosterone (DHEA)
Adrenal medulla
 Regulated by neural innervation
 Secretes epinephrine and
norepinepherine
 Cause sympathetic-like response
 Activate by stress (fight or flight response)
“Girls From Russia Make Good Soup”

14. Thyroid Gland

15. Goiter Formation
 Caused by hypothyroidism
 Low-iodine intake; nutritional
deficiency
 Endemic goiter
 Caused by hyperthyroidism
 Autoimmune response
 Grave’s disease

16. Pancreas
 The pancreas is both an
endocrine and an exocrine
gland.
 Endocrine cells are located
in islets of Langerhans.
 Alpha cells secrete glucagon
 Beta cells secrete insulin

17. This is what we will see in lab today

18. Figure 11.11

19. Figure 11.30

20. Diabetes Mellitus
 Type I Diabetes Mellitus [insulin-dependent]
 “adolescent-onset diabetes”
 Caused by destruction of the beta cells.
 Lack of insulin secretion leads to extracellular hyperglycemia and increased
lipolysis
 Ketonemia
 Diabetic ketoacidosis: a condition of insulin deficiency causing increased hepatic
ketogenesis; occurs in Type I diabetes only.
 10% of diabetic population
 Type II Diabetes Mellitus [non insulin-dependent]
 “maturity-onset diabetes”
 Insulin resistance (target cells do not respond normally)
 Normal or elevated [insulin] initially; relative insulin deficiency
 Most patients obese
 90% of diabetic population

21. Oral Glucose Tolerance Test (OGTT)

22. Pineal Gland