1. Endocrine System
Chapter 10

2. Endocrine Glands
Endocrine glands are ductless glands and tissues that secrete hormones directly into the bloodstream.
Hormone
Hormon- gr. to excite.
Chemical messengers.
Released in small amounts.
Affect target cells.

4. General Functions of Hormones
Growth and development
Reproduction
Metabolism
Biological clock
Contraction of cardiac and smooth muscle
Glandular secretion

5. Feedback mechanisms regulate the secretion of hormones
Negative feedback- the outcome of a process feeds back on the system, shutting down the process.
Antagonistic feedback- one hormone has an opposite effect of another hormone on the system.
Positive feedback- the outcome of a process feeds back on the system, further stimulating the process.

6. Negative Feedback
Antagonistic Feedback

7. Positive Feedback
“I’m good enough, I’m smart enough, and doggone it, people like me!”

8. Positive Feedback- Oxytocin (OCT)
Sucking by the infant stimulates nerve receptors in the nipple.
The resulting impulses travel along nerves to the hypothalamus.
The hypothalamus signals the posterior pituitary to release OCT.
OCT travels via the bloodstream to the mammary glands.
Milk is ejected from the mammary glands.

9. Hypothalamus Anatomy Functions
Part of the diencephalon, inferior to the thalamus.
Functions
Regulates the internal environment through the autonomic nervous system.
Controls glandular secretions of the pituitary gland.

10. Pituitary Gland- anatomy
Pea-shaped structure.
½ inch in diameter.
Lies in the sella turcica of the sphenoid bone.
2 anatomically and functionally different portions.
Posterior
Anterior

11. Posterior Pituitary Anterior Pituitary Figure: 10-06 Title:
The two lobes of the pituitary gland.
Caption:
The two lobes of the pituitary gland, their connections with the hypothalamus, and the hormones they secrete.

12. Pineal Gland Anatomy Function Pine cone shape. In the epithalamus.
Covered by a capsule made of pia mater.
Function
Secretes melatonin that targets the brain; involved in regulating daily sleep-wake cycle.

13. Thyroid Gland Anatomy Functions Inferior to the larynx.
2 lobes, shield-shaped and deep red in color.
Isthmus connects the lobes.
30g in weight (=1 oz.).
Functions
Increases metabolic rate.
Regulate growth and development.
Isthmus

14. The Thyroid Gland Secretes Thyroid Hormone (TH)
Hypothyroidism- undersecretion of the thyroid hormone.
Fetus or infant- cretinism.
Dwarfism and mental retardation.
Adult- myxedema.
Weight gain.
Lethargy.
Loss of hair.
Lowered body temperature.

15. Hyperthyroidism- oversecretion of thyroid hormone.
Adult- Graves’ disease
Increased metabolic rate.
Enlargement of the thyroid gland.
Rapid heart rate.
High blood pressure.
Exophthalmos.
Treatment for Graves’ disease
Surgery.
Ingestion of radioactive iodine.

17. Parathyroid Glands
Anatomy- 4 small masses at the back of the thyroid gland.
Hormones- parathyroid hormones.
Target- bones, kidneys, intestines.
Hormone Functions
Increase blood calcium level.
Antagonistic action between calcitonin and parathyroid hormone maintains blood calcium levels.

18. Thymus Gland Anatomy Hormones- thymosins.
Upper mediastinum.
Large in infants (70 g), atrophied in adult (3 g).
2 lobed organ.
Hormones- thymosins.
Target- T lymphocytes (white blood cells).
Hormone Functions
Promote production and maturation of T lymphocytes.

19. Adrenal Glands Anatomy Hormones and Functions Targets- all tissues.
Almond-shaped, located at the tops of the kidneys.
Consists of adrenal medulla and adrenal cortex.
Hormones and Functions
Adrenal Medulla
Epinephrine- adrenaline. Fight or flight.
Norepinephrine- noradrenaline. “ “
Adrenal Cortex
Sex Hormones. Development.
Mineralocorticoids. Salt & water balance.
Glucocorticoids. Regulate glucose levels.
Targets- all tissues.

20. Pancreas Anatomy Target- liver, muscles, adipose tissue.
5-6 inches long, 1 inch thick.
Attached to the duodenum, posterior to the stomach.
Two tissue types.
Exocrine tissue- produce and secrete digestive juices.
Endocrine tissue- produce and secrete insulin and glucagon directly into the blood.
Target- liver, muscles, adipose tissue.
Hormones and Functions
Insulin- lowers blood sugar.
Glucagon- increases blood sugar.

21. Testes Anatomy Hormone- testosterone.
Scrotum of male.
2 oval glands.
2 inches long, 1 inch in width.
Hormone- testosterone.
Target- gonads, skin, muscles, bones.
Hormone Function
Stimulate male sex characteristics.

22. Ovaries Anatomy Hormones Estrogens. Progesterone. Targets
Abdomen of female
5 cm X 2.5 cm (2 X 1 inch).
Hormones
Estrogens.
Progesterone.
Targets
Gonads, skin, muscles, bones.
Hormone Function
Stimulate female sex characteristics.