1. ENDOCRINE SYSTEM
Module 11

2. Endocrine System at a Glance
Endocrine glands secrete hormones
Hormones regulate body activities
Metabolic rate
Water and mineral balance
Immune system reactions
Sexual functioning

3. Endocrine System at a Glance
Organs of the Endocrine System
Adrenal glands
Ovaries
Pancreas (islets of Langerhans)
Parathyroid glands
Pineal gland
Pituitary gland
Testes
Thymus gland
Thyroid gland

5. Anatomy and Physiology
Collection of glands
Secrete hormones directly into bloodstream
Chemicals that act on target organs
Increase or decrease target’s activity level
Instrumental in maintaining homeostasis
Maintain stable internal environment

6. Types of Glands Two types of glands in body Exocrine glands
Exocrine glands and endocrine glands
Exocrine glands
Release secretions into duct that carries them to outside of body
Example: sweat glands
Endocrine glands
Release hormones directly into bloodstream
Have no ducts, referred to as ductless glands
Example: thyroid gland

7. Glands of the Endocrine System
Adrenal glands – two
Parathyroid glands – four
Pancreas
Pineal gland
Pituitary gland
Ovaries – two in females
Testes – two in males
Thymus gland
Thyroid gland

9. Adrenal Glands Two glands, one located above each kidney
Each gland is composed of two sections:
Adrenal cortex
Adrenal medulla

10. The adrenal glands.

11. Adrenal Cortex Hormones are referred to as corticosteroids
Secreted by adrenal cortex
Steroid hormones
Three different families of corticosteroids
Mineralocorticoids
Glucocorticoids
Steroid sex hormones

12. Adrenal Cortex Mineralocorticoid Glucocorticoid Steroid sex hormones
Example: aldosterone
Regulates sodium (Na+) and potassium (K+) levels
Glucocorticoid
Example: cortisol
Regulates carbohydrates
Steroid sex hormones
Androgens, estrogen, and progesterone
Regulate secondary sexual characteristics

13. Adrenal Medulla Inner portion Secretes epinephrine and norepinephrine
Epinephrine is also called adrenaline
Critical during emergency situations
Increases blood pressure
Increases heart rate
Increases respiration rate

14. Ovaries Two ovaries located in pelvic cavity of females
Secrete female sex hormones, estrogen and progesterone
Estrogen is responsible for:
Female sexual characteristics
Regulation of menstrual cycle
Progesterone
Maintains suitable uterine environment for pregnancy

15. The ovaries.

16. Pancreas Located along lower curvature of stomach
Only organ that has both endocrine and exocrine functions

17. Pancreas Exocrine portion Endocrine sections of the pancreas
Releases digestive enzymes through duct into duodenum
Endocrine sections of the pancreas
Islets of Langerhans
Produce insulin and glucagon

18. Pancreas Insulin Produced by beta cells
Stimulates cells of body to take in glucose from bloodstream
Lowers blood sugar level
Occurs after eating a meal and absorbing carbohydrates

19. Pancreas Glucagon Produced by alpha cells
Stimulates liver to release stored glucose into bloodstream
Raises blood sugar levels
Occurs when body needs more glucose

20. The pancreas.

21. Parathyroid Glands Four tiny glands
Located on dorsal surface of thyroid gland

22. Parathyroid Glands Secretes parathyroid hormone (PTH)
Regulates level of calcium in bloodstream
If calcium levels in blood fall too low:
Parathyroid hormone levels in the blood increase
Stimulate bone breakdown
Releasing more calcium into bloodstream

23. Pineal Gland Small pine cone-shaped gland
Part of thalamus region of brain
Secretes melatonin
Not well understood, but plays a role in regulating body’s circadian rhythm
24-hour clock that governs periods of wakefulness and sleepiness

24. The pineal gland is a part of the thalamus region of the brain.

25. Pituitary Gland Small marble-shaped gland Located underneath brain
Divided into anterior and posterior lobes
Regulated by hypothalamus

26. Anterior Pituitary Referred to as “master gland”
Secretes hormones that regulate other endocrine glands
Thyroid-stimulating hormone (TSH)
Regulates function of thyroid gland
Adrenocorticotropin hormone (ACTH)
Regulates function of adrenal cortex

27. Anterior Pituitary Gonadotropins FSH LH
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
FSH
Responsible for development of ova and sperm
Also stimulates ovary to secrete estrogen LH
Stimulates secretion of sex hormones
Plays a role in releasing ova in females

28. Anterior Pituitary Growth hormone (GH) Prolactin (PRL)
Also called somatotropin
Stimulates cells to grow and divide
Prolactin (PRL)
Stimulates milk production in breast
Melanocyte-stimulating hormone (MSH)
Stimulates melanocytes to produce more melanin

29. The different hormones and target tissues for the anterior pituitary.

30. Posterior Pituitary Antidiuretic hormone (ADH) Oxytocin
Also called vasopressin
Promotes water reabsorption by the kidney tubules
Oxytocin
Stimulates uterine contractions during labor and delivery
After birth stimulates release of milk from breast

31. Testes Two oval glands located in scrotum
Secrete male sex hormone, testosterone
Testosterone
Produces male secondary sexual characteristics
Regulates sperm production

32. The testes.

33. Thymus Gland Located in mediastinum Part of immune system
Also endocrine gland
Secretes thymosin

34. Thymus Gland
Thymosin
Essential for growth and development of thymic lymphocytes or T cells
Critical part of body’s immune system
Present at birth and grows to largest size during puberty
At puberty begins to shrink and eventually is replaced with connective and adipose tissue

35. The thymus gland.

36. Thyroid Gland Located on either side of trachea
Resembles a butterfly in shape
Divided into right and left lobes

37. Thyroid Gland Thyroid hormones Needs iodine to make hormones
Thyroxine (T4)
Triiodothyronine (T3)
Needs iodine to make hormones
These hormones:
Regulate energy production
Adjust metabolic rate

38. Thyroid Gland Also secretes calcitonin
Regulates level of calcium in bloodstream
If calcium levels in blood rise too high:
Calcitonin levels in blood increase
Increases deposition of calcium into bone
Lowers levels of calcium in bloodstream
Its action is opposite of parathyroid hormone

39. The thyroid gland is divided into a left and right lobe.

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PERSPECTIVE
Diabetes is one on the most commonly known diseases related to the endocrine system- do you know any one diagnosed with diabetes mellitus? They watch their insulin levels very closely.

44. Next up: nervous system
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