1. Biology, 9th ed, Sylvia Mader
Chapter 42
Chapter 42
Hormones & the Endocrine System
Hormones & the Endocrine System

2. The Human Endocrine System

3. Chemical Signals Pheromones Hormones
Chemical signals that work at a distance between individuals
A woman’s axillary extract can alter another woman’s menstrual cycle
Hormones
Chemical signals that work
At a distance between organs, or
Locally between adjacent cells

4. Target Cell Concept

5. Action of Hormones Hormones
Chemical signals produced by one cell that regulate the metabolism of other cells
Steroid Hormones
Can cross cell membranes
Peptide Hormones
Most bind to receptor in plasma membrane
First Messenger
Causes internal release of cAMP
Second Messenger

6. Peptide Hormone

7. Steroid Hormone

8. Human Endocrine System
Endocrine glands
Ductless glands that secrete hormones directly into the bloodstream
Most endocrine hormones are peptides
Only gonads and adrenal cortex produce steroid hormones
Effects of hormones are moderated in two ways
Negative feedback opposes release
Antagonistic hormones oppose each other’s actions

9. Hypothalamus and Pituitary Gland
Hypothalamus regulates internal environment
Acts through autonomic system
Also controls glandular secretions of pituitary gland
Posterior Pituitary
Antidiuretic Hormone (ADH)
Controlled by negative feedback
Oxytocin
Controlled by positive feedback
Anterior Pituitary
Hypothalamus controls by producing
Hypothalamic-releasing hormones, and
Hypothalamic-inhibiting hormones

10. Hypothalamus and the Pituitary

11. Anterior Pituitary Hormones
Anterior pituitary hormones that affect other glands:
Thyroid-Stimulating Hormone (TSH)
Adrenocorticotropic Hormone (ACTH)
Gonadotropic Hormones
Anterior pituitary hormones that do NOT affect other glands
Prolactin (PRL)
Melanocyte-Stimulating Hormone (MSH)
Growth Hormone (GH)

12. Effect of Growth Hormone

13. Acromegaly

14. Composed of large number of follicles filled with
Thyroid Glands
Composed of large number of follicles filled with
Triiodothyronine (T3), and
Thyroxine (T4)
Thyroid hormones increase metabolic rate
Thyroid-induced abnormalities
Simple goiter - Poor hormone production
Cretinism - Poor thyroid development
Myxedema - Hypothyroidism
Exophthalmic goiter - Hyperthyroidism

15. Simple Goiter

16. Cretinism

17. Regulates blood calcium level (in part)
Calcitonin
Regulates blood calcium level (in part)
Secreted by thyroid gland when blood calcium level rises
Brings about deposit of calcium in the bones
Low calcium level in blood stimulates the release of parathyroid hormone (PTH)
Parathyroid hormone causes
Phosphate level in blood to decrease, and
Calcium level in blood to increase
Insufficient production of parathyroid hormone leads to tetany

18. Regulation of Blood Calcium Level

19. Paired – One sits atop each kidney (ad-renal)
Adrenal Glands
Paired – One sits atop each kidney (ad-renal)
Each consists of outer cortex and inner medulla
Inner portion, the adrenal medulla
Produces
Epinephrine, and
Norepinephrine
Short-term response to stress (fight or flight)
Outer portion, adrenal cortex
Mineralocorticoids, and
Glucocorticoids
Long-term response to stress

20. Adrenal Glands

21. Glucocorticoids Cortisol Raises blood glucose level
Promotes breakdown of muscle proteins to amino acids
Promotes metabolism of fatty acids
Counteracts inflammatory response

22. Atrial natriuretic hormone (ANH) is antagonistic to aldosterone
Mineralocorticoids
Aldosterone
Promotes two renal functions:
Absorption of sodium, and
Excretion of potassium
Renin-angiotensin-aldosterone system
Raises blood pressure
Angiotensin II constricts arterioles
Aldosterone causes kidneys to reabsorb sodium (causing water retention)
Atrial natriuretic hormone (ANH) is antagonistic to aldosterone

23. Regulation of Blood Pressure and Volume

24. Addison Disease

25. Cushing Syndrome

26. Made up up exocrine and endocrine tissue
Pancreas
Made up up exocrine and endocrine tissue
Endocrine Portion of the Pancreas:
Consists of pancreatic islets
Produce and secrete
Insulin
Secreted during high blood glucose level
Stimulates uptake of glucose by cells
Glucagon
Secreted during low blood glucose level
Stimulates liver to break down glycogen
Exocrine Portion of the Pancreas:
Secretes enzymes and buffers into intestine

27. Regulation of Blood Glucose Level

28. Other Endocrine Glands
Gonads
Testes
Produce testosterone
Secondary sex characteristics
Ovaries
Produce estrogen and progesterone
Reproduction

29. The Effects of Anabolic Steroid Use

30. Other Endocrine Glands
Pineal Gland
Produces melatonin
Involved in Circadian rhythms
Thymus Gland
Secrete thymosins
Aid in differentiation of lymphocytes
Prostaglandins
Produced within cells
Not distributed in blood

31. Melatonin Production