1. Endocrine System
Chp 13

2. Endocrine System: Regulates body functions with Hormones
Produced by endocrine glands [e.g. pituitary]
Circulate in the blood stream
Steroids - lipid soluble
Nonsteroids - not lipid soluble
Often interact with nervous system
Act on specific cells [target cells] in the body

3. Endocrine System Characteristics
Access to every cell
Each hormone acts only on specific target cells
Target cells have receptors for specific hormones
Endocrine control slower than nervous system
Endocrine & nervous systems interact

4. Steroid Hormone Action on a Target Cell
Figure 13.2

5. Classification of Hormones: Steroid
Steroid Hormones:
Lipid soluble, chemically derived from cholesterol
Enter target cells
Activate specific genes to produce specific proteins
Slower acting than nonsteroid hormones, minutes to hours

6. Nonsteroid Hormone Action on a Target Cell
Figure 13.3

7. Classification of Hormones: Nonsteroid
Nonsteroid hormones:
Water soluble
Bind to receptors on target cell membranes
Work through intermediate mechanisms to activate existing enzymes
Faster action than steroid hormones, seconds to minutes

8. Role of Negative Feedback Loops
Figure 13.4

9. Hypothalamus and the Posterior Pituitary Gland
Connection to hypothalamus: hormones made in hypothalamus, stored in posterior pituitary
Hormones: nonsteroidal operate here
Antidiuretic hormone (ADH): conserves water in kidneys, regulates water balance in body
Oxytocin: causes uterine contractions during labor & milk ejection through neuroendocrine reflex

10. Hypothalamus & the Anterior Pituitary Gland
Connection to hypothalamus: releasing and inhibiting hormones from hypothalamus travel to pituitary through pituitary portal system
Hormones: nonsteroidal operate here
ACTH- stimulates adrenal cortex
TSH- acts on thyroid gland
FSH, LH, Prolactin- related to control of reproductive cycles and lactation
Growth Hormone- widespread effects on body

11. Pituitary Disorders Hypersecretion of ADH - excessive water retention
Diabetes Insipidus - hyposecretion of ADH, inability to conserve water appropriately
Gigantism- hypersecretion of growth hormone
Pituitary Dwarfism- hyposecretion of growth hormone

12. Pancreas: Endocrine Functions include
Hormones secreted by islets of Langerhans are
Nonsteroidal:
Glucagon - raises blood sugar
Insulin- lowers blood sugar

13. Roles of Insulin and Glucagon in Regulating Blood Glucose
Figure 13.9

14. Adrenal Glands: 2 small endocrine glands located just above kidneys
Adrenal cortex - secretes steroid hormones
Produces small amounts of estrogen & testosterone
Produces:
Cortisol [regulates blood glucose]
Aldosterone [regulates sodium & potassium]

15. Adrenal Glands: Medulla
Adrenal medulla- secretes nonsteroid hormones
Secretion: stimulated by sympathetic nervous system
Nonsteroidal hormones that control metabolism, blood pressure & heart rate
Epinephrine [adrenaline]
Norepinephrine
They both enhance function of sympathetic
nervous system (Fight or Flight Response)

16. Thyroid Gland
Secretion: mediated through hypothalamus-pituitary secretions
Secretes Steroidal hormones:
Thyroxine (T4) and Triiodothyronine (T3) - both regulate production of ATP from glucose, affects metabolic rate
Calcitonin: lowers blood calcium levels

17. Parathyroid Glands Secretion: response to lowered blood calcium levels
Hormone: Parathyroid hormone (PTH), nonsteroidal
Removes calcium and phosphate from bone
Increases absorption of calcium by the digestive tract
Increases renal retention of calcium and excretion of phosphate

18. Testes Hormone secreted = Testosterone (steroidal) Functions:
Regulates development and normal functioning of sperm, male reproductive organs, male sex drive
Development of male secondary sex characteristics

19. Ovaries Hormones (steroidal) & functions:
Estrogen- initiates development of secondary sex characteristics, regulates menstrual cycle
Progesterone - regulates menstrual cycle

20. Other Chemical Messengers
Histamine - inflammation
Prostaglandins - local control of blood flow
Growth factors - local acting/ mitotic activity

21. Disorders of the Endocrine System
Thyroid Disorders:
Hypothyroidism - underactivity of thyroid
Children: slows body growth, brain development & delays puberty
Adults: causes edema, weight gain, lethargy, low body temp.
Hyperthyroidism: [Graves Disease]
Overactive thyroid
Causes- Increased BMR, hyperactivity, nervousness, weight loss

22. Adrenal Gland Disorders:
Addison’s Disease: failure of adrenal cortex to secrete sufficient cortisol & aldosterone
Lowers blood glucose & sodium
Symptoms: Chronic fatigue, weakness, weight loss & abdominal pain
Cushing’s Syndrome: excessive cortisol produced
High blood glucose & reduced muscle mass
Retension of too much salt & water
Symptoms: weakness & fatigue, edema, high blood pressure