1. Chapter 2
The Endocrine System

2. Introduction
The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood
Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells
bloodstream to
hormones
Glands
into
secrete
target tissues

3. Hormones Endocrine glands
Ductless
Release hormones
Directly into target tissues
Into bloodstream to be carried to target tissues
Hormones – chemicals secreted by a cell that affect the functions of other cells

4. Hormones (cont.)
Many are derived from steroids that easily cross the cell membrane
Examples of steroid hormones
Estrogen
Progesterone
Testosterone
Cortisol
hormones

5. Hypothalamus Hormones
Oxytocin
Antidiuretic hormone (ADH)
Hormones transported to the posterior pituitary for storage
Directs posterior pituitary to release hormones
Glands

6. Pituitary Gland Controlled by the hypothalamus
Located at the base of the brain
Two lobes
Anterior lobe
Posterior lobe

7. Pituitary Gland (cont.)
Growth hormone
Prolactin
Stimulates milk production
Stimulates increase in size of muscles and bones
Anterior
Lobe
Thyroid-stimulating
Luteinizing
Stimulates the thyroid gland to release its hormones
Females: stimulates ovulation and estrogen production
Males: stimulates testosterone production
Follicle-stimulating
Adrenocorticotropic
Females: stimulates estrogen production and maturation of the ova
Males: stimulates sperm production
Stimulates the adrenal cortex to release its hormones

8. Pituitary Gland (cont.)
Oxytocin
Posterior
Lobe
Females: causes contraction of the uterus and ejection of breast milk
Males: stimulates contraction of the prostate and vas deferens during sexual arousal
Antidiuretic hormone (ADH)
Stimulates the kidneys to conserve water

9. Thyroid Gland and Parathyroid Glands
Located below the larynx
Divided into follicles that store some of the hormones
Major hormones
Calcitonin
Thyroid hormones
T T4
Stimulate protein synthesis and increase cellular energy production
Lowers blood calcium levels by activating osteoblasts that build new bone tissue
Glands

10. Thyroid Gland and Parathyroid Glands (cont.)
Four located on the posterior surface of the thyroid gland
Secrete parathyroid hormone (PTH)
Agonist to calcitonin by raising blood calcium levels through activation of osetoclasts (dissolve bone)
As bone dissolves, calcium levels in blood increase
Glands

11. Adrenal Glands Located on top of each kidney
Divided into the adrenal medulla and adrenal cortex
Adrenal medulla
Central portion
Hormones
Epinephrine
Norepinephrine
Same effects as sympathetic nervous system
Glands

12. Adrenal Glands (cont.) Adrenal cortex Outermost portion
Secretes many hormones, but main ones are
Aldosterone
Stimulates body to retain sodium and water
Important in maintaining BP
Cortisol
Released when stressed
Decreases protein synthesis, resulting in slowed tissue repair
Decreases inflammation

13. Pancreas Located behind the stomach
Both exocrine gland and endocrine gland
Exocrine – secretes digestive enzymes into a duct leading to the small intestine
Endocrine – secretes hormones into bloodstream
Glands

14. Pancreas (cont.) Insulin Glucagon
Islets of Langerhans secrete hormones into bloodstream
Alpha cells secrete glucagon
Beta cells secrete insulin
Insulin
Glucagon
Blood glucose concentrations
Blood glucose concentrations
Protein synthesis
Protein synthesis

15. Other Hormone-Producing Organs
Pineal body
Small gland
Located between cerebral hemispheres
Melatonin
Regulates circadian rhythms
May play a role in onset of puberty
Thymus gland
Located between lungs
Thymosin
Promotes production of T lymphocytes
Glands

16. Other Hormone-Producing Organs (cont.)
The gonads
Ovaries
Estrogen
Progesterone
Testes
Testosterone
Stomach
Gastrin
Small intestine
Secretin
Cholecystokinin
Heart
Atrial natriuretic peptide – regulates BP
Kidneys
Erythropoietin – stimulates blood cell production
Glands

17. Back
Back

18. Common Diseases and Disorders
Disease/Disorder
Description
Acromegaly
Too much growth hormone produced in adults; enlargement of bones and thickened skin
Addison’s disease
Adrenal gland fails to produce enough corticosteroids
Cretinism
Extreme form of hypothyroidism present prior to or soon after birth
Cushing’s disease
Hypercortisolism; over-production of cortisol
Diabetes insipidus
Kidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH

19. Common Diseases and Disorders (cont.)
Disease/Disorder
Description
Diabetes mellitus
Type I
Type II
Gestational
Chronic disease characterized by elevated blood glucose levels
Insulin-dependent diabetes mellitus; usually develops in childhood
Noninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens
Occurs during pregnancy; usually temporary
Dwarfism
Too little growth hormone (somatotropin) produced during childhood

20. Common Diseases and Disorders (cont.)
Disease/Disorder
Description
Gigantism
Too much growth hormone produced during childhood
Goiter
Enlargement of thyroid gland, causing swelling in neck; deficiency of iodine in diet
Grave’s disease
Hyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormone
Myxedema
Thyroid gland produces inadequate amounts of thyroid hormone; common in females over 50