ENDOCRINE SYSTEM

I. Introduction: Endocrine Glands are ductless glands that secrete hormones into the blood; controlled by the Hypothalamus.

II. Glands

A. Pituitary = Hypophysis:

1. Adenohypophysis =

a. Growth hormone (GH) - regulates mitosis & growth of body cells

b. Thyroid stimulating hormone (TSH) -

c. Adrenocorticotropic hormone (ACTH) - controls activity of adrenal cortex

d. Follicle stimulating hormone (FSH) -

e. Luteinizing hormone (LH) - Stimulates release of male & female sex hormones

f. Prolactin (PRL) –

g. Melanocyte releasing hormone (MSH)

2. Neurohypophysis = Posterior Lobe = Posterior Pituitary:

a. Oxytocin – i. causes uterine contractions during labor and milk release during suckling.

ii.

iii.

b. Antidiuretic hormone (ADH, Vasopressin) -

B. Thyroid: bilobed, just below larynx.

1. Thyroid Hormone (TH) - it increases cellular activity in skeletal,

2. Calcitonin - is released in response to increased blood calcium levels.

C. Parathyroids: 4 masses on back of thyroid. They release parathyroid hormone (PTH) in response to low calcium levels.

D. Pancreas: Hormones are secreted from Pancreatic Islets

1. Beta Cells: secrete Insulin in response to high levels of glucose.

2. Alpha Cells: secrete Glucagon in response to low levels of glucose.

E. Adrenal gland: atop kidneys; 2 areas: Cortex and Medulla

1. Cortex - secretes steroids = Corticosteroids (in response to ACTH); 3 types

a. Mineralocorticoids -

b. Glucocorticoids -

c. Gonadocorticoids – produces sex hormones (normally very little of Estrogen, Progesterone, and Testosterone)

2. Medulla - secretes Epinephrine (adrenaline) & Norepinephrine (noradrenalin),

F. Gonads

1. Testes - testosterone

2. Ovaries - estrogen & progesterone

G. Thymus: bilobed; located at tracheal bifurcation. The thymus secretes Thymosin,

Which of the following hormones is responsible for sodium and potassium balance?
a.    Glucocorticoid
b.    Mineralocorticoid
c. Parathyroid hormone (PTH)
d. Calcitonin
e.    Thyroid hormone (TH)