Chapter 33: The Endocrine System

secrete hormones directly into the interstitial fluid; Ductless glands; Secrete hormones

diffuse into the bloodstream through capillaries and are carried to target cells throughout the body

Cells throughout the body

• change plasma membrane permeability and/or membrane potential by opening or closing ion channels

• synthesis of proteins

• activate or deactivate enzymes; stimulate secretory activity

• Stimulates mitosis

released in direct response to changing blood levels of ions/nutrients

released in response to hormones produced by other endocrine glands

released in response to nerve impulses

Located inferior to the hypothalamus

anterior pituitary secretes hormones that stimulate activity of various effector organs; the effector organ activity acts as negative feedback to control hypothalamic and pituitary secretion

Growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), Prolactin (PRL)

GH deficiency in children; slowed growth of long bones; normal body proportions

hypersecretion of GH in children; abnormally tall; normal body proportions

hypersecretion of GH in adults; enlargement/thickening of bony areas; coarse/malformed facial features

Inferior to the thalamus; part of the limbic system

releasing hormones that control anterior pituitary hormone secretion

Oxytocin and Antidiuretic Hormone

oxytocin; anti-diuretic hormone (ADH); inhibited by ethanol; diabetes insipidus; * large outputs of urine and excessive thirst; * deficient ADH release

Butterfly-shaped gland found lateral to the upper trachea & inferior to the larynx

Releases T3 and T4 hormones; Releases Calcitonin

thyroid follicle cells (follicular cells)

enlarged thyroid due to insufficient iodine

severe hypothyroidism in children

severe hypothyroidism in adults

hyperthyroidism; autoimmune disease

parafollicular cells

Located on the posterior aspect of each lobe of the thyroid gland

Releases calcitonin to regulate calcium

Increases Blood Ca2+ and Mg2+ levels and decreases blood HPO42- level; Increases bone resorption by osteoclasts; Increases Ca2+ reabsorption and HPO42- excretion by kidneys; Promotes formation of calcitriol (active form of Vitamin D), increases rate of dietary Ca2+ and Mg2+ absorption

Located on top of each kidney

Secretes Corticosteroids and Catecholamines

Mineralocorticoids, Corticosteroids, Gondacortoids

Aldosterone

Cortisol

hyposecretion of glucocorticoids & mineralocorticoids

hypersecretion of glucocorticoids

• androgens and estrogens

• probably contribute to the onset of puberty

• adrenal androgens in adult females → source of sex drive → possibly converted to estrogen after menopause

Catecholamines - Epinephrine/Norepinephrine (EPI/NE)

on the curve of the duodenum

secretes insulin and glucagon

beta cells

hyposecretion or hypoactivity of insulin

alpha cells

Fallopian tubes of the uterus

Releases Estrogen and Progestins

estrone and estradiol

prepares the uterus for implantation of a fertilized egg

progesterone

promotes further thickening of the uterine wall

Scrotum

Releases Andregoens

testosterone

produces and maintains secondary male characteristics such as facial hair

Attached to the roof of the third ventricle of the brain

secretes melatonin

resets the body’s biological clock

located inferior to the thyroid gland in the thoracic cavity posterior to the sternum

Produces hormones to promote maturation of the immune system’s T-Cells

Thymosin, Thymic Humoral Factor (THF), Thymic Factor (TF), Thymopoietin

Essential in the development and maturation of the immune system; Removal of the gland during early childhood result in greater susceptibility to acute infections