FUNCTIONS OF THE ENDOCRINE SYSTEM AND MAJOR ENDOCRINE

FUNCTIONS OF THE ENDOCRINE SYSTEM AND MAJOR ENDOCRINE ORGANS: HYPOTHALAMUS AND PITUITARY Pages 312 -317

© 2015 Pearson Education, Inc. THE ENDOCRINE SYSTEM A control system of the body By way of hormones (chemical messengers) that are released directly into the blood Hormones like: control and/or assist processes Reproduction Growth and development Mobilization of body defenses Homeostasis Metabolism

© 2015 Pearson Education, Inc. MAJOR ENDOCRINE ORGANS Pituitary gland Hypothalamus Thyroid gland Parathyroid glands Adrenal glands Pancreas Pineal gland Thymus gland Gonads (ovaries and testes)

FIGURE 9. 3 LOCATION OF THE MAJOR ENDOCRINE ORGANS OF THE BODY. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal glands Pancreas Ovary (female) Testis (male)

© 2015 Pearson Education, Inc. FEATURES OF MAJOR ENDOCRINE ORGANS Some are purely endocrine glands (ductless) Hormones Anterior are secreted directly into the blood pituitary, thyroid, adrenals, parathyroids Other glands are mixed glands, with both endocrine and exocrine functions Exocrine glands dump into ducts pancreas, gonads

© 2015 Pearson Education, Inc. PITUITARY GLAND Referred About to as the “master endocrine gland” the size of a pea Hangs from the hypothalamus in the brain Has two functional lobes Anterior pituitary—glandular tissue Produces Posterior releases hormones pituitary—nervous tissue hormones after neural stimulation

© 2015 Pearson Education, Inc. HYPOTHALAMUS produces releasing and inhibiting hormones These influence pituitary action Such hormones are released into circulation that connects the hypothalamus to the anterior pituitary Synthesizes oxytocin two hormones: and antidiuretic hormone Stored in posterior pituitary

FIGURE 9. 4 HORMONES RELEASED BY THE POSTERIOR LOBE OF THE PITUITARY AND THEIR TARGET ORGANS. Optic chiasma Axon terminals Hypothalamic neurosecretory cells Hypothalamus Arterial blood supply Anterior lobe of the pituitary Posterior lobe of pituitary Capillary bed Venous drainage Hormones produced by the hypothalamus are released into blood by nerve impulses ADH Oxytocin Kidney tubules Mammary glands Uterine muscles

© 2015 Pearson Education, Inc. THE HYPOTHALAMUS-POSTERIOR PITUITARY RELATIONSHIP The posterior pituitary stores hormones synthesized by the hypothalamus Oxytocin Stimulates uterine contractions Causes milk ejection in a breastfeeding woman Antidiuretic Inhibits hormone (ADH) urine production (diuresis) promotes water reabsorption by the kidneys

© 2015 Pearson Education, Inc. HORMONES OF THE ANTERIOR PITUITARY Six anterior pituitary hormones endocrine 1. 2. 3. 4. targets (tropic hormones): Thyroid-stimulating hormone (thyrotropic hormone) Adrenocorticotropic hormone Follicle-stimulating hormone Luteinizing hormone nonendocrine 1. 2. targets: Growth hormone Prolactin

© 2015 Pearson Education, Inc. HORMONES OF THE ANTERIOR PITUITARY Characteristics of all anterior pituitary hormones They are proteins Use a second-messenger systems Regulated by hormonal stimuli Regulated by feedback inhibition (most often negative)

FIGURE 9. 5 HORMONES OF THE ANTERIOR PITUITARY AND THEIR MAJOR TARGET ORGANS. Releasing hormones secreted into portal circulation Hypothalamus Anterior pituitary Posterior pituitary Adrenocorticotropic hormone (ACTH) Growth hormone (GH) Bones and muscles Prolactin (PRL) Follicle-stimulating hormone (FSH) and luteinizing Mammary hormone (LH) glands Testes or ovaries Thyrotropic hormone (TH) Thyroid Adrenal cortex

© 2015 Pearson Education, Inc. ANTERIOR PITUITARY HORMONE FUNCTION Growth growth hormone (GH) of skeletal muscles and long bones Prolactin (PRL) Stimulates/maintains breast milk production Adrenocorticotropic Regulates endocrine activity of the adrenal cortex Thyrotropic A. K. A. hormone (ACTH) hormone (TH), thyroid-stimulating hormone (TSH) Influences growth and activity of the thyroid gland

© 2015 Pearson Education, Inc. Gonadotropic Regulate hormones hormonal activity of the gonads Follicle-stimulating Stimulates follicle development in ovaries Stimulates sperm development in testes Luteinizing hormone (FSH) hormone (LH) Triggers ovulation of an egg in females Stimulates testosterone production in males