Chapter 10: The Endocrine System Essentials of human Anatomy and Physiology Fifth Edition Seeley, Stephens and Tate Chapter 10: The Endocrine System

The Endocrine System Living systems require coordination and integration Endocrine and nervous systems are the control systems of the body Endocrine control: Slower Longer acting Slide 9.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Endocrine System Nervous system control (later) More rapid Short duration The two systems are interrelated Act to maintain homeostasis Slide 9.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Endocrine System Endocrine glands vs. Exocrine glands Endocrine glands make hormones Hormones released into blood Circulate throughout the body Act only at “receptor sites” on target cells: very specific Slide 9.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Endocrine System Hormones control several major processes Reproduction Growth and development Mobilization of body defenses Maintenance of much of homeostasis Regulation of metabolism Slide 9.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormone Overview Hormones (Gr. “to set in motion”) are produced by specialized cells Blood transfers hormones to target sites Hormones alter the physiology of other cells Slide 9.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Chemistry of Hormones Amino acid-based hormones Proteins Peptides Amines Steroids – made from cholesterol Prostaglandins – made from highly active lipids Slide 9.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Mechanisms of Hormone Action Hormones affect only certain tissues or organs (target cells or organs) Target cells must have specific protein receptors Hormone binding influences the function of the cells Slide 9.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Effects Caused by Hormones Changes in plasma membrane permeability or electrical state Synthesis of proteins, such as enzymes Activation or inactivation of enzymes Stimulation of mitosis Slide 9.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Steroid Hormones: Mechanism of Action (DNA or “Gene Expression”) Hormones diffuse through the plasma membrane of target cells Enter the nucleus Bind to a specific protein within the nucleus Slide 9.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Steroid Hormone Action Hormone-protein complex binds to a specific site on the cell’s DNA Activates genes that result in synthesis of new proteins New protein influences cell function Slide 9.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Steroid Hormone Action Figure 9.1a Slide 9.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nonsteroid Hormone Action: “Second Messenger System” Hormone binds to a membrane receptor Hormone does not enter the cell Sets off a series of reactions that activates an enzyme Slide 9.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nonsteroid Hormone Action: “Second Messenger System” Catalyzes a reaction that produces a second messenger molecule Cyclic AMP (cAMP) cAMP activates additional intracellular changes to promote a specific response Slide 9.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nonsteroid Hormone Action Figure 9.1b Slide 9.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Control of Hormone Release Hormone levels in the blood are maintained by negative feedback A stimulus (like low hormone levels in the blood) triggers the release of more hormone Hormone release stops once an appropriate level in the blood is reached Slide 9.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormonal Stimuli of Endocrine Glands Endocrine glands are activated by other hormones Figure 9.2a Slide 9.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Humoral Stimuli of Endocrine Glands Changing blood levels of certain ions stimulate hormone release Figure 9.2b Slide 9.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neural Stimuli of Endocrine Glands Nerve impulses stimulate hormone release Most are under control of the sympathetic nervous system Figure 9.2c Slide 9.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Location of Major Endocrine Glands Figure 9.3 Slide 9.14 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pituitary Gland Size of a grape Hangs by a stalk from the hypothalamus Protected by the sphenoid bone (what part??) Has two functional lobes Anterior pituitary – glandular tissue Posterior pituitary – nervous tissue Slide 9.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Anterior Pituitary Six anterior pituitary hormones Two affect non-endocrine targets Four stimulate other endocrine glands (tropic [“tropic” = “feeding”] hormones) All six are secreted by the anterior pituitary (glandular tissue) Slide 9.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Anterior Pituitary Characteristics of all anterior pituitary hormones Proteins (or peptides) Act through second-messenger systems Regulated by hormonal stimuli, mostly negative feedback Slide 9.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Anterior Pituitary Figure 9.4 Slide 9.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Growth Hormone (GH) Action: growth of skeletal muscles and long bones; maintains size Target: bone and muscle Slide 9.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Prolactin (PRL) Action: Stimulates and maintains milk production following childbirth Target: mammary tissue Function in males is unknown Slide 9.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Adrenocorticotropic hormone (ACTH) Action: Regulates endocrine activity of the adrenal cortex Target: Cells of adrenal cortex Slide 9.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Thyroid-stimulating hormone (TSH) Action: Influences growth and activity of the thyroid gland Target: cells of the thyroid gland Slide 9.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Gonadotropic hormones Target: male/female gonads Action: Follicle-stimulating hormone (FSH) Stimulates follicle development in ovaries Stimulates sperm development in testes Slide 9.20a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of Anterior Pituitary Hormones Gonadotropic hormones (continued) Luteinizing hormone (LH) Action: Triggers ovulation in females Causes ruptured follicle to become the corpus luteum in females Stimulates testosterone production in males (ICSH) Slide 9.20b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pituitary - Hypothalamus Relationship Release of hormones is controlled by the hypothalamus Hypothalamus produces two hormones Made by neurons transported the posterior pituitary by neurons Slide 9.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pituitary - Hypothalamus Relationship The posterior pituitary is NOT an endocrine gland Does NOT make hormones Is NOT glandular Only releases hormones Slide 9.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Posterior Pituitary Oxytocin Target: Smooth muscle of uterus, breast Action: stimulates contractions of the uterus during labor causes milk ejection Slide 9.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Posterior Pituitary Antidiuretic hormone (ADH) Target: Kidney tubules Action: Inhibits urine production In large amounts, causes increased blood pressure (vasopressin) Slide 9.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones of the Posterior Pituitary Figure 9.5 Slide 9.22b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings