Chapter 10: The Endocrine System

Essentials of human Anatomy

and PhysiologyFifth Edition

Seeley, Stephens and Tate

The Endocrine SystemThe Endocrine System

Slide 9.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Living systems require coordination and integration

Endocrine and nervous systems are the control systems of the body

Endocrine control:

Slower

Longer acting

The Endocrine SystemThe Endocrine System

Slide 9.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nervous system control (later) More rapid

Short duration

The two systems are interrelated

Act to maintain homeostasis

The Endocrine SystemThe Endocrine System

Slide 9.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Endocrine glands vs. Exocrine glandsEndocrine glands make hormones

Hormones released into blood

Circulate throughout the body

Act only at “receptor sites” ontarget cells: very specific

The Endocrine SystemThe Endocrine System

Slide 9.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones control several major processes Reproduction Growth and development Mobilization of body defenses Maintenance of much of homeostasis Regulation of metabolism

Hormone OverviewHormone Overview

Slide 9.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones (Gr. “to set in motion”) are produced by specialized cells

Blood transfers hormones to target sites

Hormones alter the physiology of other cells

The Chemistry of HormonesThe Chemistry of Hormones

Slide 9.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Amino acid-based hormones

Proteins

Peptides

Amines

Steroids – made from cholesterol

Prostaglandins – made from highly active lipids

Mechanisms of Hormone ActionMechanisms of Hormone Action

Slide 9.4Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Effects Caused by HormonesEffects Caused by Hormones

Slide 9.5Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Changes in plasma membrane permeability or electrical state

Synthesis of proteins, such as enzymes

Activation or inactivation of enzymes

Stimulation of mitosis

Steroid Hormones: Mechanism of Steroid Hormones: Mechanism of Action Action (DNA or “Gene Expression”)(DNA or “Gene Expression”)

Slide 9.6Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormones diffuse through the plasma membrane of target cells

Enter the nucleus

Bind to a specific protein within the nucleus

Steroid Hormone ActionSteroid Hormone Action

Slide 9.6Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Steroid Hormone ActionSteroid Hormone Action

Slide 9.7Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.1a

Nonsteroid Hormone Action: Nonsteroid Hormone Action: “Second Messenger System”“Second Messenger System”

Slide 9.8Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hormone binds to a membrane receptor

Hormone does not enter the cell

Sets off a series of reactions that activates an enzyme

Nonsteroid Hormone Action: Nonsteroid Hormone Action: “Second Messenger System”“Second Messenger System”

Slide 9.8Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Catalyzes a reaction that produces a second messenger molecule

Cyclic AMP (cAMP)

cAMP activates additional intracellular changes to promote a specific response

Nonsteroid Hormone ActionNonsteroid Hormone Action

Slide 9.9Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.1b

Control of Hormone ReleaseControl of Hormone Release

Slide 9.10Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Hormonal Stimuli of Endocrine Hormonal Stimuli of Endocrine GlandsGlands

Slide 9.11Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Endocrine glands are activated by other hormones

Figure 9.2a

Humoral Stimuli of Endocrine Humoral Stimuli of Endocrine GlandsGlands

Slide 9.12Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.2b

Changing blood levels of certain ions stimulate hormone release

Neural Stimuli of Endocrine GlandsNeural Stimuli of Endocrine Glands

Slide 9.13Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nerve impulses stimulate hormone release

Most are under control of the sympathetic nervous system

Figure 9.2c

Location of Major Endocrine GlandsLocation of Major Endocrine Glands

Slide 9.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.3

Pituitary GlandPituitary Gland

Slide 9.15Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Hormones of the Anterior PituitaryHormones of the Anterior Pituitary

Slide 9.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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)

Hormones of the Anterior PituitaryHormones of the Anterior Pituitary

Slide 9.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Characteristics of all anterior pituitary hormones Proteins (or peptides)

Act through second-messenger systems

Regulated by hormonal stimuli, mostly negative feedback

Hormones of the Anterior PituitaryHormones of the Anterior Pituitary

Slide 9.17Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.4

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.18Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Growth Hormone (GH)

Action: growth of skeletal muscles and long bones; maintains size

Target: bone and muscle

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.19Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Prolactin (PRL)

Action: Stimulates and maintains milk production following childbirth

Target: mammary tissue

Function in males is unknown

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.19Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Adrenocorticotropic hormone (ACTH) Action: Regulates endocrine activity of the

adrenal cortex

Target: Cells of adrenal cortex

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.19Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Thyroid-stimulating hormone (TSH) Action: Influences growth and activity of the

thyroid gland Target: cells of the thyroid gland

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.20aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Gonadotropic hormones

Target: male/female gonads

Action: Follicle-stimulating hormone (FSH)

Stimulates follicle development in ovaries

Stimulates sperm development in testes

Functions of Anterior Pituitary Functions of Anterior Pituitary HormonesHormones

Slide 9.20bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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)

Pituitary - Hypothalamus Pituitary - Hypothalamus RelationshipRelationship

Slide 9.21Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Release of hormones is controlled by the hypothalamus

Hypothalamus produces two hormones

Made by neurons

transported the posterior pituitary by neurons

Pituitary - Hypothalamus Pituitary - Hypothalamus RelationshipRelationship

Slide 9.21Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The posterior pituitary is NOT an endocrine gland Does NOT make hormones

Is NOT glandular

Only releases hormones

Hormones of the Posterior PituitaryHormones of the Posterior Pituitary

Slide 9.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Oxytocin Target: Smooth muscle of uterus, breast

Action:

stimulates contractions of the uterus during labor

causes milk ejection

Hormones of the Posterior PituitaryHormones of the Posterior Pituitary

Slide 9.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antidiuretic hormone (ADH) Target: Kidney tubules

Action:

Inhibits urine production

In large amounts, causes increased blood pressure (vasopressin)

Hormones of the Posterior PituitaryHormones of the Posterior Pituitary

Slide 9.22bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.5