CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 30 The Endocrine System

CHAPTER

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.

30The Endocrine

System


30-2

Learning Outcomes

30.1 Define the term endocrine glands.

30.2 Describe the general functions of the endocrine system.

30.3 Define the term hormone.

30.4 Explain the difference in hormone control by positive and negative feedback loops.


30-3

Learning Outcomes (cont.)

30.5 Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads.

30.6 List the hormones released by the pituitary gland and give the functions of each.

30.7 List the hormones released by the thyroid gland and parathyroid glands and give the functions of each.


30-4


30.8 List the hormones released by the adrenal glands and give the functions of each.

30.9 List the names of the endocrine cells of the pancreas, the hormones released by them, and the function of each hormone.

30.10 List the hormones released by the pineal body, thymus, and gonads, and give the functions of each.


30-5


30.11 Name the hormones produced by the kidneys and heart, listing which organ produces the hormone, and the hormone’s function.

30.12 Describe stressors and their effect on the body.

30.13 Describe the causes, signs and symptoms, and treatment of various endocrine disorders.


30-6

target tissues

Introduction

• The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood– Regulates chemical reaction in cells and therefore

control functions of the organs, tissues, and other cells

Glandssecrete

hormones

into

bloodstream

to


30-7

Hormones

• Endocrine glands – Ductless– Release hormones

• Directly into target tissues• Into bloodstream to be carried to target tissues

• Hormones – chemicals secreted by a cell that affect the functions of other cells


30-8

Hormones (cont.)

• Many are derived from steroids that easily cross the cell membrane

• Examples of steroidal hormones– Estrogen– Progesterone– Testosterone– Cortisol Hormones


30-9

Hormones (cont.)

• Nonsteroidal hormones– Made of amino acids or

proteins and cannot cross the cell membrane easily

– Bind to receptors on the surface of the cells

– G-protein – activated by the hormone-receptor complex

• Activates enzymes inside cell

• Prostaglandins– Local, or tissue, hormones– Derived from lipid

molecules– Do not travel in the

bloodstream– Target tissues are located

close by– Produced by organs such

as• Kidneys• Heart• Stomach • Uterus• Brain


30-10

Feedback Loops

• Control hormone levels

• Negative feedback loop– Hormone release stops in response to

decrease in stimulus• Stimulus (eating) raises blood glucose levels• Pancreas releases insulin in response to elevated

blood glucose• Blood glucose decreases as it is used by the body

or stored in the liver• Insulin release stops as blood glucose levels

normalize


30-11

Feedback Loops (cont.)

• Positive feedback loop– As long as stimulus is present, action of

hormone continues• Infant nursing at mother’s breast stimulates

hypothalamus stimulates posterior pituitary• Oxytocin released stimulates milk production

and ejection from mammary glands• Milk release continues as long as infant continues

to nurse


30-12

Apply Your Knowledge

Match the following:

___ Chemicals that effect cell function A. Nonsteroidal hormone

___ Easily cross cell membranes B. Steroidal hormone

___ Made of amino acids C. G-protein

___ Target nearby cells D. Prostaglandins

___ Activated by hormone-receptor E. Hormones complex

___ Cannot cross cell membranes easily

___ Estrogen and cortisol

B

A

D

C

A

B

E

ANSWER:


30-13

Hypothalamus

• Hormones– Oxytocin– Antidiuretic hormone (ADH)

• Hormones transported to the posterior pituitary for storage

• Directs posterior pituitary to release hormones

Glands


30-14

Pituitary Gland

• Controlled by the hypothalamus• Located at the base of the brain

– Protected by a bony structure called the sella turcica – The optic chiasm is located just above the pituitary

gland• Carries visual information to the brain for interpretation

• Two lobes– Anterior lobe– Posterior lobe

Glands

Pituitary Gland


30-15

AnteriorLobe

Growth hormone Prolactin

Adrenocorticotropic (ACTH)

Thyroid-stimulating (TSH)

Follicle-stimulating

Luteinizing

Stimulates milk production

Stimulates the adrenal cortex to release its hormones

Stimulates the thyroid gland to release its hormones

Females: stimulates estrogen production and maturation of the ovaMales: stimulates sperm production

Females: stimulates ovulationand estrogen productionMales: stimulates testosterone production

Pituitary Gland (cont.)

Stimulates increase in size of muscles and bones


30-16

PosteriorLobe

PosteriorLobe

Antidiuretic hormone (ADH)

Oxytocin

Stimulates the kidneys to conserve water

Females: causes contraction of the uterus and ejection of breast milkMales: stimulates contraction of the prostate and vas deferens during sexual arousal

Pituitary Gland (cont.)


30-17



___ Stored in posterior pituitary A. Follicle-stimulating hormone

___ Milk production B. Prolactin

___ Produced by hypothalamus C. Luteinizing hormone

___ Stimulates sperm production D. ADH

___ Maturation of ova E. Oxytocin

___ Stimulates ovulation

___ Conservation of water

___ Production of testosterone

___ Contraction of uterusE

D

B

D, E

C

A

A

C

D, E

ANSWER:

Super!


30-18

T3 T4

Thyroid Gland

Located below the larynx Divided into follicles that store some of the hormones

Major hormones

Stimulate protein synthesis and increase cellular energy production

Lowers blood calcium levels by activating osteoblasts that build new bone tissue

Glands


30-19

Parathyroid Glands

• Four located on the posterior surface of the thyroid gland

• Secrete parathyroid hormone (PTH)– Agonist to calcitonin by raising blood calcium

levels through activation of osteoclasts (dissolve bone)

• As bone dissolves, calcium levels in blood increase

Glands


30-20


True or False:

__ Thyroid hormones stimulate protein synthesis.

__ The thyroid gland does not store hormones.

__ PTH activates osteoblasts.

__ Calcitonin increases cellular energy production.

__ The four parathyroid glands are located on the thyroid gland.

__ Calcitonin lowers blood calcium levels.

F

F

F

T

T

T

ANSWER:

PTH activates osteoclasts.

Thyroid hormone increases cellular energy production.

Thyroid follicles store some hormones.


30-21

Adrenal Glands

• Located on top of each kidney• Divided into the adrenal medulla and

adrenal cortex• Adrenal medulla

– Central portion– Hormones

• Epinephrine • Norepinephrine• Same effects as sympathetic nervous

system Glands


30-22

Adrenal Glands (cont.)

• Adrenal cortex– Outermost portion– Secretes many hormones, but main ones are

• Aldosterone– Stimulates body to retain sodium and water– Important in maintaining BP

• Cortisol – Released when stressed– Decreases protein synthesis, resulting in slowed tissue

repair– Decreases inflammation


30-23



____ Adrenal medulla A. Cortisol

____ Sodium retention B. Epinephrine

____ Decreases inflammation C. Aldosterone

____ Sympathetic effects D. Norepinephrine

____ Maintains blood pressure

____ Released during stress

____ Adrenal cortexA, C

B, D

A

C

A

C

B, D

ANSWER:

Excellent!


30-24

Pancreas

• Located behind the stomach

• Both exocrine gland and endocrine gland– Exocrine – secretes

digestive enzymes into a duct leading to the small intestine

– Endocrine – secretes hormones into bloodstream

Glands


30-25

Pancreas (cont.)

• Islets of Langerhans secrete hormones into bloodstream– Alpha cells secrete glucagon– Beta cells secrete insulin

Blood glucose concentrations

Protein synthesis

Blood glucose concentrations

Protein synthesis


30-26


What are the effects of insulin and glucagon?

ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis.

Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis.

Yippee!


30-27

Other Hormone-Producing Organs

• Pineal body– Small gland– Located between

cerebral hemispheres

– Melatonin• Regulates circadian

rhythms• May play a role in

onset of puberty

• Thymus gland– Located between

lungs– Thymosin

• Promotes production of T lymphocytes

Glands


30-28

Other Hormone-Producing Organs (cont.)

• The gonads– Ovaries

• Estrogen• Progesterone

– Testes • Testosterone

• Stomach– Gastrin

• Small intestine– Secretin– Cholecystokinin

• Heart – Atrial natriuretic

peptide – regulates BP

• Kidneys – Erythropoietin –

stimulates blood cell production

Glands


30-29

BackBack


30-30



___ Between lungs A. Pineal body

___ Melatonin B. Heart

___ Estrogen/testosterone C. Kidneys

___ Gastrin D. Thymus gland

___ Secretin E. Small intestine

___ Erythropoietin F. Stomach

___ Atrial natriuretic peptide G. Gonads

___ Thymosin

___ Cholecystokinin

C

E

F

G

A

E

D

B

D

ANSWER:


30-31

The Stress Response

• Stressor – Any stimulus that

produces stress– Types

• Physical factors • Psychological factors• Positive stimuli


30-32

The Stress Response (cont.)

• Physiologic response to stress caused by hormone release– General stress syndrome

• Increased heart rate, respiratory rate, and BP• Increase in glucose and fatty acids in blood, which

leads to weight loss• Increase in cortisol if stress prolonged

– Decreased body repair– Susceptibility to illness


30-33



___ Extreme heat A. Physical stress

___ Death of friend B. Psychological stress

___ Fractured leg C. Positive stimulus

___ Wedding

___ Exam

___ Hearing an explosion nearby

___ “A” on an exam

___ Flu

___ Car stolen

B

B

B

A

A

C

B

C

A

ANSWER:


30-34

Common Diseases and Disorders

Disease/Disorder Description

Acromegaly Too much growth hormone produced in adults; enlargement of bones and thickened skin

Addison’s disease Adrenal gland fails to produce enough corticosteroids

Cretinism Extreme form of hypothyroidism present prior to or soon after birth

Cushing’s disease Hypercortisolism; over-production of cortisol

Diabetes insipidus Kidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH


30-35

Common Diseases and Disorders (cont.)


Diabetes mellitus

Type I

Type II

Gestational

Chronic disease characterized by elevated blood glucose levelsInsulin-dependent diabetes mellitus; usually develops in childhood

Noninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens

Occurs during pregnancy; usually temporary

Dwarfism Too little growth hormone (somatotropin) produced during childhood


30-36

Common Diseases and Disorders (cont.)


Gigantism Too much growth hormone produced during childhood

Goiter Enlargement of thyroid gland, causing swelling in neck; deficiency of iodine in diet

Graves’ disease Hyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormone

Myxedema Thyroid gland produces inadequate amounts of thyroid hormone; common in females over 50


30-37


True or False:

___ Acromegaly develops as a result of too much growth hormone in a

child.

___ In diabetes insipidus, the kidneys fail to reabsorb water.

___ Too little growth hormone in childhood results in dwarfism.

___ Myxedema is the result of hyperthyroidism.

___ Addison’s disease is the result of too little corticosteroid.

___ Cushing’s disease is the result of too little ACTH.

___ Cretinism is an extreme form of hyperthyroidism present at birth.F

T

T

T

F

F

ANSWER:

F

hypothyroidism

too much ACTH

hypothyroidism

in an adult

Correct!


30-38

In Summary

30.1Endocrine glands are ductless glands, releasing hormones directly into the bloodstream and tissues.

30.2The organs of the endocrine system produce hormones that regulate the chemical reactions within cells, controlling the functions of organs, tissues, and other cells.

30.3Hormones are chemicals released by cells that affect the functioning of other cells.


30-39

In Summary (cont.)

30.4 In a negative feedback loop, a stimulus causes a body reaction, which is detected by another area of the body, which stops the reaction. The rise in blood sugar causing the pancreas to release insulin to lower blood sugar is an example. In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the suckling releases milk from the mother’s breast until the suckling stops.


30-40

In Summary (cont.)

30.5The hypothalamus, pituitary, and pineal glands are located within the brain. The thyroid and parathyroid glands are located in the neck. The thymus is found in the mediastinum. The adrenal glands are located above each kidney, and the pancreas is located behind the stomach. In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac.


30-41

In Summary (cont.)

30.6The pituitary gland releases the following hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT. Each hormone’s specific function may be found in Table 30-1.

30.7The thyroid gland releases calcitonin, T3, and T4 which are important in growth and protein synthesis. The parathyroid releases PTH which balances the action of calcitonin.


30-42

In Summary (cont.)

30.8The adrenal medulla secretes epinephrine and norepinephrine, which work with the sympathetic nervous system. The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP maintenance and cortisol, which decreases inflammation.

30.9The endocrine cells of the pancreas are known as the Islets of Langerhans. The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release insulin.


30-43

In Summary (cont.)

30.10The pineal body releases melatonin to regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone.

30.11The kidneys produce erythropoietin, affecting the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP.


30-44

In Summary (cont.)

30.12Stressors are defined as stimuli that produce a stress response, a physiologic response to the stimulus that changes the body’s functioning in some way.

30.13 The diseases and disorders of the endocrine system are as varied as the organs and hormone dysfunctions that cause them. An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter.


30-45

End of Chapter 30

Its not stress that kills us,

it is our reaction to it.

~ Hans Selye

Documents

CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 30 The Endocrine System