Chapter 26 Hormones and the Endocrine System...pituitary, connects the nervous and endocrine systems The hypothalamus –Blurs the distinction between endocrine and nervous systems

Copyright © 2009 Pearson Education, Inc.

PowerPoint Lectures for

Biology: Concepts & Connections, Sixth Edition

Campbell, Reece, Taylor, Simon, and Dickey

Chapter 26 Hormones and the

Endocrine System

Lecture by Edward J. Zalisko


Introduction: Gender Benders

Endocrine disruptors

– Environmental pollutants

– Interfere with the action of hormones

– Some are estrogen mimics in the environment that may produce

– Demasculinized male alligators

– Bass with male and female characteristics

– Decrease in size and functioning of polar bear genitalia


THE NATURE OF CHEMICAL REGULATION


26.1 Chemical signals coordinate body functions

Hormones

– Chemical signals

– Usually carried in the blood

– Cause specific changes in target cells

– Secreted by

– Endocrine glands

– Neurosecretory cells

Secretoryvesicles

Targetcell

Bloodvessel

Hormonemolecules

Endocrine cell

Hormonemolecules

Targetcell

Bloodvessel

Neurosecretorycell



The endocrine system

– Consists of all hormone-secreting cells

– Works with nervous system to regulate body activities



The nervous system also

– Communicates

– Regulates

– Uses electrical signals via nerve cells



Comparing the endocrine and nervous systems

– Nervous system reacts faster

– Endocrine system responses last longer

Neurotransmittermolecules

Nervecell

Nervecell

Nervesignals


26.2 Hormones affect target cells by two main signaling mechanisms

Hormone signaling involves three key events

– Reception

– Signal Transduction

– Response



Amino-acid-derived hormones

– Are water-soluble

– Include proteins, peptides, and amines

– Bind to plasma-membrane receptors on target cells

– Initiate a signal transduction pathway

Animation: Water-Soluble Hormone

26_02AWaterSolubleHorm_A.html

26_02AWaterSolubleHorm_A.html

Plasmamembrane

Receptorprotein

Water-soluble

hormone

(epinephrine) 1

Target

cell

Plasmamembrane

Receptorprotein

Water-soluble

hormone

(epinephrine)

2

Signaltransductionpathway

Relaymolecules

1

Target

cell

Plasmamembrane

Receptorprotein

Target

cell

Water-soluble

hormone

(epinephrine) 1

2


Relaymolecules

Glycogen Glucose

Cellular response(in this example, glycogen breakdown)

3



Steroid hormones

– Nonpolar lipids made from cholesterol

– Can diffuse through plasma membranes

– Bind to a receptor protein in the cytoplasm or nucleus

– Hormone-receptor complex carries out the transduction of the hormonal signal

Animation: Lipid-Soluble Hormone

26_02BLipidSolubleHorm_A.html

26_02BLipidSolubleHorm_A.html

Lipid-soluble

hormone

(testosterone)

Targetcell

Nucleus

1

Lipid-soluble

hormone

(testosterone) 1

Targetcell

Nucleus

Receptorprotein

2

Lipid-soluble

hormone

(testosterone) 1

Targetcell

Nucleus

Receptorprotein

2

DNA

Hormone-receptorcomplex

3

Lipid-soluble

hormone

(testosterone) 1

Targetcell

Nucleus

Receptorprotein

2

DNA


3

mRNATranscription

Newprotein

Cellular response:activation of a gene and

synthesis of new protein

4


THE VERTEBRATE ENDOCRINE SYSTEM


26.3 Overview: The vertebrate endocrine system consists of more than a dozen major glands

The vertebrate endocrine system

– Consists of more than a dozen glands

– Secretes more than 50 hormones


Glands

– Some are specialized for hormone secretion only

– Some also do other jobs


Hypothalamus

Parathyroid glands

Pineal gland

Pituitary gland

Thyroid gland

Thymus

Adrenal glands(atop kidneys)

Pancreas

Ovary(female)

Testes(male)


Hormones

– Some have a very narrow range of targets and effects

– Some have numerous effects on many kinds of target cells



26.4 The hypothalamus, which is closely tied to the pituitary, connects the nervous and endocrine systems

The hypothalamus

– Blurs the distinction between endocrine and nervous systems

– Receives input from nerves about body conditions

– Responds by sending out appropriate nervous or endocrine signals

– Uses the pituitary gland to exert master control over the endocrine system



The pituitary gland consists of two parts

– Posterior pituitary

– Composed of nervous tissue

– Stores and secretes oxytocin and ADH

Brain

Hypothalamus

Posterior pituitary

Anterior pituitary

(Bone)

Hypothalamus

Posteriorpituitary

Anteriorpituitary

Hormone Neurosecretorycell

Bloodvessel

Oxytocin ADH

Kidney tubulesUterine musclesMammary glands



Anterior pituitary

– Synthesizes and secretes hormones that control the activity of other glands

– Is controlled by the hypothalamus

– Releasing hormones stimulate the anterior pituitary

– Inhibiting hormones inhibit the anterior pituitary

Endocrine cells ofthe anterior pituitary

Pituitary hormones

Releasing hormones

from hypothalamus

Neurosecretorycell

Blood

vessel

FSHandLH

TSH ACTH Prolactin

(PRL)

Growthhormone

(GH)

Endorphins

Thyroid Adrenal

cortex

Testes or

ovaries

Mammary

glands

(in mammals)

Entire

body

Pain

receptors

in the brain

TSH

TRH

Hypothalamus

Anteriorpituitary

Thyroid

Thyroxine

Inhibition

Inhibition


HORMONES AND HOMEOSTASIS


26.5 The thyroid regulates development and metabolism

Thyroid gland hormones

– Thyroxine (T4) and triiodothyronine (T3)

– Regulate

– Metabolism

– Development

– Negative feedback

– Maintain homeostatic levels of T4 and T3 in the blood

No inhibition

No iodine

No inhibition

InsufficientT4 and T3

produced

Hypothalamus

Anteriorpituitary

Thyroid

Thyroid growsto form goiter

TRH

TSH


26.5 The thyroid regulates development and metabolism

Thyroid imbalance can cause disease

– Hyperthyroidism

– Too much T4 and T3 in the blood

– Leads to high blood pressure, loss of weight, overheating, and irritability

– Produces Graves’ disease

– Hypothyroidism

– Too little T4 and T3 in the blood

– Leads to low blood pressure, overweight, often cold, lethargy


26.6 Hormones from the thyroid and parathyroids maintain calcium homeostasis

Blood calcium level is regulated by a tightly balanced antagonism between

– Calcitonin from the thyroid

– Parathyroid hormone (PTH) from the parathyroid glands

Calcitonin

87

6

5

4

32

1

9

Thyroid

gland

releases

calcitonin

Stimulus:

Rising

blood Ca2+

level

(imbalance)

Blood Ca2+ rises

Ca2+

level

Ca2+

level

Homeostasis: Normal blood

calcium level (about 10 mg/100 mL)Stimulus:

Falling

blood Ca2+

level

(imbalance)

Blood Ca2+ falls

Stimulates

Ca2+ deposition

in bones

Reduces

Ca2+ uptake

in kidneys

PTH

StimulatesCa2+ releasefrom bones

IncreasesCa2+ uptakein intestines

Activevitamin D

IncreasesCa2+ uptakein kidneys

Parathyroidglandsrelease parathyroidhormone (PTH)

Parathyroid

gland

5

4

32

1

Blood Ca2+ rises

Ca2+

level

Ca2+

level


calcium level (about 10 mg/100 mL)Stimulus:

Falling

blood Ca2+

level(imbalance)

PTH

StimulatesCa2+ releasefrom bones

Increases

Ca2+ uptakein intestines

Activevitamin D

IncreasesCa2+ uptakein kidneys

Parathyroid

glands

release parathyroid

hormone (PTH)

Parathyroid

gland

Calcitonin

87

6

9

Thyroidglandreleasescalcitonin

Stimulus:Risingblood Ca2+

level(imbalance)

Ca2+

level

Ca2+

level


calcium level (about 10 mg/100 mL)

Blood Ca2+ falls

StimulatesCa2+ depositionin bones

ReducesCa2+ uptakein kidneys


26.7 Pancreatic hormones regulate blood glucose levels

The pancreas secretes two hormones that control blood glucose

– Insulin—signals cells to use and store glucose

– Glucagon—causes cells to release stored glucose into the blood

Insulin

4

Beta cellsof pancreas stimulatedto release insulin intothe blood

Glucoselevel

Homeostasis: Normal blood glucose level

(about 90 mg/100 mL)

Glucoselevel

Glucagon

Low bloodglucose level

High blood

glucose level

Bodycellstake up moreglucose

Blood glucose level

declines to a set point;

stimulus for insulin

release diminishes

Liver takesup glucoseand stores it asglycogen

Alphacells ofpancreas stimulatedto release glucagoninto the blood

Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)

Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)

Blood glucose level

rises to set point;

stimulus for glucagon

release diminishes

Liverbreaks downglycogen andreleases glucoseto the blood

7

6

1

2

5

8

3

Insulin

4

Beta cellsof pancreas stimulatedto release insulin intothe blood

Glucoselevel



Glucoselevel

High blood

glucose level

Bodycellstake up moreglucose

Blood glucose level

declines to a set point;

stimulus for insulin

release diminishes

Liver takesup glucoseand stores it asglycogen

Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)

1

2

3

Glucoselevel



Glucoselevel

Glucagon

Low bloodglucoselevel

Alphacells ofpancreas stimulatedto release glucagoninto the blood

Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)

Blood glucose level

rises to set point;

stimulus for glucagon

release diminishes

Liverbreaks downglycogen andreleases glucoseto the blood

7

6

5

8


26.8 CONNECTION: Diabetes is a common endocrine disorder

Diabetes mellitus

– Results from

– A lack of insulin or

– A failure of cells to respond to it

– Affects about 21 million Americans


26.8 CONNECTION: Diabetes is a common endocrine disorder

Two common types of diabetes mellitus

– Type 1 (insulin-dependent)

– Autoimmune disease

– Insulin-producing cells destroyed

– Type 2 (non-insulin-dependent)

– Deficiency of insulin

– More commonly, reduced response to insulin

– More than 90% of diabetics are type 2

– Associated with being overweight and underactive

Blo

od

glu

co

se (

mg

/100 m

L)

Hours after glucose ingestion

Normal

400

Diabetic

300

250

200

150

100

50

00

350

1 2 3 4 512


26.9 The adrenal glands mobilize responses to stress

Hormones from the adrenal glands help maintain homeostasis when the body is stressed



Nerve signals from the hypothalamus stimulate the adrenal medulla to secrete

– Epinephrine

– Norepinephrine

These hormones quickly trigger the fight-or-flight responses



Adrenocorticotropic hormone (ACTH) from the pituitary causes the adrenal cortex to secrete

– Glucocorticoids

– Mineralocorticoids

These hormones

– Boost blood pressure

– Boost energy in response to long-term stress

Hypothalamus

Stress

Releasing hormone

Blood vessel

Anterior pituitary

Adrenal cortex

ACTH

Nervecell

Nerve cell

Adrenal medulla

3

4

5

2

Nervesignals

AdrenalmedullaAdrenal

gland

Adrenalcortex

Kidney

Spinal cord(cross section)

Epinephrine andnorepinephrine

MineralocorticoidsGlucocorticoids

Long-term stress responseShort-term stress response

Mineralocorticoids Glucocorticoids

2. Increased bloodvolume and bloodpressure

1. Retention ofsodium ions andwater by kidneys

2. Immune system maybe suppressed

1. Proteins and fatsbroken down andconverted to glucose,leading to increasedblood glucose

1. Glycogen broken down to glucose;

increased blood glucose

2. Increased blood pressure

3. Increased breathing rate

4. Increased metabolic rate

5. Change in blood-flow patterns,

leading to increased alertness and

decreased digestive and kidney activity

ACTH

1

Hypothalamus

Stress

Releasing hormone

Blood vessel

Anterior pituitary

Adrenal cortex

ACTH

Nervecell

Nerve cell

Adrenal medulla

3

4

5

2

Nervesignals

AdrenalmedullaAdrenal

gland

Adrenalcortex

Kidney

Spinal cord(cross section)

Epinephrine and

norepinephrine


ACTH

1

Long-term stress responseShort-term stress response

Short-term stress response

1. Glycogen broken down to glucose;

increased blood glucose

2. Increased blood pressure

3. Increased breathing rate

4. Increased metabolic rate

5. Change in blood-flow patterns,

leading to increased alertness and

decreased digestive and kidney activity

Long-term stress response


2. Increased bloodvolume and bloodpressure

1. Retention ofsodium ions andwater by kidneys

2. Immune system maybe suppressed

1. Proteins and fatsbroken down andconverted to glucose,leading to increasedblood glucose


26.10 The gonads secrete sex hormones

Steroid sex hormones

– Include estrogens, progestins, and androgens

– Produced by the gonads in response to signals from

– Hypothalamus

– Pituitary



Estrogens and progestins

– Stimulate the development of female characteristics

– Maintain the female reproductive system



Androgens

– Such as testosterone

– Trigger the development of male characteristics


26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals

Prolactin in humans

– Stimulates mammary glands to grow and produce milk during late pregnancy

– Suckling by a newborn stimulates further release of prolactin

– High prolactin during nursing inhibits ovulation


Prolactin

– Nonhuman mammals—stimulates nest building

– Birds—regulates fat metabolism and reproduction

– Amphibians—movement to water

– Fish—migration between salt and fresh water

26.11 EVOLUTION CONNECTION: A single hormone can perform a variety of functions in different animals

New protein

Cellular response

mRNA

DNA


Receptorprotein

Lipid-solublehormone

Water-solublehormone

Receptorprotein


Posterior pituitary:

Composed of nervous tissue;

stores and secretes hormones

made by hypothalamus

Brain Hypothalamus:

Master control

center of the

endocrine system

Anterior pituitary:

Composed of

endocrine tissue;

controlled by

hypothalamus;

produces and

secretes its

own hormones

Pineal gland

e. regulates metabolism

f. related to daily rhythm

g. raises blood calcium levels

h. boosts water retention

Parathyroid gland

Hypothalamus

a. lowers blood glucose

b. stimulates ovaries

c. triggers fight-or-flight

d. promotes male traits

Anterior pituitary

Testes

Adrenal medulla

Pancreas

Thyroid gland

4. insulin

5. melatonin

6. FSH

1. thyroxine

2. epinephrine

3. androgens

7. PTH

8. ADH


You should now be able to

1. Explain how endocrine disruptors are causing environmental problems

2. Compare the mechanisms and functions of the endocrine and nervous systems

3. Distinguish between the two major classes of vertebrate hormones

4. Describe the different types and functions of vertebrate endocrine organs



5. Describe the interrelationships between the hypothalamus and pituitary glands

6. Describe the functions of the thyroid and parathyroid glands

7. Explain how insulin and glucagon manage blood glucose levels

8. Describe the causes and symptoms of types 1 and 2 diabetes



9. Compare the functions of the adrenal gland hormones

10. Describe the three major types of sex hormones and their functions

11. Describe the diverse functions of prolactin in vertebrate groups

Chapter 26 Hormones and the Endocrine System...pituitary, connects the nervous and endocrine systems The hypothalamus –Blurs the distinction between endocrine and nervous systems

Documents