Chapter 16:The Endocrine System

Arnold Adolph Berthold 1803 – 1861Founder of Endocrinology

Berthold’s Experiment in Roosters….

Castration Castration &Reimplantationof testis

Castration &Transplantationof testis

Berthold’s Conclusion...

-A secretory, blood-borne product of the transplanted testesis responsible for the normal development of the birds in thesecond and third group

Today, it is called TESTOSTERONE

-’problem’: no one knows why Berthold did the experiment in the first place…. No clear rationale for it.

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.1: Location of the major endocrine organs of the body, p. 605.

Pineal glandHypothalamus

Pituitary gland

Thyroid gland

Parathyroid glands(on dorsal aspectof thyroid gland)

Thymus gland

Adrenal glands

Pancreas

Ovary(female)

Testis(male)

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.3: PIP second-messenger mechanism of amino acid-based hormones, p. 608.

PIP2

IP3

ReceptorGTP

GTP

CatecholaminesTRHADHGnRHOxytocin

Triggers responses of target cell

GDP

Extracellular fluid

Cytoplasm

Inactiveprotein kinase C

Activeprotein kinase C

Phospholipase C

Gq

Ca2+ Ca2+-calmodulin

Hormone

Endoplasmicreticulum

DAG

GTP

1

2 34 5

5

6

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.4: Direct gene activation mechanism of steroid hormones, p. 609.

Steroidhormone

Steroidhormone

Cytoplasm

Receptor-chaperonincomplex

Molecularchaperones

Receptor-hormonecomplex

Hormoneresponseelements

Binding

Transcription Chromatin

mRNA

Nucleus

New protein

Translation

Ribosome

mRNA

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.5: Three types of endocrine gland stimuli, p. 612.

Capillary blood contains lowconcentration of Ca2+, whichstimulates…

Capillary(low Ca2+ in blood)

Parathyroidglands

Thyroid gland(posterior view)

PTH

Parathyroidglands

…secretion of parathyroid hormone (PTH) by parathyroidglands

Humoral

CNS(spinal cord)

Medulla ofadrenalgland

Preganglionic SNS fiber stimulatesadrenal medulla cells…

PreganglionicSNS fiber

…to secrete catecholamines

Capillary

Neural

Hypothalamus

Thyroidgland

Adrenalcortex

The hypothalamus secretes hormones that…

…stimulatethe anteriorpituitary glandto secretehormonesthat…

Hormonal

Gonad(Testis)

Pituitarygland

…stimulate other endocrine glandsto secrete hormones

(a) (b) (c)

1 1 1

2

32

2

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.6: Relationships of the pituitary gland and hypothalamus, p. 613.

Neuronsin the ventralhypothalamus

Hypothalamicneurons in thesupraoptic nuclei

Hypothalamicneurons in theparaventricular nuclei

Hypophyseal portal system

Anterior lobe

Venule

Infundibulum(connecting stalk)

Neurohypophysis(storage area forhypothalamichormones)

Posteriorlobe

Venule

Hypothalamic-hypophyseal tract

Inferiorhypophysealartery

OxytocinADH

TSH, FSH, LH, ACTH, GH, PRL

Superiorhypophysealartery

Secretory cells ofadenohypophysis

• Primary capillary plexus• Hypophyseal portal veins• Secondary capillary plexus

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.7: Metabolic actions of growth hormone (GH), p. 615.

Growth hormone

Feedbackmechanism Inhibits GH synthesis

and release

Anteriorpituitary

Liver andother tissues

Insulin-like growthfactors (IGFs)

Indirectgrowth-promotingactions

Anti-insulinactions

Extraskeletaleffects

Skeletal effects Fat Carbohydratemetabolism

Increased cartilageformation andskeletal growth

Increased proteinsynthesis, andcell growth andproliferation

Increasedlipolysis

Increased bloodglucose and otheranti-insulin effects

Direct effects

Hypothalamussecretes growthhormone – releasinghormone (GHRH), andsomatostatin (GHIH)

Key:

Increases, stimulates

Reduces, inhibits

Initial stimulus

Physiological response

Result

Inhibits GHRH releaseStimulates GHIH release

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.8: Gross and microscopic anatomy of the thyroid gland, p. 620.

(a) (b)

Hyoid bone

Thyroid cartilage

Internal carotidartery

Common carotidartery

Epiglottis

External carotidarterySuperior thyroidartery

Isthmus ofthyroid gland

Left subclavianarteryLeft lateral lobeof thyroid gland

Inferior thyroidartery

Trachea

BrachiocephalicarteryAorta

Colloid-filledfollicles Follicle cells

Parafollicular cell

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.11: The parathyroid glands, p. 624.

(a) (b)

Pharynx(posterioraspect)

Thyroidgland

Parathyroidglands

Trachea

Esophagus

Capillary

Chiefcells

Oxyphilcells

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.12: Effect of parathyroid hormone on bone, the intestine, and the kidneys, p. 625.

Hypocalcemia (low bloodcalcium) stimulatesparathyroid glands

PTH release fromparathyroid glands

Rising Ca2+ inblood inhibitsPTH release

Activatesosteoclasts;calcium andphosphateions releasedinto blood

Increasescalciumabsorptionfrom food

Promotes activationof vitamin D

Increasescalciumreabsorption

Bone

Intestine

Kidney

PTH:

Blood-stream

= Ca2+ ions

= PTH molecules

Key:

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.13: Microscopic structure of the adrenal gland, p. 626.

(a) (b)

• Cortex

Kidney

• Medulla

Adrenal gland

CapsuleZona

glomerulosa

Zonafasciculata

Zonareticularis

Adrenalmedulla

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.16: Stress and the adrenal gland, p. 631.

Short term More prolongedStress

Hypothalamus

Nerve impulses

Adrenalcortex

CRH (corticotropin-releasing hormone)

Corticotrophcells ofanteriorpituitary

To target in blood

ACTH

Mineralocorticoids Glucocorticoids

1. Retention of sodium and water by kidneys2. Increased blood volume and blood pressure

1. Proteins and fats converted to glucose or broken down for energy2. Increased blood glucose3. Suppression of immune system

Long-term stress response

Short-termstress response

Spinal cord

Adrenalmedulla

Preganglionicsympatheticfibers

Catecholamines(epinephrineand norepinephrine)

1. Increased heart rate2. Increased blood pressure3. Liver converts glycogen to glucose and releases glucose to blood4. Dilation of bronchioles5. Changes in blood flow patterns leading to decreased digestive system activity and reduced urine output6. Increased metabolic rate

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.18: Regulation of blood glucose levels by insulin and glucagon, p. 633.

Stimulatesglycogenbreakdown

GlycogenGlucose

Liver

Stimulatesglycogenformation

Stimulatesglucose uptakeby cells

Tissue cells

Stimulus:Rising blood glucose level

Homeostasis: Normal blood glucose level (about 90 mg/100 ml)

Stimulus:Declining bloodglucose level

Bloodglucoserises tonormalrange

Bloodglucosefalls tonormalrange

Glucagon

Pancreas

Insulin

GlycogenGlucose

Liver

Pancreas

Imbalance

Imbalance

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 16.1: Modified to emphasize the relationship between the adrenal glands and the testes and ovaries.

Adrenal glands

Ovary(female)

Testis(male)

Testes & Ovaries

These gamete producing glands produce the lion’s share of sex hormone for each sex. Ovaries are in females and Testes are in

males. There is, however, an important role for the adrenal

glands…