Www.soran.edu.iq Physiology Behrouz Mahmoudi Endocrine System 1.

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Physiology

Behrouz Mahmoudi

Endocrine System

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• What are the Properties of the Endocrine System?– Controls longer term metabolic processes– Shares some functions with nervous system– Releases hormones from endocrine cells

• Hormones are chemicals• Hormones change metabolism of many cells• Release controlled by negative feedback• Hormones act on target cells

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

Overview of the Endocrine System


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•An Overview of the Endocrine System

Overview of the Endocrine System

Figure 10-1


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• What is the Structure of Hormones?– Three chemical families

• Amino acid derivatives• Peptides and proteins

– Chains of amino acids• Lipid derivatives

– Steroids (e.g., testosterone)



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• Target Cells Peripheral cells that can respond to a particular hormone

• Hormone receptor A protein in the cell membrane, or within the cytoplasm or nucleus, to which a hormone specifically binds to trigger its actions on a target cell.



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• The Role of Target Cell Receptors in Hormonal Action

Figure 10-2


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•Mechanisms of Hormone Action

Figure 10-3(b)


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•Key Note•Hormones control cells on a sustained basis. They circulate in the blood and bind to specific receptors on or in target cells. They change membrane permeability, activate or inactivate key enzymes, or change genetic activity.



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•What is the Hypothalamus and Endocrine Control?

– Three steps of action• Hypothalamus releases hormones as an

endocrine organ• Hypothalamus releases regulatory hormones to

control pituitary gland endocrine cells• Autonomic centers cause direct neural control of

adrenal medullae



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•Three Mechanisms of Hypothalamic Control over Endocrine Organs

Figure 10-4


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The Pituitary Gland• What is the Pituitary Gland?

– Also called the hypophysis– Releases nine important hormones

• All are peptide hormones



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The Pituitary Gland

Figure 10-5

• The Location and Anatomy of the Pituitary Gland


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The Pituitary Gland

• What are the Anterior Pituitary Hormones?– Thyroid-Stimulating Hormone (TSH)

• Triggers thyroid hormone release

– Adrenocorticotropic Hormone (ACTH)• Stimulates glucocorticoid release from adrenal gland

– Follicle-Stimulating Hormone (FSH)• Stimulates estrogen secretion, egg production

(females), sperm production (males)



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The Pituitary Gland• What are the Anterior Pituitary Hormones?

(continued)– Luteinizing Hormone (LH)

• Triggers ovulation, progestin production (females), androgen production (males)

– Prolactin (PRL)• Stimulates mammary gland development and milk

secretion– Growth hormone (hGH)

• Stimulates cell growth • Melanocyte Stimulating Hormone (MSH)



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The Pituitary Gland

• What is the Posterior Pituitary Gland?– Antidiuretic Hormone (ADH)

• Reduces water loss in the urine• Increases thirst

– Oxytocin• Stimulates uterine contraction, milk delivery• Stimulates prostate gland smooth muscle



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The Pituitary Gland• Pituitary Hormones and Their Targets

Figure 10-8


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The Pituitary Gland•Key Note

•Hypothalamic regulatory factors control the anterior pituitary (source of seven hormones). Most of these control other glands (thyroid, adrenal, gonads). It also produces growth hormone. The posterior pituitary releases two hormones produced in the hypothalamus, ADH (restricts water loss) and oxytocin (stimulates contractions in the mammary glands and uterus, and the prostate gland).



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The Thyroid Gland • What is the Anatomy of the Thyroid

Gland?– Lies near thyroid cartilage of larynx– Has a rich blood supply– Contains numerous thyroid follicles

• Produce, store, release thyroid hormones



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The Thyroid Gland• What are the Thyroid Follicles and Thyroid

Hormones?– Production requires adequate iodine in the diet

– Occurs in two forms, thyroxine (T4) and triiodothyronine (T3)

– Increases metabolism and heat production (calorigenic effect)

– Required for normal development



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The Thyroid Gland• The Thyroid Gland

Figure 10-9


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The Thyroid Gland

• What is the function of the C Cells of the Thyroid Gland?– Secrete calcitonin

• Lowers blood Ca2+ levels• Increases urinary calcium loss

– Caused by high blood Ca2+ level



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The Parathyroid Glands

• What are the Parathyroid Glands?• Chief cells produce parathyroid hormone• Low blood Ca2+ triggers secretion• PTH raises blood Ca2+



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Thyroid glandproducescalcitonin

Increased excretionof calciumin kidneys

Calcium deposition inbone (inhibitionof osteoclasts)

Uncertain significancein a healthy

nonpregnant adult

Blood calciumlevels decline

HOMEOSTASISDISTURBED

Rising calciumlevels in blood

HOMEOSTASISRESTORED

HOMEOSTASIS

Normal calciumlevels

(8.5-11 mg/dl)HOMEOSTASIS

RESTORED


Falling calciumlevels in blood

Release of storedcalcium from bone

(stimulation ofosteoclasts, inhibition

of osteoblasts)

Enhancedreabsorption

of calcium in kidneys

Stimulation ofcalcitriol production

at kidneys;enhanced Ca2+, PO4

3-

absorption bydigestive tract

Parathyroidglands secrete

parathyroidhormone (PTH)

Blood calciumlevels

increase


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The Parathyroid Glands

Figure 10-11

•The Parathyroid Glands


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The Parathyroid Glands•Key Note

•The thyroid gland produces (1) hormones that adjust tissue metabolic rates, and (2) a hormone that usually plays a minor role in calcium ion homeostasis by opposing the action of parathyroid hormone.



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The Adrenal Glands• What is the Adrenal Gland

Anatomy?– Lie along superior border of each

kidney– Made of two parts

• Adrenal cortex (outer)• Adrenal medulla (inner)



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The Adrenal Glands

• The Adrenal Gland


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The Adrenal Glands

• What is the Adrenal Cortex?– Makes steroid hormones (corticosteroids)

• Glucocorticoids (e.g., cortisol)• Mineralocorticoids (e.g., aldosterone)• Androgens (male hormone)



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The Adrenal Glands

• What is the Adrenal Medulla?– Produces two related hormones

• Epinephrine (adrenaline)• Norepinephrine (noradrenaline)

– Increases heart rate and force, releases glucose, fatty acids into blood, opens airways



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The Adrenal Glands

•Key Note•The adrenal glands produce hormones that adjust metabolic activities at specific sites, affecting either the pattern of nutrient utilization, mineral ion balance, or the rate of energy consumption by active tissues.



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The Pineal Gland

• What is the Pineal Gland?– Produces melatonin

• Stops reproductive function• Allows daily wake-sleep cycle



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The Pancreas

• What is the Overview of the Pancreas?– Lies behind stomach and beneath liver– Endocrine cells organized into islets of

Langerhans– Islet cells secrete insulin and glucagon



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The Pancreas

• The Endocrine Pancreas


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The Pancreas

•The Endocrine Pancreas


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The Pancreas

• What are the Actions of Insulin and Glucagon?– Insulin

• Lowers blood glucose concentration– Glucagon

• Raises blood glucose concentration




Beta cellssecreteinsulin

Increased rate ofglucose transport

into target cell

Increased rate ofglucose utilization

and ATP generation

Blood glucoseconcentration

declines


Rising bloodglucose levels HOMEOSTASIS

RESTOREDHOMEOSTASIS

Normal glucoselevels

(70-110 mg/dl) HOMEOSTASISRESTORED


Declining bloodglucose levels

Increased breakdownof glycogen to glucose(liver, skeletal muscle)

Increased breakdownof fats to fatty acids

(adipose tissue)

Increased synthesisand release ofglucose (liver)

Alpha cellssecrete

glucagon


rises

Increased conversionof glucose to glycogen(liver, skeletal muscle)

Increased amino acidabsorption and

protein synthesis

Increased fatsynthesis

(adipose tissue)





into target cell


and ATP generation


declines



RESTOREDHOMEOSTASISNormal glucose

levels(70-110 mg/dl)



protein synthesis


(adipose tissue)



Figure 10-1415 of 16

HOMEOSTASISNormal glucose

levels(70-110 mg/dl)

HOMEOSTASISRESTORED





(adipose tissue)


Alpha cellssecrete

glucagon


rises





into target cell


and ATP generation


declines



RESTOREDHOMEOSTASIS

Normal glucoselevels

(70-110 mg/dl) HOMEOSTASISRESTORED





(adipose tissue)


Alpha cellssecrete

glucagon


rises



protein synthesis


(adipose tissue)


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Patterns of Hormonal Interaction

• What Hormones are Needed for Normal Growth?– Growth Hormone– Thyroid Hormones– Insulin– Parathyroid Hormone– Calcitriol– Reproductive Hormones



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Patterns of Hormonal Interaction

• What are Hormones and Behavior?– Sex hormones

• Testosterone causes aggressiveness• Estrogen causes sexual receptivity

– Thyroid hormones• Excess leads to nervousness, restlessness• Deficiency leads to sluggishness

– Antidiuretic hormone• Leads to feeling of thirst, water intake



Www.soran.edu.iq Physiology Behrouz Mahmoudi Endocrine System 1.

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