Mr. Franco's Website - Endocrine System 2009...Parathyroid glands secrete parathyroid hormone (PTH)...

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The Endocrine System

A. Regulates long term metabolic

processes

B. Releases hormones from

endocrine cells

1. Hormones are chemicals

2. Alter metabolism of cells

3. Release regulated by

negative feedback

4. Act on target cells

I. Overview of the Endocrine System

A. Amino acid derivatives

(epinephrine, thyroid

hormones)

B. Peptides and proteins

1. Chains of amino acids

2. Insulin, ADH

C. Lipid derivatives

1. Steroids (testosterone)

2. Eicosanoids (prostaglandins)

II. Three Families of Hormones

A. Receptors are hormone binding proteins

B. Triggers action on a target cell

III. Hormone Receptors

A. Extracellular Receptors

1. Located in cell membrane

2. Targeted by

a) Amino acid derivatives

b) Peptides

c) Eicosanoids

3. Operates through a

second messenger such

as cyclic-AMP

IV. Classes of Hormone Receptor Membrane receptor

G protein (inactive)

Cytoplasm

Nuclear envelope

Nuclear pore

Nucleus

DNA

Cell membrane

2

Membrane receptor

Hormone- receptor complex

First messengers (E, NE, peptide hormones, and eicosanoids)

Cell membrane


Cytoplasm

Nuclear envelope

Nuclear pore

Nucleus

DNA

Membrane receptor



Cell membrane


G protein (activated)

Activates adenylate cyclase

Cytoplasm

Nuclear envelope

Nuclear pore

Nucleus

DNA

Membrane receptor



Cell membrane




Cytoplasm ATP cAMP

Acts as second

messenger

Activates kinase Nuclear envelope

Nuclear pore

Nucleus

DNA

Membrane receptor



Cell membrane




Cytoplasm ATP cAMP

Acts as second

messenger

Activates kinase

Alterations in enzyme activity;

opens ion channels

Nuclear envelope

Nuclear pore

Nucleus

DNA

Membrane receptor



Cell membrane




Cytoplasm ATP cAMP

Acts as second

messenger

Activates kinase

Alterations in enzyme activity;

opens ion channels

TARGET CELL RESPONSE

Nuclear envelope

Nuclear pore

Nucleus

DNA

B. Intracellular Receptors

1. Located in cytoplasm or

nucleus

2. Targeted by steroid and

thyroid hormones

3. Operates through

changes in gene

expression

4. Thyroid hormones also

act on mitochondria

IV. Classes of Hormone Receptor

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A. Hormones directly enter capillaries

1. Most hormones travel free in

solution

2. Steroid, thyroid hormones bind to

blood proteins for transport

B. Hormones are inactivated by

1. Binding to cell receptors

2. Removal by liver, kidney cells

3. Breakdown by extracellular

enzymes

V. Hormone Secretion and Distribution VI. Control of Endocrine Secretion

A. Humoral Stimuli: Ca2+ controls

parathyroid hormone and calcitonin

release

B. Hormonal Stimuli: thyroid stimulating

hormone triggers thyroid hormone

release

C. Neural Stimuli: epinephrine release from

adrenals

VII. The Hypothalamus and

Endocrine Control

A. Secretes hormones directly

B. Secretes regulatory

hormones to control pituitary

gland

C. Autonomic centers exert

direct control of adrenal

medullae

VIII. The Pituitary Gland A. Also called the hypophysis

B. Releases nine important hormones

C. Two lobes

VIII. The Pituitary Gland 1. Anterior Pituitary

a) Thyroid-Stimulating Hormone (TSH)

• Triggers thyroid hormone release

b) Adrenocorticotropic Hormone (ACTH)

• Stimulates glucocorticoid release from adrenal gland

VIII. The Pituitary Gland c) Follicle-Stimulating Hormone (FSH)

• Stimulates estrogen secretion, egg production (females), sperm production (males)

d) Luteinizing Hormone (LH)

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

e) Prolactin (PRL)

• Stimulates mammary gland development and milk secretion

f) Growth hormone (hGH)

• Stimulates cell growth

g) Melanocyte Stimulating Hormone (MSH)

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VIII. The Pituitary Gland 2. Posterior Pituitary Hormones

a) Antidiuretic Hormone (ADH)

1) Reduces water loss in the urine

2) Increases thirst

b) Oxytocin

1) Stimulates uterine contraction, milk delivery

2) Stimulates prostate gland smooth muscle

VIII. The Pituitary Gland • Pituitary Hormones and Their Targets

IX. The Thyroid Gland A. Lies near thyroid cartilage of larynx

B. Has a rich blood supply

C. Consists of two lobes connected by the

isthmus

IX. The Thyroid Gland D. Thyroid Follicles

1. Produce and store colloid (needs iodine)

2. Two forms, thyroxine (T4) and triiodothyronine (T3)

a) Increases metabolism and heat production (calorigenic

effect) in most cells

b) Required for normal development

IX. The Thyroid Gland E. C Cells

1. Scattered outside of

follicle epithelium

2. Also called parafollicular

cells

3. Secrete calcitonin

a) Lowers blood Ca2+

levels

b) Inhibits osteoclasts of

bone

c) Increases urinary

calcium loss

4. Triggered by high blood

Ca2+ level

X. The Parathyroid Glands A. Four glands on thyroid posterior

B. Chief cells produce parathyroid hormone

C. Low blood Ca2+ triggers secretion

D. PTH raises blood Ca2+

1. PTH speeds bone breakdown by osteoclasts

2. Increases dietary absorption

3. Slows loss in kidney

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HOMEOSTASIS DISTURBED

Rising calcium levels in blood HOMEOSTASIS

Normal calcium levels

(8.5-11 mg/dl)

Thyroid gland produces calcitonin




(8.5-11 mg/dl)


Increased excretion of calcium in kidneys




(8.5-11 mg/dl)



Calcium deposition in bone (inhibition of osteoclasts)

Blood calcium levels decline




(8.5-11 mg/dl)



Calcium deposition in bone (inhibition of osteoclasts)

Blood calcium levels decline


Rising calcium levels in blood

HOMEOSTASIS RESTORED

HOMEOSTASIS


(8.5-11 mg/dl)

HOMEOSTASIS


(8.5-11 mg/dl) HOMEOSTASIS DISTURBED

Falling calcium levels in blood

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HOMEOSTASIS




Parathyroid glands secrete

parathyroid hormone (PTH)

HOMEOSTASIS




Release of stored calcium from bone

(stimulation of osteoclasts, inhibition

of osteoblasts)



HOMEOSTASIS






of osteoblasts)

Enhanced reabsorption

of calcium in kidneys



HOMEOSTASIS






of osteoblasts)



Stimulation of calcitriol production

at kidneys; enhanced Ca2+, PO4

3-

absorption by digestive tract



Blood calcium levels

increase

HOMEOSTASIS


(8.5-11 mg/dl)

HOMEOSTASIS RESTORED





of osteoblasts)



Stimulation of calcitriol production

at kidneys; enhanced Ca2+, PO4

3-

absorption by digestive tract



Blood calcium levels

increase

XI. The Adrenal Glands A. Lie along superior border of each

kidney

B. Surrounded by fibrous capsule

C. Made of two parts

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XI. The Adrenal Glands 1. Adrenal Cortex

(corticosteroids)

a) Glucocorticoids (cortisol)

1) Stimulated by ACTH

2) Affect glucose

metabolism

b) Mineralocorticoids

(aldosterone)

1) Stimulated by

angiotensin II

2) Restricts loss of water,

Na+ in urine, sweat,

digestive tract, saliva

c) Androgens (male hormone)

XI. The Adrenal Glands 2. Adrenal Medulla

a) Nerves stimulate hormone

secretion

b) Produces two related

hormones

1) Epinephrine (adrenaline)

2) Norepinephrine

(noradrenaline)

c) Increases heart rate and

force, releases glucose, fatty

acids into blood, opens

airways

XII. The Pineal Gland

A. Located deep within the brain

B. Synthesizes melatonin

1. Establishes daily wake-sleep cycle

2. Inhibits reproductive function

3. Protects neural tissue from free radicals

XIII. The Pancreas A. Exocrine and endocrine cells

B. Endocrine cells organized into islets of

Langerhans

C. Islet cells secrete insulin and glucagon

1. Insulin produced by beta cells

2. Glucagon produced by alpha cells

D. Exocrine cells secrete enzyme-rich

digestive fluid

XIII. The Pancreas E. Actions of Insulin and Glucagon

1. Insulin

a) Lowers blood glucose

b) Increases glucose uptake, storage, and use by target cells

c) Targets liver, muscle, fat cells

2. Glucagon

a) Raises blood glucose concentration

b) Increases glycogen breakdown and glucose synthesis

c) Targets liver cells


Rising blood glucose levels HOMEOSTASIS

Normal glucose levels

(70-110 mg/dl)

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Beta cells secrete insulin




(70-110 mg/dl)


Increased rate of glucose transport

into target cell




(70-110 mg/dl)



into target cell

Increased rate of glucose utilization

and ATP generation




(70-110 mg/dl)



into target cell


and ATP generation




(70-110 mg/dl)

Increased conversion of glucose to glycogen (liver, skeletal muscle)



into target cell


and ATP generation




(70-110 mg/dl)


Increased amino acid absorption and

protein synthesis



into target cell


and ATP generation

Blood glucose concentration

declines




(70-110 mg/dl)



protein synthesis

Increased fat synthesis

(adipose tissue)

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into target cell


and ATP generation


declines


Rising blood glucose levels

HOMEOSTASIS RESTORED HOMEOSTASIS


(70-110 mg/dl)



protein synthesis

Increased fat synthesis

(adipose tissue)

HOMEOSTASIS


(70-110 mg/dl)


Declining blood glucose levels

HOMEOSTASIS


(70-110 mg/dl)



Alpha cells secrete

glucagon

HOMEOSTASIS


(70-110 mg/dl)



Increased breakdown of glycogen to glucose (liver, skeletal muscle)

Alpha cells secrete

glucagon

HOMEOSTASIS


(70-110 mg/dl)




Increased breakdown of fats to fatty acids

(adipose tissue)

Alpha cells secrete

glucagon

HOMEOSTASIS


(70-110 mg/dl)





(adipose tissue)

Increased synthesis and release of glucose (liver)

Alpha cells secrete

glucagon


rises

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HOMEOSTASIS


(70-110 mg/dl) HOMEOSTASIS

RESTORED





(adipose tissue)

Increased synthesis and release of glucose (liver)

Alpha cells secrete

glucagon


rises

XIV. Endocrine Functions of Other

Organs A. Intestines- Secretes hormones to control digestion

B. Kidneys (3 hormones)

1. Calcitriol—Stimulates calcium and phosphate absorption in intestine

2. Erythropoietin (EPO)—Stimulates red blood cell production by bone marrow

3. Renin—Enzyme that leads to angiotensin II that triggers aldosterone from adrenal cortex


Organs C. Heart- Secretes atrial natriuretic

peptide (ANP) to lower blood

volume or blood pressure

D. Thymus- Secretes thymosins that

control immune system defenses

E. Adipose tissue (fat cells)

1. Secretes leptin to control

appetite

2. Secretes resistin to reduce

insulin response


Organs F. Testis (male gonad)

1. Interstitial cells secrete androgens (testosterone)

2. Sustentacular cells secrete inhibin (anterior pituitary)

G. Ovary (female gonad)

1. Follicle cells secrete estrogens and inhibin

2. Corpus luteum cells secrete estrogens and progesterone

H. Placenta- Secretes several hormones in pregnancy

XV. Hormones and Behavior A. Sex hormones

1. Testosterone fosters aggressiveness

2. Estrogen fosters sexual receptivity

B. Thyroid hormones

1. Excess leads to nervousness, restlessness

2. Deficiency leads to sluggishness

C. Antidiuretic hormone: Leads to feeling of thirst, water

intake

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Mr. Franco's Website - Endocrine System 2009...Parathyroid glands secrete parathyroid hormone (PTH)...

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