17-chapt20 lecture anim - Nassau Community College. – Insulin lowers the blood sugar level, while glucagon raises it. 14 The Action of Hormones • Hormones act on target cells

8/30/2013

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Chapter 20

Lecture and

Animation Outline

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20.1 Overview of the Endocrine System

• The endocrine system consists of glands and tissues that secrete hormones.

• Hormones are chemicals that affect other glands

or tissues, located far away from the sites of hormone production.

• Like the nervous system, the endocrine system influences other organ systems in maintaining

homeostasis.

– Influence on cellular metabolism, growth and development

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• Growth factors – hormones that promote

cell division and mitosis

• Local hormones – not carried by the blood

– Affect tissues locally

– Ex: prostaglandins

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• Endocrine glands

– Have no ducts

– Secrete hormones into tissue fluid

– Hormones diffuse into the bloodstream

• Exocrine glands

– Secrete their products through ducts

• Ex: salivary glands send saliva to the mouth through salivary ducts

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Hormones and Homeostasis

• Homeostasis requires cooperation between

the endocrine and nervous systems.

Endocrine System Nervous System

Secretes hormones into

the blood

Transmits nerve impulses

Slower response Faster response

More prolonged response Less prolonged response

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• The blood concentration of a substance prompts an endocrine gland to secrete its

hormones.

– Ex: The parathyroid gland secretes a hormone when blood Ca+2 level falls below normal.

– Osteoclasts respond to hormone by slowly

releasing Ca+2 from bone.

– It take time for the response, but it is long-lasting.

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The Endocrine SystemCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

hypothalamus

pituitary gland(hypophysis)

thymus gland

thyroid gland

parathyroid glands(posterior surface o f thyroid)

adrenal glands

pancreas

ovary (female)

testis(male)

pineal gland

Figure 20.1

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9

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• Production of most hormones controlled by

two things

– Negative feedback

• Sensitive to either the

condition it regulates or the blood level of the hormone it

is producing

– Action of other hormones

• Insulin and glucagon


stimulus

Sensor

Homeostasis

response to stimulusdata to control center

change of internal

conditionsnegative feedback

and return to normal

Control center

Effect

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• Example of negative feedback

– As the blood glucose level rises, the pancreas

secretes insulin.

– Insulin causes the liver to store glucose, and glucose is removed from the blood.

– The stimulus for insulin production is, thereby,

inhibited.

– The pancreas stops secreting insulin.

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• Hormone regulation by release of an

antagonistic hormone

– The effect of insulin is offset by the secretion of glucagon.

– Insulin lowers the blood sugar level, while

glucagon raises it.

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The Action of Hormones

• Hormones act on target cells.

– May increase uptake of a substance

– May bring about alteration of structure of target cell

• Hormones fall into two chemical classes.

– Peptide hormones – peptides, proteins, glycoproteins or modified amino acids

– Steroid hormones – same complex of four rings, but varying side chains

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• Hormones function as chemical signals.

– Chemical signals - a means of communication between cells, body parts, or even individuals

• Typically affect the metabolism of target cells with

appropriate receptors

– For peptide hormones, receptors on cell surface

– For steroid hormones, receptors inside cell (cytoplasm or

nucleus)

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receptors

capillary

hormone

target cells

Figure 20.2

nontarget cell

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• The peptide hormone initiates a chemical signaling process after binding to its receptor; it serves as the first messenger.

• The activated receptor leads to the production of a second messenger, (cAMP is most common).

• The 2nd messenger sets in motion an enzymatic cascade.

• Each enzyme, in turn, activates another enzyme.

• During each step in the cascade, more reactions occur (1000-fold response possible).

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Peptide

Hormone Action


ATP

1. Epinephrine binds to a

receptor in the plasma

membrane.

capillary

epinephrine

(first messenger)

activated

enzymereceptor protein

2. Binding leads to

activation of an

enzyme that changes

ATP to cAMP.

cAMP

(second messenger)

glucose

(leaves cell

and goes

to blood)

3. cAMP activates an

enzyme cascade.

plasma

membrane

4. Many molecules of

glycogen are broken

down to glucose,

which enters thebloodstream.

glycogen

Figure 20.3

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• The steroid hormone has an alternate way because it can diffuse through the target cell membrane.

• The hormone can bind to its receptor either in the

cytoplasm or nucleus.

• The hormone receptor complex then binds to DNA to activate transcription of a certain gene into mRNA.

• mRNA translation results in enzymes or other

proteins that can carry out a response to the hormone.

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Steroid Hormone

Action

2. Hormone binds

to receptor inside

nucleus.

nucleus

cytoplasm

1. Hormone diffuses

through plasma

membrane because

it is lipid soluble.

steroid

hormone

plasma

membrane

DNAreceptor

protein

mRNA

protein

ribosome

mRNA

4. mRNA moves to

ribosomes, and protein

synthesis occurs.

3. Hormone-receptor

complex activates

gene and synthesis

of a specific mRNAmolecule.

Figure 20.4


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Pheromones

• Pheromones are chemical signals that act between individuals of the same species.

– Effects better known in animals other than humans

• Ex: female moths release an attractant that acts on male

moths even miles away

– Humans do produce pheromones

• Airborne chemicals released by scalp, oral cavity, axilla, genital areas

• Possibly plays role in mate attraction

• Axillary secretions can affect the menstrual cycle

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20.2 Hypothalamus and Pituitary Gland

• The hypothalamus regulates the internal environment in two ways.

– Through the autonomic nervous system

• Heartbeat, blood pressure, appetite, body temperature, water balance

– Through control of pituitary gland secretions

• Posterior pituitary

• Anterior pituitary

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Posterior Pituitary

• Neurons in the hypothalamus called neurosecretory

cells produce antidiuretic hormone (ADH) and

oxytocin.

– Hormones travel down axons and are stored in

axon terminals in the posterior pituitary.

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Posterior Pituitary

• ADH - Antidiuretic hormone

– Released from posterior pituitary in response to increased concentration of blood (not enough

water)

– Causes increased reabsorption of water in the kidneys

• As water reabsorption occurs, the blood concentration becomes normal and ADH is shut off.

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Posterior Pituitary

• Oxytocin

– Causes uterine contractions and milk letdown

during lactation

– Neurological impulses from pressure and irritation

of uterus causes oxytocin release

• Oxytocin causes contractions which causes more pressure and irritation� more oxytocin� more contractions

– An example of positive feedback

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Anterior Pituitary

• A portal system, consisting of two capillary networks connected by a vein, lies between the

hypothalamus and the anterior pituitary.

– Hypothalamus controls the anterior pituitary by

producing

• Hypothalamic-releasing hormones

– Stimulates the anterior pituitary gland to release certain

hormones

• Hypothalamic-inhibiting hormones

– Prevents the secretion of certain hormones

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Anterior Pituitary

• Three anterior pituitary hormones have target effects on other glands.

– Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce thyroid hormones.

– Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce glucocorticoids.

– Gonadotrophic hormones (FSH and LH) stimulate the gonads to produce estrogen and testosterone.

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20.2 Hypothalamus and

Pituitary Gland

• Anterior Pituitary

– In each instance, the blood level of the last hormone in the hypothalamus-anterior pituitary-target gland control system exerts negative feedback over secretions of the first two structures.


target gland

feedbackinhibits

release ofhormone 1

feedbackinhibits

release ofhormone 2

target gland hormone(hormone 3)

stimulating hormone(hormone 2)

anterior pituitary

releasing hormone(hormone 1)

hypothalamus

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Anterior Pituitary

• Three anterior pituitary hormones do not affect other glands.

– Prolactin (PRL) stimulates the mammary glands to synthesize milk.

– Melanocyte-stimulating hormone (MSH) stimulates the pigment-producing melanocytes of the skin.

– Growth hormone (GH) stimulates bone and muscle growth and increases protein synthesis and fat metabolism.

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Hypothalamus and the PituitaryCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

1. Neurosecretory cells produce

hypothalamic- releasing and

hypothalamic-inhibiting hormones.

2. These hormones are secreted into

a portal system.

3. Each type of hypothalamic

hormone either stimulates or

inhibits production and secretionof an anterior pituitary hormone.

4. The anterior pituitary secretes

its hormones into the bloodstream,

which then delivers them tospecific cells, tissues, and glands.

Adrenal cortex:

adrenocorticotropic

hormone (ACTH)

Thyroid:

thyroid-stimulating

hormone (TSH)Anterior pituitary

optic

chiasma

1. Neurosecretory cells produce

ADH and oxytocin.

2. These hormones move down

axons to axon endings.

3. When appropriate, ADH and

oxytocin are secreted from axon

endings into the bloodstream.

portal system

Posterior pituitary

Kidney tubules:

antidiuretic

hormone (ADH)

Smooth muscle

in uterus:

oxytocin

Mammary glands:

oxytocin

Ovaries, testes:

gonadotropic

hormones (FSH, LH)

Bones, tissues:

growth hormone

(GH)

Mammary glands:

pr olactin (PRL)

hypothalamus

Figure 20.5

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20.3 Thyroid and Parathyroid Glands

• The thyroid gland is a large gland located

in the neck.

– Attached to the trachea just below larynx

• The parathyroid glands are embedded in

the posterior surface of the thyroid gland.

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Thyroid Gland

• Thyroid gland has many follicles, each a small spherical structure of thyroid cells that produce

– Triiodothyronine (T3) (three iodine atoms)

– Thyroxine (T4) (four iodine atoms)

• Thyroid requires iodine to produce these hormones

– Iodine deficiency causes simple goiter

• T3 and T4 increase metabolic rate

– Stimulate most body cells to metabolize glucose and utilize more energy

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Thyroid Gland

• Thyroid gland also produces calcitonin

– Calcium-regulating hormone

– Produced in response to increased blood calcium levels

– Causes uptake of calcium by bone

• Calcium is important in muscle contraction, nerve

conduction, and blood clotting

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Parathyroid Gland

• Parathyroid glands produce parathyroid hormone (PTH)

– Causes an increase in blood calcium and a decrease in blood phosphate

– Increases osteoclast activity and the reabsorption of calcium by the kidneys

• Also stimulates activation of vitamin D needed for calcium absorption in the digestive tract

– When blood calcium levels increase, PTH is shut off

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Regulation of Blood

Calcium Level

calcitonin

Bones

take up Ca2+

from blood.

Thyroid gland

secretes

calcitonininto blood.

Blood Ca2+

lowers.

Homeostasis (normal blood Ca2+)

Blood Ca2+

rises.

activated

vitamin D

Parathyroid

glands

release PTHinto blood.

parathyroid

hormone

(PTH)

Intestines

absorb Ca2+

from digestivetract.

Kidneys

reabsorb Ca2+

from kidneytubules.

Bones

release Ca2+

into blood.

Figure 20.6


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20.4 Adrenal Glands

• The adrenal glands sit atop the kidneys.

– Two parts of the adrenal gland that function independently

– Adrenal medulla (outer portion)

• Under the control of the nervous system

– Adrenal cortex (inner portion)

• Under the control of adrenocorticotropic hormone (ACTH), an anterior pituitary hormone

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Adrenal Medulla

• The hypothalamus initiates nerve impulses by way of the brain stem, spinal cord, and sympathetic

nerves to the adrenal medulla.

• The adrenal medulla secretes two hormones

– Epinephrine (adrenaline)

– Norepinephrine (NE)

• Epinephrine and norepinephrine bring rapid short-term changes.

– Response to stress (fight or flight response)

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Adrenal Cortex

• Hormones of the adrenal cortex result in long-term changes.

– Two types of hormones

• Glucocorticoids

– Regulate carbohydrate, protein, and fat metabolism leading to an increase in blood glucose level

• Mineralocorticoids

– Regulate salt and water balance leading to an

increases in blood volume and blood pressure

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Adrenal Cortex: Glucocorticoids

• Cortisol is the principal glucocorticoid hormone stimulated by ACTH.

• Actions

– Promotes breakdown of muscle proteins to amino acids

• Liver uses amino acids to make glucose

– Promotes metabolism of fatty acids, spares glucose

– Overall: Promotes a rise in blood glucose

• Beneficial under stress

– Counteracts inflammatory response• Can also suppress the immune system

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Adrenal Cortex: Mineralocorticoids

• Mineralocorticoid secretion is not controlled

by the anterior pituitary.

– Aldosterone is the principal mineralocorticoid hormone that targets the kidney.

• Increases absorption of Na+, excretion of K+

• Regulates blood volume and pressure

• Secretion controlled through release of renin from the kidney

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• Renin

– Released when blood Na+ levels and blood pressure are low

– Activates angiotensinogen to angiotensin I

– Converts angiotensin I to angiotensin II by enzyme in lung capillaries

– Angiotensin II stimulates adrenal cortex to release aldosterone

– Effect: Angiotensin II constricts arterioles

Aldosterone causes the kidneys to reabsorb sodium.

Blood pressure rises.

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Regulation of

Blood Pressure

and Volume

atrial natriuretic

hormone (ANH)

Heart secretes

atrial natriuretic

hormone (ANH)into blood.

Kidneys excrete

Na+ and water

in urine.

Blood pressure

drops.

Homeostasis (normal blood pressure)

Blood pressure

rises.

Kidneys

reabsorb Na+

and water fromkidney tubules.

Kidneys secrete

renin into blood.

renin

angiotensin

I and II

Adrenal cortex

secretes

aldosteroneinto blood.

aldosterone

Figure 20.8


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• Atrial natriuretic hormone (ANH)

– Produced when atria of the heart are stretched

• Represents an increase in blood volume

– Inhibits the release of aldosterone

– Results in natriuresis: excretion of Na+ in the urine

– Water follows passively so blood volume and

therefore pressure decreases

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hypothalamus

epinephrine

Stress Response:

Long Term

Protein and fat metab-

olism instead of

glucose breakdown.

Reduction of

inflammation; immune

cells are suppressed.

Sodium ions and water

are reabsorbed by

kidney.

Blood volume and

pressure increase.

Glucocorticoids

Stress Response:

Short Term

Heartbeat and blood

pressure increase.

path of nerve

impulses

spinal cord

(cross section)

neurosecretory

cells produce

hypothalamic-

releasing

hormone

Mineralocorticoids

anterior

pituitary

secretes

ACTH

ACTH

Blood glucose level rises.

Muscles become

energized.

adrenal medulla adrenal cortexmineralocorticoids

glucocorticoids

stress

norepinephrine

neuron

cell body

Figure 20.7

Sympathetic Fibers

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20.5 Pancreas

• Pancreas is composed of two types of tissue

– The exocrine portion secretes digestive enzymes released into the small intestine by ducts.

– Pancreatic islets are the endocrine portion of the gland.

• Three types of endocrine islet cells

– Alpha cells produce glucagon

– Beta cells produce insulin

» Regulation of blood glucose levels

– Delta cells produce somatostatin

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20.5 Pancreas

• Insulin– Released after eating

– Stimulates uptake of glucose by cells• Especially muscle, liver, and adipose cells

• Decreases blood glucose

• Glucagon– Released before eating when glucose is low

– Targets liver and adipose tissue

– Increases blood glucose

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Regulation of

Blood Glucose

Level


insuli

n

Glucose levelrises.

After eating,

pancreas

secretes insulininto blood.

Before eating,

pancreas secretes

glucagon intoblood.

glucagon

Liver breaks

Down glycogen

to glucose.Glucose enters

blood.

Adipose tissue

breaks downfat.

Homeostasis (normal blood glucose)

Glucose level

drops.

Muscle cells

store glycogen

and build protein.

Adipose tissue

uses glucose

from blood toform fat.

Liver stores

glucose from

blood asglycogen.

Figure 20.9

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20.5 Pancreas

• Somatostatin

– Also known as growth hormone inhibiting hormone

– Also produced by cells in the stomach and small intestine

– Main effects

• Inhibit release of growth hormone by the anterior pituitary

• Suppress the release of various hormones produced by the digestive system, including insulin and glucagon

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20.6 Other Endocrine Glands

• The gonads are the testes in males and

the ovaries in females.

• The gonads are endocrine glands.

• Other glands and certain tissues also produce hormones.

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Testes and Ovaries

• Testes

– Produce sperm and androgens (e.g., testosterone)

– Responsible for male secondary sex characteristics

• Beard growth, enlargement of vocal cords and larynx

– Stimulate oil production by oil glands

– Involved in pattern baldness

– Responsible for increased muscle development

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Testes and Ovaries

• Some athletes take supplemental amounts of illegal anabolic steroids.

– Include testosterone or related chemicals

– Many side effects from taking anabolic steroids

• Acne

• Body odor

• Baldness

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The Side Effects of

Anabolic Steroid UseCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

deepening of voice in women

balding in men and

women; hair on face and

chest in women

breast enlargement in men and

breast reduction in women

liver

dysfunction

and cancer

kidney disease and

retention of fluids,

called "steroid bloat"

reduced testicular

size, low sperm count,

and impotency

stunted growth in

adolescents by causing

premature ossification

of growth plates

in women, increased

size of ovaries;

cessation of ovulation

and menstruation

high blood cholesterol and

atherosclerosis; high blood

pressure and damage to heart

severe acne

'roid mania–

delusions and hallucinations;

depression upon withdrawal

Figure 20.10

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Testes and Ovaries

• Ovaries

– Produce eggs, estrogen, and progesterone

– Estrogen

• Stimulates growth of uterus and vagina

• Required for egg maturation

• Responsible for secondary sex characteristics

– Breast development along with progesterone

– Fat distribution

– Body hair

– Progesterone

• Regulation of uterine cycle along with estrogen

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Thymus and Pineal Glands

• Thymus gland

– Largest and most active during childhood

– Secretes thymosins, hormones involved with maturation of T-lymphocytes

• Pineal gland

– Produces melatonin

• Involved with sleep/wake cycles and circadian rhythms

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Hormones from Other Tissues

• Some organs usually not considered endocrine glands can secrete hormones.

• The heart produces natriuretic hormone.

• The stomach and small intestine produce

hormones that regulate digestive secretions.

• Other tissues secrete hormones.

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Leptin

• Leptin

– Leptin is a protein hormone produced by adipose

tissue.

– Leptin stimulates the satiety center in the hypothalamus to signal that an individual has had enough to eat.

– It is thought that leptin in obese individuals may be ineffective.

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Growth Factors

• Growth factors• Stimulate mitosis in tissues

• Some released in blood, others act locally

– Granulocyte-macrophage colony-stimulating factor

• Produced by many different tissues

• Causes bone marrow stem cells to produce granulocytes

and macrophages

– Platelet-derived growth factor

• Wound healing

– Epidermal growth factor and nerve growth factor

• Wound healing

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Prostaglandins

• Prostaglandins

– Produced from arachidonic acid

– Act locally; effects depend on location

• Muscle contractions in uterus

• Mediation of pyrogens’ effects

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20.8 Disorders of the Endocrine System

• The endocrine glands play a major role in regulating the development and function of many

body systems.

• An increase or decrease in production of a hormone can cause significant disease.

• Cancer often causes an increase in hormone secretion by affecting the gland.

• Various conditions that destroy glands result in

decreased secretion of a hormone.

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Disorders of the Pituitary Gland

• Diabetes insipidus (DI)

– The posterior pituitary secretes too little ADH. (antidiuretic hormone)

• Large amounts of urine are produced, resulting in dehydration.

• Pituitary dwarfism

– Too little growth hormone is secreted by the anterior pituitary.

• Condition is characterized by small stature but normal proportions.

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• Gigantism

– Excess growth hormone is produced during childhood.

– Gigantism also promotes the development of

diabetes mellitus.

Figure 20.11

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• Acromegaly

– Excess growth hormone in adulthood

– Long bones cannot grow, so the effect is

noticeable in the hands, feet, and facial bones

Figure 20.12

Age 9 Age 16 Age 33 Age 52


(all): Reprinted from Clinical Pathological Conference, American Journal of Medicine, Vol. 20, page 133, “Acromegaly, Diabetes, Hypermetabolism, Proteinuria

and Heart Failure,” copyright 1956, with permission from Elsevier.

63


• Cushing Syndrome

– Excess production of ACTH (usually by tumor)

– Adrenal cortex then produces excess cortisol

• Protein is metabolized, fat is deposited in the midsection

Before treatment Four months after treatment

Figure 20.13

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Disorders of the Thyroid, Parathyroid and Adrenal Glands

• Hypothyroidism

– Not enough thyroid hormone is produced.

– Failure of thyroid function in infancy or childhood results in congenital hypothyroidism.

• Individuals are short and stocky; mental retardation results if treatment does not begin within 1st two months of life

– Treatment consists of the administration of thyroid hormones.

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a. Congenital hypothyroidism b. Simple goiter c. Exophthalmic goiter

affected eye


a: © Medical-on-Line/Alamy; b: © Biophoto Associates/Photo Researchers, Inc.; c: © Dr. P. Marazzi/SPL/Photo Researchers, Inc.

66

Disorders of the Thyroid, Parathyroid and Adrenal Glands

• Hashimoto thyroiditis is a form of hypothyroidism that occurs in adults.

– The immune system produces antibodies that destroy the thyroid gland.

– Myxedma is a group of clinical symptoms in adults not treated for the condition.

• Symptoms include: weight gain, hair loss, constipation or slow heart rate

– Treatment is the administration of thyroid hormones.

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Disorders of the Thyroid, Parathyroid

and Adrenal Glands

• Goiter– Lack of dietary iodine

makes the thyroid unable to produce sufficient T3

and T4.

– The thyroid gland is consequently constantly stimulated by TSH.

– The result is an enlarged thyroid gland.

Figure 20.14b. Simple goiter


© Biophoto Associates/Photo Researchers, Inc.

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and Adrenal Glands

• Hyperthyroidism

– Results from oversecretion of thyroid hormones

• Graves disease arises from

antibodies reacting with the TSH receptor, mimicking

effect of TSH.

– Symptoms include

protruding eyes,

nervousness, hyperactivity, and

abnormal heart rhythms.

Figure 20.14

c. Exophthalmic goiter

affected eye


© Dr. P. Marazzi/SPL/Photo Researchers, Inc.

69


and Adrenal Glands

• Disorders of the parathyroid

– Insufficient parathyroid production results in a drop in blood calcium levels.

– The body shakes from continuous muscle contraction (tetany).

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and Adrenal Glands

• Disorders of the adrenal glands

– Addison disease

• The most common cause is destruction of the adrenal cortex by

the immune system.

• Symptoms include weakness, weight loss, abdominal pain, and

a bronzing of the skin.

• Decreased production of mineral corticoids can affect Na+ and K+ levels, which can adversely affect the heart.

Figure 20.15


a: © Custom Medical Stock Photo; b: © NMSB/Custom Medical Stock Photos

a. b.

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Diabetes Mellitus

• Diabetes mellitus

– Affects an estimated 25.8 million Americans, or 8.3% of the population (as of 2010)

– Affects ability to regulate glucose metabolism

• Type 1 sufferers do not produce enough insulin.

• Type 2 sufferers cannot use insulin produced.

– As blood glucose rises, glucose and water are lost in the

urine

– Cells do not take up the glucose

– Causes increased thirst, increased hunger

• A glucose tolerance test is often used for diagnosis.

72

Glucose Tolerance TestCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

1 2 3

250

300

Blo

od

Glu

co

se

(m

g/1

00

ml)

150

50

100

200

renal threshold

diabeticnondiabetic

glucose

givenTime (hours)

Figure 20.16

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Diabetes Mellitus

• Two types of diabetes mellitus

– Type 1 – insulin-dependent• Lack of insulin may be due to exposure to environmental

agent, such as a virus, or an autoimmune condition.

• As cells break down fats for energy, ketones build up in

the blood.

– Ketoacidosis�coma�death

• Insulin overdose can cause hypoglycemia,

unconsciousness

– Immediate ingestion of glucose required to counteract

74

Diabetes Mellitus

• Two types of diabetes mellitus

– Type 2

• Insulin-resistant

• Linked to obesity - adipose tissue may produce a substance that impairs insulin receptor function

• Insulin levels often low - cells may not have sufficient insulin receptors

• Controlled by diet, exercise, medications

75

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Diabetes Mellitus

• Diabetics need to monitor their blood sugar several times daily, regardless of which diabetes

type they have.

• Monitoring is usually done by poking a finger to obtain blood drops to be tested using an external device.

• New testing devices are being introduced.

• Insulin pumps are replacing the needle and

syringe as an injection method.

77Figure 20.17b.

a.


(both): Courtesy of Insulet Corporation

78

Diabetes Mellitus

• Long-term complication of diabetes

– Blindness

– Kidney disease

– Cardiovascular disorders

• Can lead to reduced blood flow to limbs (gangrene)

– Diabetic coma in pregnancy (if not managed)

• The child has a higher risk of being stillborn or dying shortly after birth.

Documents

17-chapt20 lecture anim - Nassau Community College. – Insulin lowers the blood sugar level, while glucagon raises it. 14 The Action of Hormones • Hormones act on target cells