Warm Up 2/14/11Announcements:• Pick up a new warm up sheet from the counter• Warm ups due THIS Friday• End of six weeks THIS Friday• Make up testing TODAY after schoolWarm Up:1. What is homeostasis?2. What is the chemical messenger released by

neurons which act on a target cell?3. What is anabolism?4. Differentiate between exocrine and endocrine

glands.

Endocrine System

Chapter 16

Overview• Overall goal of endocrine system: maintain

a stable internal environment (homeostasis)• Endocrine glands are “ductless glands” • Endocrine glands secrete hormones which

travel through the blood to a target cell– Receptor must be present on target cell

• Glands of the endocrine system are present throughout the body

• Most cells are regulated by the endocrine system

Endocrine vs Nervous System

• Both systems function to maintain homeostasis• Main differences:

Feature Endocrine System Nervous System

Effector cells Target cells throughout the body

Postsynaptic cells in muscle and glandular tissue only

Chemical messenger Hormone Neurotransmitter

Distance traveled by messenger

Long – in blood Short – across synaptic cleft

Regulatory effects Slow to appear; long-lasting Appear rapidly; short

Endocrine vs Nervous System

Major Endocrine Glands

Classification of Hormones

• Classified by Function– Tropic hormones: target other endocrine

glands and stimulate their growth & secretion– Sex hormones: target reproductive tissues– Anabolic hormones: stimulate anabolism in

their target cell

Classification of Hormones

• Classified by Chemical Structure– Steroid Hormones

• Derived from cholesterol• Lipid soluble; can pass through phospholipid

bilayer

– Nonsteriod Hormones• Synthesized from amino acids• Proteins, Glycoproteins, peptides, amino acid

derivatives (Fig 16-3)

Chemical Classifications of Hormones

Warm Up 2/15/11Announcements:1. Make up testing today after school (room 2212)2. Extra credit due this FridayWarm Up:1. What is the overall goal of the endocrine system?2. What is the chemical messenger released by the

endocrine system?3. Describe the regulatory effects of the endocrine system?4. What are the two ways hormones can be classified?5. What is the main difference between steroids and

nonsteroids? 6. True/False: Cells can be targets for multiple hormones.

How Hormones Work• Hormones bind to receptors on target

cells– Lock & key

• Hormone-receptor interactions produce regulatory changes within the target cell– Ex: initiating protein synthesis;

activation/inactivation of enzymes; opening/closing of ion channels

• Endocrine glands produce more hormone molecules than necessary to hit the target cells– Excess hormones are excreted in urine or

broken down by metabolic processes

How Hormones Work

• Synergism: combinations of hormones have a greater effect on the target cell compared to a single hormone acting alone

• Permissiveness: a small amount of one hormone allows a second hormone to exhibit its full effect on the target cell

• Antagonism: two hormones produce opposite effects

Mechanisms of Steroid Hormone Action• Steroids are lipids not soluble in blood plasma

(mostly H2O)• In blood steroids attach to plasma proteins• Steroid reaches a target cell dissociates from

plasma protein diffuses into target cell• In the nucleus a hormone-receptor complex is

formed• Hormone-receptor complexes in the nucleus trigger

protein synthesis (transcription & translation)• Increase steroid = increase response (protein

synthesis)• Regulatory effects of hormones are slow to appear

Mechanisms of Steroid Hormone Action

Mechanisms of Nonsteriod Hormone Action

• Nonsteroid hormones operate according to the second messenger hypothesis– Nonsteroid hormone is the “1st messenger” and

binds to a receptor on the plasma membrane of the target cell

– The “message” is relayed inside the cell to a “2nd messenger” which triggers the appropriate cellular response

Second Messenger Mechanism1. Nonsteroid

hormone (1st messenger) binds with receptor on plasma membrane

2. Hormone-receptor complex activates a membrane protein called the G protein

3. G protein activates guanosine triphosphate (GTP) which also activates another membrane protein (adenyl cyclase)

Second Messenger Mechanism4. Adenyl cyclase

removes 2 phosphate groups from ATP creating cyclic adenosine monophosphate (cAMP) (second mesenger)

5. cAMP activates or inactivates protein kinases

6. Protein kinases activate specific intracellular enzymes

Second Messenger Mechanism

7. Enzymes influence specific cellular reactions (target cell’s response to hormone)

Second Messenger Mechanism

Summary:• Hormone or 1st messenger binds to plasma

membrane receptor• Triggers formation of intracellular 2nd messenger• 2nd messenger activates cascade of chemical

reactions• Target cell’s response to the hormone is

produced

Another Second Messenger• Some hormones produce effects in target cells by

triggering opening of calcium channels– Hormone binds to receptor on plasma membrane– Ca2+ channels open– Ca2+ binds with calmodulin– Ca2+/Calmodulin complex acts as 2nd messenger– Enzymes are activated/inactivated– Target cell’s response is produced

Calcium-Calmodulin as 2nd Messenger

Regulation of Hormone Secretion

• Hormone secretion is controlled by a negative feedback loop– Ex: parathyroid hormone (PTH) and blood

calcium levels (fig 16-10)– Ex: insulin and blood glucose levels

Endocrine Feedback

Loop

Hyper vs Hyposecretion

• Tumors or abnormalities of the endocrine glands cause secretion of too much or too little hormone

• Hypersecretion: production of too much hormone

• Hyposecretion: production of too little hormone– Results in lack of target cell response– Also caused by target cell insensitivity

Regulation of Target Cell Sensitivity

• Sensitivity of target cell depends on number of receptors it has for a specific hormone

• Receptors are constantly begin broken down and re-synthesized by the cell

• Up-regulation: synthesis of new receptors > degeneration of old receptors– Increase target cell sensitivity to that particular

hormone

• Down-regulation: synthesis of new receptors < degeneration of old receptors– Decrease target cell sensitivity

Prostaglandins

• Group of lipid molecules that play an important role in the body but to not classify as hormones

• Structure: 20-carbon unsaturated fatty acid with a 5 carbon ring

Prostaglandins

• Secreted into the bloodstream• Metabolize quickly; circulating levels

remain low• Prostaglandins are produced in certain

tissues and travel to other cells within the same tissue

• Tissues that secrete prostaglandins:– Kidneys, lungs, brain, thymus, seminal

vesicles

Warm Up 2/16-2/17/11Announcements1. End of the six weeks is FRIDAY2. Gradebook is updated except for last warm up and extra credit3. Extra credit due FRIDAYWarm Up:1. Differentiate between synergism, permissiveness and

antagonism.2. What is the main difference between the mechanisms of steroid

action and nonsteroid action on a target cell.3. What two molecule can act as 2nd messengers?4. By what mechanism is hormone secretion controlled?5. Differentiate between up-regulation and down-regulation. What

do each result in?

Pituitary Gland• Also called hypophysis• Located on ventral surface of brain, inferior to the

hypothalamus• “Master gland” because functions are crucial to life• Composed of two parts: Anterior Pituitary and

Posterior Pituitary

Anterior Pituitary • Hormones secreted from Anterior Pituitary:

– Growth Hormone– Prolactin– Trophic hormones

• Thyroid-stimulating hormone (TSH)• Adrenocorticotropic hormone (ACTH)• Gonadotropic hormones

– Follicle-stimulating hormone (FSH)– Luteinizing hormone (LH)

Growth Hormone• Growth Hormone (GH) – promotes growth by

stimulating protein anabolism • Increased protein anabolism allows increased

growth rate• Target cells:

– Promotes growth of bone and muscle

• GH has a hyperglycemic effect; antagonist of insulin– Hyperglycemic effect because GH stimulates fat

metabolism– Interaction vital to maintaining homeostasis of blood

glucose levels

Growth Hormone Abnormalities

• Hypersecretion– Prior to ossification of the epiphyseal plates

hypersections of GH results in rapid skeletal growth Gigantism

– After closure of epiphyseal plates hypersecretion causes cartilage to continue to form new bone Acromegaly

• Distorted appearance; enlarged hands, feet, face, jaw; thickened skin

Growth Hormone Abnormalities

• Hyposecretion– Results in stunted body growth pituitary

dwarfism– Treated with genetically engineered growth

hormone

Prolactin (PRL)

• Also called lactogenic hormone

• Initiates milk secretion (lactation)

• Target cells: Mammary glands

• During pregnancy PRL promotes development of breasts

• At birth PRL stimulates milk production

Prolactin Abnormalities

• Hypersecretion:– Lactation in non-nursing women– Disruption of menstrual cycle– Impotence in men

• Hyposecretion:– Insignificant unless mother wishes to

breastfeed

Trophic Hormones

• Review: a trophic hormone stimulate effects of other endocrine glands

• Trophic hormones released from anterior pituitary gland:– Thyroid-stimulating hormone (TSH)– Adrenocorticotropic hormone (ACTH)– Gonadotrophic hormones

• Follicle-stimulating hormone (FSH)• Luteinizing hormone (LH)

Thyroid-stimulating hormone (TSH)

• Promotes and maintains growth and development of thyroid gland

• Required for thyroid gland to secrete its hormones

Adrenocorticotropic hormone (ACTH)

• Promotes and maintains normal growth and development of the cortex (outer portion) of the adrenal gland

• Required for adrenal cortex to secrete its hormone

Gonadotrophic hormones

• Target cells: gonads (testes & ovaries)

• Follicle-stimulating hormone (FSH)– Females:

• Stimulates growth & development of an ovum that is released each month during ovulation

• Stimulate estrogen release from the ovaries

– Males• Stimulates development of seminiferous tubules

and maintains sperm production in the testes

Gonadotrophic hormones

• Luteinizing hormone (LH)– Females:

• Triggers ovulation• Promotes development of corpus luteum which

secretes progesterone and estrogen; these hormones help maintain pregnancy

– Males:• Stimulates cells of the testes to synthesize and

secrete testosterone

Control of Anterior Pituitary Secretion

• The hypothalamus releases chemical called releasing hormones which influence hormone secretion from the anterior pituitary gland

• This regulatory mechanism is a negative feedback loop

Posterior Pituitary • Hormones secreted from Posterior Pituitary:

– Antidiuretic Hormone (ADH)– Oxytocin (OH)

Antidiuretic Hormone (ADH)

• Target cells: kidney• Prevents formation of large volumes of

dilute urine• Antidiuresis• Helps conserve water balance• Example:

– Blood is hypertonic change detected by osmoreceptors ADH is released water reabsorbed in kidneys and returned to blood

ADH Abnormalities

• Hyposecretion– Diabetes insipidus– Increased urine output of dilute urine– “high and dry”– Na+ levels are increased; ICF dehydrated

• Hypersecretion– Syndrome of inappropriate antidiuretic hormone

(SIADH)– Decreased urine output– Fluid overload; low Na+ levels

Oxytocin (OT)• Target cells: mammary glands & uterine smooth

muscle • Operates on a positive feedback loop• Stimulates uterine smooth muscle contractions

– During childbirth stretching of receptors causes continued release of oxytocin until after delivery of the placenta

• Ejection of milk into ducts of the breast of lactating women– When breastfeeding the suckling action of the baby causes

secretion of additional oxytocin increasing milk production– Breastfeeding also helps the uterus continue to contract

back to normal size during the postpartum period

Warm Up 2/18/11

Announcements:• Turn in extra credit to the tray – please keep or recycle

the article• Check grades onlineWarm Ups:• What is a trophic hormone?• What are the six hormones release from the anterior

pituitary?• What is the action of antidiuretic hormone?• What are the functions/actions of oxytocin?• Differentiate between gigantism and acromegaly.

Project Reminders• Make sure your illustrations shows both the

anterior and posterior pituitary.• Show ovaries and testes (only testes)• Remember that trophic hormones will be a double

pathway• Plan ahead – we have not learned about all of the

hormones yet so make sure you leave room for future information

• You will be adding additional organs to represent target cells

• Questions??

Warm Up 2/21/11

Announcements:1. 5th six weeks starts TODAY2. Tentative test date for chapter 16 – Friday March 4th

3. Project due Friday March 4th 4. Please ROLL project at the end of classWarm Up:1. What causes diabetes insipidus? Describe the fluid

and electrolyte balance of a patient with this diagnosis.2. True/False: Prostaglandins are classified as hormones.3. True/False: Hyposecretion of prolactin can be life-

threatening. Defend your answer.

Pineal Body

• Regulates the body’s biological clock– Patterns of eating– Sleeping– Female reproductive cycle– Behavior

• Secretes melatonin – Induces sleep– Secretion is inhibited by sunlight– Target cell in humans is unknown

Melatonin & Seasonal Affective Disorder

• Also know as “winter depression”

• During shorter days, melatonin secretion increases causes a depressed feeling in affected patients

• Treatment– Exposure to high-intensity lights to inhibit

melatonin secretion

Thyroid Gland• The thyroid gland is composed of two lateral

lobes connected by an isthmus

• Located on the anterior and lateral surfaces of the trachea, below the larynx

Thyroid Hormones

• Tetraiodothyronine or thyroxine (T4)

– Most abundant thyroid hormone– Contains 4 iodine atoms– May have effect on target cells, but mostly

serve as precursor to T3

• Triodothyronine (T3)

– “principal thyroid hormone”– Contains 3 iodine atoms

Thyroid Hormones• Both hormone bind to plasma proteins once

secreted into the bloodstream

• Function:– Regulate metabolic rate of all cells– Regulate cell growth– Regulate tissue differentiation

• Target cells: “general” because thyroid hormones can potentially interact with all cells of the body

Hypersection

• Graves Disease– Autoimmune condition (thyroid stimulating

antibodies causes abnormal secretion)– Weight loss– Increases basal metabolic rate– Increased heart and respiratory rate– exophthalmos

Exophthalmos

Hyposecretion of Thyroid Hormone

• Cretinism – develops during the growth years due to hypothyroidism– Low metabolic rate– Retarded growth and sexual development– Mental retardation (possibly)

• Hypothyroidism later in life– Decreased metabolic rate– Loss of mental & physical vigor– Weight gain– Loss of hair – Yellow discoloration of the skin– myxedema

Goiter• Caused by lack of iodine in the diet• Iodine is needed to synthesize thyroid

hormone• Lack of iodine causes drop in thyroid

hormone production/secretion• Negative feedback loop informs

hypothalamus and anterior pituitary to release releasing hormones and TSH

• Lack of iodine causes enlargement of thyroid gland

Calcitonin

• The 3rd hormone secreted from the thyroid gland

• Target cells – bone• Function – regulates calcium levels in the

blood by decreasing blood calcium levels– Increases action of osteoblasts (build bone)

and inhibits action of osteoclasts (breakdown bone)

– Antagonist to parathyroid hormone

Warm Up 2/22/11

Announcements:1. Quiz on block day – will cover notes up through today2. Test and Project due next Friday (3/4)3. Bring your book on block day to help with projectWarm Up:1. How/why does melatonin cause “winter depression”?2. Name the two thyroid hormones. Which is considered

the “principle thyroid hormone”? Why?3. What is/are the target(s) of the thyroid hormones?4. What is needed to synthesize thyroid hormones?5. Calcitonin serves as an antagonist to which other

hormone?

Parathyroid Glands• Parathyroid glands are embedded in the

posterior aspect of the thyroid glands

• Usually 4 or 5 parathyroid glands

Parathyroid Hormone• Secreted from Parathyroid glands• Target cells: bone and kidney• Action: maintains calcium homeostasis

– Increases osteoclast activity; decrease osteoblast activity

– Calcium absorbed in kidneys and returned to the bloodstream

– Activates vitamin D in the kidneys which increases intestinal absorption of calcium

• Parathyroid hormone is an antagonist to calcitonin

Adrenal Glands

• Located on top of both of the kidneys

• Composed of two parts:– Outer portion adrenal cortex– Inner portion adrenal medulla

• Both parts of the adrenal glands are structurally and functionally different; often treated as two different glands

Adrenal Cortex

• Composed of three distinct layers or zones– Outer zone secrete mineralocorticoids– Middle zone secrete glucocorticoids– Inner zone secrete glucocorticoids and

gonadocorticoids

Mineralocorticoids• Mineralocorticoids – regulate electrolytes in the

body• In humans the most important mineralcorticoid is

aldosterone• Target cell – kidneys• Function – maintaining sodium homeostasis in the

blood– In the kidneys, sodium ions are reabsorbed from the

urine back to the blood– Sodium ions are exchanged for potassium or hydrogen

ions– Aldoesterone also promotes water retention because re-

absorption of sodium ions also causes water to be reabsorbed

Regulation of Aldosterone Secretion• Aldosterone secretion is controlled by the renin-

angiotensin mechanism• This mechanism is a negative feedback loop that

helps maintain homeostasis of blood pressure1. Blood pressure drops in the kidneys renin (an

enzyme) is secreted2. Renin converts angiotensinogen to angiotensin I3. Angiotensin I travels to the lungs where enzymes split

the molecule forming angiotensin II4. Angiotensin II travels to the kidneys where it simulates

the secretion of aldosterone5. Aldosterone causes reabsorption of sodium ions

followed by water reabsorption increase in blood pressure

Glucocorticoids

• Main glucocorticoid secreted from the adrenal cortex is cortisol (also hydrocortisone)

• Target cells – general; affect every cell in the body

Cortisol - Functions

• Accelerate protein breakdown into amino acids– Amino acids travel to liver and are converted

to glucose (gluconeogenesis)– Increased glucocorticoids (cortisol)

increased breakdown of proteins in tissue (tissue wasting) hyperglycemia

• Shift cells from carbohydrate catabolism to lipid catabolism for energy sources– Further causes hyperglycemia

Cortisol – Functions cont…

• Help maintain blood pressure– Permissiveness relationship with epinephrine

and norepinephrine– Epi and NE cause vasoconstriction of blood

vessels

• Suppression of immune system responses

Gonadocorticoids

• The adrenal cortex secretes small amounts of male hormones (androgens)

• Secretes in males and females

• Causes appearance of pubic and axillary hair in males and females

Glucocorticoid Hypersecretion• Cushing Syndrome

– Too much cortisol is being secreted– Causes:

• Could be caused by hypersecretion of ACTH from anterior pituitary (tumor)

• Cirrhosis of liver or liver failure can’t breakdown hormones

– Signs/Symptoms:• Abnormal hair growth• buffalo hump • muscle wasting• skin breakdown (thin skin)• striae across abdomen and thighs• truncal obesity• Susceptible to infection

Adrenal Insufficiency

• Hyposecretion of mineralcorticoids & glucocorticoids Addison Disease

• Signs/Symptoms:– Drop in blood sodium– Hypoglycemia– Increase in blood potassium– Dehydration – Weight loss

Adrenal Medulla

• Secretes two nonsteroids in the catecholamine class– Epinephrine and norepinephrine– Bind to sympathetic effectors and enhance

the effects of the “fight or flight” response of the autonomic nervous system

Warm UpAnnouncements:

1. Project due next Friday (3/4)

2. Chapter 16 test next Friday (3/4)

3. TAKS next week – different schedule

Warm Up – Matching (write it out – it helps you learn )

1. Aldosterone A. Hypersecretion of ADH

2. Cortisol B. Mineralcorticoid

3. Addison Disease C. Adrenal Insufficiency

4. Cushing Syndrome D. Glucocorticoid

5. SIADH E. Hypersecretion of cortisol

Pancreas

• Located in the LUQ

• Contains both endocrine and exocrine tissue

• Endocrine portion is made up of tiny islands of cells called pancreatic islets (also islets of Langerhans)

• Alpha cells secrete glucagon

• Beta cells secrete insulin

Pancreatic Hormones• Glucagon

– Increases blood glucose levels• Converts glycogen to glucose in liver cells• Stimulates gluconeogenesis

– Target cells liver

• Insulin– Decreases blood glucose levels

• Promotes movement of glucose, amino acids, fatty acids into cells

• Promotes metabolism of these molecules once by cells

– Target cells general (all cells)

• Glucagon and Insulin produce antagonistic effects (fig 16-27, page 512)

Diabetes

• Results from either – 1) inadequate or absence of insulin

production– 2) Insulin resistance – decreased insulin

receptors results in decreased effectiveness of glucose uptake

Diabetes – Signs & Symptoms

• Hyperglycemia – elevated amounts of glucose in the blood– Results glucose not entering the cells properly

• Glycosuria – glucose present in the urine– Elevated glucose levels in the blood exceeds

kidney’s abilities to reabsorb glucose; glucose “spills over” into the urine

• Polyuria – increased urine production– Water follows glucose lost in urine

Diabetes – Signs & Symptoms

• Polydipsia – excessive thirst– Polyuria causes dehydration

• Polyphagia – excessive and continuous hunger– Although blood sugar is high cells are

“starving” because cells cannot uptake glucose

**3 P’s = polyuria, polydipsia, polyphagia**

Diabetic Ketoacidosis• Diabetics are unable to utilize glucose for energy –

cells must use protein and fat• Large quantities of fat metabolism results in build

up of acidic metabolites called ketone bodies• Signs/Symptoms

– Acidosis– Abdominal pain– Nausea/vomiting– Fruity breath– Decreased LOC– Coma– death

Type 1 Diabetes

• Absolute deficiency of insulin production

• Cause of beta cell destruction is unknown

• Requires insulin injections or an insulin pump

Type 2 Diabetes

• Previously called non-insulin-dependent diabetes (NIDDM) or adult onset diabetes

• Beta cell produce reduced amounts of insulin

• Loss of insulin receptors on target cells leads to insulin resistance

• Treated with insulin injections, oral diabetic medication and lifestyle modifications

Complications of Diabetes

Untreated or poorly controlled diabetes can lead to many complications that affect almost every system in the body:

• Atherosclerosis – build up of fatty materials in the blood vessls– Lead to heart attack, stroke, reduced

circulation

• Diabetic retinopathy – can lead to blindless

Complications of Diabetes

• Neuropathy – nerve damage– Amputations

• Kidney disease– May require dialysis

Warm Up 2/28/11

Announcements:1. Project due this Friday2. Test – Chapter 16 – This Friday3. Warm Ups due this Friday4. Please make up quiz ASAP (today after

School)5. Corrections in notes (highlighted in red –

online)Warm Up:Explain the relationship between diabetes and “the

3 P’s”.

Gonads – Testes & OvariesTestes:

• Composed mainly of coils of seminiferous tubules & interstitial cells

• Interstitial cells secrete testosterone • Target cells – general• Function:

– Growth & maintenance of male sexual characteristics– Sperm production

• Testosterone secretion is regulated by the gonadotropin leutinizing hormone (LH)

Gonads – Testes & Ovaries

Ovaries:

• Estrogen– Secreted by cells of the ovarian follicles– Target cells: general– Functions:

• Promote development & maintenance of female sexual characteristics

• Breast development• Regulation of menstrual cycle

Gonads – Testes & OvariesOvaries:• Progesterone (“pregnancy-promoting

hormone”)– Secreted by corpus luteum– Target cells: general– Functions (with estrogen):

• Maintains the lining of the uterus to maintain a pregnancy

• Remember Estrogen & Progresterone secretion is regulated by FSH and LH (gonadotropic hormones)

Placenta

• Tissue that forms along the lining of the uterus

• Serves as the connection between the circulatory systems of the mother and developing fetus

• Secretes human chorionic gonadotropin (hCG)

• Target cells: ovaries

Placenta

• Function:– Stimulates hormone (estrogen &

progesterone) secretion from the ovaries– High levels of estrogen & progesterone help

maintain uterine lining for pregnancy

• hCG is high during the 1st trimester

• A high hCG level is used to confirm a pregnancy