Endocrine System

Gap Junctions

Pores in cell membrane allow signaling chem to move from cell to cell

Neurotransmitter

Released from Neurons to travel across gap to 2nd Cell

Paracrine (Local) Hormones

Secreted into Tissue Fluids to affect nearby cells

Hormones

Chem messengers that travel in bloodstream

Endocrine System

Endocrine Glands + Heart, Brain, Small Intestine

Hypothalamus

Connected to Pituitary Gland by a Complex of Blood Vessels called

Hypothalamo-hypophyseal Portal

Produces Hormones that are Stored in Posterior Pituitary

Tropic Hormones

Hormones that regulate other Endocrine Glands

Pituitary Gland (Hypophysis)

Suspended from Hypothalamus by Stalk (Infundibulum)

Made up of 2 parts

• Adenohypophysis (Anterior 3/4)

• Neurohypophysis (Posterior 1/4)

  • Hypothalamo-Hypophyseal Tract is bundle of Axons

Housed in Sella Turcica of Sphenoid Bone

1.3 cm in Diameter

Pituitary Hormone - Posterior (Neuro) Lobe

Pituitary Hormone - Posterior (Neuro) Lobe

OT - Oxytocin

ADH - Antidiuretic Hormone

Triggered by Nerve Signals

ADH (Antidiuretic Hormone)

Retain Water

Also Vasopressin because it causes Vasoconstriction

OT (Oxytocin)

Released during Love

Uterine Contraction

Shoot Semen

Stims Labor Contraction and Milk

Hypothalamic Hormones

Gonadotropin - Releasing Hormone

Thyrotropin - Releasing Hormone

Corticotropin - Releasing Hormone

Prolactin - Releasing/Inhibiting Hormone

Growth Hormone - Releasing/Inhibiting Hormone / Somatostatin

Anterior Pituitary Hormone

Follicle Stim Hormone

Luteinizing Hormone

Thyroid Stim Hormone / Thyrotropin

Adrenocorticotropic Hormone

Prolactin

Growth Hormone

Tropic Hormone

Hormones that target other Hormone Glands

Gonadotropins

TSH

ACTH

Gonadotropins

Target Gonads

FSH and LH

Age

Hormone Production Declines

ACTH (Adrenocorticotropic Hormone)

Response to Stress

Effects Adrenal Cortex

Promotes Secretion of Glucocorticoids

Growth Hormone

Pituitary makes 1000x more than other Hormones

Targets Liver to make Somatomedins or IGF (Insulin-Like Growth Factor)

More Mitosis

High during first 2 Hours of Sleep, After Protein Meals, and After Exercise

Low after Carbohydrate Meal

Decline with Age

Anterior Lobe Control

Releasing Hormones and Inhibiting Hormones of Hypothalamus

Posterior Lobe Control

Neuroendocrine Reflexes

Hormones released in response to NS

Suck > Nerve Endings > Hypothal > Posterior Lobe > OT > Milk

Positive Feedback

Uterus Stretch > OT Release > More Uterus Stretch till Childbirth

Man Castrated

GnRH (Gonadotropin-Releasing Hormone) would INCREASE

Lack of Negative Feedback

Hypopituitarism

Pituitary Dwarfism

• Childhood GH Down

Panhypopituitarism

• No Pituitary Secretion

• Infertility + Metabolic Disorders

Diabetes Insipidus

• No ADH, 10x Urine Output

• Diabetes = Excessive Urine Production, not just Low Blood Sugar

Treated with Hormone Replacement Therapy

Hyperpituitarism

Child

• Gigantism

Adult

• Acromegaly - Thick Bones, Soft Tissue in Face Hands Feet

Pineal Gland

Peak Age 1-5, Shrinks at 7

25% at End of Puberty

Regs Puberty Timing

Sync Circadian Rhythm

• Makes Melatonin from Serotonin at Night

• Changes Seasonally
  

Seasonal Affective Disorder

• Occurs in Winter

• Depression + Sleepiness, Crave Carbs

  • 2-3 Hours Sunlight Helps

Thymus

Shrinks after Puberty

Biggest in Kids

Regs Dev and Later T Lymphocyte Activation

• Thymosin, Thymopoietin, Thymulin

Thyroid Gland

Largest Endocrine Gland in Adult

2 Lobes connected by Isthmus

Thyroid Hormone

T3 and T4 (Thyroxine)

• Increase Metabolic Rates and O2 use

• Heat Production

• Heart Rate + Contraction

• Respiratory Rate

Calcitonin

• Less Blood Calcium (Ca2+)

  • Makes Bones

Thyroid Gland Disorders

Congenital Hypothyroidism

• Weird Bone Dev

  • Thick Face Features

  • Low Temp

  • Brain Damage

Myxedema - Adult Hypothyroidism

• Low Metabolic Rates

• Sluggish

• Weight Gain, Constipation

• Cold

• High BP and and Tissue Swell

Goiter

Enlarged Thyroid Gland

Endemic Goiter

• Dietary Iodine Deficiency

• TG needs Iodine to make TH

  • No TH = No Negative Feedback = Increase in TRH + TSH
    

Toxic Goiter (Graves Disease)

• Autoimmune Disease

• Antibodies mimic TSH = More TH = More Metabolism

• Increased Heart Rate

• Exophthalmos

  • Bulging of Eyes due to Fluid

Parathyroid Gland

4 Small Glands

Secrete PTH

Breaks Bone to Absorb

Parathyroid Gland Disorders

Hypoparathyroidism

• Low Blood Calcium Levels

• Tetanus

• Muscles Can’t Relax = Spasms

• Suffocation
  

Hyperparathyroidism - Excess PTH

• Can be from Tumor

• Eat Bones

• Bones Fragile

• Blood Ca2+ High (Hypercalcemia)

• Renal Calculi (Kidney Stones)

• Muscle Weakness

• CARDIAC ARREST

Why Blood Ca2+ Is Important

Ca2+ Binds to Negative Particles Outside Cell

• Makes it Positive Outside, Negative Inside

If not Positive, Na Channels Open

Adrenal Glands (Suprarenal)

Adrenal Cortex

• 3 Layers

  • Zona Glomerulosa

  • Zona Fasciculata

  • Zona Reticularis

Adrenal Medulla

Adrenal Medulla

Chromaffin Cells - Modified Neurons lacking Dendrites and Axons

Secretes Catecholamines

• Hormone + Neurotransmitter

• Epinephrine 85% (Adrenaline)

• Norepinephrine 15% (Nor-Adrenaline)

Like SNS in Dev and Function

Lasts Longer because Hormone

Corticosteroids

25+ in 3 Categories

Mineralocorticoids

• Aldosterone

  • Electrolyte Balance

  • Promotes Na+ Retention and K+ Excretion

Glucocorticoids

• Cortisol

  • Stims Fat and Protein Catabolism and Gluconeogenesis

  • Anti-Inflammatory

Sex Steroids

• Androgens

  • Body Hair, Voice, Fat Distribution

• Estrogen

  • Important after Menopause when Ovaries Stop Producing Estrogen

Adrenal Disorders

Pheochromocytoma - Tumor of Adrenal Medulla

• More Nor / Epinephrine

• High BP, Metabolism, Blood Sugar

• Glycosuria - Glucose in Urine

• Hot, Indigestion
  

Cushing Syndrome - Too Much Glucocorticoid

• High Cortisol, Protein Breakdown

  • Loss of Muscle and Bone Mass

• High Blood Sugar

• Swelling, Weakness

  • Weird Fat accumulation in Face and Shoulders

Adrenogenital Syndrome (AGS)

Too much Androgen

Big Penis / Clitoris

Premature Puberty

Deep Voice + Hair in Women

Addison Disease

Low Mineralocorticoids + Glucocorticoids

Low Blood Sugar

Na+ and K+ Imbalance

Low BP

Weight Loss

More Pituitary ACTH

Stims MELANIN = Bronze Skin

Pancreas

Both Endo and Exocrine

Digestive Hormones

Pancreatic Hormones

Insulin - Beta Cells

• Lowers Blood Glucose

• Nutrient Storage Effect

Glucagon - Alpha Cells

• Increases Blood Glucose

• Stims Glycogen Breakdown

• Fat Breakdown

• Absorbs Amino Acids for Gluconeogenesis

Somatostatin - GH Inhibiting Hormone - Delta Cells

• Paracrine Secretion

  • Diffuse to cells within Same Organ

• Regs Alpha and Beta Secretion

Diabetes Mellitus

Due to Low Insulin or Inaction

Signs and Symptoms - 3 P’s = Excessive

• Polyuria - Urine

• Polydipsia - Thirst

• Polyphagia - Hunger

Hyperglycemia - High Blood Sugar

Glycosuria - Glucose in Urine

Type 1 Diabetes Mellitus - Insulin Dependent (IDDM)

Juvenile Diabetes

10% of Diabetes

Autoimmune Destruction

Treated with Diet or Blood Monitoring

Requires Insulin Injections

Type 2 Diabetes Mellitus - Non Insulin Dependent (NIDDM)

90%

Insulin RES

Linked to Diet

3 Risks

• Hereditary

• Age

• Obesity

Treated with Weight Loss Program, Diet, Exercise, Meds

Endocrine Function of Other Organs

Heart - Atrial Natriuretic Factor/Peptide (ANF or ANP)

• When BP is High, Lowers BP

• Increase Urine and Sodium Output

Kidneys - Calcitriol and Erythropoietin

• Increase Ca2+ and Phosphate Absorption

• Stims Bone Marrow for RBCs

Stomach and Small Intestines - Enteric Hormone (Gut)

• Coordinates Digestion

Liver - Angiotensinogen

• Precursor of Angiotensin II

  • Vasoconstrictor

• Erythropoietin 15%

• Somatomedins

  • Helps action of GH

Placenta - Estrogen, Progesterone

• Regs Pregnancy

• Stims Fetus Dev

• Stims Mammary Glands

Hormone Chemistry

Steroids

• Derive from Cholesterol - Lipids / Fat Based

• Hydrophobic

  • Need Transport Protein through Bloodstream

• Sex Steroids, Corticosteroids

Peptides and Glycoproteins

• 3 - 200 Amino Acids

• Hydrophilic

• OT and ADH

• All Releasing/Inhib Hormone

• Most Anterior Pituitary Hormone

Monoamines

• Derived from Tyrosine

• Most are Hydrophilic

• Nor/Epinephrine, Dopamine, TH

Hormone Synthesis

Cholesterol > Progesterone

Progesterone makes 4 Steroids

• Testosterone

• Estrogen

• Cortisol

• Aldosterone

Peptides

• Rough ER removes Segment

Monoamines

• All from Tyrosine except Melatonin, which is from Tryptophan

• Thyroid Hormone is Weird here

  • Made from 2 Tyrosine

  • Requires Iodine, a Mineral

Easily Enter Cell

Steroids because HydroPHOBIC

Peptides, Glycoprotein, Monoamines circulate well in Blood

Hormone Transport and Action

Steroids + TH needs Transport Protein

• Easily Enter Cell

Monoamines +Peptides - Transports well in Blood

• Can’t Enter Cell, Must Bind to Receptors

Secondary Messenger System

Binds to Receptor

Activates G Protein

Activates Adenylate Cyclase

Produces cAMP

Activates Protein Kinase

Phosphorylate Enzymes

Makes Metabolic Pathway

Hormone Receptors

On:

• Plasma Membrane

• Mitochondria

• Organelles

• In Nucleus

Thousands

• Turn on/off Metabolic Pathway

Exhibit

• Specificity - Specific to 1 Hormone

• Saturation - Can only respond to so much

Hormone Clearence

Taken + Degraded by Kidney and Liver

Excreted in Bile or Urine

Metabolic Clearance Rate (MCR)

Half-Life - Time taken to clear 50%

Stress + Adaptation

Anything that Affects Homeostasis

The Way Body Reacts

• General Adaptation Syndrome (GAS) - 3 Stages

  • Alarm Reaction

  • Stage of Res

  • Stage of Exhaustion

Alarm Reaction

Fight or Flight

Increase in

• Nor/Epinephrine

• Heart Rate

• BP

• Blood Glucose

• Circulation to Muscles

• Aldosterone (Na+ H2O Retention)

Stage of Resistance

After few Hours, Glycogen reserves GONE

Hypothalamus secretes Corticotropin Hormone

PT releases ACTH

Adrenal Cortex releases Cortisol + Glucocorticoids

Fat and Protein Breakdown

Gluconeogenesis

Depressed Immune System

Gastric Secretion that may lead to Ulcers

Suppress Sex Hormones

Stage of Exhaustion

When Stress for Months, Fat Reserves Gone, Homeostasis Overwhelmed

Proteins breakdown + Muscles Die

Loss of Glucose Homeostasis

High Aldosterone

• Electrolyte Imbalance

  • Loss of K+ - Hypokalemia

  • Loss of H+ - Alkalosis (High Blood pH)

DEATH

Paracrine Secretions

Short Distance Chem Messengers

Not like Neurotransmitter or Hormones

Histamines

• Mast Cells in Connective Tissue

• Relax Blood Vessels

Nitric Oxide

• Vasodilation

Somatostatin

• Inhibit Alpha Beta

Catecholamines

• Adrenal Medulla to Stim Cortex

Eicosanoids - Paracrine Secretion

From Polyunsaturated Fatty Acid

• Arachidonic Acid

Leukotrienes

• From Arachidonic Acid By Lipoxygenase

• Mediates Allergies

Prostacyclin

• By Cyclooxygenase

• Inhibits Clot and Vasoconstriction

Thromboxane

• By Cyclooxygenase

• After Injury

• Overrides Prostacyclin

Prostaglandins

• Yap Yap not important

Anti Inflammatory Drugs

SAIDs - Steroidal Anti Inflam Drugs

• Cortisol and Corticosterone

• Blocks Arachidonic Acid

• Inhibits Synth of all Eicosanoids

NSAIDs

• Aspirin and Ibuprofen

• Blocks Cyclooxygenase

• Does not affect Leukotrienes

Lack of ADH

Leads to Diabetes Insipidus

Which Group of Hormones Req Cholesterol for Synth

Steroids

Which Group of Hormones is Never Hydrophilic

SteroidsD

Driving in Stress can Cause Release of

ACTH

Oxytocin is made by

Hypothalamus

It is released by Posterior Pituitary into Bloodstream but not made there

Produced in Hypothalamus, Stored in Posterior Lobe, When Blood Osmolarity Rises

ADH

Major Nitrogenous Waste

Urea

Right Kidney is Lower Because of

Liver

Filtration of Blood Plasma begins at

Glomerular Capillaries

Not Renal Tubule

Collecting Duct

SNS increases Glomerular Filtration

TRUE