Glucagon:

• extremely potent
  -triggered by decrease blood glucose levels, rising amino acid levels, or sympathetic nervous system
  -raises blood glucose levels by targeting liver to:
  
  

-Break down glycogen into glucose
-synthesize glucose from lactic acid and other non-carbohydrates
-release glucose into the blood

*Insulin:

• secreted warm blood glucose level increase
• insulin lowers blood glucose levels in three ways:
  -enhances membrane transport of glucose into fat and muscle cells
  -inhibits breakdown of glycogen to glucose
  -inhibits conversion of amino acids are fats to glucose

Positive feedback:

• Oxytocin and ADH

  
  

  -each composed of nine amino acids

  
  

  -almost identical but different into amino acids

  
  

• Oxytocin:

  
  

  -strong stimulant of uterine contractions released during childbirth

  
  

  -also access hormonal trigger for milk ejection

  
  

  -both are positive feedback mechanisms

  
  

  -act as Neuro transmitter in brain

  
  

• Hormones are released to initiate actions that lead to an additional release of that hormone

Negative feedback:
Hormone release

• blood levels of hormones
  -controlled by negative feedback systems
  -increased hormone effects on target organs can exhibit further hormone release
  -levels vary only within narrow, desirable range
  -hormone release is triggered by:
• Endocrine Gland stimuli
• Nervous System Modulation

Parathyroid hormone: PTH is most important hormone in Ca2+ homeostasis

• secreted in response to low blood levels Ca2+
• inhibited by rising levels of Ca2+
  
  

Functions:

• stimulate osteoclasts digest bone matrix and Ca2+ in blood
• enhances reabsorption Ca2+ and secretion of phosphate by kidneys
• promote activation of vitamin D by kidneys which leads to increase absorption of Ca2+

Mineralocorticoids: regulates electrolyte concentrations

• Aldosterone: most potent mineralocorticoid
  -stimulates Na+ reabsorption by kidneys
  -results in increased blood volume and blood pressure
  -stimulates k+ elimination by kidneys

Thyroxine & Triiodothyronine: Body's major metabolic hormone and found in both forms

• both are iodine containing amine hormones
• TH affects virtually every cell in body
• enters target sell in binds to intracellular receptor within nucleus
• triggers transcription of various metabolic genes

Glucocorticoids:

• influence Metabolism of most cells and helps resist stressors
• keep blood glucose levels relatively constant
• maintain blood pressure by increasing the action of vasoconstrictions

Prolactin: Stimulated by decreased PIH release enhanced by estrogens, birth control pills, breast-feeding, and dopamine blocking drugs. Inhibited by PIH
-Target organ: Breast secretary tissue

Gonadocorticoids:

• weak androgens converted to testosterone and tissue cells, some to estrogens
• many contribute to:
  -onset of puberty in appearance of secondary sex characteristics
  -Sex drive in women
  -source of estrogen in postmenopausal women

Luteinizing hormone: Stimulated by GnRH & Inhibited by feedback inhibtion exerted by estrogen and progesterone in females and testosterone in males

• Target organ: ovaries in Testes

Epinephrine & Norephrine: Effects of catecholamine:

• Vasoconstriction
• increased heart rate
• increase blood glucose levels

• blood diverted to brain, heart, and skeletal muscles

  
  

• both hormones have basically same affects but:

  
  

  -Epinephrine is more a stimulator of metabolic activities

  
  

  -Norepinephrine has more of an influence on peripheral vasoconstriction and blood pressure

Follicle stimulating hormone: stimulated by GnRH & inhibited by feedback inhibition exerted by inhibin, and estrogens and female and testosterone in males

• Target organ: Ovaries and Testes

Estrogen & Progesterone: gonads produce same steroid sex hormones as those of adrenal cortex, just lesser amounts

• ovaries produce estrogen and progesterone
  
  

Estrogen:
-maturation of reproductive organs
-appearance of secondary sex characteristics
-which progesterone, causes breast development and cyclic changes in uterine mucosa

Adrenocorticotropic hormone: Stimulated by CRH, stimuli that increase CRH release include fever, hypoglycemia, and other stressors. Inhibited by feedback inhibition exerted by glucocorticoids.

• Targe organ: Adrenal cortex

Testosterone: testes produce testosterone

• initiates maturation of male reproductive organs
• causes appearance of male secondary sex characteristics and sex drive
• necessary for normal sperm production
  -maintains reproductive organs in the functional state

Thyroid- stimulating hormone: Stimulated by TRH & in infants indirectly by cold temperatures. Inhibited feedback inhibition exerted by thyroid hormones on anterior pituitary and hypothalamus and by GHIH.

• Target organs: Thyroid gland

Melatonin: melatonin affects:

• timing of sexual maturation of puberty
• day/night cycles
• psychological processes that show rhythmic variations
• production of antioxidant and detoxification molecules in cells

Hypersecretion - cushing's syndrome/disease:

• depressed cartilage/bone formation and immune system; inhibits inflammation; disrupts neutral, cardiovascular, and gastrointestinal function
• causes colon tumor on pituitary, lungs, pancreas, kidney, or adrenal cortex; overuse of corticosteroids
• cushingoid signs: "Moon" face or "buffalo hump"
• treatment: removal of tumor discontinuation of drugs

Hyposecretion - Addison's disease: usually involved defecates in both glucocorticoids and mineralocorticoids

• decrease in plasma glucose in Na+ levels
• Weight loss, severe dehydration and hypotension are common
• treatment: Corticosteroid replacement therapy
• Early sign is characteristics bronzing of skin due to high levels of ACTH which triggers melatonin production in melanocytes

Hypersecretion: most common type of Graves' disease

• auto immune disease: body makes abnormal antibodies directed against thyroid follicular cells
• symptoms include elevated metabolic rate, sweating, rapid and irregular heartbeats, nervousness, and weight loss despite adequate food
• treatments include surgical removal of thyroid or radioactive iodine to destroy active thyroid cells

Diabetes mellitus (DM): can be due to:

• hyper secretion of insulin: type one
• hypo activity of insulin: type two
  
  

Three cardinal signs of DM:
-Polyuria: huge urine output

• glucose acts as osmotic diuretic
• Polydipsia: excessive thirst
• from water loss due to polyuria
• Polyphagia: excessive hunger and food consumption
• cells cannot take up glucose and are "Starving"

Hyposecretion: hyposecretion of TH in adults can lead to myxedema

• symptoms include low metabolic rate, thick and or dry skin, puffy eyes, feeling chilled, constipation, edema, mental sluggishness, and lethargy
• If due to lack of iodine a goiter may develop
• lack of iodine decreases TH levels, which triggers increase TSH secretion, triggering thyroid to synthesize thyroglobulin
• TH is critical for normal growth and brain development in early childhood
• congenital hypothyroidism is usually caused by poor development of thyroid gland

Ketones: when sugars cannot be used as fuel, as in DM, fats are used causing lipidema: high levels of fatty acids in blood

• fatty acids metabolism results information of ketones
• ketones are acidic and they're build up in blood can cause ketoacidosis
• also causesketonuria: ketone bodies in urine

Hypersecretion of Growth hormone: hypersecretion of GH is usually caused by anterior pituitary

• in children results in gigantism
• can reach heights of 8 feet
• in adult acromegaly
• overgrowth of hands, feet, and face
  
  

hyposecretion of GH

• in children results in pituitary dwarfism
• mini reach heights of only 4 feet
• in adults usually causes no problems

Hyperinsulinism: excessive insulin secretion

• causes hypoglycemia: low blood glucose levels
• symptoms: activity, nervousness, disorientation, unconsciousness, even death
• Treatment: sugar ingestion

Diabetes insipidus:

• ADH deficiency due to damage to hypothalamus or posterior pituitary
  
  • Must keep well hydrated