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Integration & Control: The Endocrine System
Endocrine System
 Works w/ nervous system to
control all functions of the
body
 Endocrine glands
 Ductless
 Hormones
 Pineal, pituitary, thyroid,
pancreas, etc.
 Exocrine glands
 Ducts
 Non-hormones
 Salivary, sebaceous, sweat
Endocrine System
 Hormones
 Chemical signals
 Carried in bloodstream
 Affect cells away from gland
 Homeostatic
Hormones
 Positive feedback
 Increase in hormone stimulates
further secretion
 Uterine contractions stimulate
oxytocin
 Negative feedback
 Increase in hormone inhibits
further secretion
 Thyroid Stimulating Hormone
produces T3/T4
Hormones
 Peptide hormones
 Water soluble
 Mostly protein
 Attach to cell membrane

Trigger secondary messenger within cell
 Epinephrine, oxytocin, antidiuretic hormone (ADH),
etc.
Hormones
 Steroid hormones
 Water insoluble
 Cholesterol-based
 Cross into cell
 Bind to receptors in cytoplasm or nucleus
 Estrogen, testosterone, cortisol, etc.
Pituitary Gland
 “Master Gland”
 Associated with & directed
by hypothalamus
 Posterior & Anterior lobes
Pituitary Gland
 Posterior Lobe
 Stores secretions from
hypothalamus
 Oxytocin


Uterine contractions
Milk “let down”
 ADH


Conserves water
Kidney tubules reabsorb water
Pituitary Gland
 Anterior Lobe
 Prolactin


Breast development
Stimulates & sustains milk
production
Pituitary Gland
 Anterior Lobe
 Growth Hormone (GH)


Stimulates body cells to grow & divide
Mostly young bones & muscles
 Thyroid-Stimulating Hormone
(TSH)


Thyroid gland growth
Secretion of thyroid hormones
 Adrenocorticotropic Hormone
(ACTH)


Adrenal gland growth
Secretion of cortisol from adrenal gland
Pituitary Gland
 Anterior Lobe
 Follicle-Stimulating
Hormone (FSH)



Stimulates estrogen secretion
Stimulates egg production
(females)
Stimulates sperm production
(males)
 Luteinizing Hormones



Stimulates ovulaton
Stimulates progesterone
secretion (females)
Stimulates testosterone
secretion (males)
Pituitary Gland
 Anterior Lobe
 MelanocyteStimulating
Hormone (MSH)



Stimulates melanocytes
in skin
Increases during human
pregnancy
Increases in amphibians
in dark location
Pituitary Gland
 Anterior Lobe
 Endorphins




Natural pain-killers
Sense of well-being
Strenuous exercise, excitement,
orgasm
“Runner’s High”
Thyroid Gland
 Regulates speed of all basic
cellular processes
 Energy burning
 Protein synthesis
 Thyroxine (T4),
Triiodothyronine (T3)
 Controls metabolism
 Affects growth
 Calcitonin
 Lowers blood calcium levels
 Increases deposit of calcium in
bones
Parathyroid Gland
 Calcium metabolism
 Parathyroid Hormone (PTH)
 Breaks down bone to release
calcium
 Increases intestinal absorption
 Increases kidney retention
Adrenal Gland
 Cortex
 Produces corticosteroids
 Mineralocorticoids

Aldosterone—controls
electrolytes through kidneys
 Glucocorticoids
 Cortisol—“stress hormone”
 Increases blood pressure & blood
glucose
 Suppresses immune system
 Andgrogens
 Testosterone
 Cause masculine traits
Adrenal Gland
 Medulla
 Hormones released under stress
 Controlled by sympathetic
nervous system
 Epinephrine

80% of medullary hormones


Increases heart rate, blood
pressure, and blood sugar
Increases sympathetic effects
 Norepinephrine
 20% of medullary hormones
 Maintains blood pressure
Thymus Gland
 Large in infant
 Increases until puberty
 Shrinks until adulthood
 Thymosin
 Normal development of
immune system
Pineal Gland
 Melatonin
 Regulates biological clock
 Regulates sleep cycle
 “Lower” vertebrates, cells resemble
photoreceptor cells of eye

May be triggered by light
Pancreas
 Endocrine & exocrine
 Digestive enzymes
 Glucagon
 Breaks down glycogen to
glucose
 Frees stored glycogen in liver
 Insulin
 Lowers blood glucose
 Increases uptake of glucose
into body cells
Ovaries
 Estrogen
 Female sexual characteristics
 Sperm maturation & libido in
males
 Progesterone
 Prepares uterus for egg
implantation
 Regulates menstrual cycle
Testes
 Testosterone
 Male sexual characteristics
 Sexual behaviors
 “Male” behaviors


Aggression
Territoriality
Other organs
 Kidneys
 Erythropoietin—stimulates red blood cell production
 Skin
 Calcidiol—inactive form of vitamin D
 Skeletal muscle
 Thrombopoietin—stimulates platelet formation
 Adipose (fat)
 Leptin—decrease appetite, increase metabolism
Hormonal Imbalances
 Hypersecretion of GH
 Gigantism—in children
 Acromegaly—in adults
Hormonal Imbalances
 Hyposecretion of GH
 Pituitary dwarfism—children,
slow bone growth
Hormonal Imbalances
 Hypothyroidism
 Fatigue
 Thin, brittle hair & nails
 Weight gain
 Poor muscle tone
 Goiter
 Inflammation of thyroid gland
 Can be due to iodine deficiency
Hormonal Imbalances
 Hyperthyroidism
 Weight loss
 Ravenous appetite
 Irritability, anxiety
 Fatigue
 Hyperactivity
 Graves’ disease




Protrusion of eyes
Edema (fluid accumulation)
Thickening of skin
Goiter
Hormonal Imbalances
 Diabetes insipidus
 Deficiency of ADH
 Increased urine output
 Chronic dehydration risk
 Diabetes mellitus
 Deficiency of insulin
 High blood glucose levels
 Type I—usually before age 20, pancreas cells stop
producing, autoimmune
 Type II—usually after age 40, insulin levels normal, cells
don’t respond to it
Hormonal Imbalance
 Addison’s disease
 Adrenal gland produces insufficient
glucocorticoids
 Low blood pressure
 Darkening of skin
 Vomiting, diarrhea
 Mood, personality changes
 Cushing’s disease
 Overproduction of glucocorticoids
 Weight gain
 Thin skin, often stretched
 Muscle weakness
 Hirsuitism (horses & humans)
 Hyperglycemia