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Endocrine system
Endocrine system
• 3 types of regulatory molecules:
• 1) Hormones: regulatory chemicals secreted
into blood by endocrine gland
– Work only on ____________ cells (those that can
be influenced by its “message”)
Endocrine system
• 3 types of regulatory molecules:
• 2) Neurohormones: hormones released into blood
by some neurons
Endocrine system
• 3 types of regulatory molecules:
• 3) Paracrine hormones: chemicals secreted by
cells of organ that influence others in organ (not
transported by blood)
Endocrine system
3) Paracrine hormones. Example: prostaglandins. Derived
from cholesterol
• Many functions: one is to promote inflammation (pain,
fever)
• Aspirin, ibuprofen, celebrex: inhibit prostaglandin
production but vary in side effects (some can cause
_____________ in small intestine, etc)
Endocrine system
• Hormone chemistry:
• 1) polypeptides: chains of amino acids (<100 aa’s
long). Ex, insulin, ADH (antidiuretic hormone)
Structure of insulin
Endocrine system
• Hormone chemistry:
• 2) glycoproteins: long polypeptide (>100 aa’s
long) with carbohydrate attached. Ex, FSH
(follicle stimulating hormone) and luteinizing
hormone (LH)
Endocrine system
• Hormone chemistry:
• 3) amines: variations of the amino acids tyrosine
and tryptophan. Ex, adrenalin, thyroxine.
tyrosine
tyramine
tryptophan
adrenaline
Endocrine system
• Hormone chemistry:
• 4) steroids: lipids derived from cholesterol. Ex,
testosterone, estradiol, progesterone
cholesterol
Endocrine system
• Most hormones are hydrophilic (water soluble)
• Recall from BIOL 1020 that cell membranes are
hydrophobic
• This means that water-soluble molecules can’t
cross them.
• How signal transmitted into cells? By __________
protein in membrane
Endocrine system
• Hydrophilic hormone example
• Hormone binding temporary, detaches and can
travel to another cell and bind again (and again)
• 1 hormone molecule can signal many ________!
Endocrine system
• Hydrophobic hormones are steroids and thyroxine
• They penetrate membranes and bind to receptors
inside cell
Endocrine system
• Example hydrophobic hormones are steroids
(testosterone, estradiol) and thyroxine
Endocrine glands
• Pituitary gland: located under brain
• Has two portions: anterior (in front) and posterior (in rear).
Each portion with different embryonic origin and very
different functions
Endocrine glands
• Posterior pituitary gland hormones
– Antidiuretic hormone (ADH): influences water
reabsorption in kidneys.
– Note: alcohol consumption inhibits ADH secretion (so
frequent need to _______________).
Endocrine glands
• Posterior pituitary gland hormones
– Oxytocin: stimulates milk “let-down” in nursing mothers
(milk secreted into ducts in breast). Also stimulates
uterine contractions during childbirth.
Endocrine glands
• Anterior pituitary gland hormones
– growth hormone (GH): stimulates growth of bone and
muscle
– Too much: gigantism
8 feet 11 inches, 485
pounds.
Lived 22 years, never
stopped growing!
Endocrine glands
• Anterior pituitary gland hormones
– growth hormone (GH): stimulates growth of bone and
muscle
– Too little: pituitary dwarfism
Endocrine glands
Anterior pituitary gland hormones
– follicle stimulating hormone (FSH) and luteinizing hormone
(LH): involved in menstrual cycle in females and sperm
production in males
Endocrine glands
Anterior pituitary gland hormones
– follicle stimulating hormone (FSH) and luteinizing hormone
(LH): involved in menstrual cycle in females and sperm
production in males
– prolactin (PRL): stimulates milk production in mammals
Endocrine glands
• Thyroid gland: in throat just under larynx
Endocrine glands
• Thyroid gland hormone (main):
– Thyroxine: helps set body’s metabolic rate
– Too little: ______________. Often severe retardation.
Endocrine glands
• Parathyroid glands: On thyroid
– Make parathyroid hormone (PTH): vital to maintain Ca+2 level
in body
– Can influence Ca+2 reabsorption in kidney, Ca+2 release from
bone, and absorption of Ca+2 in small intestine.
Endocrine glands
• Adrenal glands: Located on kidneys
Endocrine glands
• Adrenal glands
– Located on kidneys
– Have cortex (outer) and medulla (inner) portions
Endocrine glands
• Adrenal glands
– Medulla: secretes ______________ when stimulated by
nerve system. Part of “fight or flight” response.
Increase heart rate, blood pressure, blood glucose.
Reduced blood flow to skin and digestive system
Endocrine glands
• Adrenal glands
– Cortex: secretes corticosteroids. Involved in _________
balance, glucose balance, etc.
Endocrine glands
• Pancreas
– Located below liver in abdomen
Endocrine glands
• Pancreas
– Recall Islets of Langerhans. Make insulin and
glucagon. Together, regulate glucose in blood.
Endocrine glands
• Gonads (testes and ovaries)
Endocrine glands
• Gonads (testes and ovaries)
• Make steroid sex hormones
• Testosterone, estradiol, progesterone (discussed)
Endocrine disruptors
• Chemicals from environment that can interfere
with endocrine system
• Chemical structures similar to those of some
hormones
• Examples: pesticides, herbicides, etc.
Endocrine disruptors
• Ex, Lake Apopka, Florida
• 1980: chemical spill of pesticide DDT
• Affected development of male alligators (lower
testosterone levels, smaller __________ size,
anatomical defects)
Endocrine disruptors
• Human concerns:
• Puberty of females coming earlier
• Many possible causes, but endocrine
disruptors may be involved
Endocrine disruptors
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Ex, Michigan 1973
Chemical called PBB accidentally mixed into cattle food
Meat and dairy products reached 4,000 people
Daughters of women exposed surveyed in late 1990s
Menstruation started ______ years earlier in daughters of
exposed women