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 system3) 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

adrenalinetryptophan

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, neverstopped growing!

Endocrine glands• Anterior pituitary gland hormones

– growth hormone (GH): stimulates growth of bone and muscle

– Too little: pituitary dwarfism

Endocrine glandsAnterior pituitary gland hormones

– follicle stimulating hormone (FSH) and luteinizing hormone (LH): involved in menstrual cycle in females and sperm production in males

Endocrine glandsAnterior 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• 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