Regents Biology2009-2010

Endocrine System

Regulation - How we maintain homeostasis nervous system

nerve signals control body functions electrical (+/- charges) AND chemical

(neurotransmitters) endocrine system

hormones (proteins) chemical signals ONLY control body functions

Regents Biology

Homeostasis maintaining internal balance in the body-

organism must keep internal conditions stable even if environment changes

also called “dynamic equilibrium” use feedback mechanisms

example: body temperature – 37 C – monitored by nervous system

humans: too cold = shiver – (muscles contact – R – produce heat) too warm = sweat

Regents Biology

Hormones chemical messages from one body part to

cells in other parts of body travel through bloodstream hormones are proteins communication needed to coordinate

whole body maintaining homeostasis hormones work SLOWER than nerve

impulses

Regents Biology

Endocrine System Endocrine system releases hormones

glands which secrete (release) chemical signals into blood

chemicals cause changes in other parts of bodygrowth hormone (HGH)sex hormonesresponse hormonesmetabolism hormonesand more….

Regents Biology

Getting the correct signalhormone fits receptor on “target” cell

targettissue/cell

non-targetcells

secretingcell (gland)

can’tread

signal

can’tread

signal

hormone

receptor

Regents Biology

Review Protein Synthesis• Start with DNA (gene) in the nucleus• Transfer info to RNA – DNA can’t leave the

nucleus• RNA moves to ribosome – amino acid chain

is made• Moves to ER – packaged into a vessicle• Then to Golgi – repackaged in to another

vessicle• Vessicle moves to cell membrane• Secretion by exocytosis (active transport)

Regents Biology

Regents Biology

Pituitary many hormones: master gland HGH – human growth hormone TSH – thyroid stimulating hormone FSH – follicle stimulating hormone; LH – leutinizing hormone

Thyroid thyroxine – regulates metabolism

Parathyroid Parathyroid hormone – regulates Calcium metabolism

Adrenal adrenaline – “fight or “flight”

Pancreas Insulin – lowers blood sugar Glucagon – raises blood sugar

Ovary - estrogen, progesterone Testes - testosterone

Glands

Regents Biology

Negative Feedback

Response to changed body condition if body is high or low from normal level

signal tells body to make changes that will bring body back to normal level

once body is back to normal level, signal is turned off

high

hormone 1

lowersbody condition

gland

specific body condition

Like the thermostat in your house

Regents Biology

Maintaining homeostasis

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition

gland

Feedback

Regents Biology

liver

pancreas

liver

Regulation of Blood Sugar

blood sugar level(90mg/100ml)

insulin

body cells take

up glucose from blood

liver storessugar as glycogen

reducesappetite

glucagon

pancreas

liver releasesglucose

triggershunger

high

low

After a meal

Between meals

Regents Biology

Feedback: Maintaining Homeostasis Balancing glucose levels in blood

pancreas

pancreas

insulin

liver takes upglucose

for storage

cellstake up

glucose from blood

liver releasesglucose to blood

depress appetite

stimulatehungerglucagon