January 25, 2016 Journal: What is the function of the

endocrine system?

After you complete this journal, hand in your journals. You should have at least 15 entries.

Introduction to the Endocrine System

Endocrine System Series of organs and glands that

secrete hormones into your bloodstream

What does the Endocrine System control?

1.Growth & development2. Reproduction3. Reducing body stress4. Maintaining water, electrolyte and

nutrient balance5. Regulating cellular metabolism and

energy balance6.Maintain homeostasis

Major Endocrine

Glands

Hypothalamus & Pituitary

Glands

Thyroid & Parathyroid Gland

Capsule

Adrenal Glands

Pancreas

Ovaries and Testes

Hormones Chemical messengers released by

endocrine glands that are released into the blood stream and travel all over your body

Cause a widespread response

Neurotransmitters HormonesChemical Messenger Chemical Messenger

Released at chemical synapse

Released into bloodstream

Intended for close target Travels to distant targets

Effect happens quickly Effect takes time

Effect wears off quickly Effect lasts longer

Affects single cell Affects many cells

Chemical Messenger Comparison

How Hormones Work Hormones bind to receptors on the

outside or inside of target cells • If the receptor is on the outside…

It changes cell membrane permeability It changes enzyme activity inside the cell

• If it binds to receptors inside the cell… Its called a steroid Interact directly with the cell’s DNA to change

cell activity

Control of Endocrine Activity

Most endocrine organs are active all the time, but the amount of hormone produced changes

Homeostasis including the amount of hormones produced is regulated through positive and negative feedback loops

Control of Hormones Neural Control

• Hormone levels controlled by the nervous system Ex: Adrenal gland secretes hormones to prolong

sympathetic response Hormonal Control

• Glands are arranged in a hierarchy and each regulate the gland below them in the chain Ex: Hypothalamus controls the pituitary gland which

controls the adrenal gland which produces a hormone called cortisol, which allows humans to deal with stress

Humoral Control• Hormone levels controlled by body fluids

Ex: Pancreas secretes insulin in response to rising blood sugar