Regulation: Endocrine System

Class NotesOctober 11, 2007

Hormones The endocrine system acts through chemical messengers called hormones

Hormones influence growth, development, and metabolic activities

Hormones are produced by glands and secreted into the bloodstream

Endocrine Glands

Checkpoint…

Hormones are called ____________ ______________.

Why are hormones important? What do they do?

Hormones are produced by __________ and secreted into the bloodstream.

So, we now understand that there are 9 major endocrine glands, which produce 100 different hormones…

Plus all our vital organs, muscles and bones…

So how does everything fit inside???

Surface Area to Volume Ratio

Surface Area to Volume Ratio

Endocrine glands are generally very small, but they have to produce large amounts of hormones.

When you cut a gland in half (cross-section), there are folds that create more surface area.

More surface area = more hormones

Folds increase surface area

Checkpoint…

So if hormones are chemical messengers secreted into the bloodstream by glands…

Then how do the glands know when to produce the hormone and when to stop producing the hormone?

Well…

What is feedback?

Opinions Advice Response to someone else’s work Critique Peer- editing

Feedback Mechanisms Hormone levels in the blood

cannot be too high or too low Too much or too little

hormone can cause harm to the body, so the body has a feedback mechanism to maintain normal hormone levels

Feedback lets the glands know when to start and stop producing hormones!!

Examples of feedback

Insulin regulates sugar levels in the blood- the pancreas (gland) will secrete insulin when blood sugar levels are low. Once the sugar levels go back up the pancreas will stop producing insulin.