ENDOCRINE SYSTEMpp 1031-1042

Warm-up 4/15: a. Describe the function of the

Endocrine System.b. What tissues/ organs are part of

the endocrine system?

FUNCTION

• Controls body function with chemical messengers

• Hormones: chemical messengers• Glands: secrete chemicals/hormones

HORMONES

• Amino acid-based hormones: first messenger binds to cell surface receptor causing second messenger inside the cell to initiate cell activity

• Steroid hormones: diffuse through cell membrane to bind to a protein which starts transcription

GLANDS• exocrine: secrete nonhormonal chemicals

through ducts (sweat, saliva, mucous, digestive, etc)

• endocrine: secrete hormones into the bloodstream a. gonads: sex hormones b. thyroid: metabolism c. adrenal gland: adrenaline d. pituitary: hormones that affect other glands and growth hormones e. pancreas: insulin and glucagons to regulate sugar f. thymus: stimulates formation of T-cells

FEEDBACK MECHANISMS

• Homeostasis: stable internal environment• Last step of the series controls the first

NEGATIVE FEEDBACK

• A secondary substance inhibits production of the initial stimulating substance

A = InsulinB = glucagon (sugar)

Negative feedback loops are necessary for homeostasis.

Negative Feedback Loop

Holding breath, CO2 levels rise,

Control system forces exhale, inhale

O2 / CO2 level returns to normal

POSITIVE FEEDBACK

• A secondary substance stimulates production of the initial stimulating substance

Birth

HW

• Worksheet: Nervous and Sense Organs (Due Tuesday)

• Trifold Vocab: homeostasis, neuron, gland, hormone, positive feedback loop, negative feedback loop, synapse, neurotransmitter (Due Wednesday)