1. 4
The endocrine system
Endocrine glands release __________ into the bloodstream…
…Hormones regulate growth, metabolism, sexual development and behavior, and other functions.
hormones

2. The Endocrine System
The Endocrine System is the body’s “slow” chemical communication system.
Communication is carried out by hormones
Preview Question 4: How does the endocrine system-the body’s slower information system-transmit its messages?
Hormones
Neurotransmitters

4. The Endocrine System: Glands and Hormones
Hormones – chemical messengers in the bloodstream
Pulsatile release (several times per day in brief bursts) by endocrine glands
Negative feedback system (levels of hormones increase until signals are sent to glands to stop secretion of that hormone)
Endocrine glands:
Pituitary – “master gland,” growth hormone
Thyroid – metabolic rate
Adrenal – salt and carbohydrate metabolism
Pancreas – sugar metabolism
Gonads – sex hormones
Hormones are chemical messengers in the bloodstream that are secreted by the endocrine glands in a pulsatile manner – that is, several times per day in brief bursts or pulses. The levels of many hormones increase to a certain level, then signals are sent to the hypothalamus or other endocrine glands to stop secretion of that hormone – a negative feedback system.
These glands include: the pituitary – the master gland that secretes substances influencing the operation of all the other glands, as well as growth hormone; the thyroid gland – which controls metabolic rate; the adrenal glands – which control salt and carbohydrate metabolism; the pancreas – which secretes insulin to control sugar metabolism; and the gonads – which secrete sex hormones involved in the development of secondary sex characteristics and reproduction.

5. Hormones
Hormones are chemicals synthesized by the endocrine glands that are secreted in the bloodstream.
Hormones affect the brain and many other tissues of the body.
For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar, and feelings of excitement during emergency situations.

7. Endocrine System
Why is the pituitary gland called the “master gland”?

8. Review
Can you remember feeling an extended period of discomfort after some particularly stressful event? How long did those feelings last? Why?