The Endocrine System - Day 2

The Endocrine System - Day 2

• It's a signaling molecule

• It can be either:

  • A protein

  • An amino acid chain

  • A lipid

  • A gas

What IS A Hormone?

​Cholesterol, a lipid that is used to make sex hormones

Cholesterol is the starting molecule, used by the body, to make testosterone and estradiol

• Testosterone - the major male sex hormone

• Estradiol - the major female sex hormone

Cholesterol, Testosterone, and Estradiol

Effects of Testosterone and Estradiol

Heart Health

Bone Health and Strength

Liver Function

Mood Management

Estradiol

Deepening of the voice

Hair growth

Muscle Mass and Strength

Bone Mass and Strength

Testosterone

Poll

Choose the statement you think is correct.

• Only men produce testosterone.

• Only women produce estrogen.

• Men and women produce both testosterone and estrogen in differing amounts.

• Some hormones just cause glands to create other hormones!

• Hormone Cascade - One hormone triggers production of a second hormone, which may trigger the production of another, which may keep going

Hormone Cascades

Open Ended

Have you heard of the "flight or fight response"? If so, describe it in your own words.

• One of the most important hormone cascades in the human body is the Hypothalamic-Pituitary-Adrenal (HPA) Axis

• It’s responsible for the “fight or flight” response in stressful situations

The HPA Axis

The HPA Axis in Detail

The HPA Axis involves:

• The Hypothalamus (in the brain)

• The Pituitary Gland

• The Adrenal Glands

The hypothalamus releases CRH (a hormone)

• This causes the pituitary gland to release ACTH (another hormone!)

• This causes the adrenal glands to release cortisol (yep, another hormone!)

How The Body Responds to the HPA Axis

Cortisol causes the body to:

• Increase your blood pressure - your brain is receiving oxygen faster and can think faster for a short period of time

• Release glucose into the bloodstream - you have more energy for a short period of time

• Shut down “non-emergency” functions in your body like the immune system and sex cell production - your body isn’t using energy that it needs for more important tasks

Once cortisol reaches the hypothalamus, it stops producing CRH and the HPA Axis cascade stops

• This causes the adrenal glands to stop producing cortisol

• This is also an example of a negative feedback loop

How The HPA Axis Stops

Open Ended

I will pair you up.

1. Google "negative feedback loop in endocrine system".

2. Read one website and discuss it with your partner.

3. Briefly describe it in your own words.