Key Endocrine Glands and Hormones

1. Introduction

The endocrine system consists of glands that release hormones into the bloodstream to regulate body processes over minutes to days. Compared with the nervous system (fast, short-lived), endocrine signaling is slower but longer-lasting.

Endocrine system functions include

Regulating growth and development
Controlling metabolism and energy balance
Maintaining homeostasis (fluids, electrolytes, glucose)
Coordinating reproduction and sexual maturation
Shaping stress responses and circadian rhythms

2. Major Endocrine Glands

To start our study of the endocrine system, study the diagram and table below.

Human endocrine system diagram with lettered labels; A thymus in upper chest; B pineal gland in brain; C pituitary gland below the thalamus; D thyroid gland surrounding the trachea below the larynx; E parathyroid glands on the posterior surface of the thyroid; F adrenal glands sitting atop the kidneys; G pancreas in the abdomen; H ovaries (female); I testes (male). — Human endocrine system. Click for a key

Letter	Structure	Primary Function
A	Thymus	Site where T cells (T lymphocytes) mature. T cells are a key component of the immune response. The thymus is both an immune organ and an endocrine gland, releasing hormones that guide the maturation of T cells.
B	Pineal gland	Secretes melatonin; helps regulate circadian rhythms and sleep–wake cycles.
C	Pituitary gland	Often called the “master gland”; releases hormones that regulate other endocrine glands, growth, reproduction, and water balance.
D	Thyroid gland	Produces hormones that regulate metabolic rate, energy use, and heat production throughout the body.
E	Parathyroid glands	Regulate blood calcium levels; essential for normal nerve, muscle, and bone function.
F	Adrenal glands	Release hormones involved in stress responses, metabolism, blood pressure regulation, and electrolyte balance.
G	Pancreas	Regulates blood glucose levels by secreting insulin and glucagon; functions as both an endocrine and digestive organ.
	Uterus	Not an endocrine gland, but a hormone-responsive organ; supports pregnancy and responds to ovarian hormones. We’ll learn more about the uterus in our unit on the reproductive system.
H	Ovaries (female)	Produce estrogen and progesterone; regulate the menstrual cycle, reproduction, and female secondary sex characteristics.
I	Testes (male)	Produce testosterone; support sperm production and male secondary sex characteristics.

3. Quiz: Key Glands and their Functions

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[h]Key Glands and their Functions

[i]

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4. Eighteen Hormones to Get to Know

In what’s above, you learned about the major glands of the endocrine system. Now let’s learn about the hormones that these glands secrete. You’ll do this by matching hormones with their glands and functions. Don’t worry if you have to guess a bit. Once you match everything correctly, the completely table so that you can start to be familiar with each hormone.

4a. Hormones: interactive table

[qwiz style=”width: 600px !important; min-height: 400px !important;” qrecord_id=”sciencemusicvideosMeister1961-Eighteen Hormones Interactive Table”]

[h] Eighteen hormones to get to know: Interactive table

[q labels =”top”]

Hormone	Source Gland	Primary Function / Notes
______________________	Pancreas	Lowers blood glucose by helping body cells absorb glucose.
______________________	Pineal gland	Regulates sleep–wake cycles and circadian rhythms.
______________________	Adrenal glands	Longer-term stress hormone; increases available energy and suppresses immune responses.
______________________	Ovaries	Supports female secondary sex characteristics and bone maintenance.
______________________	Thymus	Guides the maturation of T cells in the immune system.
______________________	Adrenal glands	Rapid fight-or-flight response; increases heart rate and blood flow to muscles.

[l]Adrenaline (epinephrine)

[f*] Correct!

[fx] No, that’s not correct. Please try again.

[l]Cortisol

[f*] Excellent!

[fx] No, that’s not correct. Please try again.

[l]Estrogen

[f*] Good!

[fx] No. Please try again.

[l]Insulin

[f*] Correct!

[fx] No. Please try again.

[l]Melatonin

[f*] Good!

[fx] No, that’s not correct. Please try again.

[l]Thymosin

[f*] Good!

[fx] No, that’s not correct. Please try again.

[q labels=”top”]

Hormone	Source Gland	Primary Function / Notes
______________________	Pancreas	Raises blood glucose by stimulating the liver to release glucose.
______________________	Ovaries	Regulates the menstrual cycle and supports pregnancy.
______________________	Pituitary gland	Stimulates growth of bones and muscles; supports overall body growth.
______________________	Parathyroid glands	Raises blood calcium levels by releasing calcium from bone.
______________________	Digestive tract & brain	Helps regulate mood, energy levels, and biological rhythms.
______________________	Adrenal glands	Contribute to secondary sex characteristics in both males and females.

[l]Androgens

[fx] No. Please try again.

[f*] Great!

[l]Glucagon

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]Growth hormone (GH)

[fx] No, that’s not correct. Please try again.

[f*] Good!

[l]Parathyroid hormone (PTH)

[fx] No. Please try again.

[f*] Excellent!

[l]Progesterone

[fx] No. Please try again.

[f*] Good!

[l]Serotonin

[fx] No, that’s not correct. Please try again.

[f*] Excellent!

[q labels=”top”]

Hormone	Source Gland	Primary Function / Notes
______________________	Thyroid gland	Increases metabolic rate and energy use by cells.
______________________	Hypothalamus / posterior pituitary	Stimulates uterine contractions and milk release.
______________________	Hypothalamus	Acts as a neurohormone that inhibits prolactin release; also a neurotransmitter.
______________________	Thyroid gland	Lowers blood calcium levels by promoting calcium storage in bone.
______________________	Pituitary gland	Stimulates milk production in mammary glands.
______________________	Testes	Supports male secondary sex characteristics and sperm production.

[l]Calcitonin

[fx] No, that’s not correct. Please try again.

[f*] Correct!

[l]Dopamine

[fx] No. Please try again.

[f*] Great!

[l]Oxytocin

[fx] No. Please try again.

[f*] Correct!

[l]Prolactin

[fx] No, that’s not correct. Please try again.

[f*] Excellent!

[l]Testosterone

[fx] No. Please try again.

[f*] Good!

[l]Thyroxine (T4)

[fx] No, that’s not correct. Please try again.

[f*] Good!

[x]

[restart]

[/qwiz]

4b. Hormones fill-in-the-blanks quiz

[qwiz qrecord_id=”sciencemusicvideosMeister1961-Eighteen Hormones Fill-in-the-Blanks”]

[h]Hormones Fill-in-the-blanks

[i]

Epinephrine (Adrenaline): One of the hormones you’ll meet in this unit

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[/qwiz]