S1.9 Endocrine System

What does the Endocrine System do?

Messenger system comprising of feedback loops of Hormones that are released by Internal Glands and Target distant Organs. The Hypothalamus is the Neural Control center of ALL Endocrine System.

Endocrine System in Brain - Overview

• Hypothalamus

  • Product the following, but stored in the Pituitary gland

    • Oxytocin (Store, not produce)

      • Causes increased contraction of the uterus during labor

      • Stimulate the release of milk into the ducts of the breasts.

    • Antidiuretic Hormone (ADH) (Store, not produce)

      • Contricts blood vessels and controls salt in the body

• Pineal Gland

  • Melatonin

    • Melatonin

      • Involved in the sleep-wake cycle

• Pituitary Gland

  • Anterior

    • Growth Hormone

      • Promotes the growth of children

    • Prolactin (PRL)

      • Stimulate milk production in the mammary glands

    • Thyroid-Stimulating (TSH)

      • Activate the release of Thyroid Hormones

    • Follicle - StimulatingFollicle-Stimulating

      • Formation of Ova or Sperm

    • Luteinizing Hormone

      • Stimulate ovulation in Females and Androgen in Men

    • Adrenocorticorropiuc (ACTH)

      • Triggers the release of cortisol from the Adrenal Glands

  • Posterior (Does not produce its own hormone. It Holds Hormones made by the hypothalamus)

    • Oxytocin (Store, not produce)

      • Causes increased contraction of the uterus during labor

      • Stimulate the release of milk into the ducts of the breasts.

    • Antidiuretic Hormone (ADH) (Store, not produce)

      • Contricts blood vessels and controls salt in the body

Endocrine System in the Brain - Quiz

1. Which gland produces oxytocin and antidiuretic hormone (ADH), though they are stored in the pituitary gland?

2. Which hormone causes increased contraction of the uterus during labor?

3. Which hormone stimulates the release of milk into the ducts of the breasts?

4. Which hormone constricts blood vessels and helps control salt and water balance in the body?

5. Which gland secretes melatonin?

6. Which hormone is involved in regulating the sleep-wake cycle?

7. Which part of the pituitary gland produces its own hormones?

8. Which hormone promotes growth in children?

9. Which hormone stimulates milk production in the mammary glands?

10. Which hormone activates the release of thyroid hormones?

11. Which hormone stimulates the formation of ova in females and sperm in males?

12. Which hormone triggers ovulation in females and androgen production in males?

13. Which hormone triggers the release of cortisol from the adrenal glands?

14. Which part of the pituitary gland does not produce hormones but stores and releases those made by the hypothalamus?

15. Which two hormones are stored in the posterior pituitary gland?

• Hypothalamus

• Oxytocin

• Oxytocin

• Antidiuretic Hormone (ADH)

• Pineal Gland

• Melatonin

• Anterior Pituitary

• Growth Hormone (GH)

• Prolactin (PRL)

• Thyroid-Stimulating Hormone (TSH)

• Follicle-Stimulating Hormone (FSH)

• Luteinizing Hormone (LH)

• Adrenocorticotropic Hormone (ACTH)

• Posterior Pituitary

• Oxytocin and Antidiuretic Hormone (ADH)

Endocrine System in Neck/Chest - Overview

Gland	Hormone	Function	Memory Tip
Thyroid	Thyroxine (T4)	Increases the rate of chemical reactions in cells; helps control growth & development	😊
Thyroid	Triiodothyronine (T3)	Stimulates the nervous system (wakefulness, alertness, responsiveness)	"T" for Thyroid = Both hormones turn up the metabolic rate
Thyroid	Calcitonin	Lowers blood calcium	"Calci-tone it down" = Lowers down calcium in the blood
Parathyroid	Parathyroid Hormone	Raises blood calcium	Parathyroid = Pushes it up (increases calcium in blood)
Thymus	Thymosin	Helps make T cells	Thymosin = Thymus must stimulate immunity

Endocrine System in Neck/Chest - Quiz

🟩 Questions

1. Which thyroid hormone increases the rate of chemical reactions in cells and helps control growth and development?

2. Which thyroid hormone stimulates the nervous system in wakefulness, alertness, and responsiveness to external stimuli?

3. Which two thyroid hormones help increase metabolic rate?

4. Which thyroid hormone lowers blood calcium levels?

5. What is the function of the parathyroid hormone?

6. Which hormone increases calcium levels in the blood?

7. Which gland produces a hormone that helps make T cells?

8. What is the function of thymosin?

1. Thyroxine (T4)

2. Triiodothyronine (T3)

3. Thyroxine (T4) and Triiodothyronine (T3)

4. Calcitonin

5. Raises blood calcium

6. Parathyroid Hormone

7. Thymus

8. Helps make T cells

Endocrine System in Abdomen/Plevin -Overview

• Adrenal Gland

• Pancreas

• Gonads

  • Ovaries

  • Testes

Abdomen/Pelvin:

Region	Gland / Part	Hormone	Function	Memory Tip / Notes
Adrenal Medulla		Epinephrine	Works on the heart; part of the fight-or-flight response	“Epi = No rush = Rush of both hormones during fight or flight”
		Norepinephrine	Works on blood vessels; prepares body for fight-or-flight	Same as above
Adrenal Cortex		Glucocorticoids	Steroid hormones are involved in glucose, protein, and fat metabolism	Example: Cortisol — “Cortisol Controls Stress”
		Mineralocorticoids	Steroid hormones that help regulate salt and water balance	Example: Aldosterone — “Aldo Stores Na”

Gonads - Ovaries/Testes

Gland	Hormone	Function	Memory Tip
Pancreas	Insulin	Controls blood sugar and metabolism; turns food into energy	Insulin puts sugar IN
	Glucagon	Helps regulate blood glucose; raises glucose when it's low	GLUcagon raises GLUcose
Gonads	Estrogen	Develops female sex characteristics	—
	Progesterone	Creates healthy uterine lining for menstruation and pregnancy	—
	Androgen	Develops male sexual reproduction and characteristics	—

Endocrine

En = Enter

Releases hormones into their surroundings

No special ducts

Exocrine

Ex = Exit

A gland that makes substances and releases them thru a duct or opening to the body.

Ducts required

Endocrine System in Abdomen/Plevin -Overview

Endocrine System in Abdomen/Plevin - Quiz

✅ Questions

1. Which hormone controls blood sugar levels and helps turn food into energy?

2. Which hormone helps regulate blood glucose by increasing it when it drops too low?

3. What is the function of insulin in relation to blood sugar?

4. What is the function of glucagon in relation to blood sugar?

5. Which hormone develops female sex characteristics?

6. Which hormone creates healthy uterine lining for the menstrual cycle and pregnancy?

7. Which hormone develops male sexual reproduction and characteristics?

8. Which gland produces insulin and glucagon?

9. Which gland produces estrogen, progesterone, and androgen?

🟨 Answers

1. Insulin

2. Glucagon

3. Puts sugar into the cells (lowers blood sugar)

4. Raises glucose levels in the blood

5. Estrogen

6. Progesterone

7. Androgen

8. Pancreas

9. Gonads

Endocrine Function Cells

Term	What It Is	What It Does
Gastrin	A hormone made by G-cells in the stomach	Stimulates the stomach to produce HCl (hydrochloric acid) and enzymes
HCl Acid	A strong acid secreted by parietal cells	Helps digest food, kill bacteria, and activate digestive enzymes

🧬 Relation to the Endocrine System:

• Gastrin is a hormone, so it’s part of the endocrine system.

• It travels through the bloodstream (like other endocrine hormones) to signal target cells (parietal cells).

• Endocrine glands don’t use ducts — just like gastrin is released directly into the blood to act.

🧬 Endocrine vs. Exocrine System – Comparison Table

What they release?

Where they release?

Example of each?

Function of each?

What they target?

🔹 Feature	Endocrine System	Exocrine System
Definition	Glands that release hormones into the blood	Glands that release substances through ducts
Secretion Type	Hormones	Enzymes, sweat, saliva, oil, milk, etc.
Secretion Path	Directly into the bloodstream	Through ducts to body surfaces (skin, mouth, etc.)
Examples of Glands	Pituitary, thyroid, adrenal, pancreas (endocrine part)	Sweat glands, salivary glands, pancreas (exocrine part)
Target Area	Internal organs and tissues	External or specific local areas
Function	Regulates body functions (growth, metabolism)	Aids in digestion, cooling, lubrication, etc.

Hormones

A regulatory substance in an organisms and transported in tissue fluids to stimulate specific cells or tissue into action.

Hormones can come from varies biomolecules

Hormone Biomolecules:

Derived from Amino Acid (Polypeptides)

Derived from Lipids (Steroids)

Function:

Hormones bind to specific target cells and will cause some kind of action to occur.

The function of hormones really depends on the the receptor and target cell.