Endocrine System Overview

Endocrine System Overview

• The endocrine system is a network of glands that produce and release hormones.
• Hormones are chemical messengers that travel through the bloodstream to organs and tissues, instructing them on how to function.
• Understanding the endocrine system helps us understand how the body stays balanced and responds to changes.

Objectives

• Identify the parts and functions of the endocrine system.
• Explain how hormone release is regulated by the nervous system (hypothalamus, pituitary gland, thalamus, pineal gland).

What are Glands?

• Glands are specialized organs in the body that produce and release substances, such as hormones.
• Endocrine glands release hormones directly into the bloodstream, enabling them to reach the target organs.
• Major glands include the pituitary, thyroid, adrenal, and pancreas.

Hypothalamus

• Located in the brain, it connects the nervous system to the endocrine system.
• It regulates body temperature, hunger, thirst, sleep, and emotions.
• It controls the pituitary gland by sending signals, reacting to bodily changes.

Pituitary Gland

• Often called the "master gland," it's located below the hypothalamus.
• It releases various hormones controlling other endocrine glands (thyroid, adrenal, reproductive organs).
• Some examples of hormones it releases include growth hormone (GH), adrenocorticotropic hormone (ACTH), and prolactin.

Thyroid Gland

• Located in the neck, it produces hormones like thyroxine (T4) and triiodothyronine (T3).
• These hormones regulate metabolism, energy levels, and body temperature.

Symptoms of Hypothyroidism and Hyperthyroidism

• Hypothyroidism: Characterized by symptoms such as thinning hair, puffy face, dry skin, constipation, slow heartbeat, and weight gain. The thyroid gland isn't producing enough thyroid hormone.
• Hyperthyroidism: Characterized by symptoms such as fine brittle hair, increased perspiration, bulging eyes, enlarged thyroid, and unexplained weight loss. The thyroid gland is producing too much thyroid hormone.

Parathyroid Gland

• Four small glands on the thyroid gland.
• They release parathyroid hormone (PTH), regulating calcium levels in the blood.

Adrenal Gland

• Located on top of each kidney.
• They produce hormones like cortisol (stress response) and adrenaline (fight-or-flight response).

Pancreas

• An organ with both endocrine and digestive functions.
• It produces insulin and glucagon, regulating blood sugar levels.

Diabetes: Insulin vs. Glucagon

• Insulin: Released when blood sugar is high, helping the body absorb glucose for energy.
• Glucagon: Released when blood sugar is low, causing the liver to break down glycogen (stored glucose), increasing blood sugar.

Pineal Gland

• Located in the brain, it produces melatonin, regulating sleep-wake cycles.

Gonads (Ovaries and Testes)

• These produce sex hormones (estrogen, progesterone, testosterone).
• Essential for reproductive functions and secondary sexual characteristics.

Additional Hormones

• Estrogen, Progesterone, and Testosterone.
• They each play vital roles in a range of bodily functions.

Thymus

• Located in the chest, it produces thymosin, involved in immune system development.

How the Nervous System Controls Hormone Release

• The hypothalamus acts as a primary link between the nervous and endocrine systems.
• It receives signals from various parts of the body (e.g. brain, including thalamus) regarding physiological states such as temperature and stress.
• The hypothalamus synthesizes and secretes releasing or inhibiting hormones that control the pituitary gland.
• It regulates stress responses (Hypothalamic-Pituitary-Adrenal (HPA) axis).
• The pituitary gland responds to the hypothalamus releasing hormones, to release various hormones for the body's needs.

Pituitary Gland Mechanism

• The anterior pituitary responds to releasing hormones from the hypothalamus
• It secretes hormones like growth hormone (GH), prolactin (PRL), and follicle-stimulating hormone (FSH), and luteinizing hormone (LH).
• These hormones regulate a variety of bodily functions, including growth, milk production, and reproduction.

Pituitary Gland (Posterior Pituitary)

• The posterior pituitary releases hormones like oxytocin and antidiuretic hormone (ADH).
• These hormones are produced by the hypothalamus and transported via neurons to the posterior pituitary.

Thalamus

• Plays a role in sensory processing and relays sensory and emotional signals to the hypothalamus.
• By integrating sensory and emotional information, it affects how the hypothalamus releases hormones, especially during stress.

Pineal Gland Mechanism

• The hypothalamus, specifically the suprachiasmatic nucleus (SCN), controls the pineal gland's activity.
• The SCN responds to light signals received from the retina.
• In darkness, the SCN prompts the pineal gland to release melatonin, which promotes sleep.

This quiz covers the key components and functions of the endocrine system, including the regulation of hormone release by the nervous system. Learn about the major glands and their roles in maintaining balance within the body. Test your understanding of how these systems interact to influence bodily functions.