Endocrine System Overview

Dr. Yanga's Colleges, Inc. - Science 10 - Endocrine System

• The endocrine system is composed of glands that secrete hormones
• Hormones regulate metabolism, growth/development, mood, and reproduction
• The endocrine system is also called a "system of checks and balances" that keeps the body system healthy
• It functions like a thermostat, turning on and off in response to hormone levels
• Hormones are organic substances released by endocrine glands directly into the bloodstream
• Hormones act as chemical messengers, stimulating many organs
• Hormones alter physiological and metabolic behaviors of target cells, maintaining homeostasis
• Changes in hormone levels (too high or too low) indicate problems in the endocrine system
• Stress, infections, and fluctuations in blood's fluid/electrolyte balance influence hormone levels

Lesson Objectives

• Identify major endocrine glands
• Explain the role of hormones involved in the female and male reproductive systems (S10LT-IIIb-34)
• Explain different endocrine system disorders

Endocrine Glands and Hormones

• Hypothalamus: A small gland at the base of the brain, regulates body activities, metabolism, and reproduction. It helps regulate body temperature, blood pressure, and water use. It produces the hormone oxytocin.

• Oxytocin: Two main actions of oxytocin are womb (uterus) contractions during childbirth and lactation. It is also associated with empathy, trust, sexual activity, and relationship-building; sometimes referred to as the "love hormone"

• Antidiuretic Hormone (ADH) or Vasopressin: Produced by the hypothalamus, conserves body fluid by reducing water excretion in urine.

• Diabetes Insipidus: An uncommon disorder from an imbalance of body fluids, often caused by damage to the hypothalamus or pituitary gland which affects the production of antidiuretic hormones.

• Pituitary Gland: Located at the base of the brain, considered the "master gland" as it stimulates other endocrine glands. Secretes several hormones, including:

  • Melanocyte Stimulating Hormone (MSH): Stimulates melanocytes and melanin production.
  • Thyroid Stimulating Hormone (TSH): Stimulates thyroid gland.
  • Adrenocorticotropic Hormone (ACTH): Stimulates adrenal gland.
  • Growth Hormone (GH): Regulates skeletal system growth
  • Prolactin: Stimulates milk production in mammary glands
  • Follicle Stimulating Hormone (FSH): Stimulates gonads to produce sex gametes.
  • Luteinizing Hormone (LH): Stimulates gonads to produce sex hormones and the release of the egg.

• Acromegaly: A hormonal disorder caused by a pituitary gland tumour (adenoma), leading to excessive growth hormone (GH) production.

• Dwarfism and Gigantism: Conditions related to abnormal growth hormone secretion.

• Prolactinoma and Hypopituitarism: Examples of health conditions linked to the pituitary gland function.

• Pineal Gland: Secretes melatonin that regulates the sleep-wake cycle; light decreases the production, signalling the body to wake

• Thyroid Gland: Butterfly-shaped gland in the lower neck, secretes hormones like thyroxine (T4) that influence the body's metabolism, growth, and temperature. Also produces calcitonin (a hormone which affects calcium and phosphate in the blood).

• Hyperthyroidism: An overactive thyroid gland produces too much thyroid hormone.

• Hypothyroidism: An underactive thyroid gland produces not enough thyroid hormone.

• Parathyroid Glands: Four tiny glands, located behind the thyroid gland. They release parathyroid hormone (PTH) which regulates calcium and phosphorus levels in the bloodstream

• Hypocalcemia: Low blood calcium levels due to underactive parathyroids.

• Hypercalcemia: High blood calcium levels, linked to osteoporosis and kidney stones.

• Pancreas: A heterocrine gland (endocrine and exocrine functions); produces insulin (lower blood glucose) and glucagon (increase blood glucose levels)

• Diabetes Mellitus: Pancreas related condition, usually stemming from the body not responding properly to insulin; Type 1 develops at a young age and requires insulin; type 2 often in adults and modifiable with lifestyle changes

• Adrenal Glands: Located atop the kidneys, composed of the adrenal cortex (outer) and medulla (inner).

  • Mineralocorticoids: The most crucial of these is aldosterone; it helps maintain salt/water balance, influencing blood pressure.
  • Catecholamines: The adrenal medulla produces these, which trigger the body's "fight-or-flight" stress response; examples are adrenaline and noradrenaline.

• Cushing Syndrome: Excessive cortisol production in the adrenal cortex. Characterized by symptoms like skin thinning, obesity, diabetes, high blood pressure, muscle weakness, excessive facial hair, and irregular periods in women.

• Addison's Disease: Underactive adrenal glands, causing hormone deficiency.

• Gonads: Include ovaries (female) and testes (male); important in producing gametes (sex cells) and sex hormones.

• Homeostasis: The body's process of regulating internal conditions (e.g., temperature, blood sugar). It is facilitated via a feedback loop - sensors, control center, communicating system (nervous and endocrine), and targets.

• Sensors: Gather information inside and outside the body, often using neurons that carry impulses to the brain and spinal cord.

• Control center: Receives information, processes it, and responds by sending messages.

• Communicating system: Transfers messages, primarily via the nervous and endocrine systems.

• Target: A specific organ or cell responsible for enacting the response message sent by the communicating system (the nervous and endocrine systems).

This quiz covers essential concepts of the endocrine system, including the functions of various hormones and glands. Test your understanding of how hormones travel through the body and their roles in processes like childbirth and homeostasis. Ideal for students studying biology or health sciences.