The Endocrine System Overview

The Endocrine System

• The endocrine system comprises glands and cells that secrete hormones into the bloodstream
• Hormones have a slower and longer-lasting effect on the body compared to the nervous system

Major Endocrine Organs

• Hypothalamus: Controls the secretion of hormones

• Pituitary gland: Often called the "master gland", it controls the secretion of hormones

  • Posterior pituitary: Doesn't produce hormones; it stores and releases hormones from the nervous system.
  • Anterior pituitary: Produces hormones that trigger responses in other endocrine glands

• Parathyroid glands: Located on the thyroid gland, they regulate calcium levels

• Thyroid gland: Produces hormones that control metabolism

• Adrenal glands: Responsible for the stress response, secreting adrenaline, noradrenaline, and cortisol

• Pancreas: Produces insulin and glucagon, regulating blood sugar levels

• Ovaries (female): Produce estrogen and progesterone

• Testes (male): Produce testosterone

• Pineal gland: Produces melatonin, a hormone that regulates sleep

Types of Glands

• Exocrine glands: Secrete substances into ducts that carry them outside the body, unlike endocrine glands that secrete substances directly into the bloodstream
  • Examples include salivary glands, sweat glands, and mammary glands

Hormones

• Hormones are chemical substances secreted by glands to affect the functions of other cells (target cells)
• Hormones travel in the blood to their target cells, which have specific receptors for the hormones
• Target cells respond to the binding of the hormone by altering their function.

Tropic Hormones

• Tropic hormones influence other endocrine glands, stimulating the release of other hormones from them.
  • Example: Follicle-stimulating hormone (FSH), released by the pituitary gland, stimulates the ovaries to release estrogen.

Pituitary Hormones

• Anterior Pituitary Hormones:
  • Growth Hormone: Promotes cell division, protein synthesis, and bone growth
  • Prolactin: Stimulates milk production
  • Melanocyte-stimulating hormone (MSH): Affects skin pigmentation
  • Adrenocorticotropic hormone (ACTH): Controls the adrenal cortex response to stress
  • Thyroid-stimulating hormone (TSH): Influences thyroid hormone production
  • Gonadotropins (LH and FSH): Regulate reproductive functions

Anterior vs. Posterior Pituitary

• Posterior pituitary releases hormones made by the hypothalamus
• Anterior pituitary responds to hormones from the hypothalamus to release its own hormones

Thyroid Gland

• A goiter is an abnormal enlargement of the thyroid gland. Iodine is required for proper function, and a lack of iodine can cause the pituitary to overproduce TSH, enlarging the thyroid
• The thyroid gland produces triiodothyronine (T3) and thyroxine (T4) to control metabolism and are vital for normal brain development

Stress Response

• Short-term stress: Triggers the "fight or flight" response

  • Hypothalamus activates the pituitary and the adrenal glands, releasing adrenaline, noradrenaline, and cortisol.
  • These hormones trigger responses such as increased heart rate, blood pressure, and breathing rate.

• Long-term stress: If stress is prolonged or is frequent, the body releases glucocorticoids(increase blood sugar such as Cortisol), Mineralocorticoids (increase blood pressure such as aldosterone) and gonadocorticoids (supplement hormones produced by gonads) to maintain the stress response, and these hormones have long-term adverse effects

  • Long-term effects include: suppression of the immune system, decreased serotonin levels, impaired cognitive function, increased blood pressure, and long-term health issues

• Other factors like lack of sleep, caffeine, alcohol, and certain foods can increase cortisol levels.

Cortisol

• Immediate impact: Cortisol raises blood glucose by converting muscle protein and fat to glucose.
• Long-term impact: Continuous cortisol release can suppress the immune system, decrease serotonin, impair cognition, increase blood pressure, lower overall health

Stress and Weight Gain

• Chronic stress can lead to weight gain through hormonal changes and other factors

Dealing with Stress

• Effective stress management strategies include seeking support, taking time for fun and relaxation, setting realistic goals, exercising regularly, adequate sleep, and mindful eating

Death From Overwork

• Karoshi (death from overwork) is a phenomenon observed in Japan, where long work hours and high-stress jobs lead to heart attacks and strokes.

Explore the intricacies of the endocrine system, including its major glands and their functions. This quiz covers essential concepts such as hormone secretion and the roles of various glands like the pituitary and thyroid. Test your knowledge on how hormones impact metabolism and the body's stress response.