Endocrine System Overview

Endocrine System Overview

• The endocrine system secretes hormones that regulate internal body activities, including reproduction and fertilization.
• It's comprised of glands and the hormones they release.

Components of the Endocrine System

• Glands: Specialized organs that produce and release substances (hormones) into the bloodstream.
• Hormones: Chemical messengers secreted by endocrine glands or tissues, traveling throughout the bloodstream to affect target cells.

Types of Glands

• Endocrine glands: Ductless, releasing hormones directly into the bloodstream.
• Exocrine glands: Release secretions through ducts to specific tissues. (e.g., brain and heart release important substances, but aren't usually classified as endocrine glands)

Hormones: Characteristics and Effects

• Chemical messengers secreted into the bloodstream.
• Travel throughout the body, affecting only cells with specific receptors.
• Can affect distant organs or cells.
• Imbalances (hypo/hyper secretion) can be harmful.

Major Endocrine Glands

• Pineal
• Hypothalamus
• Pituitary
• Thyroid
• Parathyroids
• Thymus
• Adrenals
• Pancreas
• Ovaries
• Testes

Pituitary Gland: A Closer Look

• Known as the "Master Gland", located in the brain.
• Controlled by the hypothalamus.
• Made up of anterior and posterior regions.
• Secretes endorphins, responsible for pain reduction.
• Releases at least 8 hormones. (Diagram showing connections to other organs is important)

Human Growth Hormone

• Crucial for the development of bones, muscles, and other organs.
• Enhances protein synthesis.
• Supports tissue repair and healing.
• Imbalances can cause conditions like gigantism and dwarfism.

Thyroid Stimulating Hormone

• Regulates thyroid gland secretions.
• Essential for thyroid gland growth and development.

Follicle Stimulating Hormone

• Target tissue: follicles in ovaries.
• Function: follicle maturation and estrogen secretion.

Luteinizing Hormone

• Target tissue: ovaries.
• Function: Promotes ovulation and progesterone production.

Prolactin

• Target tissue: mammary glands, ovaries.
• Function: Milk production, stimulating mammary gland development during pregnancy.

Adrenocorticotropic Hormone (ACTH)

• Responsible for producing and releasing glucocorticoids by the adrenal gland.

Melanocyte-Stimulating Hormone

• Regulates skin pigmentation and melanin deposit in response to sunlight.

Antidiuretic Hormone

• Target tissues: kidneys.
• Functions: Conserves water by decreasing urine production (also known as vasopressin).

Oxytocin

• Target tissues: uterus.
• Functions: Stimulates uterine contractions during labor, delivery, and parturition; controls milk secretion.

Hypothalamus

• Located in the brain, controls pituitary gland function.
• Secretes hormones like TRH, GnRH, and CRH, triggering the release of other hormones.

Thyroid Gland

• Located below the larynx.
• Produces calcitonin, maintaining calcium levels.
• Produces thyroxine (T4) and triiodothyronine (T3), crucial for protein synthesis, oxygen use regulation, metabolism, and growth.
• Imbalances like hyperthyroidism (overactive) and hypothyroidism (underactive) have specific symptoms.
• Iodine deficiency can cause goiter

Parathyroid Gland

• Located on the back side of the thyroid.
• Produces parathyroid hormone (PTH), regulating blood calcium, magnesium, and phosphate levels.

Pancreas

• Located in the duodenum of the small intestine.
• Secretes insulin and glucagon – controlling blood sugar levels.
• Insulin lowers blood glucose levels.
• Glucagon raises blood glucose levels.

Adrenal Gland

• Located on top of each kidney—made of cortex (outer) and medulla (inner).

Adrenal Cortex

• Outer region of the adrenal gland.
• Secretes mineralocorticoids for maintaining mineral balance (sodium and potassium), glucocorticoids for protein/fat breakdown and glucose formation (anti-inflammatory effects), and androgens for secondary sex characteristics.

Adrenal Medulla

• Inner region of the adrenal gland.
• Secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) involved in the fight-or-flight response.

Pineal Gland

• Located in the brain.
• Secretes melatonin to regulate sleep-wake cycles.
• Secretes serotonin (neurotransmitter important for metabolism, mood, and sleep).

Thymus Gland

• Located in the chest.
• Promotes immune function (especially in development).
• Secretes thymosin, affecting immune system tissues.

Gonads (Testes)

• Produce testosterone, responsible for sperm production and male secondary sex characteristics.

Gonads (Ovaries)

• Produce estrogen, developing female secondary sex characteristics.
• Produce progesterone for pregnancy preparation and other body cycles in females.

Explore the intricate workings of the endocrine system, which regulates various internal activities through hormones. This quiz covers the components, types of glands, and characteristics of hormones, emphasizing their vital role in the body.