Endocrine System Overview

Endocrine System Overview

• The endocrine system works with the nervous system to regulate body functions.
• The nervous system uses electrical impulses and neurotransmitters for rapid, localized effects (seconds).
• The endocrine system uses hormones to influence growth, development, and metabolism; effects last longer (minutes to weeks).

Endocrine Glands vs. Exocrine Glands

• Exocrine glands have ducts that carry secretions to the body surface or cavities.
• Examples include tear glands, sweat glands, and mammary glands.
• Endocrine glands lack ducts and release hormones directly into the bloodstream.
• Examples include glands that produce hormones for blood sugar regulation.

Hypothalamus-Pituitary Complex

• This is the "command center", regulating other endocrine glands' hormone production.
• The hypothalamus is a brain region; the pituitary is a gland connected to the hypothalamus by the infundibulum.
• The pituitary has two lobes (anterior and posterior), with different origins and functions.
• The anterior pituitary is a glandular tissue, regulated by releasing hormones from the hypothalamus via the hypophyseal portal system (network of blood vessels).
• The posterior pituitary is neural tissue, storing and releasing hormones made in the hypothalamus; Oxytocin and ADH.

Anterior Pituitary Hormones

• Hormones from the anterior pituitary target different organs with specific effects.
• Growth hormone (GH) affects growth.
• Prolactin stimulates milk production.
• Adrenocorticotropic hormone (ACTH) targets the adrenal cortex.
• Thyroid-stimulating hormone (TSH) targets the thyroid.
• Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) target the reproductive system.

Posterior Pituitary Hormones

• The posterior pituitary stores and releases hormones made by the hypothalamus, namely:
• Antidiuretic hormone (ADH) regulates water balance.
• Oxytocin triggers uterine contractions and milk production.

Pituitary Lesions

• Hypersecretion (hyperpituitarism) often results in selective excess of hormones, like growth hormone.
• Hyposecretion (hypopituitarism) can be selective or generalized.

Gigantism and Acromegaly

• Excessive growth hormone (GH) secretion.
• Gigantism in childhood, before epiphyseal closure affects overall bone and height growth.
• Acromegaly in adults, after epiphyseal closure affects soft tissue growth and bone thickening.

Growth Hormone Deficiency

• Insufficient growth hormone production resulting in stunted growth in children and delayed puberty.

Galactorrhea

• Inappropriate lactation (milk production).
  • Often linked to prolactin-secreting pituitary tumors.

Hyperthyroidism (Thyrotoxicosis)

• Overproduction of thyroid hormones.
• Symptoms mimic adrenergic excess.
• Common causes: Graves disease, thyroiditis.

Hypothyroidism

• Underproduction of thyroid hormones.
• Symptoms include fatigue, cold intolerance, weight gain, and slowed metabolism.

Cretinism

• Congenital hypothyroidism, causing severe physical and mental retardation, typically diagnosed during infant screening.

Parathyroid Glands

• Regulate calcium levels in the blood.
• Parathyroid hormone (PTH) increases blood calcium.
• Calcium is crucial to many body processes.

Simple Non-Toxic Goiter

• Enlargement of the thyroid gland without a functional problem.
• Often due to iodine deficiency, but not always.

Adrenal Glands

• Located atop the kidneys.
• Adrenal cortex releases steroid hormones (cortisol, aldosterone). -Cortisol regulates glucose metabolism.
  • Aldosterone regulates mineral balance
• Adrenal medulla produces epinephrine (adrenaline) and norepinephrine, stress hormones.

Pheochromocytoma

• Adrenal medulla tumor, secreting excess catecholamines, causing extreme hypertension.

Pancreas

• A mixed gland: exocrine (digestive enzymes) and endocrine (insulin and glucagon).
• Exocrine function involves acinar cells secreting digestive enzymes into the pancreatic duct.
• Endocrine function involves pancreatic islets (islets of Langerhans) secreting insulin and glucagon to regulate blood sugar.

Testes

• Male gonads responsible for producing sperm and androgens (testosterone)

Ovaries

• Female gonads, producing eggs and the female sex hormones estrogen and progesterone.

Explore the intricacies of the endocrine system and its interplay with the nervous system. This quiz covers key concepts such as the distinctions between endocrine and exocrine glands, as well as the vital role of the hypothalamus-pituitary complex. Test your knowledge on how hormones affect various bodily functions.