Endocrine System: Thyroid and Parathyroid Glands

Iodine Deficiency

• Iodine deficiency can lead to goiter, a condition characterized by an enlarged thyroid gland.

Calcium Regulation

• Parathyroid hormone (PTH) is the primary hormone responsible for regulating blood calcium levels.

Exophthalmos and Weight Loss

• Graves' disease, an autoimmune disorder affecting the thyroid, is characterized by exophthalmos (protrusion of the eyeballs) and weight loss.

Thyroid Hormones and Metabolism

• Thyroid hormones (T3 and T4) influence metabolism by increasing basal metabolic rate, regulating growth and development, and affecting the body's energy consumption.

Parathyroid Hormone (PTH) Function

• PTH acts to increase blood calcium levels by stimulating bone resorption (breakdown), increasing calcium reabsorption by the kidneys, and promoting the activation of vitamin D, which enhances calcium absorption in the intestines.

Hyperthyroidism in Adults

• Hyperthyroidism in adults can lead to increased metabolic rate, weight loss, heat intolerance, and rapid heartbeat.

Thyroid Gland Incorrect Statement

• The thyroid gland does not produce insulin, which is secreted by the pancreas.

Thyrocalcitonin (TCT) Function

• Thyrocalcitonin (TCT), also known as calcitonin, is secreted by the thyroid gland and acts to decrease blood calcium levels by inhibiting bone resorption and promoting calcium deposition in bone.

Glucagon's Role

• Glucagon, secreted by the pancreas, raises blood glucose levels by stimulating the breakdown of glycogen in the liver and promoting glucose production.

Adrenal Medulla Hormones

• The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), collectively known as catecholamines.

Parathyroid Hormone and Calcium Levels

• PTH increases blood calcium levels, which is essential for various bodily functions like muscle contraction, nerve impulse transmission, and bone health.

Catecholamines' Effects

• Catecholamines, released during stress, increase heart rate, blood pressure, and blood glucose levels.

Thymosins Function

• Thymosins, secreted by the thymus gland, are essential for the development and maturation of T lymphocytes, which play a critical role in the immune system.

Insulin's Role

• Insulin, secreted by the pancreas, lowers blood glucose levels by promoting glucose uptake by cells, stimulating glycogen synthesis (storage of glucose in the liver), and inhibiting the breakdown of glycogen.
• Insulin is also important for regulating fat and protein metabolism.

Pregnancy Maintenance Hormone

• Progesterone, secreted by the ovaries and the placenta, plays a crucial role in maintaining pregnancy by preparing the uterus for implantation and supporting the development of the fetus.

Mineralocorticoids Function

• Mineralocorticoids, such as aldosterone, secreted by the adrenal cortex, regulate electrolyte balance, particularly sodium and potassium, in the body.

Parathyroid Hormone's Role

• Parathyroid hormone (PTH) is primarily responsible for regulating blood calcium levels by stimulating bone resorption, increasing calcium absorption in the intestines, and enhancing calcium reabsorption by the kidneys.

Thymus Function with Age

• The thymus gland, which is active during childhood, gradually shrinks and becomes less functional as an individual ages.

Adrenal Medulla Secretions

• The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), collectively known as catecholamines.

Emergency Response Triggered by Catecholamines

• Catecholamines trigger the 'fight-or-flight' response during emergencies by increasing heart rate, blood pressure, and blood glucose levels, preparing the body for immediate action.

Underproduction of Adrenal Cortex Hormones

• Addison's disease, a condition resulting from underproduction of hormones by the adrenal cortex, can cause fatigue, weight loss, low blood pressure, and salt craving.

Thymosin Functions

• Thymosins are not directly involved in regulating blood calcium levels.

Adrenal Gland Part Secreting Catecholamines

• The adrenal medulla is responsible for secreting catecholamines, specifically epinephrine and norepinephrine.

Catecholamines and Blood Sugar

• Catecholamines like epinephrine and norepinephrine raise blood sugar levels by stimulating the breakdown of glycogen in the liver, making more glucose available for energy during emergencies.