Endocrine System Quiz

Hormonal Regulation

• Hormonal regulation is a complex process maintaining the body's internal environment.
• The endocrine system utilizes glands secreting hormones into the circulatory system.
• Hormones are chemical messengers regulating various bodily functions.
• Hormone release is controlled via negative feedback mechanisms.

Hormone Transport and Action

• Hormones can be transported in free or bound forms (to a carrier).
• Water-soluble hormones (epinephrine, norepinephrine, amino acids) circulate unbound.
• Lipid-soluble hormones (steroids, thyroid hormones) primarily circulate bound to proteins.
• Hormones bind to receptors within target cells, initiating intracellular cascades.
• Receptor location is determined by the hormone's solubility.

The Hypothalamic-Pituitary Axis

• The hypothalamic-pituitary axis is central to hormonal regulation.
• The hypothalamus, in the brain, controls the endocrine system by releasing hormones regulating the pituitary gland's function.
• The pituitary then regulates other endocrine glands.

Thyroid and Parathyroid Glands

• Thyroid gland: Produces thyroxine (T4) and triiodothyronine (T3).
• Thyroid hormone secretion is regulated by the hypothalamic-pituitary axis.
• Thyroxine (T3) and triiodothyronine (T4) regulate growth, maturation, cell metabolism, heat production, and oxygen consumption.
• Parathyroid glands: Produce parathyroid hormone (PTH).
• PTH regulates calcium homeostasis.
• PTH acts as an antagonist to calcitonin.

Pancreas

• Pancreas is both an endocrine and exocrine gland.
• Endocrine function is in islets of Langerhans.
• Alpha cells: secrete glucagon.
• Beta cells: secrete insulin and amylin.
• Delta cells: secrete somatostatin and gastrin.
• F cells: secrete pancreatic polypeptide.
• Insulin facilitates glucose uptake, promotes protein, lipid, and nucleic acid synthesis.
• Amylin delays nutrient uptake and suppresses glucagon secretion.

Adrenal Glands

• Adrenal glands are located above the kidneys, composed of cortex and medulla.
• Cortex produces glucocorticoids (e.g., cortisol) and mineralocorticoids (e.g., aldosterone).
• Medulla secretes catecholamines (epinephrine, norepinephrine).
• Adrenal hormones affect carbohydrate metabolism, anti-inflammatory effects, and regulating sodium/potassium balance.

Alterations in Hormonal Regulation

• Endocrine disorders arise from feedback system failure, glandular dysfunction, or secretory cell defects.
• Target cell dysfunction can be caused by reduced receptors, impaired receptor function, or abnormal receptor expression.
• Intracellular disorders disrupt hormone action in subsequent pathways (e.g., receptor signaling cascades).

Graves' Disease

• An autoimmune disorder characterized by overproduction of thyroid hormones (T3 and T4).
• Antibodies mimic the action of TSH, leading to hyperthyroidism.
• Clinical presentations include bulging eyes, fluid accumulation under the skin (particularly shins), jitteriness, rapid heartbeat.

Myxedema

• A severe form of hypothyroidism, often associated with prolonged, untreated hypothyroidism.
• Characterized by altered dermis composition (non-pitting edema), puffy skin, altered consciousness, and potential cardiovascular complications.

Diabetes Mellitus

• A chronic metabolic disorder characterized by hyperglycemia.
• Results from defects in insulin secretion, action, or both, affecting glucose metabolism.
• Insulin, produced by beta cells in the pancreas, facilitates glucose transport into cells.

Complications of Diabetes Mellitus

• Acute complications: hypoglycemia, diabetic ketoacidosis (DKA), hyperosmolar hyperglycemic syndrome (HHS)
• Chronic complications: microvascular disease (retinopathy, nephropathy, neuropathy), macrovascular disease (cardiovascular disease, stroke, peripheral vascular disease).

Diagnosing Diabetes Mellitus

• Diagnoses include fasting blood glucose test, random blood glucose test, and oral glucose tolerance test.
• Hemoglobin A1C test monitors long-term blood sugar control.