Chapter 26 - endocrine glands

Introduction to Endocrine Functions

• Sympathetic Nervous System:

  • Activates during sunlight hours, indicating wakefulness.

  • Epinephrine plays a role in blood vessel tone and heart rate.

• Melatonin:

  • Secreted in darkness to promote sleep and cellular repair.

  • Supplementation: 5-10 mg may be given to patients lacking melatonin.

The Pancreas and Its Functions

• Dual Function:

  • Acts as both an endocrine organ (produces insulin) and an exocrine gland (secretes GI enzymes).

• Islets of Langerhans:

  • Comprised of 1-2 million islets that contain beta and alpha cells.

  • Insulin (beta cells): A hormone essential for glucose transport into cells.

  • Glucagon (alpha cells): Involved in regulating blood sugar levels; stimulates glycogen breakdown (glycogenolysis) and new glucose formation (gluconeogenesis).

Hormonal Interactions and Processes

• Glycogenolysis:

  • Breakdown of glycogen into glucose; occurs mainly in the liver.

• Gluconeogenesis:

  • Formation of glucose from non-carbohydrate sources, including fats and proteins.

The Thymus and Immunity

• Thymus Gland:

  • Enlarges during childhood; shrinks post-puberty.

  • Produces thymosin which stimulates T cell production (T lymphocytes), crucial for immune response.

Digestive Hormones

• Gastrin:

  • Stimulates gastric juices (like hydrochloric acid production) aiding digestion.

• Secretin and Cholecystokinin:

  • Secreted from the upper small intestine; regulate pancreatic and gallbladder function.

Placenta as an Endocrine Gland

• Hormones:

  • Secretes estrogen and human chorionic gonadotropin (HCG) during pregnancy.

  • Role in maintaining pregnancy and preparing the body for birth.

Renin-Angiotensin-Aldosterone System (RAAS)

• Aldosterone:

  • Key regulator of sodium and water retention; affects urinary output and blood pressure.

• Erythropoietin (EPO):

  • Stimulates red blood cell production, particularly relevant in kidney disease management.

Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP)

• ANP:

  • Produced in the heart's atria; regulates blood volume and pressure.

• BNP:

  • Released by the brain; indicative of heart perfusion needs; used diagnostically for heart failure.

Pain and Inflammation Hormones

• Prostaglandins:

  • Involved in pain response; give rise to inflammation.

  • Examples of over-the-counter medications like ibuprofen act as prostaglandin inhibitors.

• Leukotrienes:

  • Mediate inflammatory responses; relevant in asthma management.

Interdependence of Body Systems

• Endocrine and Nervous Systems:

  • Interconnected; hormones can stimulate or inhibit nerve impulses and vice versa.

• Endocrine and Circulatory Systems:

  • Hormones travel through blood; vital for systematic responses to internal changes.

Feedback Mechanisms

• Negative Feedback:

  • Inhibits hormone production once homeostasis is achieved, e.g., insulin levels post-glucose consumption.

• Positive Feedback:

  • Continual hormone production until a specific outcome is achieved, e.g., oxytocin during childbirth.

Aging Effects on Endocrine Functions

• Decrease in:

  • Reproductive hormones, insulin sensitivity, and thyroid hormone production in older adults.

  • Increased prevalence of conditions like diabetes and osteoporosis.

• Sperm Production:

  • Decreases with age in men but reproductive capabilities can persist.

Clinical Implications and Nursing Considerations

• Monitor signs of:

  • Hypoglycemia in diabetic patients, especially those on insulin.

  • The importance of therapeutic approaches to manage pain and inflammation (e.g., medications like ibuprofen and Tylenol).

• Patient Education:

  • Emphasize the necessity of lifestyle modifications and understanding hormone functions related to aging and chronic illnesses.