Endocrine System Overview

Endocrine System Overview

  • The endocrine system is responsible for secreting hormones into the body.

    • Hormones play a crucial role in maintaining the fight or flight response.

    • During stress, cortisol is secreted through the adrenal glands, influencing metabolism and helping maintain homeostasis.

Homeostasis

  • Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions.

Role of the Endocrine System

  • The endocrine system influences multiple physiological processes:

    • Regulation of metabolism: Thyroid hormones affect metabolic rate.

    • Reproductive system regulation: Secretion of sex hormones.

Sex Hormones

  • The pituitary gland secretes:

    • Follicle-stimulating hormone (FSH): Stimulates the growth of ovarian follicles in females.

    • Luteinizing hormone (LH): Triggers ovulation in females and testosterone production in males.

    • FSH is associated with estrogen in females and activates ovarian functions.

    • LH is associated with testosterone production in males.

Secondary Sex Characteristics

  • Females: Develop breasts, pubic hair, and undergo changes during puberty.

  • Males: Development of facial and chest hair, descent of testicles, and sperm production begins during puberty.

Growth Hormone

  • Growth hormone (GH) is secreted by the pituitary gland, which is vital during puberty for bone growth and overall physical development.

  • Growing pains in children often occur due to rapid growth, particularly noticeable in boys).

Endocrine Functions

  • Functions of the endocrine system also include:

    • Regulation of body temperature.

    • Blood pressure regulation.

    • Control of respiration and electrolyte balance.

Parathyroid Hormone

  • The parathyroid glands secrete:

    • Parathyroid hormone (PTH) and calcitonin.

Insulin Regulation

  • Pancreas is responsible for blood glucose regulation through:

    • Insulin: Lowers blood glucose levels.

    • Glucagon: Raises blood glucose levels.

    • If pancreatic function is compromised (e.g., pancreatic cancer), glucose and insulin levels become erratic.

Adrenal Gland Functions

  • The adrenal glands produce cortisol, epinephrine, and norepinephrine, which regulate the body's stress response.

    • Epinephrine and norepinephrine are critical for the fight or flight response, helping to increase heart rate and blood pressure during stressful situations.

Hormonal Dysregulation with Age

  • With aging, hormonal production declines:

    • Menopause in females leads to decreased estrogen and progesterone.

    • In males, testosterone levels decrease over time.

    • The pituitary gland shrinks, affecting hormone release, notably FSH and LH.

Thyroid Changes with Age

  • The thyroid gland may become lumpy or nodular with age, requiring monitoring from healthcare providers.

  • Changes in pancreas function may elevate blood glucose levels, leading to conditions like prediabetes.

Hypophyseal Functions

  • Pituitary gland (master gland) regulates:

    • Growth hormone (GH): Stimulates growth in bones and muscles.

    • Thyroid-stimulating hormone (TSH): Stimulates thyroid functions.

    • Adrenocorticotropic hormone (ACTH): Stimulates adrenal gland hormone production.

    • Other hormones include FSH, LH, prolactin, and oxytocin.

Prolactin

  • Prolactin plays a role in milk production during breastfeeding, facilitating milk letdown.

Oxytocin

  • Oxytocin is responsible for uterine contractions during childbirth and the milk letdown reflex during breastfeeding.

Anterior vs. Posterior Pituitary

  • Anterior pituitary: Secretes hormones like TSH, ACTH, FSH, LH, and growth hormone.

  • Posterior pituitary: Stores hormones produced by the hypothalamus, like ADH and oxytocin.

Hypertrophy in Adolescents

  • If growth hormone levels remain elevated post-puberty, conditions like gigantism (in children) and acromegaly (in adults) can occur.

    • Gigantism: Prolonged growth in children leading to excessive height.

    • Acromegaly: Enlarged features (hands, feet) due to excessive growth hormone in adults.

Acromegaly Symptoms

  • Includes a protruding forehead, prominent hands and feet, headaches, and fatigue due to an overactive pituitary gland, leading to an enlarged heart and other complications.

Diagnosis and Treatment of Acromegaly

  • Diagnosed via MRI to visualize the pituitary gland.

  • Treatable through hormone therapy or surgical removal of tumors affecting hormone secretion.

Radiation Treatment in Hormonal Disorders

  • Patients undergoing radiation treatment must take precautions to avoid exposure to others, including:

    • Isolating themselves from individuals, especially vulnerable populations.

    • Protocols include flushing toilets multiple times and not sharing household items.

Thyroid Disorders

Hypo and Hyperthyroidism

  • Hypothyroidism: Autoimmune disease causing low thyroid function leading to fatigue and weight gain.

  • Hyperthyroidism: Overactive thyroid, leading to weight loss, anxiety, and increased metabolism.

Grave's Disease

  • A specific condition characterized by bulging eyes (exophthalmos). It may be treated with radioactive iodine, thyroidectomy, or medication.

Cushing's vs. Addison's Disease

  • Cushing's disease: Excessive cortisol levels leading to symptoms like obesity, skin changes (purple striae), and hypertension.

    • Can occur as a result of prolonged steroid use.

  • Addison's disease: Adrenal insufficiency leading to fatigue, weight loss, hyperpigmentation, and crisis/ shock without adequate stress response.

    • Treated with hormone replacement therapy (e.g., glucocorticoids).

Patient Symptoms

  • Addison's disease may lead to severe responses to stress, while Cushing's is defined by oversupply of cortisol.

Signs of Addison's Disease

  • Patient may exhibit hyperpigmentation and significant weakness due to inadequate cortisol production.

Management Approach

  • Monitoring and maintaining hormone levels is crucial to prevent crises and stabilize conditions in both Addison's and Cushing's disease.

Diabetes Management

Diabetes Insipidus vs. SIADH

  • Diabetes Insipidus: Deficiency of antidiuretic hormone leading to excessive urination and risk of dehydration.

  • SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion): Inappropriate retention of water leading to fluid overload and diluted blood electrolytes.

    • Treatment varies as SIADH often requires fluid restriction and diuretics, while diabetes insipidus requires hydration.

Distinguishing Features

  • Diabetes insipidus: Polyuria, polydipsia, clear urine, and often associated with high sodium levels.

  • SIADH: Fluid retention, confusion, hypernatremia.

Hyperparathyroidism Issues

  • Hyperparathyroidism is characterized by high levels of calcium due to overactive parathyroid glands, leading to symptoms like weakness and kidney stones.

Treatment Approaches in Parathyroid Diseases

  • Manage calcium levels carefully, considering IV calcium or vitamin D supplementation for deficiencies.