Endocrine System II_2025_post

Endocrine System Overview

• Definition: The endocrine system is responsible for hormone production, which regulates various functions in the body.

Exam Review

• Announcements:

  • Exam review scheduled during discussion at 3:30.

  • Students should review their exams, focusing on common themes and test-taking strategies.

Ergogenic Aids

• Types of Aids:

  • Anabolic steroids

  • Human Growth Hormone (HGH)

  • Erythropoietin (EPO)

• Considerations:

  • Study clinical uses and side effects of ergogenic aids.

  • Be aware of rules and regulations regarding their use.

  • Check out the Drug Free Sport Resource Exchange Center at drugfreesport.com for more information.

Endocrine System Functions

• 5 Main Functions:

  1. Reproduction

  2. Growth and Development

  3. Homeostasis

  4. Metabolism

  5. Response to Stress

Hormonal Communication in the Body

• Mechanisms of Action:

  • Negative Feedback Loop:

    • Involves a control center, sensor (receptor), and effector.

    • Responses adjust variables to maintain homeostasis.

  • Second Messenger System:

    • Uses molecules to relay signals within cells.

  • Direct System:

    • Hormones act directly on target organs or tissues.

Components of the Negative Feedback Loop

1. Input: Information sent along the afferent pathway to the receptor.

2. Stimulus: Change in variable detected by the receptor.

3. Control Center: Processes the information and determines response.

4. Output: Information sent along the efferent pathway to activate the effector.

5. Response: Effector function influences magnitude of stimulus and returns variable to homeostasis.

Pituitary Gland Hormones and Functions

• Anterior Lobe Hormones:

  • Somatotropin (Growth Hormone): Promotes growth of bones, muscles, and organs.

  • Thyroid-stimulating Hormone (TSH): Stimulates activity in the thyroid gland.

  • Follicle-stimulating Hormone (FSH): Promotes development in ovaries and testes.

  • Luteinizing Hormone: Triggers ovulation and regulates hormone production in gonads.

  • Prolactin: Stimulates milk production in the breasts.

  • Adrenocorticotropic Hormone (ACTH): Stimulates adrenal cortex secretions.

Endocrine Dysfunctions

• Pituitary Disorders:

  • Hyperpituitarism: Excessive hormone production.

  • Acromegaly: Abnormal growth due to excess GH in adults.

  • Giantism: Excess GH in children leading to increased height.

  • Cushing’s Disease: Caused by excess ACTH leading to high cortisol levels.

  • Hyperthyroidism: Overactivity of the thyroid gland.

  • Hypopituitarism: Underactivity of the pituitary, leading to hormone deficiencies.

Posterior Pituitary Functions

• Posterior Lobe Hormones:

  • Antidiuretic Hormone (ADH): Reabsorbs water in kidneys to control fluid balance.

  • Oxytocin: Stimulates uterine contractions during childbirth.

Diabetes Insipidus (DI)

• Characteristics:

  • Lack of response to ADH causing polyuria (excessive urination) and polydipsia (excessive thirst).

  • Types of DI include Central and Nephrogenic DI due to various causes including genetic factors and certain medications.

Thyroid Hormones and Functions

• Thyroid Gland:

  • T4 (Thyroxine) and T3 (Triiodothyronine): Regulate metabolism and energy generation in cells.

  • Calcitonin: Helps to lower calcium levels in the blood by regulating bone deposition.

Parathyroid Hormone (PTH) Functions

• PTH Action: Increases calcium levels in the blood by releasing calcium from bones and increasing absorption in kidneys and intestines.

Endocrine Dysfunction in Thyroid

• Grave’s Disease: Hyperthyroidism causing elevated metabolism and systemic effects.

• Hypothyroidism: Symptoms include fatigue, weight gain, dry skin, and bradycardia, resulting from insufficient thyroid hormones.

Calcium Homeostasis

• Hormonal Regulation:

  • Calcitonin: Decreases blood calcium levels.

  • PTH: Increases blood calcium levels by affecting bones, intestines, and kidneys.

Adrenal Gland Functions

• Cortex Hormones:

  • Mineralocorticoids (Aldosterone): Maintain fluid and electrolyte balance.

  • Glucocorticoids (Cortisol): Manage stress response and metabolism.

  • Sex Hormones: Influence secondary sexual characteristics.

Adrenal Medulla Hormones

• Epinephrine & Norepinephrine: Regulate the fight or flight response, affecting heart rate, blood pressure, and energy availability.

Stress Response and Disease

• Stress Impact: Influences various disease processes including cognition, immune response, and metabolic syndrome.

Cushing's Syndrome

• Presentation: Characterized by weight gain, facial changes (moon face), and susceptibility to infections due to cortisol excess.

• Symptoms: May include easy bruising, hypertension, diabetes, and skin changes.

Adrenal Insufficiency

• Addison's Disease: Characterized by weakness, weight loss, and skin changes due to low levels of cortisol and aldosterone.

• Secondary Insufficiency: May result from pituitary disorders or rapid withdrawal from corticosteroids.

Bone Health and Endocrine Changes

• Osteoporosis Risk: Declines in estrogen and testosterone contribute to bone density loss in aging, emphasizing the importance of exercise and calcium supplementation.

Conclusion

• The endocrine system plays a vital role in maintaining homeostasis through hormonal regulation of various bodily functions.