The Endocrine System

Presented by: Robin Johns, PhD, RN, Augusta University

Page 1: Functions of the Endocrine System

• Key Functions:

  • Growth and development

  • Sex differentiation

  • Metabolism

  • Adaptation to changing environments

• Important Roles:

  • Regulation of digestion

  • Use and storage of nutrients

  • Electrolyte and water metabolism

  • Reproductive functions

Page 2: Hormones and Their Characteristics

• Adipose Tissue:

  • Largest endocrine organ in the body

• Hormones:

  • Specialized organic molecules acting as chemical messengers

  • Travel through blood to target sites

  • Can act locally (paracrine or autocrine)

  • Present in body fluids at all times

• Characteristics:

  • A single hormone can have various effects in different tissues

  • A single function can be regulated by multiple hormones

Page 3: Signals & Receptors

• Interaction:

  • Hormones (signals) interact with receptors on target cells

  • Release of signals occurs from glands

  • Involves second messenger systems

Page 4: Control of Hormone Levels

• Regulation Types:

  • Diurnal: Fluctuates with sleep-wake cycles (e.g., GH, ACTH)

  • Cyclic: Secreted in a cyclic manner (e.g., female sex hormones)

• Feedback Mechanisms:

  • Monitor substances like glucose (insulin) and water (ADH)

  • Involves hypothalamic-pituitary-target cell systems

• Factors Affecting Control:

  • Positive feedback

  • Negative feedback

Page 5: Factors Affecting Target Cell Response

• Response Factors:

  • Number of receptors (up-regulation/down-regulation)

  • Affinity of receptors for hormones

  • Conditions affecting affinity (e.g., pH levels)

Page 6: Hypothalamic & Pituitary Hormones

• Hypothalamus:

  • Coordinating center for endocrine and autonomic functions

• Hypothalamic Hormones:

  • GHRH, Somatostatin, Dopamine, TRH, CRH, GnRH

• Anterior Pituitary Cell Types:

  • Thyrotrophs (TSH), Corticotrophs (ACTH), Gonadotrophs (LH, FSH), Somatotrophs (GH), Lactotrophs (Prolactin)

Page 7: Functions of Anterior Pituitary Hormones

• Hormonal Functions:

  • GH: Body growth and metabolism

  • TSH: Thyroid function

  • ACTH: Glucocorticoid hormone levels

  • FSH & LH: Gonadal function

  • Prolactin: Breast growth and milk production

• Assessment Measures:

  • Blood tests, urine tests, stimulation/suppression tests, genetic tests, imaging

Page 8: Disorders of the Endocrine System

• Disturbances:

  • Hypofunction: Underproduction of hormones (causes: congenital defects, aging, receptor defects)

  • Hyperfunction: Excessive hormone production (causes: stimulation, tumors)

Page 9: Categories of Endocrine Disorders

• Primary Disorders: Originate in the target gland

• Secondary Disorders: Normal target gland function altered by pituitary issues

• Tertiary Disorders: Result from hypothalamic dysfunction

Page 10: Pituitary Tumors

• Types:

  • Primary: Originate at the site

  • Secondary: Metastatic lesions

  • Functional: Secrete hormones

  • Nonfunctional: Do not secrete hormones

• Conditions:

  • Hypopituitarism: Gradual onset, can be acute

  • Hyperpituitarism: Symptoms vary based on hormone overproduction

Page 11: Measurement of Hormones

• Key Hormones:

  • Serum cortisol, prolactin, thyroxine (T4), testosterone/estrogen, GH

• Question: Identify primary disorder from gland lesions.

Page 12: Hormones for Growth and Maturation

• Essential Hormones:

  • GH, Insulin, Thyroid hormones (T3, T4), Androgens

• Growth Hormone Functions:

  • Linear bone growth, cell size increase, fatty acid usage, carbohydrate reduction

Page 13: Growth Hormone Effects

• Deficiency: Short stature or dwarfism

• Excess: Gigantism

Page 14: Effects of Growth Hormone Excess in Adults

• Conditions:

  • Acromegaly: Overgrowth of cartilage, organ enlargement, metabolic disturbances

Page 15: Major Functions of Thyroid Hormones

• Functions:

  • Increase metabolism, protein synthesis, growth, and development

• Alterations:

  • Hypothyroidism: Decreased metabolism, myxedema, elevated cholesterol

  • Hyperthyroidism: Increased metabolism, sympathetic responsiveness

Page 16: Manifestations of Thyroid Disorders

• Hypothyroidism Symptoms: Sluggishness, cold intolerance, weight gain

• Hyperthyroidism Symptoms: Anxiety, tachycardia, weight loss

Page 17: Diagnosing Thyroid Disorders

• Diagnostic Measures:

  • T3, T4, TSH levels, imaging, biopsy

• Graves Disease: Autoimmune hyperthyroidism with goiter and ophthalmopathy

Page 18: Thyroid Storm

• Symptoms: High fever, cardiovascular effects, severe CNS effects

Page 19: Adrenal Cortex Hormones

• Types:

  • Mineralocorticoids (Aldosterone), Glucocorticoids (Cortisol), Adrenal sex hormones

• Conditions:

  • Addison’s Disease: Primary adrenal insufficiency

  • Acute Adrenal Crisis: Life-threatening situation

Page 20: Manifestations of Adrenal Cortical Insufficiency

• Symptoms: Weight loss, fatigue, gastrointestinal issues, hypotension

Page 21: Cushing Syndrome

• Causes: Excessive ACTH production, adrenal tumors

• Symptoms: Altered fat metabolism, muscle weakness, glucose derangements

This note summarizes the key points from the transcript on the endocrine system, its functions, hormones,