Notes on Human Body Organ Systems

Organs interact with each other to perform functions, grouped together in organ systems. Different specialties in medicine reflect the various organ systems.

Integumentary System

Comprises skin, appendages (like hair and nails), and glands.

  • Largest organ system, covering approximately 22 square feet.
  • Functions:
    • Protects against heat, cold, chemicals, and bacteria.
    • Regulates body temperature through sweat and the dilation of blood vessels in the skin.
    • Synthesizes vitamin D when exposed to sunlight, which is crucial for bone health.
  • Components:
    • Epidermis: Outer layer, primarily made of keratinized cells that provide a protective barrier.
    • Dermis: Beneath epidermis, composed of:
    • Papillary Layer: Superficial, contains capillaries and sensory neurons.
    • Reticular Layer: Deep, thicker layer that houses larger blood vessels, connective tissue, and hair follicles.
    • Hair Follicles & Oil Glands: Located within the skin, essential for the production of sebum that lubricates the skin and hair.
Conditions & Treatments
  • Basal Cell Carcinoma
    • Causes: Light skin, sun exposure.
    • Symptoms: Non-healing sore or lesion, may appear as a shiny bump.
    • Treatments: Curettage, electrodesiccation, Mohs surgery, topical chemotherapy in some cases.
  • Squamous Cell Carcinoma
    • Similar causes and treatments as basal cell, but can be more aggressive.
  • Malignant Melanoma
    • Symptoms: New or changing mole, itchy or bleeding, asymmetrical shape.
    • Treatments depend on stage: surgery, lymph node biopsy, chemotherapy, immunotherapy for advanced stages.
  • Alopecia
    • Hair loss possibly due to stress, hormonal changes, autoimmune conditions. No cure but transplants can help, and corticosteroids may assist in regrowth.
  • Cellulitis
    • Symptoms: Red, painful skin, fever may be present. Treatment: antibiotics, may require hospitalization in severe cases.
  • Eczema
    • Treatment: Steroids and NSAIDs, moisturizers to manage symptoms.
  • Rosacea
    • Treatments may include antibiotics, topical agents, and laser therapy to reduce redness.
Skeletal System

Provides body support, includes bones, joints, cartilage, spine, and skull.

  • Bones are alive and serve multiple functions:
    • Produce blood cells in the bone marrow.
    • Store fats in adipocytes within the bone.
    • Regulate minerals (phosphorus and calcium) necessary for bodily functions.
  • Anatomical Terminology:
    • Proximal: Near center (e.g., patella to fibula).
    • Distal: Farther from center (e.g., clavicle to ribs).
    • Ipsilateral: Same side (e.g., left radius and ulna).
    • Contralateral: Opposite sides (e.g., right and left femur).
Conditions & Treatments
  • Osteoarthritis
    • Caused by inflammatory processes, joint stiffness, results in pain during movement.
    • Treatments: NSAIDs, injections, surgery for severe cases to improve mobility.
  • Rheumatoid Arthritis
    • Autoimmune, causing deformity and mobility loss, affects joints symmetrically.
    • Treatments: NSAIDs, exercise, disease-modifying antirheumatic drugs (DMARDs), surgeries in advanced cases.
  • Osteoporosis
    • Caused by lifestyle, hormonal changes, vitamin D deficiency, increasing fracture risk.
    • Treatments: Hormone therapy, exercise, supplements, bisphosphonates.
Muscular System

Composed of muscles producing movement by contracting and relaxing. Muscles exist throughout the body, not limited to extremities.

  • Anatomy of Abdomen
    • Anterior abdominal wall contains layers of muscles that run diagonal to the midline.
    • External Oblique: Superficial layer, aids in twisting the torso.
    • Internal Oblique: Lies deeper, running in opposite direction to external oblique, assists in trunk rotation and flexion.
Nervous System

Regulates responses to stimuli, made up of the Central Nervous System (CNS) and Peripheral Nervous System (PNS).

  • CNS: Brain and spinal cord, responsible for processing information.
  • PNS: Nerves from brain and spinal cord, transmits signals to and from the rest of the body.
  • Functionality of Nervous System:
    • Afferent Neurons: Carry information to CNS.
    • Efferent Neurons: Carry commands from CNS to muscles.
    • Example: Touching water to check temperature involves both neuron types for sensory and motor response.
Conditions & Treatments
  • Alzheimer's Disease
    • Symptoms: Confusion, memory loss, and difficulties with language.
    • No cure, but treatment can slow progression and improve quality of life.
  • Bell's Palsy
    • Symptoms: Sudden facial weakness, drooping on one side of the face. Treatment: NSAIDs, physical therapy to recover function.
Cardiovascular System

Transports nutrients and waste throughout the body via blood and lymph.

  • Components: Heart, arteries, veins, lymphatic vessels.
    • Heart: Pumps oxygen-rich blood to body and returns deoxygenated blood.
    • Blood Circulation: Begins in left ventricle, pumps blood to arteries; Blood travels through capillaries, exchanging nutrients and waste, then returns to heart via veins.
Conditions & Treatments
  • Hypertension
    • Treatment: Lifestyle changes, medication to lower blood pressure.
  • Angina
    • Treatment: Medications for underlying causes, lifestyle adjustments for risk reduction.
  • Myocardial Infarction
    • Immediate emergency treatments include CPR and anticoagulants, possible surgical intervention.
Respiratory System

Responsible for gas exchange: oxygen intake and carbon dioxide removal.

  • Components:
    • Organs: Lungs, trachea, larynx, diaphragm.
    • Function: Prevent gas exchange failure as body cannot survive without oxygen for long.
Conditions & Treatments
  • Asthma
    • Treatments: Avoiding allergens, bronchodilators, inhaled corticosteroids to manage symptoms.
  • Chronic Obstructive Pulmonary Disease (COPD)
    • Treatment includes smoking cessation, inhalers, pulmonary rehabilitation to ease symptoms.
Gastrointestinal System

System responsible for digestion and nutrient absorption, starting at the mouth and ending at the anus.

  • Common Conditions:
    • Appendicitis: Inflammation requires appendectomy for treatment.
    • Cholelithiasis (Gallstones): Treatment involves surgery to remove gallbladder if stones cause issues.
Genitourinary System

Filters blood, produces urine (Kidneys, ureters, bladder).

  • Common Conditions:
    • Acute Kidney Failure: Treatments depend on underlying cause; may need dialysis or medical management.
    • Urinary Tract Infection (UTI): Treatment typically involves antibiotics to clear infection.
Endocrine System

Involves hormone regulation via glands (pituitary, thyroid, etc). Hormones control various physiological processes such as metabolism, growth, and mood regulation.

  • Common Conditions:
    • Diabetes Mellitus: Treatments vary based on type; insulin or oral medications for management.
Immune System

Defends against disease using white blood cells and other components. Acts as an army protecting the body from foreign pathogens