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  • Anatomy: The scientific study of the structure of bodies and their parts. It is concerned with the identification and description of the body structures of living things.

  • Macroscopic or Gross Anatomy: The study of body structures that are visible the naked eye, meaning they do not require magnification to be observed.

  • Microscopic Anatomy: The study of body structures that are too small to be se with the naked eye and require the use of a microscope for observation.

  • Regional Anatomy: The study of all the structures (bones, muscles, nerves, blc vessels, etc.) in a particular region of the body, such as the head, abdomen, or a at once.

  • Systematic Anatomy: The study of the body's organ systems, with each syster (e.g., the circulatory system, nervous system) being examined throughout the entire body.

  • Specialization Areas in Anatomy:

  • Gross (Macroscopic) Anatomy

  • Microscopic Anatomy (Cytology and Histology)

  • Regional Anatomy

  • Systematic Anatomy

  • Developmental Anatomy (Embryology, Fetology)

  • Pathological Anatomy

  • Radiographic Anatomy

  • Comparative Anatomy

  • Approaches to Studying Anatomy:

  • Regional Anatomy

  • Systematic Anatomy

  • Surface Anatomy

  • Gross (Macroscopic) Anatomy

  • Microscopic Anatomy

  • Branches of anatomy similarity: All branches aim to understand the structur living organisms and their parts, describing physical form, organization, and relationships of body components.

  • Physiology: The scientific study of the functions and mechanisms of living systen It explores how organisms, organ systems, organs, cells, and biomolecules carry o the chemical and physical functions that exist in a living system.

  • Homeostasis: The process by which living organisms maintain a relatively stable internal environment despite changes in external conditions. This involves a dynan equilibrium of physiological processes to ensure optimal functioning.

2. Levels of Organization of the Human Body

• Chemical Level:

  1. Subatomic Particles: Particles smaller than an atom (protons, neutrons, electrons).

  2. Atoms: The basic unit of matter and the smallest particle of a chemical element retaining its chemical identity. Consists of a nucleus (protons, neutrons) surrounded by electrons.

  3. Molecules: A group of two or more atoms held together by chemical bonds.
    Smallest unit of a compound that can exist independently and retain chemical properties.

• Cellular Level:

  1. Organelles: Specialized structures within a living cell that perform specific functions necessary for the cell's survival and operation (e.g., mitochondria, nucleus, ribosomes).

  2. Cells: The fundamental structural and functional units of all known living organisms. Smallest units of life that can replicate independently (e.g., muscle cells, nerve cells).

• Tissue Level:

1. Tissues: Groups of similar cells that work together to perform a specific functio (e.g., epithelial, connective, muscle, nervous tissue).

• Organ Level:

1. Organs: A structure composed of two or more different types of tissues that wo together to perform specific functions in the body (e.g., heart, lungs).

• Organ System Level:

1. Organ Systems: A group of organs that work together to perform one or more functions in the body. The human body has 11 major organ systems.

• Organismal Level:

1. Organism: Any individual living entity, characterized by the ability to maintain homeostasis, undergo metabolism, grow, respond to stimuli, reproduce, and evolve.

• Biosphere: The sum of all the ecosystems on Earth, encompassing all life and the areas where life exists, including land, water, and atmosphere.

3. Comparison of Chemical and Human Body Levels of Organization

  • Chemical Level: Most fundamental, non-living (subatomic particles, atoms, molecules) serving as building blocks.

  • Human Body Levels (Cellular to Organismal): Progressively complex, living levi built upon chemical components, exhibiting emergent properties and intricate coordination.

  • Similarities:

  • Hierarchical Foundation: Higher levels are built upon simpler ones.

  • Interdependence: Components at each level interact and influence each other.

  • Emergent Properties: New properties arise at each increasing level of complex

  • Differences:

  • Complexity: Chemical level is simplest; organismal is most complex.

  • Life Status: Chemical level is non-living; life emerges at the cellular level.

  • Scope: Chemical level is universal for matter; higher levels are specific to biolog systems.

4. Requirements of Human Life

  • Fundamental Composition: A pure substance or element contains atoms, which are made up of protons, neutrons, and electrons or subatomic particles.

  • Cells make up tissues, tissues make up organs, organs make up organ systems.

  • The human body is made up of multiple different body systems. Organ systems ar made up of organs that work together.

4.1 Metabolism

• Metabolism = anabolism + catabolism

  • Catabolism: Metabolic process that breaks down complex molecules into simpl ones, releasing energy (e.g., glucose breakdown for ATP).

  • Anabolism: Metabolic process that builds complex molecules from simpler one: requiring energy input (e.g., protein synthesis from amino acids).

  • The cellular energy currency is adenosine triphosphate (ATP).

4.2 Energy and Thermodynamics

  • First Law of Thermodynamics (Law of Conservation of Energy): Energy canne be created or destroyed, only transformed.

  • Functions in Human Life: Energy is ingested (chemical potential energy from foo and transformed into usable forms (ATP) for mechanical work (muscle contraction thermal energy (heat for thermoregulation), chemical synthesis (growth, repair), a electrical energy (nerve impulses). Energy is conserved and eventually released as heat or work.

4.3 Oxygen vs. Carbon Dioxide

  • Oxygen (02):

  • Role: Essential reactant for aerobic cellular respiration, producing AT P.

  • Source: Inhaled from atmosphere via respiratory system.

  • Transport: Binds to hemoglobin in red blood cells.

  • Deficiency Effect: Life-threatening (hypoxia/anoxia) due to impaired energy production.

  • Carbon Dioxide (CO2):

  • Role: Primary waste product of aerobic respiration; critical regulator of blood pl (via carbonic acid-bicarbonate buffer system) and primary stimulus for breathin

  • Source: Produced internally by cells during metabolism.

  • Transport: As bicarbonate ions, dissolved in plasma, or bound to hemoglobin.

  • Imbalance Effect: Excess (hypercapnia) leads to acidosis; deficiency (hypocapnia) leads to alkalosis.

  • Comparison: Both gases involved in respiration; essential for homeostasis. O2 is. reactant for energy, CO, is a product/waste and a pH/respiratory regulator. Body I net intake of O2 and net output of CO2.

4.4 Nutrients

• Water: Essential inorganic nutrient; regulates temperature, transports substances lubricates, acts as a solvent.

  • Micronutrients: Essential nutrients required in small amounts (vitamins, minerals for metabolic processes; do not directly provide energy.

  • Energy-Yielding Nutrients (Macronutrients, provide AT P):

  1. Carbohydrates: Primary immediate energy source.

  2. Fats (Lipids): Concentrated energy, cell membranes, hormones, vitamin absorption.

  3. Proteins: Can yield energy during starvation.

• Body-Building Nutrients (primarily for growth, repair, maintenance):

1. Proteins: Composed of amino acids; structural components (muscles, tissues), enzymes, hormones, antibodies.

4.5 Optimal Temperature and Pressure

  • Optimal Temperature Range: For human core body temperature, approximately 36.5°C to 37.5°C (97.7°F to 99.5°F).

  • Controlled Hypothermia (Therapeutic Hypothermia): Intentionally lowering core temperature (32°C to 36°C) to reduce metabolic rate and minimize tissue damage. Used after cardiac arrest, in neonatal hypoxic-ischemic encephalopath (HIE), severe traumatic brain/spinal cord injury, and during complex surgeries.

  • How it aids in medical treatment: Reduces oxygen and nutrient demand, particularly for the brain, and mitigates secondary injury after ischemia or traum

  • Atmospheric Pressure: Helps blood gas exchange by:

  1. Mechanical Ventilation (Breathing): Pressure differences (atmospheric vs. intrapulmonary) drive air into lungs during inhalation.

  2. Partial Pressures and Gas Exchange: Gradients in partial pressures of O2 anc
    CO2 (relative to atmospheric pressure) drive their diffusion between alveoli anc blood.

4.6 Environmental Interactions

  • Decompression Sickness (DCS): Condition where dissolved gases (e.g., nitroge form bubbles in blood/tissues due to rapid pressure reduction (e.g., fast ascent frc diving).

  • Acclimation: Reversible physiological adjustment of an organism to short-term changes in its immediate environment (days-weeks).

  • • Adaptation: Heritable genetic changes in a population over generations, making i better suited to its habitat; permanent evolutionary modification.

4.7 Homeostasis Feedback Loops

• Negative feedback: Primary mechanism for maintaining homeostasis. Counterac change, bringing conditions back to the set point. Response reduces the initial stimulus.

• Components: Receptor (detects change) Control center (processes, determine response) Effector (carries out response).

• Example: Regulation of body temperature. Rising temperature leads to sweating vasodilation, and cooling.

• Positive feedback: Intensifies or enhances the original stimulus, pushing the variable further from the set point. Used for rapid, amplifying changes, not direct homeostasis.

• Example: Childbirth (oxytocin release intensifies contractions until birth).

• Example: Blood clotting (platelets attract more platelets to rapidly form a plug).

5. Anatomical Terminology (Comprehensive)

5.1 Anatomical Position

• Standard frame of reference: Standing upright, feet flat, arms at sides, palms and face forward.

• All directional terms (superior/inferior, etc.) are defined relative to this position.

• Subject's left is on your right if facing you; always interpret relative to the body in anatomical position.

5.2 Planes, Sections, and Orientation

• Section: Actual cut to reveal internal anatomy.

• Plane: Imaginary flat surface through the body.

• Sagittal plane: Vertical, divides body into right and left portions.

• Median (midsagittal) plane: Divides body into equal right and left halves.

• Parasagittal planes: Parallel to median, divide into unequal portions.

• Frontal (coronal) plane: Vertical, perpendicular to sagittal; divides body into anterior (front) and posterior (back).

• Transverse (horizontal) plane: Perpendicular to long axis; divides body into superior (upper) and inferior (lower) portions (CT scans typically transverse).

5.3 Directional Terms

  • Primary Pairs:

  • Anterior (ventral) vs Posterior (dorsal): Front vs back (humans prefer anteric posterior).

  • Rostral vs Caudal: Toward the head vs toward the tail (often used for brain/spin cord).

  • Superior vs Inferior: Above vs below (relative to head/feet).

  • Medial vs Lateral: Toward midline vs away from midline.

  • Proximal vs Distal: Nearer to vs farther from limb attachment (shoulder/hip).

  • Ipsilateral vs Contralateral: Same side vs opposite side.

  • Superficial vs Deep: Near surface vs away from surface.

  • Intermediate Directions: Combinations (e.g., inferolateral).

  • Human vs. Animal Usage Nuance:

  • Anterior/Ventral and Posterior/Dorsal usage differs between bipeds (humans and quadrupeds. In humans, ventral aligns with anterior (front), dorsal with posterior (back). Many human anatomy texts minimize ventral/dorsal to avoid confusion.

5.4 Major Body Regions

  • Axial region: Head, neck, and trunk.

  • Trunk subdivision: Thoracic (above diaphragm) and Abdominal (below diaphragm).

  • Abdominal quadrants (intersecting at umbilicus): Right Upper Quadrant (RUQ)
    Right Lower Quadrant (RLQ), Left Upper Quadrant (LUQ), Left Lower Quadrant (LLQ).

  • Abdominal regions (nine-region scheme/tic-tac-toe grid):

  • Vertical lines: midclavicular lines.

  • Horizontal lines: subcostal line and intertubercular line.

  • Regions (top-to-bottom, left-to-right): Hypochondriac (R & L), Lumbar (R & L), Inguinal (R & L), Epigastric (top middle), Umbilical (center middle), Hypogastric (pubic; bottom middle).

  • • Appendicular region: Upper and lower limbs.

  • • Upper limb: Arm (brachial), forearm (antebrachial), wrist (carpal), hand (manus digits (fingers).

  • • Lower limb: Thigh (femoral), leg (crural), ankle (tarsal), foot (pedal), toes (digit:

  • • Segment concept: A limb segment lies between two joints (e.g., arm is shoulde elbow).

  • • Digit segmentation: Thumb has 2 segments; other digits have 3 segments.

6. Body Cavities and Serous Membranes

• Global Idea:

• Body cavities enclose organs and are lined by two-layered serous membranes (parietal layer lines cavity wall, visceral layer covers organ surface), producing lubricating serous fluid.

• Cranial cavity: Enclosed by cranium, contains brain. Lined by meninges.

• Vertebral canal: Enclosed by vertebral column, contains spinal cord. Lined by meninges.

• Thoracic cavity:

• Mediastinum: Central compartment between lungs; contains heart, major vesse esophagus, trachea, thymus.

• Pleural cavities: Two, each contains a lung. Lined by pleura (parietal and visce layers); contains pleural fluid.

• Pericardial cavity: Contains the heart. Lined by pericardium (parietal and visc layers); contains pericardial fluid.

• Clinical note: Cardiac tamponade (fluid in pericardial cavity) and pneumothorax pleural effusion (air/fluid in pleural cavity) can be life-threatening.

• Abdominopelvic cavity:

• Abdominal cavity: Contains most digestive organs, kidneys, ureters.

• Pelvic cavity: Inferior to pelvic brim; contains rectum, urinary bladder, reproductive organs.

• Peritoneum: Serous membrane lining abdominopelvic cavity parietal peritoneu and covering viscera (visceral peritoneum).

• Peritoneal cavity: Space between peritoneal layers, containing peritoneal fluid.

• Peritoneal relationships:

  • Intraperitoneal: Organs enveloped by peritoneum and suspended by mesenteri (e.g., stomach, small intestine).

  • Retroperitoneal: Organs behind peritoneum (e.g., kidneys, pancreas, aorta).

  • Mesentery: Double layer of peritoneum suspending viscera (e.g., mesocolon fol large intestine).

  • Greater omentum: Fatty apron-like fold from stomach, overlays intestines.

  • Lesser omentum: Fold from stomach to liver.

  • Clinical note: Peritonitis (inflammation of peritoneum) is serious.

  • Potential spaces: Spaces between membranes (e.g., pleural, peritoneal) that ci open under disease conditions.

7. Organ Systems (11 Total)

  • Integumentary system: Skin, hair, nails. Function: Protection, barrier, temperati regulation, sensation.

  • Skeletal system: Bones, cartilages, ligaments. Function: Support, protection, mineral storage, blood cell production, leverage for movement.

  • Muscular system: Muscles. Function: Motion, posture, heat production.

  • Nervous system: Brain, spinal cord, nerves. Function: Internal communication ar control (sensory input, motor output, rapid signaling).

  • Endocrine system: Glands (e.g., pituitary, thyroid, adrenal). Function: Regulatior via hormones, long-term homeostasis.

  • Circulatory (cardiovascular) system: Heart, blood vessels, blood. Function:
    Transport of nutrients, gases, wastes, hormones.

  • Lymphatic system: Lymph nodes, lymphatic vessels, spleen, thymus, tonsils.
    Function: Immune defense, fluid balance, transport of fats.

  • Digestive system: Oral cavity, esophagus, stomach, intestines, liver, pancreas.
    Function: Breakdown/absorption of nutrients; waste elimination.

  • Respiratory system: Nose, pharynx, larynx, trachea, bronchi, lungs. Function: G exchange (02/CO2) and acid-base balance.

  • Urinary system: Kidneys, ureters, urinary bladder, urethra. Function: Waste elimination, fluid/electrolyte balance, acid-base regulation.

  • Reproductive system: Male (testes, ducts, penis); Female (ovaries, oviducts, uterus, vagina). Function: Reproduction.

• Cross-system relationships: Some organs participate in multiple systems (e.g., pancreas in endocrine and digestive).

8. Medical Imaging

• X-rays:

• Discovered by: Wilhelm Conrad Röntgen in 1895.

• Function: Creates images of internal body structures (especially bones) by pas: electromagnetic radiation; denser tissues appear white.

• Computed Tomography (CT/CAT scans):

• When requested: For detailed images beyond X-rays, or for specific soft tissue complex bone structures. Useful for acute trauma, neurological conditions (stro! tumors), abdominal/pelvic conditions (appendicitis, kidney stones), cancer stagi vascular diseases, lung conditions, musculoskeletal issues, and guiding procedures.

• Magnetic Resonance Imaging (MRI):

• Definition: Uses a powerful magnetic field and radio waves (no ionizing radiatio to create detailed images of organs and soft tissues (brain, spinal cord, muscles ligaments, tendons); detects tumors, inflammation, vascular abnormalities.

• Positron Emission Tomography (PET):

• Definition: Uses radioactive tracers (radiotracers) to visualize and measure metabolic activity and physiological functions. Tracers emit positrons, which annihilate with electrons, producing gamma rays detected by scanners.

• Key uses: Oncology (cancer detection, staging, treatment monitoring), Neurolo!

(Alzheimer's, Parkinson's, epilepsy, brain tumors), Cardiology (myocardial perfusion, heart damage).

• Ultrasonography (Ultrasound):

• Definition: Uses high-frequency sound waves to create real-time images. Non-invasive, no ionizing radiation. Safe for pregnancies, soft tissues, fluid-filled structures, and blood flow (Doppler ultrasound). Widely used for abdominal, obstetric, cardiac, and musculoskeletal evaluations.