Anatomy & Physiology: Foundational Concepts, Organ Systems, and Cellular Structure

Getting Started: Scientific Method and Measurement

Scientific Method

The scientific method is a systematic approach used in scientific investigation to ensure objectivity and reproducibility.

• Observation: Careful focus on the subject of study.

• Hypothesis: A proposed explanation based on observations, facts, or prior knowledge.

• Data Collection:

  • Qualitative observation: Descriptive data using senses.

  • Quantitative observation: Numerical data using scientific equipment (e.g., density, mass).

  • Experiments: Procedures to test cause-effect relationships under controlled conditions.

  • Variables:

    • Independent variable: Factor changed by the experimenter.

    • Dependent variable: Factor that changes in response to the independent variable.

    • Control: Sample/system under normal conditions for comparison.

• Manipulation and Analysis:

  • Range: Highest value - lowest value

  • Average (mean): Sum of items divided by number of items

  • Percent: Expressed to two decimal places (e.g., 25% = 0.25)

• Graphs: X-axis = independent variable; Y-axis = dependent variable

• Curve: Line connecting data points on a graph

• Reporting Conclusion:

  • Theory: Hypothesis validated many times

  • Biological Principle: Widely verified and used theory

Metrics and Measurement

The metric system is a decimal-based, non-varying system of measurement.

• Length:

  • Meter (m): Base unit

  • Centimeter (cm): 1/100 meter

  • Millimeter (mm): 1/1000 meter

  • Micrometer (μm): 1/1,000,000 meter

• Volume:

  • Liter (L): Base unit

  • Milliliter (mL): 1/1000 liter

• Mass:

  • Gram (g): Base unit

  • Weight: Force due to gravity acting on mass

Temperature Measurements

• To find Celsius: $^\circ F = ( ^\circ C \times \frac{9}{5}) + 32$

• To find Fahrenheit: $^\circ C = ( ^\circ F - 32 ) \times \frac{5}{9}$

Organ Systems

Overview of Organ Systems

An organ system is a group of organs working together to perform specific functions. There are 12 major organ systems in the human body.

• Integumentary System: Skin, hair, nails; protection, excretion, body temperature regulation.

• Skeletal System: Bones, ligaments, tendons, joints; support, protection, movement, blood cell formation.

• Muscular System: Muscles; movement, heat production.

• Nervous System: Brain, spinal cord, nerves; body homeostasis, communication.

• Endocrine System: Glands; hormone production, regulation of body processes.

• Lymphatic System: Lymph, lymphatic vessels, white blood cells; immunity, fluid balance.

• Cardiovascular System: Heart, blood, blood vessels; transport of oxygen, nutrients, waste.

• Respiratory System: Nasal cavity, trachea, lungs; oxygen intake, carbon dioxide removal.

• Digestive System: Stomach, intestines, etc.; ingestion, digestion, absorption, excretion.

• Urinary System: Bladder, kidneys, ureters, urethra; excretion of nitrogenous wastes.

• Reproductive System: Genitals; perpetuation of the species.

Key Structures to Know

• Thymus

• Heart

• Lungs

• Trachea

• Esophagus

• Primary bronchi

• Diaphragm

• Stomach

• Pancreas

• Small intestine

• Cecum

• Large intestine

• Rectum

• Anus

• Spleen

• Liver

• Kidneys

• Ureter

• Urinary bladder

• Inferior and superior vena cava

• Descending aorta

• Vagina

• Urethra

• Uterine tube

• Vas/Ductus deferens

• Prostate gland

• Testes

• Vermiform appendix

Exercise #1: The Language of Anatomy

Anatomical Position

The anatomical position is the standard reference posture: standing upright, arms at sides, palms facing forward.

Surface Body Landmarks

• Abdominal: Anterior body trunk inferior to ribs

• Brachial: Arm

• Carpal: Wrist

• Cervical: Neck

• Digital: Fingers

• Femoral: Thigh

• Inguinal: Groin

• Mammary: Breast

• Nasal: Nose

• Oral: Mouth

• Orbital: Eye

• Patellar: Knee cap

• Pelvic: Pelvis

• Pubic: Genital

• Thoracic: Chest

• Cephalic: Head

• Dorsum: Back

• Lumbar: Lower back

• Popliteal: Back of knee

• Sacral: Tail bone

• Scapular: Shoulder blade

• Vertebral: Spinal cord

Body Orientation

• Superior/Inferior: Above/below

• Anterior/Posterior: Front/back

• Medial/Lateral: Toward/away from midline

• Cephalad/Caudal: Head/tail (in four-legged animals)

• Dorsal/Ventral: Back/belly side

• Proximal/Distal: Closer/further from trunk

• Superficial/Deep: Surface/internal

Body Planes and Sections

• Sagittal (Longitudinal) Plane: Divides body into right and left

• Frontal Plane: Divides body into anterior and posterior

• Transverse (Cross) Plane: Divides body into superior and inferior

Body Cavities

• Dorsal Body Cavity: Cranial (brain) and spinal (spinal cord)

• Ventral Body Cavity: Thoracic (heart, lungs) and abdominopelvic (digestive organs, pelvic organs)

Abdominal Quadrants and Regions

• Quadrants:

  • Right Upper Quadrant (RUQ)

  • Left Upper Quadrant (LUQ)

  • Right Lower Quadrant (RLQ)

  • Left Lower Quadrant (LLQ)

• Regions:

  • Right Hypochondriac, Epigastric, Left Hypochondriac

  • Right Lumbar, Umbilical, Left Lumbar

  • Right Iliac, Hypogastric, Left Iliac

Other Body Cavities

• Oral Cavity: Mouth, teeth

• Nasal Cavity: Respiratory system

• Orbital Cavity: Eyes

• Middle Ear Cavity: Sound transmission

• Synovial Cavity: Freely moving joints (e.g., knee)

Serous Membranes of the Ventral Cavity

• Serosa: Double-layered membrane covering body cavities and organs

• Parietal Layer: Adheres to cavity walls

• Visceral Layer: Adheres to organs

• Examples: Peritoneum (abdomen), Pleura (lungs), Pericardium (heart)

Mucous Membranes

• Composed of epithelial cells on loose connective tissue

• Line body cavities open to exterior (e.g., digestive, respiratory, urinary tracts)

• Secrete mucus (except urinary tract)

Exercise #3: The Microscope

Compound Microscope

The compound microscope is used to magnify small specimens using multiple lenses.

• Base: Support

• Sub-stage light: Source of light

• Stage: Platform for specimen

• Condenser: Concentrates light on specimen

• Iris diaphragm lever: Regulates light amount

• Coarse adjustment knob: Focus on specimen

• Fine adjustment knob: Precise focusing

• Head: Holds ocular lens

• Arm: Vertical support

• Ocular: Eyepiece, usually 10x magnification

• Objective lenses: Low (4x), high (45x), oil immersion (100x)

Stereo/Dissecting Microscope

• Used for viewing objects too large for compound microscope

• Resolution: Ability to distinguish two close objects as separate

• Compound microscope: 2 μm resolution; human eye: 100 μm

Microscopic Field and Depth of Field

• Microscopic field: Distance seen at various magnifications (decreases at higher magnification)

• Equation for changing microscopic fields: $\text{Size in mm of field at smallest magnification} \times \left( \frac{\text{Total magnification of smallest magnification}}{\text{Total magnification of desired field}} \right)$

• Depth of field: Depth at which specimen is clearly in focus

Exercise #4: The Cell

Cell Structure

The cell is the basic structural and functional unit of all living things. It maintains boundaries and performs metabolic functions.

• Nucleus: Contains genetic material (DNA), controls cell activities

• Plasma Membrane: Boundary between inside and outside; phospholipid bilayer with embedded proteins

• Cytoplasm: Contains organelles and cytosol

Organelles

• Ribosome: Site of protein synthesis

• Endoplasmic Reticulum (ER): Tubular system for transport; rough ER (with ribosomes), smooth ER (lipid synthesis)

• Golgi Apparatus: Modifies and packages proteins

• Lysosome: Contains digestive enzymes

• Peroxisome: Contains peroxides, detoxifies substances

• Mitochondria: Site of ATP production

Cytoskeletal Elements

• Microtubules: Part of spindle

• Intermediate Filaments: Resist mechanical forces

• Microfilaments: Cell movement, membrane stability

• Centrioles: Direct formation of spindle, basis for cilia/flagella

Cell Division

• Mitosis: Nuclear division

• Cytokinesis: Cytoplasmic division

• Both produce two identical daughter cells

Phases of Mitosis

• Prophase: Chromatin condenses into chromosomes

• Metaphase: Chromosomes align at cell equator

• Anaphase: Chromatids separate

• Telophase: Chromosomes diffuse, nucleus reforms, cytokinesis ends

Cytokinesis is the end of cell division, resulting in two daughter cells.