Human Body Systems Overview

Cardiovascular System

• Transports: nutrients, waste products, gases, and hormones throughout the body.
• Plays a critical role in the immune response and thermoregulation.

Lymphatic System

• Consists of lymph vessels, lymph nodes, and lymph.
• Functions:
  • Removes foreign substances from blood and lymph.
  • Contributes to disease fighting.
  • Maintains tissue fluid balance.
  • Absorbs and transports fatty acids and fats to the circulatory system.

Respiratory System

• Includes the lungs and respiratory passages.
• Functions:
  • Exchanges gases between blood and air.
  • Helps regulate blood pH.

Digestive System

• Consists of the mouth, esophagus, stomach, intestines, liver, and pancreas.
• Functions:
  • Mechanical and chemical digestion.
  • Absorption of nutrients.
  • Elimination of waste.

Urinary System

• Includes the kidneys, urinary bladder, ureters, and urethra.
• Functions:
  • Removes waste products from the circulatory system.
  • Helps regulate blood pH, ion balance, and water balance.

Reproductive System

• Includes gonads, accessory structures, and genitals of both sexes.
• Functions:
  • Performs the processes of reproduction.
  • Controls sexual functions and behaviors.

Basic Life Processes

• Characteristics that distinguish living organisms from non-living matter.
• Organization: Parts of an organism have specific relationships and interact to perform specific functions.
• Metabolism: All chemical reactions occurring in the body.
  • Catabolism: Complex substances are broken down into simpler building blocks.
  • Anabolism: Complex substances are synthesized from simpler ones.

Anatomy Defined

• Derived from Greek words meaning "cutting up."
• Involves dissection to study the internal and external structures of the body.
• Covers the development, microscopic organization, and relationships between body parts.
• Focuses on the interrelation between structure and function.

Subdivisions of Anatomy

• Gross (Macroscopic) Anatomy: Study of large structures visible through dissection.
  • Microscopic Anatomy: Study of smaller structures and fine details requiring a microscope.
    • Histology: Study of tissues.
    • Cytology: Study of cells.
• Embryology: Study of structures from fertilized egg to the eighth week in utero.
• Comparative Anatomy: Comparison of anatomical structures in different animals.
• Surface Anatomy (Superficial Anatomy): Description of anatomical features visible without dissection.
  • Includes the form and proportion of the human body, and surface landmarks corresponding to deeper structures.
• Systemic Anatomy: Study of organ systems.
• Regional Anatomy: Study of specific body regions.
  • Emphasizes the relationship between structures in a particular region.
• Radiographic Anatomy: Study of tissue or organ anatomy based on X-ray visualizations.

Organ System Level

• An organ system is a group of organs working together for a specific function.
• Examples include: Nervous, digestive, and respiratory systems.

Organismal/Organismic/Organism Level

• The highest and most complex level of organization encompassing all organ systems.
• All systems work together to sustain life, forming a complete, functioning organism.

Integumentary System

• Consists of skin and accessory organs (hair, nails, sweat, and sebaceous glands).
• Functions:
  • Covers, cushions, and protects underlying tissues.
  • Protects against water loss.
  • Perceives stimuli through sense receptors.
  • Helps regulate body temperature.
  • Synthesizes chemicals (e.g., vitamin D precursors).

Skeletal System

• Includes bones, cartilages, ligaments, and joints.
• Functions:
  • Provides the body's framework.
  • Offers support and protection.
  • Provides attachments for muscles and ligaments, allowing movement.
  • Produces blood cells and stores minerals.

Muscular System

• Consists of muscles.
• Functions:
  • Produces body movements and maintains posture.
  • Produces body heat.

Nervous System

• Consists of the brain, spinal cord, nerves, and sensory receptors.
• Functions:
  • Major regulatory system: detects sensations.
  • Controls movement and physiological and intellectual functions.
  • Coordinates body activities.
  • Receives and transmits stimuli.

Endocrine System

• Consists of endocrine glands and their hormones.
• Functions:
  • Major regulatory system: participates in metabolism, reproduction, and other body functions.

Homeostasis

• The maintenance of a relatively stable internal environment despite external changes.
• Requires continuous adjustments and is essential for life.

Feedback Systems

• Control mechanisms that involve three basic components:
  • Receptor: Monitors changes in the controlled condition and sends input to the control center.
  • Control Center: Sets the range for the controlled condition, evaluates input, and generates output commands.
  • Effector: Receives output from the control center and produces a response that changes the controlled condition.

Negative Feedback System

• Reverses a change in a controlled condition, returning it to its normal state.
• Most homeostatic mechanisms are negative feedback systems.
• Regulates conditions that are fairly stable over long periods (e.g., blood pressure, blood glucose level, and body temperature).

Directional Terms

• Used to describe the relative position of body parts.
  • Superior: Toward the head or upper part of a structure.
  • Inferior: Away from the head or lower part of a structure.
  • Anterior: Toward the front of the body.
  • Posterior: Toward the back of the body.
  • Medial: Toward the middle or midline of the body.
  • Lateral: Away from the midline of the body.
  • Proximal: Nearer to the origin of a structure (e.g., the shoulder is proximal to the wrist).
  • Distal: Farther from the origin of a structure (e.g., the wrist is distal to the shoulder).
  • Superficial: Toward or on the surface of the body.
  • Deep: Away from the surface of the body.

Planes and Sections

• Imaginary flat surfaces used to divide the body or an organ for visualization.
  • Sagittal Plane: Vertical plane dividing the body into right and left sides.
    • Midsagittal/Median Plane: Divides the body into equal right and left halves.
  • Transverse/Cross-sectional/Horizontal Plane: Parallel to the surface, dividing the body into superior and inferior parts.
  • Frontal or Coronal Plane: Vertical, divides the body into anterior and posterior parts.
  • Oblique Plane: Passes through the body at an angle between the transverse plane and either a sagittal or frontal plane.