MA

Chapter1a (1)

The Human Body: An Orientation

Overview of Anatomy and Physiology

  • Anatomy: The study of structure.

    • Subdivisions:

      • Gross or Macroscopic Anatomy:

        • Regional anatomy

        • Surface anatomy

        • Systemic anatomy

      • Microscopic Anatomy:

        • Cytology (study of cells)

        • Histology (study of tissues)

      • Developmental Anatomy:

        • Embryology (developmental changes from conception to birth)

Essential Tools for the Study of Anatomy

  • Mastery of anatomical terminology is crucial for effective communication.

  • Observation to identify structures.

  • Manipulation of structures to understand their functioning.

  • Palpation: Using hands to feel structures and their characteristics.

  • Auscultation: Listening to the sounds made by internal organs.

Physiology

  • Physiology: The study of function at various levels.

    • Subdivisions: Based on organ systems like renal physiology and cardiovascular physiology.

Essential Tools for the Study of Physiology

  • Ability to focus on many levels from systemic level to cellular and molecular levels.

  • Basic physical principles: Important concepts include electrical currents, pressure, and movement.

  • Basic chemical principles: Understanding chemical reactions that underpin physiological processes.

Principle of Complementarity

  • Anatomy and physiology are inseparable; structure and function are correlated.

    • Function reflects structure: What a structure can do is dependent on its specific form.

    • The phrase "Form follows function" encapsulates this relationship.

Levels of Structural Organization

  • Atoms: Basic units that combine to form molecules.

  • Molecules: Combine to form organelles.

  • Cellular Level: Cells are made up of molecules.

  • Tissue Level: Tissues consist of similar types of cells.

  • Organ Level: Organs are made up of different types of tissues.

  • Organ System Level: Organ systems consist of different organs that work together closely.

  • Organismal Level: The human organism comprises many organ systems.

Organ Systems of the Body

  1. Integumentary System:

    • Components: Skin, nails, hair.

    • Functions: Protects deeper tissues, synthesizes vitamin D, houses sensory receptors and glands.

  2. Skeletal System:

    • Components: Bones, joints.

    • Functions: Protects and supports organs, framework for muscles, blood cell formation, mineral storage.

  3. Muscular System:

    • Components: Skeletal muscles.

    • Functions: Manipulation of environment, locomotion, facial expression, posture, heat production.

  4. Nervous System:

    • Components: Brain, nerves, spinal cord.

    • Functions: Fast-acting control system, responds to changes.

  5. Endocrine System:

    • Components: Glands (e.g., pineal, pituitary, thyroid).

    • Functions: Secretes hormones, regulates growth, metabolism, and reproduction.

  6. Cardiovascular System:

    • Components: Heart, blood vessels.

    • Functions: Transports blood, carries oxygen and nutrients, removes wastes.

  7. Lymphatic/Immune System:

    • Components: Lymphatic vessels, thymus, spleen.

    • Functions: Returns fluid to blood, disposes of debris, mounts immune responses.

  8. Respiratory System:

    • Components: Nasal cavity, bronchus, lungs.

    • Functions: Supplies blood with oxygen, removes carbon dioxide.

  9. Digestive System:

    • Components: Mouth, esophagus, stomach, intestines.

    • Functions: Breaks down food, absorbs nutrients, eliminates waste.

  10. Urinary System:

    • Components: Kidneys, ureters, bladder.

    • Functions: Eliminates wastes, regulates water and electrolyte balance.

  11. Reproductive System:

    • Components: Testes, ovaries.

    • Functions: Produces offspring, males produce sperm and hormones, females produce eggs.

Organ Systems Interrelationships

  • All 11 organ systems are interrelated, working cooperatively to sustain life.

  • Cells rely on organ systems to meet survival needs.

Necessary Life Functions

  1. Maintaining boundaries: Between internal and external environments (e.g., skin).

  2. Movement: Of body parts (skeletal muscles) and substances (smooth and cardiac muscles).

  3. Responsiveness: Ability to sense and respond to stimuli.

  4. Digestion: Breakdown and absorption of food.

  5. Metabolism: All chemical reactions (catabolism and anabolism).

  6. Excretion: Removal of wastes.

  7. Reproduction: Cellular division for growth/repair, production of offspring.

  8. Growth: Increase in size of a body part or the organism.

Survival Needs

  1. Nutrients: Necessary for energy and cell building (carbohydrates, fats, proteins).

  2. Oxygen: Essential for ATP production.

  3. Water: Most abundant chemical, site for chemical reactions.

  4. Normal body temperature: Impacts metabolic reactions.

  5. Atmospheric pressure: Necessary for breathing and gas exchange.

Homeostasis

  • Definition: Maintenance of a stable internal environment despite external changes.

  • Dynamic state of equilibrium: Continuous adjustments maintain stability.

Homeostatic Control Mechanisms

  • Continuous monitoring and regulation of variables through nervous and endocrine systems.

Components of a Control Mechanism

  1. Receptor (sensor): Monitors environment, responds to stimuli.

  2. Control Center: Determines set point, receives input from receptors, decides response.

  3. Effector: Receives output to produce a response, which acts to reduce/enhance the stimulus.

Negative Feedback

  • The response reduces or shuts off the original stimulus.

    • Examples:

      • Body temperature regulation (thermoregulation).

      • Blood volume regulation by antidiuretic hormone (ADH).

Positive Feedback

  • The response enhances or exaggerates the original stimulus.

    • Examples:

      • Labor contractions regulated by oxytocin.

      • Blood clotting by platelets.

Homeostatic Imbalance

  • Imbalance or disturbance in homeostasis can result in disease and/or death.