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.