Homeostasis and Anatomical Terminology Notes

Homeostasis and Anatomical Terminology

• Anatomy vs Physiology

  • Anatomy: Describes the structures of the body and how the parts fit together.

  • Physiology: Describes the function of body parts and how they work.

• Interrelationship:

  • The structure of a body part affects its function, and vice versa.

  • Studying structures and functions together promotes better understanding.

Levels of Organization

• Cells and Organ Systems

  • The body operates as a complex structure where cells collaborate through organ systems necessary for survival.

• Requirements for Survival:

  • Nutrients, oxygen, water, normal body temperature, and normal atmospheric pressure must be maintained.

  • Imbalance in any of these factors can lead to health issues.

Homeostasis

• Definition: Condition of equilibrium maintained through regulation and feedback.

• Regulatory Mechanisms:

  • Nervous System: Utilizes fast nerve impulses for immediate responses.

  • Endocrine System: Employs hormones which can take longer to elicit effects.

• Internal Environment:

  • Homeostasis is crucial for cells to thrive in a rapidly changing external environment.

Feedback Systems

• Process Overview:

  • A receptor detects changes and sends signals to a control center.

  • The control center evaluates the input, determines a set point and coordinates a response via an effector.

  • The effector executes the response, which then influences the initial stimulus.

• Negative Feedback:

  • The response decreases or halts the original stimulus, preventing severe fluctuations in the body.

  • Most homeostatic controls use negative feedback.

  • Examples: Sweat and shiver responses that help regulate body temperature.

Positive Feedback

• Definition: Response enhances or magnifies the stimulus, leading to an amplifying effect.

• Usage: Typically for processes that require a definitive endpoint; not continuously regulated.

• Examples:

  • Childbirth labor and blood clotting rely on this mechanism.

Homeostatic Imbalance

• Impacts: Can occur when the control center fails to respond appropriately, leading to dysfunction and diseases.

• Effects of Aging: Many aging-related changes stem from increased homeostatic imbalance.

Anatomical Terminology

• Anatomical Position:

  • Standard body position used as a reference point.

  • The body is standing, feet slightly apart, palms facing forward, thumbs pointed away.

• Body Divisions:

  • Axial Division: Head and torso.

  • Appendicular Division: Limbs (arms and legs).

• Directional Terms:

  • Terms describe the position of structures related to one another.

  • Common Directional Terms:

    • Anterior (ventral): Toward the front.

    • Posterior (dorsal): Toward the back.

    • Superior (cranial): Toward the head.

    • Inferior (caudal): Away from the head.

    • Medial: Towards the midline.

    • Lateral: Away from the midline.

    • Proximal: Closer to the point of attachment.

    • Distal: Further from the point of attachment.

    • Superficial: Toward the body surface.

    • Deep: Away from the body surface.

Body Planes

• Sagittal Plane: Divides the body into left and right sections.

• Midsagittal Plane: Divides the body into equal left and right halves.

• Frontal (Coronal) Plane: Divides the body into anterior and posterior (front and back) sections.

• Transverse Plane: Divides the body into superior and inferior (top and bottom) sections.

Body Cavities

• Types of Body Cavities:

  • Dorsal Body Cavity: Comprises the cranial and vertebral cavities which protect the central nervous system.

  • Ventral Body Cavity: Includes thoracic and abdominopelvic cavities.

  • The thoracic cavity contains the pericardial and pleural cavities, while the abdominopelvic cavity is divided into the abdominal and pelvic cavities.

• Body Cavities and Organs: Protective membranes (serous membranes) line the body cavities and organs to reduce friction.

  • Parietal Serosa: Membrane lining the cavity.

  • Visceral Serosa: Membrane covering the organs.

Health Learning Outcomes

• After the lecture, students should be able to:

  • Define anatomy and physiology.

  • Define homeostasis and explain its significance.

  • Differentiate between negative and positive feedback.

  • Describe the connection between homeostatic imbalance and disease.

  • Use correct anatomical terminology for directions and regions.

  • Locate major body cavities and subdivisions, listing associated organs.

  • Identify the four quadrants of the abdominopelvic cavity and their contained organs.