Module 1 Homeostasis Feedback and Terminology

Body Organisation and Homeostasis

Learning Objectives

• Name the organ systems and identify their major functions.

• Define homeostasis and explain its importance.

• Recognise features important in maintaining homeostasis (blood sugar control, body temperature).

• Outline negative feedback mechanisms and their characteristics.

• Recognise anatomical position for terminology references.

• Understand key anatomical terms for body regions and movements (flexion, extension, abduction, adduction).

• Locate and name major body cavities and subdivisions, identifying key organs and supporting body systems.

Health and Homeostasis

• Requirements for a Healthy Organism:

  • Maintain Boundaries: Separate internal from external environments.

  • Movement: Obtain food, breathe, protect from harm.

  • Responsiveness: Detect and respond to environmental changes.

  • Digestion: Break down food for absorption into the bloodstream.

  • Metabolism: Carry out chemical reactions for energy, growth, and processes.

  • Excretion: Remove wastes (gas, heat, liquids, solids).

  • Growth: Increase body size or size of a part.

  • Reproduction: Cell reproduction to form new cells or beings.

• Definition of Homeostasis:

  • The ability to maintain relatively stable internal conditions despite external changes.

  • Health is linked to the maintenance of homeostasis.

Hierarchy of Body Organisation

• Levels of Organisation:

  • Chemical: Basic building blocks (atoms, molecules).

  • Cellular: Cells as the fundamental unit of life.

  • Tissue: Groups of similar cells working together.

  • Organ: Structures composed of different tissues.

  • System: Groups of organs working together.

  • Organismic: The complete human organism.

• Human Anatomy (Structure) vs. Physiology (Function)

Organ Systems Overview

• Interdependency: No single body system functions independently; changes in one can impact others.

• Body Functions:

  • Structural Systems: Include skin, skeleton, and muscles, providing support and protection while enabling movement and heat production.

  • Control/Regulation Systems: Comprised of nervous and endocrine systems; crucial for responding to internal and external changes.

  • Transport Systems: Cardiovascular, lymphatic, and respiratory systems for nutrient delivery and waste transfer; respiratory system also facilitates gas exchange and immune protection.

  • Metabolic Systems: Urinary (waste removal) and digestive (nutrition and waste). These systems, alongside the respiratory system, are essential for metabolism.

  • Reproductive Systems: While not essential for individual survival, they ensure species survival via gamete production for reproduction.

Maintaining Life and Homeostasis

• The body systems work together to maintain essential life functions:

  • Maintain Boundaries

  • Movement

  • Responsiveness

  • Digestion

  • Metabolism

  • Excretion

  • Growth

  • Reproduction

• Homeostasis is dynamic, responding continually to environmental changes using set-points or limits, allowing for normal variations without needing an action to change the variable.

Control Mechanisms

• Control Mechanism Components:

  • Variable: The characteristic of interest that may change.

  • Stimulus: Change beyond normal value range.

  • Receptor: Detects the change.

  • Control Centre:

    1. Monitors signals for changes.

    2. Integrates information.

    3. Signals if a response is needed.

  • Effector: Implements actions to modify the stimulus size.

Feedback Mechanisms

• Negative Feedback:

  • Reduces stimulus size (e.g., warming the body when cold).

  • Can use multiple effectors (e.g., sweating, dilating blood vessels).

• Positive Feedback:

  • Rarely used; enhances the stimulus size.

Anatomical Position and Terminology

• Anatomical Position:

  • Standing at attention, palms facing forward, and feet slightly apart; serves as the standard reference.

  • Imaging methods (transverse, frontal, and longitudinal sections) assist in viewing the body.

Directional Terms

• Dependent Terms:

  • Superior/Inferior: Above/below (e.g., the head is superior to the neck).

  • Anterior/Posterior: Front/back (e.g., the heart is posterior to the ribs).

  • Medial/Lateral: Toward/away from midline (e.g., arm is lateral to the thorax).

• Absolute Terms:

  • Not dependent on anatomical position.

  • Cranial/Caudal: Toward head/tail.

  • Dorsal/Ventral: Back/belly side.

  • Proximal/Distal: Nearer/further to the trunk.

  • Superficial/Deep: Towards or away from the surface.

Regional Terminology

• Body Cavities:

  • Dorsal Cavity: Cranial & vertebral (brain and spinal cord).

  • Ventral Cavity: Thoracic & abdominopelvic (major organs found here).

Abdominopelvic Regions

• Understanding these regions helps develop a mental map of where organs are typically found in the body.

Joint Movement Terms

• Flexion: Bending a joint.

• Extension: Straightening a joint.

• Abduction: Movement away from midline.

• Adduction: Movement towards midline.

• Rotation: Circular movement around a joint's axis.

Specialised Movements

• Examples include movements specific to joints, e.g., mandible:

  • Depression: Opening the jaw (lower mandible).

  • Elevation: Closing jaw (raising mandible).

  • Protraction: Moving mandible forward.

  • Retraction: Moving mandible backward.