Orientation to the Body

Orientation To The Body

  • Understanding the basic concepts of human biology is critical for further study.

Human Function

  • Characteristics of Life:
    • Homeostasis: Maintaining a stable internal environment despite external changes.
    • Cellular Composition: Organisms are made of one or more cells.
    • Metabolism: The sum of all chemical reactions that occur in the body, using and converting energy.
    • Responsiveness to Environment: Ability to react to changes in the internal or external environment.
    • Development: Growth and differentiation of organisms over time.
    • Reproduction: The ability to produce new organisms.
    • Evolution: Change in species over time through inherited traits.

Anatomy

  • Definition: The study of the structure and shape of the body and its parts.
  • Key Structures:
    • Cerebrum: Largest part of the brain involved in higher cognitive functions.
    • Parietal Lobe: Processes sensory information.
    • Basal Ganglia: Involved in movement regulation.
    • Temporal Lobe: Involved in auditory processing and memory.
    • Corpus Collosum: Connects the left and right hemispheres of the brain.
    • Frontal Lobe: Responsible for decision making, problem-solving, and planning.
    • Thalamus: Relays sensory information to the cerebral cortex.
    • Hypothalamus: Controls body temperature, hunger, and thirst.
    • Pituitary Gland: Master gland of the endocrine system.
    • Amygdala: Involved in emotion regulation.
    • Pons: Connects different parts of the brain and regulates sleep.
    • Hippocampus: Crucial for memory formation.
    • Medulla Oblongata: Controls autonomic functions such as heart rate and respiration.
    • Occipital Lobe: Responsible for visual processing.
    • Cerebellum: Coordinates and regulates muscular activity.
    • Spinal Cord: Transmits signals between the brain and the body.

Physiology

  • Definition: The study of the function of the body and its parts.
  • Example of a physiological process:
    • Sodium Potassium Exchange: Movement of sodium (Na+) and potassium (K+) ions across cell membranes maintaining cellular function.

Levels of Organization of the Body

  • A. Chemicals: Atoms combine to form molecules.
  • B. Cells: Molecules combine to form the basic unit of life.
  • C. Tissues: Groups of similar cells performing a common function.
  • D. Organs: Structures composed of two or more tissue types, performing specific functions.
  • E. Organ Systems: Groups of organs working together to accomplish a common purpose.
  • F. Full Organism: An individual living being made up of various organ systems.
    • Example: Human organisms consist of various organ systems such as muscular and skeletal systems.

Organ Systems

  • Integumentary: Skin and its accessory structures (hair, nails, sweat glands).
  • Skeletal: Bones, cartilage, ligaments, and joints.
  • Muscular: Muscles and tendons.
  • Nervous: Brain, spinal cord, nerves, and sensory receptors.

Integumentary System

  • Components: Skin, hair, nails, sweat glands, oil glands.
  • Functions:
    • Acts as a waterproof barrier preventing dehydration.
    • Cushions and protects internal organs.
    • Regulates body temperature via fat insulation and mechanisms like shivering and blood flow alterations.
    • Synthesizes Vitamin D upon UV exposure.
    • Engages in self-healing and sensory detection.
    • Facilitates communication through skin receptors.

Skeletal System

  • Components: Bone, cartilage, ligaments, and joints.
  • Functions:
    • Provides support and protection for organs.
    • Serves as a framework for bodily movement.
    • Maintains pH balance in the body.
    • Facilitates hematopoiesis (blood cell formation).
    • Stores minerals.

Muscular System

  • Components: Muscles and tendons.
  • Functions:
    • Contraction and shortening of muscles result in movement.
    • Regulation of body temperature.
    • Provides protection to internal structures.

Nervous System

  • Components: Brain, spinal cord, nerves, and sensory receptors.
  • Functions:
    • Acts as a fast-acting control system coordinating body activities through electrochemical messages.
    • Processes sensory input and facilitates reaction through integration and motor output.

Anatomical Position

  • Definition: Body is erect, feet parallel, arms hanging at the sides, with palms facing forward.

Directional Terms

  • Superior (Cranial/Cephalic): Toward the head or upper part; above.
  • Inferior (Caudal): Away from the head; towards the lower part; below.
  • Anterior (Ventral): Toward the front of the body.
  • Posterior (Dorsal): Toward the back side of the body.
  • Medial: Toward the midline of the body.
  • Lateral: Away from the midline.
  • Proximal: Closer to the origin or point of attachment.
  • Distal: Farther from the origin or point of attachment.
  • Superficial: Toward the surface of the body.
  • Deep: Away from the body surface.

Practice Questions

  • Exercise for applying directional terms:
    • The knee is to the ankle.
    • The thumbs are ___ to the palms.
    • The heart is to the lungs.
    • The eyes are _ to the mouth.
    • The toes are to the ankle.
    • The frontal bone is to the brain.
    • The ribs are ___ to the lungs.
    • The muscles are __ to the skin.

Regional Terms

  • Anterior (Ventral):
    • Axillary: Armpit
    • Acromial: Tip of shoulder
    • Brachial: Arm
    • Carpal: Wrist
    • Cervical: Neck
    • Digital: Fingers or toes
    • Femoral: Thigh
    • Frontal: Forehead
    • Orbital: Eye area
    • Patellar: Kneecap
    • Tarsal: Ankle
    • Thoracic: Chest/Rib cage
    • Pectoral: Breast
  • Posterior (Dorsal):
    • Dorsal: Back
    • Plantar: Sole of foot
    • Deltoid: Shoulder
    • Gluteal: Buttock
    • Lumbar: Lower back (between ribs and hips)
    • Occipital: Back of head

Body Plans and Sections

  • Sagittal: Divides the body into right and left parts.
  • Transverse: Divides the body into superior and inferior parts.
  • Frontal (Coronal): Divides the body into anterior and posterior parts.
  • Types of sections demonstrated:
    • (a) Midsagittal (median)
    • (b) Frontal (coronal) plane
    • (c) Transverse plane

Homeostasis

  • Definition: The ability to maintain a constant internal environment in response to environmental changes.
    • Dynamic Equilibrium: A state where internal conditions fluctuate but remain within a narrow range.
  • Homeostasis Maintenance: Achieved through negative feedback mechanisms that counteract deviations from set points.
  • Homeostatic Control Mechanisms:
    • Receptor (Sensor): Detects changes in the internal environment.
    • Sensory Pathway: Transmits information to the control center.
    • Control/Integration Center: Often the brain or spinal cord, determines the necessary response.
    • Motor Pathway: Conducts commands from the control center to effectors.
    • Effector (Response): Carries out responses that restore balance.

Example of Negative Feedback Mechanism

  • Blood Pressure Regulation:
    • Carotid bodies (receptors) detect high blood pressure.
    • Sensory nerves communicate this information to the brain.
    • The cardio regulatory center in the brain commands the heart to decrease its rate, reducing blood pressure.
    • Practical example: Choke Hold which can elevate pressure and stimulate this feedback mechanism effectively.