Anatomical Planes and Body Cavities

Anatomical Planes

• Midsagittal or Median Plane: Divides the body into equal left and right sections.
• Parasagittal Plane: Divides the body into unequal left and right sections.
• Frontal or Coronal Plane: Divides the body or an organ into an anterior (front) portion and a posterior (rear) portion.
• Transverse Plane: Divides the body or an organ horizontally into upper and lower portions, producing cross sections.

Body Cavities

• Dorsal Cavity: Located towards the back of the body, divided into:
  • Cranial Cavity: Holds the brain.
  • Vertebral or Spinal Cavity: Holds the spinal cord.
• Ventral Cavity: Located toward the front of the body, divided into:
  • Thoracic Cavity: Contains the heart and lungs.
  • Abdominopelvic Cavity: Divided into the abdominal and pelvic cavities.
    • Abdominal Cavity: Holds the liver, gallbladder, stomach, pancreas, spleen, kidneys, small and large intestines.
    • Pelvic Cavity: Holds the urinary bladder and reproductive organs.
• Coelom or Body Cavity: Fluid-filled space inside the body that protects internal organs and allows for changes in organ size and shape.

Serous Membranes

• Serous Membranes: Thin membranes covering the walls and organs in the thoracic and abdominopelvic cavities.
  • Parietal Membrane: Lines the body cavity.
  • Visceral Membrane: Covers the surface of the internal organs.
• Serous Fluid: Lubricating fluid between the parietal and visceral membranes, reducing friction and protecting the organs.

Meningeal Membranes

• Meninges: A thin and delicate membrane that envelops the brain and spinal cord.
• Cerebrospinal Fluid: Located between the arachnoid mater and the pia mater, it acts as a lubricant and cushion for the brain and spinal cord.

Organ Systems

• 11 Organ Systems: Integumentary, Skeletal, Muscular, Nervous, Endocrine, Digestive, Respiratory, Circulatory, Lymphatic, Urinary, and Reproductive Systems.
• Homeostasis Maintenance: The 10 organ systems besides the reproductive system are responsible for maintaining homeostasis.
• Organ System Functions:
  • Protection: Integumentary System.
  • Support & Movement: Skeletal and Muscular Systems.
  • Integration and Coordination: Nervous and Endocrine Systems.
  • Processing & Transport: Digestive, Respiratory, Circulatory, Lymphatic, and Urinary Systems.
  • Reproduction and Development: Reproductive system.

Medical Imaging

• Essential techniques for diagnosing diseases.

Homeostasis

• Negative Feedback Mechanism: Attempts to restore the variable to its normal value.
  • Stimulus: Disruption of homeostasis.
  • Receptor: Detects the change.
  • Control Center: Processes the information and determines the appropriate response.
  • Effector: Produces the response.
  • Response: Counteracts the original stimulus, restoring homeostasis.
• Positive Feedback Mechanism: Increases the disturbance and pushes the variable further from its original value.
  • Example: Childbirth, where oxytocin stimulates uterine contractions, pushing the baby towards the cervix.

Tissues

• Tissues: A group of similar cells with a common function, contributing to the function of the organ.

Bone Formation and Growth

• Intramembranous Ossification: Replacement of sheet-like connective tissue membranes with bone tissue.
  • Flat bones and some irregular bones develop through intramembranous ossification.
• Endochondral Ossification: Replacement of hyaline cartilage with bone tissue.
  • Most bones develop through endochondral ossification.

Skeletal System

• Adult Human Skeleton: Usually consists of 206 named bones.
• Axial Skeleton: Includes the bones of the head, vertebral column, ribs, and sternum (80 bones).
• Appendicular Skeleton: Includes the upper and lower limbs, and their attachments to the axial skeleton (126 bones).

Vertebral Bones

• Cervical Vertebrae (7): Includes the atlas (C1) and axis (C2).
• Thoracic Vertebrae (12): Connect to the ribs.
• Lumbar Vertebrae (5): Support the lower back.
• Sacrum (1): Composed of fused vertebrae, located at the base of the spine.
• Coccyx (1): Tailbone, formed from 3-5 fused vertebrae.

Thoracic Cage

• Xiphoid Process: Small, cartilaginous projection at the lower end of the sternum.
• Ribs: 12 pairs of ribs
  • True Ribs (1-7): Attach directly to the sternum.
  • False Ribs (8-10): Attach indirectly to the sternum.
  • Floating Ribs (11-12): Do not attach to the sternum.
• Intercostal Spaces: Spaces between the ribs.

Appendicular Skeleton

• Clavicle: Collarbone.
• Scapula: Shoulder blade.
• Head of Humerus: Upper end of the arm bone, connecting to the scapula.

Nervous System

• Functions: Monitoring changes (stimuli), interpreting sensory input, producing motor output, mental activity, and homeostasis.
• Components: Brain and spinal cord.
• Brain: weighs about 3.3 lbs. (1.5 kg), containing 86 billion neurons ("gray matter"), and billions of nerve fibers ("white matter").
• Brain Functions: Receives information through senses, assembles sensory information into meaningful messages, stores information in memory.