Anatomy and Physiology Notes

Anatomy & Physiology

  • Anatomy: Study of body structure (Greek: "cutting up")
  • Physiology: Study of body function (Greek: "relationship to nature")
    • Key idea: Structure determines function.

Levels of Organization

  • Subatomic particles → Atoms → Molecules → Macromolecules → Organelles → Cells → Tissues → Organs → Organ Systems → Organism

Clinical Application 1.1 – Medical Imaging

  • Ultrasound
    • Uses high-frequency sound waves
    • Produces images of soft internal structures
    • Commonly used to create sonograms of a fetus in the uterus
  • Magnetic Resonance Scan (MR/MRI)
    • Uses magnetic fields to alter the alignment and spin of atoms
    • Produces high-resolution images
    • Especially useful for viewing brain and soft tissue structures

Key Concepts

  • The Cell:
    • All living things consist of cells.
  • Internal Environment:
    • Refers to the environment within the body (e.g. tissue fluid around cells).
  • Homeostasis:
    • Maintaining a stable internal environment despite external changes.
  • Interdependency of Cells:
    • Cells rely on one another to survive and function.
  • Structure and Function:
    • Structure determines what a part does — form = function.
  • Mechanisms and Processes
    • Gradients & Permeability:
      • Substances move from high to low concentration or pressure through permeable membranes.
    • Cellular Differentiation:
      • Cells become specialized due to gene expression.
    • Cell Membrane Mechanisms:
      • Control what enters/exits the cell and how it responds to signals.
    • Cell-to-Cell Communication:
      • Happens through membrane receptors that detect and respond to chemical signals.
    • Feedback Loops:
      • Help regulate internal conditions and maintain homeostasis.
    • Balance:
      • The body replaces what's lost and eliminates what's extra - a dynamic balance is always being maintained.
    • Energy Processes:
      • Drive all cellular activities and keep cells functioning.

Requirements of Organisms

  • Organisms require these environmental factors to live:
    • Food
      • Provides necessary nutrients
      • Supplies energy
    • Oxygen
      • Releases energy from food
    • Water
      • Most abundant substance in the body
      • Environment for metabolic processes (intracellular & extracellular fluids)
      • Required for transport of substances
      • Regulation of body temperature
    • Heat
      • Form of energy
      • Helps maintain body temperature
      • Partly controls rate of metabolic reactions

Homeostasis

  • Definition
    • The maintenance of a stable internal environment
  • Homeostatic Mechanisms
    • Self-regulating systems that monitor and correct the internal environment as needed.
    • 3 Main Parts:
      • Receptor - detects and provides information about a stimulus
      • Control Center - decision-maker; maintains the set point
      • Effector - muscle or gland that responds and causes change

Negative Feedback

  • Most common homeostatic mechanism
  • Effectors return conditions toward normal range
  • The response reverses the deviation from the set point
  • Prevents sudden or severe changes
  • Examples:
    • Body temperature
    • Blood pressure
    • Blood glucose levels

Positive Feedback

  • Uncommon in the body
  • The change or deviation is intensified (not reversed)
  • Effector activity increases initially
  • Typically short-lived
  • Produces unstable conditions at first, but leads to stability
  • Examples:
    • Blood clotting
    • Uterine contractions during childbirth

Organization of the Human Body

  • Main Body Portions
    • Axial portion: head, neck, trunk
    • Appendicular portion: upper and lower limbs
  • Major Body Cavities (Axial Portion)
    • Cranial cavity - brain
    • Vertebral canal (spinal cavity) – spinal cord
    • Thoracic cavity - lungs and thoracic organs
    • Abdominopelvic cavity - abdominal and pelvic organs
  • Cavity Dividers
    • Diaphragm - muscle dividing thoracic & abdominopelvic cavities
    • Mediastinum - region between lungs; contains heart, esophagus, trachea, thymus
  • Abdominopelvic Subdivisions
    • Abdominal cavity: stomach, liver, spleen, kidneys, small intestine, most of large intestine
    • Pelvic cavity: end of large intestine, urinary bladder, internal reproductive organs

Small Cavities of the Head

  • Oral cavity
  • Nasal cavity
  • Orbital cavities
  • Middle ear cavities

Thoracic & Abdominopelvic Membranes

  • Double-layered serous membranes line these cavities and secrete slippery serous fluid (reduces friction).
  • Each has:
    • Visceral layer – inner layer, covers organ
    • Parietal layer – outer layer, lines cavity wall
  • Examples:
    • Pleura - lungs
    • Pericardium - heart
    • Peritoneum - abdominopelvic organs

Body Covering, Support, & Movement

  • Integumentary System
    • Body covering
    • Protection
    • Body temperature regulation
    • Sensory reception
    • Production of Vitamin D
  • Skeletal System
    • Support and movement
    • Framework
    • Protection
    • Attachment sites
    • Storage of inorganic salts
    • Production of blood cells
  • Muscular System
    • Support and movement
    • Main source of body heat
    • Maintains posture

Integration & Coordination

  • Nervous System
    • Integration and coordination of organ function
    • Uses nerve impulses and neurotransmitters
    • Effects are rapid and short-term
  • Endocrine System
    • Integration and coordination of organ function
    • Uses chemical messengers called hormones
    • Effects are slower and longer-lasting

Transport

  • Cardiovascular System
    • Transports gases, nutrients, hormones, wastes, and blood cells
  • Lymphatic System
    • Transports fluid from tissues to blood
    • Carries fats from digestive system to blood
    • Defends body against infection

Absorption & Excretion

  • Digestive System
    • Receives food
    • Breaks down food
    • Absorbs digestion products
    • Excretes waste
  • Respiratory System
    • Moves air in and out of body
    • Exchanges gases (oxygen and carbon dioxide) between blood and air
  • Urinary System
    • Removes blood wastes
    • Regulates electrolytes, water balance, and blood pressure
    • Produces urine and transports it out of body

Reproduction

  • Reproductive System
    • Male & female systems produce and transport sex cells
    • Produce hormones
    • Female: supports fetal development and childbirth

Anatomical Terms

  • Anterior (Ventral) / Posterior (Dorsal)
    • Toward front / Toward back
  • Medial / Lateral
    • Toward midline / Away from midline
  • Bilateral
    • Paired structures on both sides
  • Ipsilateral / Contralateral
    • Same side / Opposite sides
  • Proximal / Distal
    • Closer to / Farther from trunk attachment

Sections of Cylindrical Organs

  • Used to describe how tubular body parts (like blood vessels or intestines) are sliced:
    • Cross Section
      • Cut across the structure (horizontal)
    • Oblique Section
      • Cut at an angle (diagonal)
    • Longitudinal Section
      • Cut lengthwise (vertical)

Sections of the Brain

  • Same body planes apply to the brain:
    • Mid-sagittal section: Divides brain into equal left and right halves
    • Transverse section: Divides brain into upper and lower parts
    • Coronal section: Divides brain into front and back parts