Chapter 1 Lecture 2

Hierarchy of Complexity of Living Organisms

• Levels:
  • Atom
  • Molecule
  • Organelle
  • Macromolecule
  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism

Levels of Organization

• Atoms form molecules.
• Molecules form organelles.
• Cells contain organelles.
• Cells form tissues.
• Tissues form organs.
• Organs form organ systems.
• An organism is composed of organ systems.

Chemical Level

• The basis for life.
• Organization of chemical structures distinguishes living from nonliving material.
• Organization of atoms, molecules, and macromolecules results in living matter called cytoplasm.
• Molecules relevant to life include proteins, fats, and DNA.

Organelle Level

• Chemical structures are organized into compartments (organelles) that perform individual functions.
• The function of organelles allows the cell to live.
• Examples of organelles:
  • Nucleus
  • Mitochondrion
  • Golgi apparatus
  • Endoplasmic reticulum

Cellular Level

• Cells are the smallest and most numerous units exhibiting life characteristics.
• Eukaryotic cells have a nucleus surrounded by cytoplasm within a limiting membrane.
• Cells differentiate to perform unique functions.

Cell Shapes and Functions

• Squamous: thin and flat
• Polygonal: irregularly angular with 4 or more sides
• Cuboidal: squarish
• Fibrous: threadlike
• Fusiform: thick in the middle, tapered at ends
• Stellate: starlike
• Columnar: taller than wide
• Spheroid: round
• Discoid: disc-shaped

Tissue Level

• Tissues are organizations of similar cells specialized to perform a certain function.
• Four major tissue types:
  • Epithelial
  • Connective
  • Muscle
  • Nervous

Organ Level

• Organization of different kinds of tissues to perform a special function.
• Organs are discrete and functionally complex operational units.
• Each organ has a unique size, shape, appearance, and placement in the body.

System Level

• Most complex organizational units of the body.
• Involves varying numbers and kinds of organs arranged to perform complex functions:
  • Support and movement
  • Communication, control, and integration
  • Transportation and defense
  • Respiration, nutrition, and excretion
  • Reproduction and development

Organismal Level

• The living human organism is greater than the sum of its parts.
• All components interact to allow the human to survive and flourish.

Functional Categories and Systems

• Support and Movement:
  • Integumentary System:
    • Principal Organ: Skin
    • Primary Functions: Protection, temperature regulation, sensation
  • Skeletal System:
    • Principal Organs: Bones, ligaments
    • Primary Functions: Support, protection, movement, mineral and fat storage, blood production
  • Muscular System:
    • Principal Organs: Skeletal muscles, tendons, smooth muscles
    • Primary Functions: Movement, posture, heat production
• Communication, Control, and Integration:
  • Nervous System:
    • Principal Organs: Brain, spinal cord, nerves, sensory organs
    • Primary Functions: Control, regulation, and coordination of other systems, sensation, memory
  • Endocrine System:
    • Principal Organs: Pituitary gland, adrenals, pancreas, thyroid, parathyroids, and other glands
    • Primary Functions: Control and regulation of other systems
• Transportation and Defense:
  • Cardiovascular System:
    • Principal Organs: Heart, arteries, veins, capillaries
    • Primary Functions: Exchange and transport of materials
  • Lymphatic System:
    • Principal Organs: Lymph nodes, lymphatic vessels, spleen, thymus, tonsils
    • Primary Functions: Immunity, fluid balance
• Respiration, Nutrition, and Excretion:
  • Respiratory System:
    • Principal Organs: Lungs, bronchial tree, trachea, larynx, nasal cavity
    • Primary Functions: Gas exchange, acid-base balance
  • Digestive System:
    • Principal Organs: Stomach, small and large intestines, esophagus, liver, mouth, pancreas
    • Primary Functions: Breakdown and absorption of nutrients, elimination of waste
  • Urinary System:
    • Principal Organs: Kidneys, ureters, bladder, urethra
    • Primary Functions: Excretion of waste, fluid and electrolyte balance, acid-base balance
• Reproduction and Development:
  • Reproductive System:
    • Principal Organs: Male: Testes, vas deferens, prostate, seminal vesicles, penis; Female: Ovaries, fallopian tubes, uterus, vagina, breasts
    • Primary Functions: Reproduction, continuity of genetic information, nurturing of offspring