Anatomy and Physiology: Chapter 2 - Cells and Tissues

Body Organization

• Levels: Atom → Cells → Tissues → Organs → Systems → Organism

Cells

• Complexity: Control center, transportation system, power plants, factories, packaging plants
• Microscopy:
  • Light Microscope (LM): Uses visible light
  • Electron Microscope (EM): Studies ultra-structure
• Composition: Water, protein, sugar, fats, minerals
• Major Parts of a Cell:
  • Cell Membrane:
    • Surrounds the cell; a plasma membrane regulating entry/exit
    • Bilayer of phospholipids with embedded proteins
  • Nucleus:
    • Control center, surrounded by nuclear envelope
    • Nucleus pore: Allows passage of materials
  • Chromosomes:
    • Chromatin condenses to form chromosomes
    • Human body cells: 23 pairs of chromosomes (46 total)
    • Sex cells: Egg and sperm have 23 chromosomes each
  • Gene and DNA:
    • Genes contain DNA, which regulates cell activities
    • Human Genome Project mapped ~30,000 genes
  • Karyotype:
    • Photograph of chromosomes, used to identify abnormalities
    • Example: Down syndrome (Trisomy 21)
  • Nucleolus:
    • Assembles ribosomes
  • Endoplasmic Reticulum (ER):
    • Rough ER: Contains ribosomes, manufactures proteins
    • Smooth ER: Synthesizes lipids, detoxifies in liver cells
  • Golgi Apparatus:
    • Processes and packages proteins
  • Lysosomes:
    • Contain enzymes to destroy bacteria and breakdown organelles
  • Mitochondria:
    • Power plant, involved in cellular respiration
    • Produces ATP, affects health, aging, apoptosis
  • Vesicles and Vacuoles:
    • Transport materials within the cell
  • Cytoskeleton:
    • Provides structural support, aids in transport and cell division

Cell Membrane Permeability

• Processes:
  • Diffusion: Movement from high to low concentration
  • Osmosis: Diffusion of water through a permeable membrane
  • Filtration: Passage by mechanical pressure (e.g., blood plasma)
  • Active Transport: Moves materials against concentration gradients using ATP
    • Examples: Sodium-potassium pumps, Phagocytosis, Pinocytosis

Cell Communication

• Signaling Steps:
  1. Cell sends signal (e.g., hormone)
  2. Reception: Receptors bind with signal
  3. Signal Transduction: Converts external signal to internal
  4. Response: Alters cell activity

Cell Division

• Mitosis Stages:
  • Prophase: Chromosomes visible, nuclear membrane dissolves
  • Metaphase: Chromosomes align at the cell equator
  • Anaphase: Sister chromatids separate
  • Telophase: Chromosomes uncoil, nuclear membrane forms

Tissues

• Epithelial Tissue: Protection, secretion, shapes (squamous, cuboidal, columnar)
• Glands:
  • Exocrine: Have ducts, discharge secretions
  • Endocrine: No ducts, release hormones into blood
• Connective Tissue: Joins, supports, and protects
  • Types: Loose, Adipose, Cartilage, Bone, Blood, Lymph
• Muscle Tissue: Specialized to contract
  • Types: Skeletal (voluntary), Cardiac, Smooth (involuntary)
• Nervous Tissue: Transmits information
  • Consists of neurons and glial cells

Membranes

• Epithelial Membranes: Cover/line body surfaces
  • Mucous Membranes: Line cavities open to the outside
  • Serous Membranes: Line closed cavities
  • Connective Tissue Membranes: Cover bones and cartilage
  • Synovial Membrane: Lines joint cavities

End of Chapter 2. Review materials for better understanding.