Biology Unit 1A & 1B Summary

Unit 1A & 1B Summary

• Gradients drive cellular processes: Matter and energy flow down gradients (higher concentration to lower). Types include concentration, pressure, electrical, and temperature gradients.

• Plasma membrane structure: The selectively permeable membrane separating the cell's interior from the exterior. Key components include a phospholipid bilayer (hydrophilic heads, hydrophobic tails), proteins (integral and peripheral), cholesterol (maintaining flexibility), and carbohydrates.

• Selectively permeable membrane: Allows some substances to pass while blocking others. Factors like size, polarity, and charge determine permeability.

• Simple diffusion: Movement of substances down their concentration gradient (no energy required). Factors affecting rate include steepness of the gradient, temperature, molecular size, and membrane permeability.

• Membrane transport mechanisms:

  • Passive transport: No ATP required; includes simple diffusion, facilitated diffusion, and osmosis (water movement).
  • Active transport: Requires ATP; includes primary and secondary active transport.
  • Vesicular transport: Includes endocytosis (engulfing particles) and exocytosis (expelling substances).

• Osmolarity & Tonicity: Osmolarity is the concentration of solutes; tonicity describes the ability of a solution to cause a cell to gain or lose water. Hypotonic solutions cause swelling, hypertonic solutions cause shrinkage, and isotonic solutions maintain equilibrium.

• Cytoskeleton: Provides structure, support, and intracellular movement. Consists of microfilaments (actin), intermediate filaments, and microtubules.

• Cellular Organelles and Functions: Nucleus (DNA storage), ribosomes (protein synthesis), endoplasmic reticulum (protein modification and lipid synthesis), Golgi apparatus (protein packaging), mitochondria (ATP production), lysosomes (waste breakdown), peroxisomes (detoxification).

• Anatomy & Physiology: Anatomy studies structure and physiology studies functions; structure dictates function.

• Levels of Human Structure: Moving from complex to simple: organism, organ system, organ, tissue, cell, organelle, molecule, atom.

• Four Primary Tissue Classes: Epithelial, connective, muscle, and nervous.

• Epithelial Tissue: Covers surfaces and lines organs. Classified by layers (simple/stratified) and shape (squamous, cuboidal, columnar). Functions in protection, secretion, and absorption.

• Connective Tissue: Provides support and binding, including loose, dense, adipose, cartilage, bone, and blood, with varied functions.

• Tissue repair: Regeneration (replacing with same tissue) and fibrosis (scar tissue formation).

• Homeostasis: Maintaining a stable internal environment using negative feedback (reverses change) and positive feedback (enhances change).

• Vasomotion: Blood vessel constriction and dilation to regulate blood pressure and blood flow.

• Medical Terminology: Hyper-, hypo-, and -itis prefixes/suffixes indicate increased, decreased, or inflammation. Examples: hyperglycemia (high blood sugar), arthritis (joint inflammation).

• Tissue injury and death: Atrophy (shrinkage), necrosis (unplanned death), infarction (tissue death due to blocked blood supply), and apoptosis (programmed cell death).

• Skeletal System Functions: Support, protection, movement, mineral storage, blood cell formation, and fat storage.

• Bone Structure( microscopic and macroscopic): Bone is a connective tissue consisting of cells (osteoblasts, osteocytes, osteoclasts, lining cells) and extracellular matrix with collagen and mineral salts.

• Bone Classification by Shape: Long bones (leverage), short bones (stability), flat bones (protection), irregular bones (complex functions), sesamoid bones (reduce friction).

• Long Bone Anatomy: Diaphysis, epiphyses, metaphysis, medullary cavity, periosteum, endosteum.

• Bone Growth: Endochondral ossification (cartilage template), intramembranous ossification (direct from mesenchymal cells), interstitial growth (lengthwise), and appositional growth (widthwise).

• Bone Remodeling: Constant breakdown and rebuilding controlled by osteoblasts (build) and osteoclasts (resorb) stimulated by factors like hormones and stress (Wolff's Law). Hormonal regulation important for calcium balance (calcitonin/PTH).

• Bone Fractures & Repair: Steps in fracture repair (hematoma, fibrocartilage callus, bony callus, remodeling).

• Osteoporosis: Decreased bone density, often related to aging and/or hormonal changes. Causes, symptoms, and treatments.

• Key exam concepts and study tips: Understand concepts, use diagrams, apply to real-world examples, review negative/positive feedback, and focus on dynamic nature of bones.