Chapter 1: Introduction to Anatomy & Physiology (A&P)

Principles of Homeostasis

Homeostasis is the process by which living organisms maintain a stable internal environment despite changes in external conditions. This principle is fundamental to understanding how the body functions and responds to stimuli.

• Definition: Homeostasis refers to the dynamic equilibrium maintained by physiological processes.

• Mechanisms: Involves feedback systems (primarily negative feedback) that detect and correct deviations from a set point.

• Examples: Regulation of body temperature, blood glucose levels, and pH balance.

Additional info: Negative feedback reduces the effect of a stimulus, while positive feedback amplifies it (e.g., blood clotting).

Chapter 2: Chemistry of Life

Organic Compounds

Organic compounds are molecules that contain carbon and are found in all living things. They include carbohydrates, lipids, proteins, and nucleic acids.

• Lipids: A diverse group of hydrophobic molecules, including fats, oils, and steroids.

• Saturated vs. Unsaturated Fats:

  • Saturated fats: Contain no double bonds between carbon atoms; typically solid at room temperature (e.g., butter).

  • Unsaturated fats: Contain one or more double bonds; usually liquid at room temperature (e.g., olive oil).

Additional info: The structure of fatty acids affects membrane fluidity and health implications.

Chapter 3: The Cell

Organelles

Organelles are specialized structures within cells that perform distinct functions necessary for cellular life.

• Names and Functions:

  • Nucleus: Contains DNA; controls cellular activities.

  • Mitochondria: Site of ATP (energy) production.

  • Endoplasmic Reticulum (ER): Synthesizes proteins (rough ER) and lipids (smooth ER).

  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

  • Lysosomes: Contain digestive enzymes to break down waste.

  • Ribosomes: Synthesize proteins.

• Structure of DNA in Nucleus: DNA is organized into chromosomes within the nucleus, carrying genetic information.

• Transport of Endomembrane System: The endomembrane system (ER, Golgi, vesicles) transports proteins and lipids within the cell.

Cellular Transport

Cellular transport refers to the movement of substances across the plasma membrane, essential for maintaining homeostasis.

• Structure and Function of Plasma Membrane: Composed of a phospholipid bilayer with embedded proteins; regulates entry and exit of substances.

• Passive vs. Active Transport:

  • Passive transport: Movement of substances down their concentration gradient without energy input (e.g., diffusion, osmosis, facilitated diffusion).

  • Active transport: Movement of substances against their concentration gradient, requiring energy (ATP).

• Examples of Each Type of Transport:

  • Simple diffusion: Oxygen and carbon dioxide moving across the membrane.

  • Facilitated diffusion: Glucose transport via carrier proteins.

  • Active transport: Sodium-potassium pump ( ATPase).

• Osmosis: Movement of water across a semipermeable membrane.

• Types of Solutions:

  • Hypertonic: Higher solute concentration outside the cell; water moves out, cell shrinks.

  • Hypotonic: Lower solute concentration outside; water moves in, cell swells.

  • Isotonic: Equal solute concentration; no net water movement.

Protein Synthesis

Protein synthesis is the process by which cells build proteins, involving transcription and translation.

• Steps:

  • Transcription: DNA is copied into messenger RNA (mRNA) in the nucleus.

  • Translation: mRNA is decoded by ribosomes in the cytoplasm to assemble amino acids into a protein.

• Components: Enzymes (e.g., RNA polymerase), ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA).

Additional info: The genetic code is universal and redundant, ensuring accurate protein synthesis.

Cell Cycle

The cell cycle is the series of events that cells go through as they grow and divide. It ensures proper replication and distribution of genetic material.

• Interphase Steps: Period of cell growth and DNA replication (G1, S, G2 phases).

• Mitosis Steps: Division of the nucleus into two identical daughter nuclei.

  • Prophase: Chromosomes condense, nuclear envelope dissolves.

  • Metaphase: Chromosomes align at the cell's equator.

  • Anaphase: Sister chromatids separate to opposite poles.

  • Telophase: Nuclear envelopes reform around chromosomes.

  • Cytokinesis: Division of the cytoplasm, resulting in two daughter cells.

• Division of Chromosomes: Human cells start with 46 chromosomes; after mitosis, each daughter cell has 46 chromosomes.

• Cell Cycle Checkpoints: Control mechanisms that ensure proper division (e.g., G1, G2, M checkpoints).

• Cancer: Uncontrolled cell division due to failure of cell cycle checkpoints; contrasts with normal regulated division.

Additional info: Mutations in genes regulating the cell cycle (e.g., tumor suppressors, proto-oncogenes) can lead to cancer.