Nurs 1002- Lab #2

Lab 2: Chemistry, Cells & Tissue

Introduction

This study guide covers foundational chemistry concepts, the structure and function of cells, and the principles of membrane transport. These topics are essential for understanding anatomy and physiology at the cellular and tissue levels.

Chemistry Basics for Anatomy & Physiology

Atoms, Molecules, and Compounds

Understanding the basic units of matter is crucial for studying biological systems.

• Atom: The smallest unit of an element that retains its chemical properties. Examples: Hydrogen (H), Oxygen (O).

• Molecule: Two or more atoms bonded together. Example: O2 (oxygen gas).

• Compound: A substance formed when two or more different elements combine chemically. Example: H2O (water).

Example: Water (H2O) is a compound made of two hydrogen atoms and one oxygen atom bonded together.

Organic vs. Inorganic Chemistry

• Organic compounds: Contain carbon and are typically found in living organisms (e.g., carbohydrates, proteins, lipids, nucleic acids).

• Inorganic compounds: Generally do not contain carbon-hydrogen bonds (e.g., water, salts, acids, bases).

Example: Glucose (C6H12O6) is an organic compound; sodium chloride (NaCl) is inorganic.

Cell Structure and Function

Basic Structures of Human Cells

• Plasma membrane: The outer boundary of the cell, controlling entry and exit of substances.

• Cytoplasm: The jelly-like substance inside the cell, containing organelles.

• Nucleus: The control center of the cell, containing genetic material (DNA).

Plasma Membrane Function

• Selective permeability: The plasma membrane allows only certain substances to enter or leave the cell.

• Separation: Separates the intracellular fluid (inside the cell) from the extracellular fluid (outside the cell).

• Main components: Phospholipid bilayer, proteins, and carbohydrates.

Transport Across the Plasma Membrane

Types of Membrane Transport

• Passive Transport: Movement of substances across the membrane without energy input.

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

Passive Transport Mechanisms

• Simple Diffusion: Movement of small, nonpolar molecules (e.g., oxygen, carbon dioxide) from an area of high concentration to low concentration across the membrane without assistance.

• Facilitated Diffusion: Movement of larger or polar molecules (e.g., glucose, amino acids) through membrane proteins (carrier or channel proteins) from high to low concentration.

• Osmosis: The diffusion of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.

Example: Oxygen diffuses into cells by simple diffusion; glucose enters cells via facilitated diffusion using a carrier protein.

Active Transport Mechanisms

• Primary Active Transport: Direct use of ATP to move substances (e.g., Na+/K+ pump moves sodium out and potassium into the cell).

• Secondary Active Transport: Uses the energy from the movement of one substance down its gradient to move another substance against its gradient.

Example: The Na+/K+ pump maintains the electrochemical gradient essential for nerve impulse transmission.

Osmosis and Tonicity

Osmosis affects cell volume depending on the surrounding solution's tonicity:+

Solution Type	Effect on Cell
Isotonic	No net movement of water; cell remains normal size.
Hypertonic	Water moves out; cell shrinks (crenation).
Hypotonic	Water moves in; cell swells and may burst (lysis).

Summary Table: Types of Membrane Transport

Type	Energy Required?	Direction	Example
Simple Diffusion	No	High to Low	O2, CO2
Facilitated Diffusion	No	High to Low	Glucose, amino acids
Osmosis	No	Water: Low to High solute	Water movement
Active Transport	Yes (ATP)	Low to High	Na+/K+ pump

Key Terms and Definitions

• Concentration Gradient: Difference in the concentration of a substance across a space.

• Carrier Protein: Membrane protein that assists in the transport of substances across the membrane.

• ATP (Adenosine Triphosphate): The primary energy currency of the cell.

• Phospholipid Bilayer: The fundamental structure of the plasma membrane, composed of two layers of phospholipids.

Relevant Equations

• Fick's Law of Diffusion:

$J = -D \frac{dC}{dx}$

Where:

• $J$ = rate of diffusion

• $D$ = diffusion coefficient

• $\frac{dC}{dx}$ = concentration gradient

Summary

Understanding the chemistry of life, cell structure, and membrane transport mechanisms is foundational for further study in anatomy and physiology. Mastery of these concepts enables students to comprehend how cells maintain homeostasis and interact with their environment.