Chapter 2 & 3: Cell Structure and Transport

Microscopy and Cell Types

Understanding microscopy and cell types is foundational for studying anatomy and physiology. Microscopy allows visualization of cells and tissues, while cell types vary in structure and function.

• Microscope Types: Light, Transmission Electron (TEM), Scanning Electron (SEM)

• Cell Types: Eukaryotic (with nucleus and organelles), Prokaryotic (no nucleus)

Cellular Transport Mechanisms

Cells regulate the movement of substances across their membranes through various transport mechanisms.

• Intracellular vs. Extracellular Compartments: Intracellular refers to inside the cell; extracellular is outside the cell.

• Plasma Membrane Permeability: The plasma membrane is selectively permeable, allowing some substances to pass while restricting others.

• Types of Diffusive Transport:

  • Passive Transport: Does not require energy (e.g., diffusion, osmosis, facilitated diffusion)

  • Active Transport: Requires energy (ATP) to move substances against their concentration gradient (e.g., sodium-potassium pump)

• Key Terms: Aquaporins (water channels), ion pumps, carrier proteins

Tonicity and Solutions

Tonicity describes the effect of a solution on cell volume, which is crucial for understanding cell-environment interactions.

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

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

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

Resting Membrane Potential

The resting membrane potential is the voltage difference across the plasma membrane in resting cells, primarily due to Na+ and K+ ion distribution.

• Key Concept: Maintained by the sodium-potassium pump and selective permeability of the membrane.

Cell Structures

Cells contain specialized structures (organelles) that perform distinct functions.

• Mitochondria: Powerhouse of the cell, site of ATP production.

• Plasma Membrane: Boundary of the cell, regulates entry and exit of substances.

• Microvilli: Increase surface area for absorption.

• Cilia: Move substances across cell surfaces.

• Flagellum: Provides motility (e.g., sperm cells).

• Pumps: Proteins that move ions across membranes (e.g., Na+/K+ pump).

DNA Transcription and Translation

Cells synthesize proteins through transcription (DNA to mRNA) and translation (mRNA to protein).

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

• Translation: mRNA is decoded by ribosomes to assemble amino acids into proteins.

Cell Cycle: Interphase and Mitosis

The cell cycle consists of phases that prepare the cell for division and the process of mitosis itself.

• Interphase: Cell grows, replicates DNA, and prepares for division.

• Mitosis: Division of the nucleus into two genetically identical daughter cells.

Chapter 4: Tissues

Primary Tissue Types and Characteristics

Tissues are groups of similar cells performing a common function. There are four primary tissue types in the human body.

• Epithelial Tissue: Covers surfaces, lines cavities, forms glands.

• Connective Tissue: Supports, protects, and binds other tissues (e.g., bone, blood, adipose).

• Muscle Tissue: Responsible for movement (skeletal, cardiac, smooth).

• Nervous Tissue: Transmits electrical impulses, processes information.

Key Features: Each tissue type has unique structural and functional characteristics.

Cell Shapes and Extracellular Matrix

• Cell Shapes: Squamous (flat), cuboidal (cube-shaped), columnar (tall).

• Extracellular Matrix: Non-cellular material that provides structural and biochemical support to surrounding cells.

Glands

Glands are specialized epithelial structures that produce and secrete substances.

• Exocrine Glands: Secrete products into ducts (e.g., sweat, salivary glands).

• Endocrine Glands: Release hormones directly into the bloodstream (e.g., thyroid gland).

Tissue Modifications

• Hypertrophy: Increase in cell size.

• Atrophy: Decrease in cell size or number.

Chapter 5: Integumentary System

Skin Structure and Function

The integumentary system includes the skin and its derivatives. It serves as a barrier, regulates temperature, and provides sensory information.

• Skin Layers: Epidermis (outer), Dermis (middle), Hypodermis (subcutaneous, not always considered part of skin)

• Epidermal Strata: Multiple layers within the epidermis (e.g., stratum corneum, stratum basale)

• Skin Model: Used to identify and study skin structures in lab settings.

Functions of the Skin

• Protection against pathogens and injury

• Regulation of body temperature

• Sensation (touch, pain, temperature)

• Vitamin D synthesis

Hair and Skin Cancer

• Hair: Provides protection, sensory input, and regulates body temperature.

• Skin Cancer: Uncontrolled growth of skin cells; types include basal cell carcinoma, squamous cell carcinoma, and melanoma.

Lab Practical Information

Key Lab Topics

• Diffusion and osmosis (movement of water and solutes across membranes)

• Cell cycle and mitosis (identification of stages)

• Tissue identification (especially epithelial and connective tissues)

• Classification of connective tissue (see table below)

• Skin model identification

Connective Tissue Classification Table

This table summarizes the main types of connective tissue and their characteristics.

Important Equations

• Osmosis: Where is the flux, is the permeability coefficient, and is the concentration gradient.

• Resting Membrane Potential (Nernst Equation):

Additional info:

• Students should be able to identify tissue types and stages of mitosis from images.

• Practice worksheets and lab models are essential for exam preparation.