Histology cell structure, Slides of Histology

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Cell Structure and

Function

Dr. Riad Shraim Al-Quds University Faculty of Medicine Pathology Department

OverviewOverview

 (^) Cell Theory  (^) Studying Cells ◦ (^) An overview of cell anatomy  (^) The Cell Membrane ◦ (^) Membrane structure ◦ Membrane transport  (^) The Nucleus ◦ Chromosome structure ◦ (^) Protein synthesis ◦ (^) Cell Division & Cell Cycle  (^) Cell Diversity and Differentiation

Overview of CellularOverview of Cellular

Anatomy Anatomy

Cell membrane ◦Separates external from internal environment  (^) Extracellular fluid  (^) Cytoplasm

Nucleus

Cytoplasm ◦Cytosol ◦Organelles

Types of proteins in the cellTypes of proteins in the cell membrane membrane  (^) Integral Proteins

• incorporated or embedded in the lipid layers
• when completely span the lipid bilayer  they are called transmembrane proteins
• may change their location & accumulate at one region of the cell membrane forming localized aggregation = a process called Capping  (^) Peripheral Proteins
• loosely bound to the surface of membrane

Membrane TransportMembrane Transport

 Permeability based on: ◦ (^) Size ◦ (^) Electrical charge ◦ (^) Molecular shape ◦ (^) Lipid solubility  What sorts of things will be: ◦ (^) Freely permeable? ◦ (^) Impermeable? ◦ (^) Selectively permeable? Process is either passive, active, or vesicular

Overview of MembraneOverview of Membrane Transport Transport  Passive transport ◦ (^) Diffusion  (^) Simple  (^) Facilitated ◦ (^) Osmosis ◦ (^) Filtration  Active transport  Vesicular Transport ◦ (^) Endocytosis  (^) Receptor-mediated  (^) Pinocytosis  (^) Phagocytosis ◦ (^) Exocytosis

Diffusion Across CellDiffusion Across Cell Membranes Membranes  Some molecules can pass easily, some not at all  Can independently move across membrane in 1 of 2 ways:

◦Moving across lipid portion

◦Passing through membrane channel

Determining factors for diffusion:

◦Lipid solubility

◦Size of membrane channels vs.

molecule

Diffusion Across the CellDiffusion Across the Cell Membrane Membrane  Diffuse through lipid portion: ◦ (^) Alcohol ◦ (^) Fatty acids ◦ (^) Steroids ◦ (^) Dissolved gases  (^) CO 2  (^) O 2  Diffuse through channels: ◦ (^) Ions ◦ (^) Water soluble compounds ◦ (^) Glucose (lg)

OsmosisOsmosis

Diffusion of water across the membrane

Solvent vs. solute

In osmosis, water will flow across a membrane toward the solution that has the highest concentration of solute

TonicityTonicity

Isotonic solution ◦No net movement of water into or out of cell  (^) Equilibrium exists

Hypotonic solution ◦Water will flow into cell, causing lyses

Hypertonic solution ◦Water will flow out of the cell, causing it to shrivel and die

Which is Which?Which is Which?

Passive:Passive: FiltrationFiltration

Hydrostatic pressure forces water across membrane ◦Some solutes too

Occurs in: ◦Blood vessels ◦Kidneys