Download INTEGUMENTARY SYSTEM

CYTOLOGY
THE STUDY OF CELLS STRUCTURE
GENERAL
Cell = Smallest Living Unit
Produced by Cell Division or Fertilization
Surrounded by Interstitial / Extracellular
Fluid
Components:
- Plasma (Cell) Membrane
- Cytoplasm
- Organelles
THE PLASMA MEMBRANE
 Phospholipid bilayer: Hydrophobic tails and
hydrophilic heads, selectively permeable
 Proteins: Peripheral and integral
Enzymes
Receptors
Transport
Anchors
 Carbohydrates: Superficial recognition sites
THE PLASMA MEMBRANE
cont.
- Fluid Mosaic Model (mosaic of floating
proteins)
- Functions of Plasma Membrane:
* Physical Barrier (Selective!)
* Regulates Exchange with Environment
* Sensitive to Extracellular Environment
* Structural Support
THE PLASMA MEMBRANE
CYTOPLASM
- Material Between Plasma Membrane &
Nucleus
- Components
* Cytosol (water + nutrients & other
solutes)
* Organelles (excludes nucleus)
* Inclusions (stored materials)
- Functions: Site of chemical reactions
ORGANELLES
“Little Organs”
Membranous organelles
- Membrane isolates secretions, enzymes or
toxins
Non-membranous organelles
NUCLEUS
(Membranous)
Double Nuclear Membrane with Pores
Nucleoplasm
- Nucleolus
* Organelle in nucleus (non-membranous)
* Assembles ribosomes
- DNA
* Chromatin - loose; protein synthesis
* Chromosomes - dense, rodlike; cell division
STRUCTURE OF THE
NUCLEUS
ENDOPLASMIC
RETICULUM (Membranous)
Smooth endoplasmic reticulum (SER)
- Synthesis of Carbohydrates, Steroids &
other Lipids
- Storage (Synthesized Materials or Ca+)
Rough endoplasmic reticulum (RER)
- Attached Ribosomes
- Protein synthesis for “export” or inclusion
in cell membrane
GOLGI COMPLEX/APPARATUS
(Membranous)
Structure:
- Flattened Membranous Sacs
Function:
- Modifies & packages proteins
- Source of lysosomes
- Renewal/modification of plasma membrane
MITOCHONDRIA
(Membranous)
Structure: Double membrane
Function: Production of ATP (95%),
cellular energy
Contains DNA
Self-Replicating
MITOCHONDRIA
LYSOSOMES (Membranous)
Structure: Vesicles filled with Digestive
Enzymes (“Suicide Bags”)
Function:
- Digestion within the cell
- Defense
- Recycle worn-out cells
Peroxisomes
Membranous sacs of enzymes
Detoxify harmful/dangerous substances
- Alcohol
- Formaldehyde
- Free Radicals
VACUOLES AND VESICLES
(Membranous)
Structure: Membranous Sac
Function: Storage, Endocytosis, Exocytosis
FORMATION OF VESICLES
RIBOSOMES (Nonmembranous)
Structure: Two subunits (rRNA + protein)
Function: Protein synthesis
Fixed or Free
CENTROSOMES AND
CENTRIOLES (Non-membranous)
Centrosome: “Cell center”
- Area of cytoplasm
- Microtubule formation center
- Contains Centrioles
Centrioles:
- Microtubules
- Form Mitotic Spindle
CYTOSKELETON (Nonmembranous)
Network of protein structures
Acts as cell’s “muscles & bones”
Determines cell shape
Supports organelles
Involved in internal transport & cellular
movements
CILIA & FLAGELLA (Nonmembranous)
Cilia – short, numerous, move substances
over free surfaces
Flagella – long, singular, move cell
Microvilli – thin folds of cell membrane,
increase surface area to maximize
absorption