Cytology - Cell Membrane Flashcards
CYTOLOGY DEFINITION
The study of cells
3 MOST COMMON CELL SHAPES
Squamous
Cuboidal
Columnar
PRIMARY CELL COMPONENTS
Cell membrane - encapsulates the cell
Cytoskeleton - Network of proteins that provides internal support for the cell
Cytoplasm - contents of the cell (cytosol & organelles)
CELL MEMBRANE
3 functions
Defines boundaries and protects the cell
Controls interactions with other cells
Controls movement of materials into and out of the cell
CELL MEMBRANE STRUCTURE
What type of membrane
Made of what components
Bilayer membrane - two layers of phospholipids
Amphiphilic - heads are in contact with the water that exists inside and outside the cell
Fatty acid tails face the inside of the bilayer. Phospholipids do not bond to eachother.
Selectively permeable
What kinds of substances can pass through cell membrane?
Small, neutral, and lipid-soluable substances
What types of substances cannot pass through a cell membrane?
Large, charged substances (ions) like water
What is found between the phospholipids and provides rigidity for the membrane?
Cholesterol
Glycolipids
Attached to the exterior surface of the cell
Combination of carbohydrates and lipids
TRANSMEMBRANE PROTEINS
Pass through the membrane and are exposed on both sides
PERIPHERAL PROTEINS
Only exposed on one side of the membrane - either to the ICF (intercellular fluid) or the ECF (extracellular fluid)
RECEPTOR PROTEIN FUNCTIONS
Receive and identify neurotransmitters and hormones from other cells and tissues
2nd messengers relay signals from outside to inside of cell to cause further changes
ENZYME PROTEIN FUNCTION
Break down chemical messengers and neutrients
ION CHANNEL PROTEINS FUNCTION
Allow water and hydrophilic solutes to pass through.
Some always open
Some open and close with electrical charge - require ATP to function
CELL IDENTITY MARKER
FUNCTION
Glycoproteins that identify the cells as self cells and not foreign cells
CELL ADHESION MOLECULES
Physically connect adjacent cells and their tissues
3 TYPES OF CELL SURFACE EXTENSIONS AND THEIR FUNCTIONS
Microvilli: numerous small projections that increase the surface area of a cell (digestion)
Cilia: Small hairlike extensions - some motile (help move fluid like mucous in resp. System) some non-motile (like in ears to help with hearing)
Flagella: Help propel cell in fluid (sperm is the only example of this.)
What part of phospholipids form the internal and external surfaces of the membrane and are in contact with ICF and ECF?
Phosphate heads
What are the properties of substances that pass easily through the membrane?
Small and non-polar (hydrophobic, meaning made from lipids)
What are properties of substances that have a difficult time passing through the membrane, requiring the assistance of channels or carriers?
Large, and charged
Two categories for transport mechanisms?
Passive: requiring no ATP
Active: requires ATP
4 TYPES OF PASSIVE TRANSPORT MECHANISMS
And their definitions
Filtration - movement of substances through membrane due to fluid pressure (hydrostatic pressure)
Simple Diffusion - movement of particles through a concentration gradient from areas of high concentration to areas of low concentration.
Osmosis - diffusion of water. Areas of high water concentration to areas of low water concentration
Facilitated Diffusion (form of Carrier-Mediated transport) - Movement through a transmembrane protein without the use of energy
Carrier-Mediated Active Transport
Movement through a transmembrane protein with the use of ATP
VESICULAR TRANSPORT
Definition
2 types
Transportation of substances across a membrane in small packages called vesicles. Requires ATP
Endocytosis: Moves substances into the cell
Exocytosis: Moves substances out of the cell
