Chap 4 Flashcards
Cells
functional units of the body
Importance Of Cytology
All body processes depend on cellular activity
Importance Of Cytology
Different cell shapes in different body tissues
Importance Of Cytology
Most cells are too small to see without a microscope
Measured in micrometers (1/10,000 cm= 1 millionth of a meter) (mm)
RBC: 7–8 μm
human egg: 120 μm
Most bacterial cells are even smaller
Plasma Membrane
Barrier separating internal contents from external environment
Plasma Membrane
Extensions of plasma membrane
Cilia, flagellum, microvilli
Nucleus
Largest structure in cell
Enclosed by a nuclear envelope
Contains DNA
Cytoplasm
Cellular contents between plasma membrane and nucleus
cytosol, organelles, and inclusions
Cytosol (intracellular fluid)
Viscous fluid of cytoplasm
High water content, with many solutes
Organelles (“little organs”)
Complex, organized structures
Unique shapes ,functions
Membrane-bound organelles
Endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria
Non-membrane-bound organelles
Ribosomes, cytoskeleton, centrosome, proteasomes
Inclusions
Stored temporarily, Not considered organelles
E.g., pigments, glycogen, triglycerides
Plasma Membrane
physical barrier between cell fluid (cytosol) and fluid that surround it (interstitial fluid or “extracellular fluid”)
Plasma Membrane Functions
Regulates movement into and out of a cell (Transport)
Establishes and maintains electrochemical gradient
Functions in cell communication
Membrane Lipids: Phospholipids
Polar, hydrophilic “head”;
2 nonpolar, hydrophobic “tails”
Phospholipid Bilayer
is the basic structure
two parallel sheets of molecules lying tail to tail
Cytosol
fluid inside the cell
interstitial fluid
outside cell
Cholesterol
Scattered within phospholipid bilayer
Strengthens and stabilizes membrane
Glycolipids
Lipids with attached carbohydrate groups
Glycolipids
Only outer phospholipid region
Helps form glycocalyx—“coating of sugar” on cell’s surface
Transport Proteins
Regulate movement of substances across membrane
E.g., channels, carriers, pumps,
Cell Surface receptors
Bind molecules called ligands
E.g., for detection of neurotransmitters and hormones
Enzymes
Catalyze chemical reactions
May be attached to either internal or external surface of a cell
Identity markers
Contribute to glycocalyx
(Spoiler: This sugar coat is used to distinguish healthy cells from cells to be destroyed)
Anchoring sites
Secure cytoskeleton to plasma membrane
Cell-adhesion proteins
Perform cell-to-cell attachments
