Histology - Cell structure and function Flashcards
size range of most mammalian cells ?
10 to 100 micrometers
bacterial cells typical size?
1 micrometer
size of a RBC
7um (6 to 8)
How is cell specialization is possible if each cell derives from the same precursor cell containing the same genetic material?
it is achieved by a particular gene expression pattern that may vary over time, but whose pattern defines the very nature of a cell type. Genes can be switched on and off at any time in cells, and the pattern in which this happens defines the function of a particular cell
On what depended the evolution of large multicellular organism
it depended on the ability of eukaryotic cells to express their heriditary information in many different ways and to function cooperatively
what is an eukaryotic cell
any cell or organism that possesses a clearly defined nucleus
A part from cells, what comprises the human body?
Extracellular material and extracellular fluid
What can contain intercellular material and fluid?
many dissolved metabolites, ions and soluble molecules and proteins
do cells in complex organism exist alone?
not usually. They are grouped together in a precise manner to fulfill specific, requisite physiological functions
What are the 4 main types of tissus comprised in the body? Or what are the four primary tissues formed by cells?
- Epithelium
- connective tissue
- muscle tissue
- nervous tissue
What is the usual histology of organs
Most often, all four tissue types are present in a single organ.
on what rely the organized pattern of cells to form tissues?
on cell adhesion and cohesion
What are organelles
Organelles are small structures found within cells (precisely in the cytoplasm) that perform very specific tasks. They are insoluble, structural and functional component of a cell
Can we visualise organelle? What size range?
Most organelles are in the sub-micrometer range and can only be visualized by electron microscopy, but some such as the nucleus and the Golgi apparatus can be observed with the light microscope
Where are found organelle ?
within the cytoplasm of a cell
What is the protoplasm ?
A gel like substance that can be subdivided into the karyoplasm (nucleoplasm) of the nucleous that sourrounds the DNA, and the cytoplasm.
Where is located the cytoplasm ?
between the cell membrane and the nucleus
What is the cytosol ?
the fluid component of the cytoplasm that contain many soluble organic and inorganic molecules
what is the membrane system of a cell?
The outer membrane (phospholipid bilayer membrane) comprising the protoplasm AND an internal set of membranes that define many intracellular organelles.
is the outer cell membrane permeable?
Selectively permeable!
What determines the fluidity of phospholipid bilayers?
The amount of cholesterol they contain - with more cholesterol making them less fluid
can the molecules residing in the cell membrane can move?
Yes, they can move as requested by the function or demands placed on a given cell
Describe the cell membrane lipids
Lipid bilayer : inner leaflet and outer leaflet. They have a polar hydrophilic side and nonpolar hydrophobic side.
what does the hydrophilic/hydrophobic by-layer permits?
it permits a self-sealing property to the membrane
what is the most common molecule in membranes?
phospholipid
describe phospholipid
have a polar head group of glycerol and two hydrophobic hydrocarbon tails that are usually fatty acids
