Histology
Lab – 1 -
Shorooq Wessam
The cells
Cells : Are the basic functional units of complex organisms , Cells are grouped together
to form tissues , the for basic tissues (epithelium , connective , muscle and nervous tissue )
that compose the body are assembled to form organs which are collected into organ
systems .
* Every cell is surrounded by biliped plasma memberane , possesses organelles .
* Protoplasm the living substance of the cell is subdivided into two compartments :
cytoplasm , extending from the plasma membrane to the nuclear envelope and Karyoplasm
, the substance forming contents of the nucleus .
Cell membarane
Each cell is bounded by acell membrane that function in :
1- Maintaining the structural intrgrity of the cell
2- Controlling movements of substances in and out of the cell ( selective permeability )
3- Regulating cell- cell intraction
4- Recognizing via receptoes , antigens and foreign cell as well as alterd cells
5- Acting as an interface between the cytoplasm and external environment
6- Establishing transport systems for specific molecules
7- Transducing extracellular physical or chemical signals into intracellular events
* Ribosomes : are small particles composed of proteins and ribosomal RNA ( rRNA ) they
function as asurfase for the synthesis of proteins .
*Endoplasmic reticulum : is largest membranous system of the cell and has two
components smooth E.R.and R.E.R. participates in protein synthesis , S.E.R.. avtive in
synthesis of steroids , cholestvtive in synthesis of steroids , cholesterol and triglycerides .
*Colgi Appartus : functions in the synthesis of carbohydrates and in the modification and
sorting of proteins manufactured on the R.E.R.
*Mitochondria : posses their own DNA and perform oxidative phosphorylation and lipid
synthesis . each mitochondrion posseses asmooth outer membrane and afolded inner
membrane , the folds of the inner membrane known as critae , greatly increase the surface
area of the membrane . the narrow apace between the inner and outer membranes is
called the inter membrane space .
*Nucleus : the nucleus is the largest organelle of the cell , It contains nearly all of the deoxy
ribonucleic acid (DNA) possessed by the cell as well as the mechanisms for ribonucleic acid
(RNA) synthesis and its resident nucleolus is the location for the assembly of ribosomal
subunits . the nucleus bounded by two lipid membranes houses three major components :
- Chromatin , the genetic material of the cell .
- Nucleolus , the center for ribosomal RNA (rRNA) synthesis .
- Nucleoplasm , containing macromolecules and nuclear particles involved in the
maintenance of the cell .
Histology
Lab -2-
Shorooq Wessam
Tissues
The different types of cells composing the human body are arranged and coorperatively
organized into four tissues .
Groups of these tissues are assembled in various organizational and functional
arrangements into organs which vary out functions of the body . the four basic tissue types
are epithelium , connective , muscle and nervous tissue ,
* Epithelial tissue :
Have numerous functions : protection , transport , secretion , absorption , control of
movement of materials between body compartments via selective permeability of
intercellular junctions between epithelial cells , and detection of sensations .
Types of epithelial :
- Simple epithelium , if the membrane is composed of asingle layer of cells .
- Stratified epithelium , if it is composed of more than one layer .
Simple epithelium classification into four types and they are :
1- Simple Sequamous epithelium that covers the external surface of the digestive organs
such as small intestine .
2- Simple cuboidal epithelium lines small excretory ducts in different organs such as in the
proximal convoluted tubules of the kidney .
3- Simple columanar epithelium covers the digestive organs such as stomach .
4- Pseudostratified columnar epithelium lines the respiratory passages such as trachea
* Stratified epithelium :
1- Stratified Sequamous epithelium there are two types keratinized epithelium is found
exposed surface of the body such as the skin . Non keratinized epithelium covers moist
cavities such as esophagus .
2- Stratified cuboidal epithelium and Stratified columnar epithelium lines the larger
excretory ducts of salivery glands .
3- transitional epithelium lines the bladder .