2 22 13 BSCI LECTURE NOTES Translation occurs in the cytoplasm o Includes all 3 types of RNA rRNA tRNA mRNA tRNA o Cleverly shaped with amino acid o The tail of the tRNA and 3 base sequences called the ANTICODON attached to the head of the tRNA o When the ribosome covers a codon on the mRNA tRNA with complementary bases ANTICODON will attach to the codon bringing along an amino acid o The anticodons are the same as the triplets except the triplets contain a T and the tRNA replaces it with a U TISSUES Tissue Level o Composed of similar cells put together to perform specific functions o Most cells in the human body aggregate to form tissues most cells are not independent connect with other cells 4 Primary Tissues o Epithelial o Connective o Muscle o Nervous Epithelial o Polarity o Avascular but have a high regenerative capacity Only if the epithelial tissues are supported by vascularized connective tissues o ALL epithelial tissues are supported by a basement membrane which acts as a selective membrane to regulate substances that diffuse from the underlying connective tissue to the overlying epithelial tissue 2 Classes of Epithelial o Membranous sheet like Simple Single layer SQUAMOUS o A single layer of flat scale like cells with flattened nuclei placed underneath the apical surface of the cells o Forms part of the filtration membrane in the nephrons in the kidneys o Part of the respiratory membrane in the lungs o Lines structures in the circulatory system Cardiovascular Blood circulation Lymphatic Lymph circulation o Line structures of the circulatory system is specifically referred to as ENDOTHELIUM Composition Location o Forms part of the serous membrane o Specifically referred to as the MESOTHELIUSM Composition Location Cuboidal o A single layer of cube like cells with centrally placed spherical nuclei o Location Lines the tubules of the nephrons in the kidney Secretion Reabsorption during urine formation o Outer layer surrounding each ovary GERMINAL EPITHELIAL Columnar o Single layer of tail cells with elongated nuclei placed closer to the basal surface of the cells o Non ciliated Lines the stomach and anal canal Stomach small intestines large intestines rectum anal canal Small intestines Cells express microvilli o Increase surface area for absorption in the small intestines o Ciliated Come with goblet cells Secrete polysaccharides called MUCIN o Interacts with water to form mucus Lines the bronchi tube like structure leading to lungs Cilia beat to create a unidirectional current that moves mucus away from the lungs o Part of the respiratory system Goblet cells secrete mucus which is moved propelled by unidirectional current produced by the cilia o Fallopian tubes Cilia beat to create unidirectional current that moves ovum egg or conceptus from the fallopian tube to the uterus Stratified Named for the epithelial cell type on the apical surface o Glandular aggregate of secretory cells 2 25 13 Pseudostratified Columnar Epithelial Tissue o Single layer of tall cells of different heights Nuclei appear at different heights giving the false appearance of stratification false appearance of layers o Ciliated Endowed with GOBLET CELLS is specifically referred to as the respiratory epithelium Composition Location o Lines most of the structures in the respiratory o Beat to create a unidirectional current that system moves mucus o Non Ciliated Lines the ducts in the male reproductive system Epidydimides vasa deferentia ejactulatory ducts urethra Confers protection to these ducts Thicker than simple epithelial and when sperm are not moved out of the male ducts the pseudostratified non ciliated columnar epithelial cells engulf and destroy sperm Stratified epithelial tissues o Names for the cell type on the apical surface of the stratified epithelium o Stratified surface Several layers of cells with scale like i e squamous apical cells o SQUAMOUS Keratinized Apical cells are impregnated with a tough fibrous protein called KERATIN Cells are coated with glycolipids Abusive resistant and water proof Location o EPIDERMIS Non keratinized Forms part of the mucus membrane which lines most of the structures in the tracts of the body o Tracts have openings to the exterior o Into skin non keratinized to keratinized Lines the entry exit structures of the tracts where this epithelium allows for movement of fluids into the structures and also allows for movement of structures through the tract Confers protection to the structures of the lines o Columnar and Cuboidal Epithelial lining of ducts which lead from exocrine glands when they confer protection to the internal surface of the ducts Transitional Epithelial o Lines the structures that convey store urine Uterus Bladder Urethra When these structures are empty transitional epithelium encroaches into the lumen open space 6 layers with cuboidal like cells on the apical surface As urine flows into these structures the transitional epithelium undergoes a transition and changes from 6 layers to 3 layers Cuboidal like cells become squamous cells This increases the capacity of the lumen of these structures 3 1 13 Ligaments connect bones at the site of joints Dense irregular CT o Bundles of collage fibers arranged in an irregular fashion They face all directions HENCE dense irregular CT can withstand pull stress force in applied in several directions o Location Forms the reticular layer of the dermis Papillary layer of dermis is composed of areolar CT o Provides nutrients to the overlying avascular epidermis o Highly vascularized o Forms the fibrous capsules that surround organs in the body o Forms the perichondriac which surrounds the avascular cartilage o Forms the periostrium that surrounds bones and provides blood vessels nutrients to the bone tissue 3rd type of dense CT ELASTIC CONNECTIVE TISSUE o Bundles of collages fibers o Bundles of elastic fibers Provide the stretch recoil property of the elastic CT o Location In the ligaments flava which run alongside there vertebral column and they allow for stretching of the vertebral column as when one bends and they recoil to the return the vertebral column to its normal position when one 2nd class of CT CARTILAGE o Secreted by chondroblasts o Consistency of the matric semi solid o Matured chondroblasts called chondrocytes reside in shallow concavities in the semi solid matrix LACUNAE o Cartilage is avascular receives nutrients oxygen from the perichondrion o 3 types of cartilage Elastic Fibro Hyaline Hyaline o
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