Biolab 4

• Histology is the science that deals with themicroscopic anatomy of tissues of plants and animals.
• Based on these characteristics, tissues are classifiedinto four basic types: (1) epithelial tissue (2)connective tissue (3) muscle tissue, and (4) nervoustissue
• Epithelial Tissue - This type of tissue is composed of tightly packedcells with very little intercellular substance. It covers theouter surface and inner lining of the body. It is also theprincipal tissue of the glands.
• Simple squamousExamine under LPO a section of simple squamous epithelium. The cellsare very thin and rectangular in profile and are arranged closely togetherto form a sheet. This type of epithelium is seen in mesentery (mesothelium)and inner lining of the blood vessels (endothelium). Label thephotomicrograph in the Activity Sheet.
• Simple cuboidalExamine, under LPO and HPO, a cross section of thyroid follicles orkidney. Take note of the simple cuboidal cells lining each circular thyroidfollicle or kidney tubules. These cells appear as box-like or cube-like cellswith more or less equal height and width. Label the photomicrograph in theActivity Sheet
• Simple columnarExamine, under LPO and HPO, a cross section of the frog’s intestine.Under LPO identify finger-like projections on the inner surface of theintestine. These are called villi. Focus on one villus under HPO andexamine the surface layer of tall and slender epithelial cells with darklystained nuclei more or less at the same level, near the bases of the cells.Among tall columnar cells are "pitcher-like" mucus glands called gobletcells. Label the photomicrograph in the Activity Sheet
• Stratified epithelium: two or more layers of epithelial cells, specifically namedbased on the shape of the cells at the surface
• Stratified squamousExamine under LPO a cross section of the frog’s skin. Focus on the outerlayer of the skin. Identify the numerous layers of epithelial cells (stratified)with shapes ranging from flattened superficial cells (squamous) to cuboidaland columnar cells of the deeper layers. The cells of the deepest layer restupon the basement membrane. Label the illustration in the activity sheet.
• Connective tissue comprises a diverse group of tissues that serve tomaintain and support the body. It is generally made up of cells and an extracellularmatrix composed of protein fibers, an amorphous ground substance and tissuefluid. This group includes connective tissue proper, connective tissues with specialproperties, and supporting connective tissues
• 1.1 Loose connective tissue/areolar tissueExamine under LPO a prepared slide of areolar tissue. This tissue iscomposed of a great deal of ground substance with several types of proteinfibers. Almost all types of cells are found in this tissue but the mostnumerous and easy to find cells are the spindle-shaped fibroblasts. Identifythese fibroblasts with their large ovoid nuclei. Label the illustration providedin the activity sheet.
• 2.1 Adipose tissueExamine, under LPO, a cross section of adipose tissue. Cells are calledadipocytes. These cells have a thin ring of cytoplasm surrounding a verylarge vacuole/space left by the dissolved lipid droplets. Nuclei are flattenedand often seen at the sides or periphery of the cell. Label the illustration inthe activity sheet.
• 2.2 BloodExamine, under LPO and HPO, a prepared slide of human blood smear.This specialized tissue is composed of blood cells and a fluid matrix, theplasma. Identify and label the blood cells in the Activity Sheet
• .1 Hyaline CartilageThis is one of the three types of cartilages. The firm, gel-like extracellularmatrix is bluish-white and translucent with predominance of collagen fibers.The cartilage cells or chondrocytes occupy small cavities called lacunaewhich are filled with tissue fluid in life. trachea. Thisis the type of cartilage also found in the nose, larynx, and in the bronchi.The cartilage tissues, in general, do not have nerves or blood vesselsrelying only on simple diffusion for nourishment. Identify and label the partsin the activity sheet.
• BoneThe hard calcified matrix deposited with inorganic salts makes it asupporting connective tissue. Bone cells or osteocytes occupy lacunaewith several canaliculi (interconnecting small canals) radiating from it. Inlife, these lacunae are filled with tissue fluid. Unlike cartilage, the bone isrich in blood vessels and nerves. Examine under LPO a ground section ofhuman bone showing Haversian systems/osteons, each of which ischaracterized by concentrically arranged collagen bundles around acentral canal, the Haversian/osteon canal. Label the illustration in theactivity sheet
• Muscle TissueMuscle tissues’ main function is to contract to provide movement. There arethree types of muscle tissues differentiated, among others, by the shape of thecells, rate of contraction, and control (voluntary/involuntary).
• Skeletal/Striated MuscleThis type of muscle tissue is primarily found attached to the bone to providebody movements and locomotion. Examine under LPO a longitudinal sectionof skeletal muscle. Note the long, cylindrical muscle fibers, each containing2 or more nuclei located near the plasma membrane. The fibers also showalternating light and dark bands or striations. Label the photomicrograph inthe Activity Sheet
• Nervous TissueThe nervous tissue’s main function is conductivity. The main components arethe nerve cells or neurons and the supporting cells called neuroglia. Examineunder LPO a prepared slide of a cow’s nerve smear. Identify a neuroncharacterized by several processes radiating from a cell body. Label the partsof a neuron in the Activity Sheet.