Tissue (Histology) Flashcards
Organs systems are comprised of 2 or more organs; organs are made of tissues (specifically 2 or more tissue types). What are the four tissue types we discussed in class?
Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue
Tissues are made up of cells; some cells are packed closely together and have very little space between them. What is this space referred to?
The space that occupies the area between cells is called the matrix. Some tissues have an open matrix (more space between cells) and others have closed matrix (very little space between cells.
Which tissue type has the largest amount of matrix?
Connective tissue has the largest amount of matrix.
In regard to matrix and blood supply, describe the characteristics of epithelial tissue.
Epithelial tissue has very little matrix (closed matrix) and very little blood supply. The closely packed cells prevent “large” contents from permeating the tissue; however, since the cells are so tightly packed together, there is also very little room for blood supply.
Describe the functions of epithelial tissue.
- Protection - epithelial tissue protects underlying structures from microbes such as bacteria and viruses. It also protects the underlying tissue from harmful environmental factors such as UV rays and chemicals.
- Maintains moisture (to the internal environment) - essentially, epithelial tissue prevents underlying tissue from drying out.
- Epithelial tissue also promotes the secretion of glandular chemicals and enzymes.
How is epithelial tissue named (provide an example)?
Epithelial tissue is names based on the cell type/shape and the number of layers. The shape of cells varies (e.g., squamous, cuboidal, columnar, fusiform, etc.), but the layer is either simple (single layer) or stratified (two or more layers). There is a third layer that mimics a combination of both (pseudostratified).
An example would be an stratified cuboidal epithelial tissue. That is, the tissue is made up of two or more layers of cuboidal cells (if more than one type of cell makes up the stratified layer, the surface layer of cells determines its name).
In terms of content movement, why is simple epithelial tissue more advantageous than stratified epithelial tissue?
Simple epithelial tissue is comprised of one layer of cells; therefore, content attempting to move through it only has to cross one layer as opposed to multiple layers (i.e., stratified).
Explain the difference between keratinized and nonkeratinized epithelium tissue.
Keratinized epithelial tissue contains a layer of dead cells formed in the epidermis of the skin. Nonkeratinized epithelial tissue lacks this layer of dead cells. These tissues are found in areas where moisture is needed on the surface (e.g., tongue, oral mucosa, vagina).
Connective tissue is tissue that does what its name suggests; it connects “stuff”. Beyond connecting tissues, describe the other functions of connective tissue.
Connective tissue is the most abundant and variable type of tissue. Beyond binding/connective responsibilities, it also assists with immunity; the blood carries leukocytes. Adipose tissue is a storage site; waiting to be used for energy. Bone stores minerals. Connective tissue helps with the production of heat.
Connective tissue is made up of several types of fibers. Explain the difference between collagen and elastic fibers.
Collagen fibers are tough fibers that have little stretching properties. These fibers are found in tendons, ligaments, and the dermis. Elastic fibers are thinner fibers made of elastin. These fibers have elastic properties, which allow the tissue to stretch and recoil (return to its natural position). These connective tissue fibers are found in the lungs, skin, and arteries.
Which connective tissue type is found on the end of long bones and what is its responsibility?
Cartilage is found on the end of long bones. This cartilage is referred to as hyaline cartilage. It’s main function is to reduce friction between the ends of bones as the joint moves through a range of motion. For example, hyaline cartilage is found on the end of the femur to reduce friction between the femur and tibia (knee). When hyaline cartilage is damaged, the risk of arthritis or degenerative joint disease.
Regarding fluid movement, which type of fibrous connective tissue has the ability to more effectively allow fluid to pass through it and why?
Loose connective (fibrous) tissue more effectively allows fluid to move through. This is because the ground substance (also known as the matrix) is more open than dense fibrous connective tissue. An example of loose connective fibrous tissue is areolar tissue.
What type of bone is porous and allows movement of nutrients in and out of the medullary cavity and why?
Spongy bone is more porous than compact bone. Because of its open matrix, there is more space between the cells of bone, which allows nutrients to move through more freely.
Nerve tissue promotes the exchange of information between the central nervous system (brain and spinal cord) and the appendicular skeleton/head/thorax (e.g., appendages, head, thorax, etc.). What part of the nerve cell receives information from other nerve tissue?
Dendrites receive information from other nerve cells and pass it to the cell body. It then travels down the axon of the nerve to the terminal buds, which send the signal to the target tissue (i.e., another nerve cell or other tissue).
In terms of cell striations, describe the difference between skeletal muscle striations and cardiac muscle striations.
Skeletal muscle cells are long unbranched striations (run parallel) with multiple peripheral nuclei. Cardiac muscle cells are short branched cells with one central nuclei per cell.
