Ch04 the tissue level of Organisation Flashcards
What is a tissue?
A tissue is a group of cells that usually have a common embryonic origin and function together to carry out specialized activities.
Name the four basic types of tissues in the human body.
Epithelial, Connective, Muscular, and Nervous tissues.
What is histology?
The science that deals with the study of tissues.
What does epithelial tissue do?
It covers body surfaces, lines hollow organs, body cavities, and ducts; and forms glands.
What is the function of connective tissue?
Connective tissue protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity.
What is the role of muscular tissue?
Muscle tissue is responsible for movement and generation of force.
What does nervous tissue do?
It initiates and transmits action potentials (nerve impulses) that help coordinate body activities.
What are cell junctions?
Points of contact between adjacent plasma membranes that may serve fluid-tight seals, anchor cells, or act as channels for ions and molecules.
What is the function of tight junctions?
Tight junctions fuse adjacent cells to form fluid-tight seals and inhibit the passage of substances between cells, found in tissues like the stomach and intestines.
What is the role of desmosomes?
Desmosomes prevent epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction.
What is a hemidesmosome?
It resembles a desmosome but anchors cells to the basement membrane instead of other cells.
What is a gap junction?
Gap junctions allow cells to rapidly communicate through connexins, enabling ion and small molecule movement.
How do epithelial and connective tissues differ?
Epithelial tissue has tightly packed cells with little extracellular matrix and no blood vessels, while connective tissue has fewer cells with more extracellular material and blood vessels.
What are the general features of epithelial tissue?
Cells arranged in sheets, densely packed, attached to a basement membrane, avascular but innervated, and capable of frequent mitosis.
What are the classifications of epithelial tissue based on cell layers?
Simple (one layer), stratified (several layers), and pseudostratified (one layer appearing as several).
What are the classifications of epithelial tissue based on cell shape?
Squamous (flat), cuboidal (cube-like), columnar (rectangular), and transitional (variable).
Where is simple columnar epithelium found and its function?
Found in the GI tract for absorption and secretion; ciliated forms help move fluids in bronchioles and fallopian tubes.
What is simple squamous epithelium specialized for?
Adapted for diffusion and filtration, found in lungs, kidneys, heart lining, and thoracic cavities.
What is the role of transitional epithelium?
It can stretch and return to a relaxed state, found lining most of the urinary tract.
What is the function of simple cuboidal epithelium?
It performs secretion and absorption, found in ovaries, kidney tubules, and thyroid gland.
What is pseudostratified columnar epithelium?
A single layer of cells giving the appearance of multiple layers, found in the upper respiratory tract.
What is keratinized stratified squamous epithelium?
It has a surface layer of dead cells filled with keratin, providing protection, such as in the skin.
What is nonkeratinized stratified squamous epithelium?
It lacks keratin and remains moist, found in the mouth and esophagus.
Where is stratified cuboidal epithelium found?
It is located in sweat gland ducts and provides protection.
