Chapter 4 Flashcards
What are tissues?
Collections of cells gathered together to form a function.
How are tissues classified?
Due to:
* Structure of the cells
* Composition of the extracellular matrix
* Functions of the cells
What is histology?
The study of tissues involving microscope work, used during autopsies and biopsies.
What are the four types of tissue?
- Epithelial Tissue
- Connective Tissue
- Muscle Tissue
- Nervous Tissue
What are the characteristics of epithelial tissue?
Cells are contiguous with little extracellular matrix, covers surfaces, forms glands, and lines cavities.
What is the apical and basal end of epithelial tissue?
Epithelial tissue usually has an apical (faces exterior) and basal end with a basement membrane.
What is the role of epithelial tissue in protection?
Protects underlying surfaces.
What are the functions of epithelial tissue?
- Protection
- Barrier - skin prevents h2o loss and prevents molecules and organisms from entering
- Receptors- like smell and taste
- Diffusion- co2 and o2 in lungs
- Secretory- glands are epithelial tissue
- Absorption- gi tract
What are the classifications of epithelial tissue based on layers?
- Simple - single layer
- Stratified - more than one layer
- Pseudostratified - single layer that appears stratified
What type of epithelium is specialized for stretch?
Transitional epithelium- found in urinary bladder
As it’s stretched, Layers decrease as cells flatten out from shifting over one another
What are desmosomes?
Structures that help attach cells to neighboring cells via glycoproteins. Associated with cells intermediate filaments.
What are tight junctions?
Hold cells together and create a permeability barrier. Keeps substances from passing between cells, so cells can regulate what is secreted or absorbed. Useful for water.
What is the function of gap junctions?
Allow for ions to pass through for inter-cellular communication through small protein channels.
Ex. Intercalated disks, which allow electrical signals (action potentials) to pass immediately from one cardiac cell to another
What are exocrine glands?
Glands with ducts open to the epithelium they are derived from, e.g., sweat glands.
What are endocrine glands?
Glands that do not have ducts and release hormones into the bloodstream.
What are the three main components of the extracellular matrix in connective tissue?
- Protein Fibers
- Ground Substance
- Fluid
What are the three types of protein fibers in connective tissue?
- Collagen - most common protein in the body. Very strong and flexible but nonelastic
- Reticular Fibers- thing collagen lattices that provide framework by filling spaces between organs and tissues
- Elastic Fibers - can return to original shape with help of protein elastin
What is the function of ground substance in connective tissue?
The chemeicals that serve as a backdrop against which fibrous proteins are seen.
What is the difference between loose and dense connective tissue?
Loose connective tissue has a loose network of protein fibers with lots of EC matrix , while dense connective tissue has thick bundles of fibers taking up most EC matrix
What types of cartilage are there?
- Hyaline Cartilage - hyaluronic acid makes it slippery for articulations (nose, rib cage, ends of bones)
- Fibrocartilage - thick collagen fibers. Very tough. Less proteiglycan than hyaline. (Knee, jaw, vertebrae)
- Elastic Cartilage - elastic and collagen gives spring back (ears)
What is the composition of bone?
Cells (osteocytes) and a mineralized matrix consisting of hydroxyapatite (inorganic) crystals and collagen (organic). Ratio is important.
What distinguishes fluid connective tissue?
Its matrix is liquid (plasma), as seen in blood.
What are the characteristics of muscle tissue?
Ability to contract or shorten with force, causing movement.
What are the types of muscle tissue?
- Striated (skeletal and cardiac) vs non (smooth)
- Voluntary (skeletal) vs involuntary (cardiac or smooth)
- Multinucleus (skeletal) or uni (cardiac and smooth)