Chapter 4: The Tissue Level Of Organization Flashcards
Tissue
Group of cells that usually have a common origin in an embryo and function together to carry out specialized activities
Cell Junctions
Contact points between the plasma membranes of tissue cells.
Connexons
Formed by connexins. Tiny fluid filled tunnels formed at gap junctions. Connect neighboring cells.
Lumen
Interior space
Fibroblasts
Connective tissue cells
Avascular
Epithelial tissue that has its own nerve supply
Exchange of Substances in Tissue
Occurs by diffusion between epithelial and connective tissue.
Secretion
Is the production and release of substances such as sweat or enzymes/
Absorption
Is the intake of fluids or other substances such as digested food from the intestinal tract.
Types of Epithelial Tissue: Simple
Simple squamous
Simple Cuboidal
Simple Columnar
Pseudostratified Columnar
Types of Epithelial Tissue: Stratified
Stratified Squamous
Stratified Cuboidal
Stratified Columnar
Transitional
Gland
Consists of epithelium that secretes substances into ducts, or onto a surface.
Eventually into the blood in the absence of ducts.
Tubular Gland
Exocrine Gland with tubular secretory parts
Acinar Gland
Exocrine Gland. Also called: alveolar glands
Rounded secretory portions
Tubuloacinar Gland
Exocrine Gland. Have both tubular and more rounded secretory parts
Connective Tissue Extracellular Matrix
Consists of 2 major elements:
1. Ground substance
2. Fibers
Ground Cells
Component of a connective tissue between the cells and fibers.
Can be: fluid, semi fluid, gelatinous or calcified
Hyaluronic Acid
A viscous slippery substance that binds cells together, lubricates joints and helps maintain the shape of the eyeball.
Chondroitin Sulfate
Provides support and adhesiveness in cartilage, bone, skin and blood vessels.
Dermatan Sulfate
Found in skin, tendons, blood vessels and heart valves.
Keratan Sulfate
Found in bone, cartilage and the cornea of the eye.
Adhesions Proteins
Found in ground substance. Responsible for linking components of the ground substance to one another and to the surface of the cell.
Fibronectin
Main adhesion protein of connective tissue. Binds to both collagen fibers and ground substances linking them together.
Also attached cells to the ground substance.
Elasticity
Ability to return to original shape after being stretched
Stroma
Is the supportive framework of many soft organs like spleen and lymph nodes.
Formed by reticular fibers that are plentiful in reticular connective tissue.
Connective Tissue: General Features
Contains two basics element: Extracellular matrix and cells
Connective Tissue Cells
Embryonic cells called mesenchymal give rise to the cells of CT.
Fibroblasts
Large flat cells with branching processes. Most numerous in CT.
Macrophages
Type of WBC. Two types: fixed and wandering.
Plasma Cells
Or plasmocytes
Most reside in CT, found in GI and resp tract.
Mast Cells
Involved in inflammatory response. Body’s reaction to injury or infection. Can bind to, ingest or kill bacteria.
Adipocytes
Fat cell or adipose cells
Found deep in skin and around organs.
Leukocytes
White blood cells. Found in significant numbers in normal CT.
Embryonic Connective Tissue
Two types: mesenchyme and mucous connective tissue
Mesenchyme
Present in the embryo and fetus.
Chondroctyes
Cells of mature cartilage
Lacunae
Spaces where chondrocytes group in extracellular matrix
Perichondrium
Covering of dense irregular connective tissue. Surrounds the surface of most cartilage and contains blood vessels and nerves that is the source of new cells.
Cartilage
Plays an important role as a support tissue in the body, precursor to bone, forming almost the entire embryonic skeleton.
Red Bone Marrow
Produces RBC, WBC and platelets
Yellow Bone Marrow
Stores triglycerides
Osteon
Basic unit of compact bone
Osteocytes
Mature bone cells
Trabeculae
Spongy bone: Consists of columns of bone contains lamellar, osteocytes, lacunae and canaliculi.
Blood Plasma
Pale yellow fluid.
Consists mostly of water and dissolved substances: nutrients, wastes, enzymes, plasma proteins, hormones, resp gases and ions.
Formed Elements
Suspended in blood plasma
RBC, WBC, platelets.
Erythrocytes
RBC .Transports o2 to body cells and remove co2 from them.
Leukocytes
WBC. Are involved in phagocytes, immunity and allergic reactions.
Thrombocytes
Platelets. Participate in blood clotting.
Epithelial Membranes
Underlying connective tissue layer.
Synoviocytes
Discontinuous layer of cells that compose synovial membranes.
Synovial Fluid
Secreted by synoviocytes.
Lubricates and nourishes the cartilage covering bones at movable joints.
Contains macrophages that remove microbes and debris from the joint cavity.
Striations
Are alternating light and dark bands within fibers that are visible under a light microscopic.
Excitable Cells
Cells that exhibit electrical excitability:
Neurons and muscle fibers.
Excitability
The ability to respond to certain stimuli by producing electrical signals such as action potentials.
Transmits: Acetylcholine
Epithelial Tissue
Covers body surfaces, forms glands
Lines hallow organs, body cavities and ducts
Connective Tissue
Protects and supports the body and organs
Stores energy reserves as fat
Muscular Tissue
Composed of specialized cells for contraction and generation of force that creates heat.
Nervous Tissue
Detects changes in conditions inside and outside the body. Responds by generating nerve action potentials that activate muscular contractions and secretions.
Nerve Impulses
Nerve action potentials
Tight Junctions
Fuse together the outer surface of adjacent plasma membranes to seal off passage ways between adjacent cells.
Desmosomes
Found in outer layer of skin.
Contains plaque
Have transmembrane glycoproteins that extend into intercellular space between adjacent cell membranes and attach cells to one another.
Heidesmosomes
Do no link adjacent cells
Transmembrane proteins are integrins.
Integrins attach to protein laminitis.
Aderens Juctions
Dense layer of protein on the inside of PM. Attaches both membrane protiens and microfilaments of the cytoskeleton.
Adhesion Belts
Extensive zones formed by aderens junctions.
Gap Junctions
Membrane proteins
Epithelial Classification
Coverings or linings. Have 2 characteristics:
1. Arrangement of cells into layer: One or more layers depending on function
2. Shape of cells: Shape depending on function
Simple Squamous
2 Types
- Endothelium: lines heart, blood vessels, lymphatic vessels
- Mesothium: forms epithelial layer of serous membrane
Endocrine Gland
Ductless, secretion is hormones via diffusion into bloodstream. Have far reaching effects and they are distributed through the body via the blood stream.
Exocrine Gland
Contains ducts. Secretion empties onto the surface of a covering or lining epithelium such as skin surface or lumen of hollow organ.
Have limited reaching effects and can be harmful if enter bloodstream.
Structure of Exocrine Glands
- Unicellular: single cell gland. Such as goblet cells, secrete mucus.
- Multicellular: composed of many cells. Such as Sudoriferous: sweat, sebaceous: oil, salivary: saliva
Categorization of Exocrine Glands
- Whether they branch or are unbranched
- Shape of secretory portions of the gland.
Simple Gland
Does not branch
Compound Gland
Does branch
Merocrine Gland
Secretions of this gland are synthesizes on ribosomes attached to the rough ER. Processed, sorted, package by Golgi complex. Released from the cells in secretory vesicles via exocytosis.
Apocrine Gland
Accumulate their secretion product at the apical surfaces secreting cells. Portion of a cell pinches off by exocytosis from the rest of the cells to release the secretion.
Halocrine Gland
Accumulate a secretory product in the cytosol. As the secretory cell matures, it ruptures and becomes the secretory product.
Epithelial Membrane
Flat sheet of pliable tissue that covers or lines a part of the body.
Consists of: epithelial layer and epithelial membranes.
Epithelial Membrane Types
Mucous
Serous
Cutaneous
Synovial
Mesothelium
Secretes serous fluid. This fluid allows organs to glide over one another or slide against the cavity walls.
Myocytes
Muscle tissue
Neuron
Or nerve cell. Sensitive to various stimuli. Convert stimuli into electrical signals called nerve action potentials. Conducts these potentials to other neurons, muscle tissue or to glands.
Neuron 3 Basic Parts
- Cell body
- Dendrites
- Axon
Cell Body
Contains the nucleus and other organelles. If nucleus dies, cell dies.
Dendrites
Short cell process. Major receiving or input portion of a neuron.
Axon
Single thin cell process. Outport portion that conducts nerve impulses towards another neuron or tissue.
Neuroglia
Do not generate or conduct nerve impulses. Play a supporting role for neurons physically and metabolically.
Synaptic Vessels
Store neurotransmitters.