Chapter 4: Introduction to Tissues Flashcards
4 basic categories of tissues
- Epithelial Tissue: covers and lines all body surfaces/cavities and are the major tissues of glands
- Connective Tissue: connects all other tissues in the body to one another
- Muscle Tissue: cells that can contract & generate force.
- Nervous Tissue: cells that can generate, send, and receive messages
Epithelial Tissue
Epithelial Tissue: covers and lines all body surfaces/cavities and are the major tissues of glands
- Function: covers/protects, absorbs, secretes, filters
Connective Tissue
Connective Tissue: connects all other tissues in the body to one another
- Function: support, protection, insulation, transportation
Muscle Tissue
cells that can contract & generate force.
- Function: movement
Nervous Tissue
cells that can generate, send, and receive messages
- Function: control & communication
Extracellular Matrix (ECM)
composed of the substances in a tissue outside the cell that consists of extracellular fluid, ground substance, & protein fibers.
Cell junctions
cells in tissue that are often linked to one another by integral proteins in neighboring cells that form structures.
-Attach cells
Tight junctions
intercellular junction that holds cells tightly together in tissue and make the space between them relatively impermeable to water and many solutes (interweave/lock together like a zipper).
- Function: keep things from moving between cells
- between cells of blood vessels (prominent where the prevent substances from leaving the blood)
-nonfunctional: allow fluid/solutes in blood to leak out of the vessel into the ECF & the function of the epithelia as a barrier would be impaired
Desmosomes
intercellular junction that hold cells together in a tissue to increase the tissues resistance to mechanical stresses (acts more like a button).
- Function: strength
- Epithelia of skin (prominent in cells with lots of mechanical stress)
-Nonfunctional: skin would not be resistant to mechanical stresses & could break down easily since cells can’t stick together well under stress
Gap junctions
intercellular junctions that connect the cytosol of neighboring cells and allow water and solutes to pass between cells. Function: allow cells to talk
- Cardiac muscles (prominent in cells that can communicate w/ electrical signals)
- Nonfunctional: cells would lose a means of communication with each other, since gap junctions allow rapid communication
Epithelial tissue
a tissue type composed of epithelial cells and a thin basal layer of ECM; function to cover/ line all body surfaces and hollow organs. Primary acts a barrier between the body and the external environment and between our organs and fluid-filled cavities.
- Avascular/ attached to basement membrane / always have a free surface
- Absorption, Secretion–>passive or active transport
Structure of Epithelial tissues
Apical Surface(top): the “free edge” of an epithelial cell/tissue
Basal Surface(bottom): the edge attached to the deeper cells
Basement membrane: two layers of ECM- basal lamia and reticular lamina- that anchor an epithelial tissue to the underlying connective tissue.
Number of cell layers
Simple Epithelia: type of epithelia tissue composed of only a single layer of cells and the underlying basal lamina
Stratified Epithelia: type of epithelia tissue composed two or more layers and the underlying basal lamina
Shape of Epithelia cells
Epithelia cells can take on THREE basic shapes. The shape of the nucleus reflects the shape of the cell.
- Squamous Cell: flattened. Fast absorption & diffusion
- Cuboidal Cell: short (wide as they are tall). Absorb nutrition & produce secretions
- Columnar Cell: column shape that is tall & elongated. Absorb nutrition & produce secretions
Transitional: shape of its cell represented a “transition” between cuboidal and squamous cells
Simple Squamous Epithelia:
diffusion transport can occur rapidly/easily of oxygen, carbon dioxide, fluids & ions.
Located: pleura, lining blood vessels
Function: Filtration & diffusion
Simple Cuboidal Epithelia:
some passive transport but mostly active transport.
Located: kidney & thyroid glands,
Function: absorption & secretion of mucus and other substances
Simple Columnar Epithelia
usually located in stomach, small intestine, gallbladder & kidney tubules
- Function: Absorption and secretion
Pseudostratified Columnar Ciliated Epithelia
epithelia cells touching the basement membrane, but not all cells reach the apical surface
-Function: located in trachea/airway; moves mucus across cell surface, protection
Stratified squamous Epithelia:
located in vagina/esophagus/anus/mouth/throat. nonkeratinized or keratinized (top layer is still living)
-Function: protection from mechanical stresses
Transitional Epithelia
consisting of multiple layers of epithelial cells that can contract & expand. Tissue can stretch
-Urinary bladder, ureters, urethra
Glandular Epithelium
makes and secretes a particular product (classified by shape & how they release their products)
Exocrine glands & endocrine glands
Exocrine gland
A gland that secretes a product through a duct to the external surface (apical) of the body or into a hollow organ that opens to the outside of the body (respiratory/ gastrointestinal/ genitourinary tract).
Secretions have local actions–>only affects the cells in their general vicinity
Example: sweat glands/ salivary glands
Endocrine gland
A gland that secretes hormone(s) directly into the bloodstream or extracellular fluid to influence the functions of distant target cells (cell-cell communication)
Areolar(loose) Connective Tissue
spread fibers results in loose connective tissue.
-Location: Capillaries & nerves, hollow organs
Dense Regular Connective Tissue:
thick collagen fibers arranged parallel to one another to form bundles, resist stress well in only ONE direction, all lined up together.
-Location: Tendon & ligament
Dense Irregular Connective Tissue
irregular bundles of collagen fibers, the organization makes it strong and allows it to resist tension in all three planes.
Location: Dermis, around joints & organs
Adipose(fat)Connective Tissue
made of adipocytes; stores fats.
Function: insulation, warmth, shock absorption, protection, & cushioning, energy reserve
Reticular Connective Tissue
net like tissue that is produced by surrounding fibroblasts
Location: lymph nodes & spleen,
Specialized Connective Tissues
more specific functions than connective tissue proper
- Blood
- Bone
- Cartilage
Blood Connective tissue
the fluid connective tissue consisting of formed elements and plasma
Erythrocytes: (red blood cells) bind & transport oxygen
Leukocytes: (white blood cells) immune cells
Platelets: blood clotting
Cartilage Connective Tissue
its tough, flexible tissue that absorbs shock & is resistant to tension, compression, shearing forces. It’s found in joints between bones, ears, nose, and certain respiratory passages. -avascular
-Cells are found in lacunae and has chondrocytes
Hyaline Cartilage: most abundant, smooth surface for joints, structural support (airway/rib cage), growth plates
Elastic Cartilage: located in two places; Ear & epiglottis. Flexible
Fibrocartilage: found in body that needs to resist stress. Vertebral, meniscus, disc in jaw, separator of pubic bone
Bone Connective Tissue
hard matrix (deposits of Ca++ salts and lots of collagen) (looks like tree trunk)
- Function: support, protection, storing calcium slats, housing bone marrow
- Mature bone tissue contains three cell types:
Osteoblasts: Bone builders
Osteocytes: mature bone; monitors & maintains
Osteoclasts: break down bone
Nervous Tissue
makes up the majority of the brain, spinal cord, & nerves
Two Major Nervous Cell Types
Neurons: generate, conduct, & receive information in the form of electrical signals called nerve impulses
Neuroglia: supportive cell that anchor neurons and blood vessels in place; much smaller cells surrounding neurons
-Purpose: anchors neurons and blood vessels in place, monitors the composition of the ECF., speed up the rate of nerve impulse transmission, & circulates the fluid that surrounds the brain and spinal cord
Basic Structure of Neuron
Cell Body(soma): central portion of neuron that contains the nucleus & bulk of the organelles. - Function: Receives signals, it’s the main metabolic & nutritional center of the cell as well
Axon: a single extension “arm” of a neuron
- Purpose: moves nerve impulse AWAY from the cell body to target cell (cell-cell communication)
Dendrites: the other “arm” radiating from the cell body; typically, short & highly branched.
- Purpose: receive messages from the axons of other neurons & BRINGS impulses to the cell body
Serous Membrane (serosae)
lines cavities that do not open to the outside such as the pleural, pericardial, and peritoneal body cavities. Secretes serous fluid (thin/watery fluid)
Parietal Layer: outer layer, it’s in contact w/ body wall
Visceral layer: inner layer, covers the organs within cavity
-Purpose: reduce friction–>lubrication
Mucous Membrane (mucosae)
lines all body passages as part of the walls of hollow organs that open to the outside of the body, including respiratory passages, mouth, nasal cavity, digestive tract, & the male/female reproductive tracts. Secretes mucus (made by goblet cells)
-Purpose: protection
