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)
What is the major cell type in nervous tissue?
Neuron - sends action potentials. Supports cells called neuroglia (insulate and nourish neuron)
What type of tissue covers structures or lines cavities?
Membrane.
What are the three types of membranes?
- Mucous
- Serous
- Synovial
What is inflammation?
The response to tissue damage occurring in response to any offensive assault to the body.
What are the classic signs of inflammation?
- Redness - vasodilation (allows WBCs to get to site quicker)
- Heat - vasodilation
- Swelling - increased permeability of bv (allows wbc to enter tissues and water follows)
- Pain - stimulate pain reception (prevent re-injury)
- Disturbance of function
What are mediators of inflammation?
Chemicals released by injured tissue, e.g., histamine and kinins and bradykinin (vasodilation and capillary permeability and pain signaling)
What is the difference between regeneration and replacement in tissue repair?
Regeneration is the substitution of the same type of cells, while replacement involves a different type of tissue (causes scar). Which method occurs depends on type of cells.
What are labile cells?
Cells that continue to divide throughout life and can regenerate if injured.
Ex. Skin and mucous membranes
What is tissue repair?
The substitution of viable cells for dead and/or damaged cells after an initial injury and inflammation.
Tissue repair can occur by regeneration or replacement.
Define regeneration in the context of tissue repair.
New cells are the same type as those that were destroyed.
What occurs during replacement in tissue repair?
A different type of tissue replaces the lost tissue, leading to scar formation and some loss of tissue function.
What are labile cells?
Cells that continue to divide throughout life and can regenerate if injured. Examples include skin and mucous membranes.
What are stable cells?
Cells that do not actively divide once mature but can undergo mitosis due to injury. Regeneration. Examples include liver and glands.
What are permanent cells?
Cells that exhibit little or no mitotic ability once mature and undergo replacement if injured, generally by connective tissue. Examples include neurons, skeletal, and cardiac
What is a key characteristic of skin repair?
Blood fills the wound and a clot is formed, containing fibrin that binds the edges together.
What role do neutrophils play in the inflammatory response during tissue repair?
They fight bacterial infection and die in the process, creating pus.
What happens to the epithelium during skin repair?
New epithelium is formed by regeneration, migrating under the scab until it meets in the middle and it is restored
What do macrophages do during tissue repair?
They remove old dead tissue, including dead neutrophils.
What is the role of fibroblasts in tissue repair?
They produce extracellular matrix components and help form capillaries in area of repair
What constitutes granulation tissue?
Fresh tissue replacing the clot, composed of fibroblasts, collagen, and capillaries.
What happens to granulation tissue over time?
It is gradually replaced by normal connective tissue.
How does a scar change over time?
It is red initially due to vascularization and later becomes white as collagen accumulates and blood vessels are compromised.
True or False: Smooth muscle has a significant ability to regenerate after injury.
False.
Fill in the blank: The inflammatory response brings in fighters of infection, such as _______.
neutrophils and macrophages.
What are simple epithelial tissues good for
Diffusion - alveoli
Absorption - intestines
What are stratified tissues good for
More protection - epidermis
Two types of stratified squamous epithelium
Moist - surface cells have nucleus-mouth, esophagus, urinary tract
karatinized - surface cells are dead, epidermis of the skin (much tougher and drier)
Both slough off the outer layer of cells
Cell connections of lateral and basal surfaces
Mechanically hold cells together (epidermis)
Help form a permeability barrier (urinary bladder)
Provide intercellular communication (intercalated disks)
Half of a demosome
Hemidesmosomes- attaches cell to basement membrane and through the cells intermediate filaments
What’s it called when epithelial tissue cells tough one another
Contiguous
Causes nutrients and gases to diffuse through basement membrane to reach the cells
Avascular- most metabolically active cells are closest to the basement membrane
Flat scale like cells
Squamous
Equal in height and width cells
Cuboidal
Taller than wide cells
Columnar
Cells that secrete mucus in cuboidal or columnar cells
Goblet cells
Glands
Secretory organs derived from epithelial tissue, with a supporting network of connective tissue
Divisions of exocrine glands
Merocrine- secrete water substances w no loss of cellular material - sweat
Apocrine glands - secrete fragments of gland cells - mammary
Holocrine - she’d entire cells - sebaceous (oil)
Qualities of connective tissue
Cells are separated
Contain an extracellular matrix (classified by this feature)
Abundant throughout the body
Specialized cells the produce maintain or destroy the extracellular matrix in connective tissue
Blasts - create (osteoblast)
Cytes- maintain (chondrocyte)
Clasts- break down (osteoclasts)
Genetic ct cells of many ct types
Fibroblasts/cytes
Example cell types of connective tissue matrix
Adipose
Mast cells
WBC’s
Macrophages
Marfans syndrome
Disorder where individual does not produce enough elastic fibers. Can affect eyes, hearts skeletal system, nervous system, and lungs
Two molecules of ground substance
Hyaluronic acid - slippery long polysaccharide chain
Proteoglycans monomers - protein core with glycogen side chains (chondroitin suflate)
Proteoglycan aggregate - core of a monomer can bind with hyaluronic acid (traps water and gives tissues ability to bounce back)
Embryonic connective tissue
Mesenchyme- source of all adult connective tissue
Mucus- remains undifferentiated. Only in umbilical cord. Aka whartons jelly
Connective tissue proper
Loose connective tissue and dense
Loose connective tissue
Areolar
Adipose
Reticular
Areolar
Protein fibers (collagen, reticular and elastic fibers) form lacy network to make up packing material of body. Surrounds organs and connects skin to underlying tissues.
Adipose
Consisted of adipocytes->
Yellow (white at birth) - most abundan. Protection, insulation, heat
and brown - found in specific areas, heat production
Brown in neck and shoulder in infants
Neck, kidney, heart in adults
Reticular
Forms framework or scaffolding for cells to hang off of- supports tissues like the liver and spleen
Dense connective tissues
Dense regular - collagen fibers arranged in one direction (gives resistance to stretch)- tendons and ligaments
Defense irregular - collagen fibers in random network or sheets - dermis, strong blood vessels
Cartilage cells
Chondrocytes
Chindrocytes
Live in lacunae with rigid cartilage matrix
What is cartilage made of
Collagen and proteoglycans (that trap water) and other molecules. Avascular.
Can be compressed and spring back into shape.
Perichondrium
Layer of dense irregular ct that surrounds cartilage.
Muscle cells
Myocytes or myofibers
Parts of a neuron
Cell body - contains nucleus
Axon - conducts impulses away. 1 per
Dendrite - receive impulses. Many per neuron
Types of neurons based on dendrites and axons
Multipolar
Bipolar
Unipolar
Mucous membrane
Made up of epithelium on a thick layer of Areolar. Line cavities that are open to outside of body (digestive, excretory, respiratory,). Protection, absorption and secretion
Serous membrane
Made up of simple squamous and a delicate layer of Areolar. Line trunk covities and cover organs inside. Produce serous fluid. Pericardial, pleural, and peritoneal.
Synovial membrane
Like freely movable joints. Produce synovial fluid which makes joints slippery
Purpose of inflammatory response
Mobilized the body’s defenses
Isolates and destroys microorganisms
Removes foreign material and dead cells
WBCs for inflammation
Neutrophils attack
Macrophages clean up
Clotting agents clot
