Unit 2 - Tissues Flashcards
Define tissue
Collections of specialized cells with specific functions
Name the four major types of tissue found in the human body.
Epithelial
Connective
Neural
Muscular
Describe the general characteristics of epithelial tissues.
Epithelial tissue line digestive, respiratory, urinary and reproductive tracts. Also, fluid or gas-filled internal cavities and passageways such as the chest cavity, inner surfaces of blood vessels and chambers of heart.
What do epithelial tissues lack?
Blood vessels
How many cell layers do epithelial tissues have?
1 or more
What is the upper surface of epithelial tissues exposed to?
The environment
4 basic functions of epithelial tissues
Provide physical protection
Control permeability
Provide sensation
Produce specialized secretions
Distinguish between simple epithelium and stratified epithelium.
A single cell layer is simple epithelium. Multiple cell layers is stratified epithelium.
Explain how the structure of simple squamous epithelium influences its function.
Simple squamous epithelium is very permeable due to its flat, thin structure.
Where is simple squamous epithelium found?
Alveoli of the lungs
Function of simple squamous epithelium
Allows the passage of materials by rapid diffusion or transport of substances inside where protection is not important and these cells can also secrete a lubricating substance
Where is simple cuboidal epithelium found?
Liver
Function of simple cuboidal epithelium
Specializes in secretion and absorption
Where is simple columnar epithelium found?
Lining of the GI tract
Function of simple columnar epithelium
Absorption and mucus secretion
Where is pseudostratified columnar epithelium found?
Respiratory tract
Function of pseudostratified columnar epithelium
Secrete and propel mucus
Where is stratified squamous epithelium found?
Epidermis in the palms of hands and soles of feet
Function of stratified squamous epithelium
Resist abrasion, retards water loss from the skin, resists penetration of pathogenic bacteria
Where is stratified cuboidal epithelium found?
Sweat glands in the ovarian follicles
Function of stratified cuboidal epithelium
Secrete sweat, involved in sperm production
Where is stratified columnar epithelium found?
Pharynx
Function of stratified columnar epithelium
Providing protection and secretion
Where is transitional epithelium found?
Urinary bladder
Function of transitional epithelium
Stretchable, blocks diffusion, prevents leaking
Describe a gland
Glands are cells, or collections of cells, specialized for secretions ranging from sweat to hormones
Describe an exocrine gland
An exocrine gland release secretions into ducts which carry the secretions onto an epithelial surface such as the skin, or an internal passageway that communicates with the outside environment
Describe an endocrine gland
An endocrine gland releases hormonal secretions into interstitial fluids
What do merocrine glands have?
Vesicles that release their secretion by exocytosis
What are apocrine glands primary mode of secretion?
Primarily merocrine mode of secretion
What do holocrine glands cells do?
Accumulate a product and then the entire cell disintegrates
Describe the general characteristics of connective tissue.
Connects the epithelium to the rest of the body via the reticular layer of the basal lamina. Other connective tissues provide structure (bone), store energy (fat), and transport materials throughout the body (blood).
Define matrix
Extracellular material composed of fibrous proteins and gel
Define ground substance
An amorphous gel-like substance in the extracellular space that contains all components of the extracellular matrix except for fibrous materials such as collagen and elastin.
List the three major types of connective tissue cells.
Fibroblast
Mast cells
Macrophages
Describe fibroblasts
Most abundant cell type; found in all connective tissues proper; secrete proteins and polysaccharide derivative hyaluronan (cement that locks cells together)
Describe mast cells
Mast cells stimulate inflammation after injury or infection; basophils are mast cells carried by blood to damaged tissues
Describe macrophages
Large, amoeba-like cells of the immune system which eat pathogens and damaged cells
What is collagen?
Most common fibers in connective tissue proper; long, straight, and unbranched; strong and flexible; resists force in one direction
What is elastin?
A protein that is branched and wavy; returns to original length after stretching
Explain the difference between loose connective tissue and dense connective tissue.
Loose connective tissues are the packing materials of the body. Dense connective tissues have high numbers of collagen fibers.
What do dense regular connective tissue have?
Tightly packed, parallel collagen fibers
What do irregular connective tissues have?
Interwoven networks of strengthening fibers
Distinguish between elastic and reticular connective tissues.
Elastic tissues are mostly elastic fibers. Reticular tissue has a 3D network of supportive fibers.
Explain why injured loose connective tissue and cartilage are usually slow to heal.
Dense and closely packed
Lack a direct blood supply
Nutrients take a long time to reach the cells
3 major types of cartilage
Hyaline
Elastic
Fibrocartilage
4 features of hyaline cartilage
Translucent and no prominent fibers
Provides stiff, flexible support
Reduces friction between bones
Found in synovial joints, rib tips, sternum, and trachea
3 features of elastic cartilage
Tightly packed elastic fibers
Supportive, bends easily
Found in the external ear and epiglottis
3 features of fibrocartilage
Very dense collagen fibers
Limits movement and prevents bone-to-bone contact
Pads knee joints, pubic bones, and intervertebral discs
Describe how bone cells are organized in bone tissue.
In cortical bone, cells and matrix surround vertically oriented blood vessels in long bones
3 major components of blood
Erythrocytes
Leukocytes
Platelets
What are erythrocytes?
Red blood cells
What are leukocytes?
White blood cells
What are platelets involved in?
Clotting
What do muscle tissues create movements involved in?
Body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation
What are muscle tissues?
Elongated cells that are specialized to contract in response to stimulation
Features of skeletal muscle
Has long threadlike cells and most of them attach to bone (exception: tongue, esophagus, facial muscles, sphincters); striated; contain multiple nuclei in 1 muscle fiber; under voluntary conscious control
Features of smooth muscle
Does not have striations; always involuntary; fibers not very long; thick in the middle and tapered in the end; has 1 centrally located nuclei; found in the digestive tract, respiratory tract, urinary tract, blood vessels, uterus; propels the contents of the organ and regulates the diameter of blood vessels
Features of cardiac muscle
Limited to the heart only; myocytes and cardiomyocytes are much shorter; fibers are branched; has notches at the end; 1 centrally located nuclei that is light around it because it contains glycogen; needs a lot of localized energy it can use to beat constantly; the end of cardiac muscle cells have intercalated discs that join 1 cell to the next; involuntary
3 types of muscle
Skeletal
Smooth
Cardiac
What is nervous tissue specialized for?
Specialized for communication by electrical and chemical signals
Explain the differences between neurons and neuroglial cells.
Neurons transmit coded information rapidly to other cells
Neuroglia protect and assist neurons
List the 4 types of membranes
Epithelial
Synovial
Serous
Mucus
Where are epithelial membranes found?
Line cavities that are exposed to the external environment and internal organs; exist in the hollow organs of the digestive, respiratory, and urogenital tracts
Where are synovial membranes found?
Lines joint cavities
Where are serous membranes found?
Covers organs and lines blood vessels and heart
Where are mucus membranes found?
Lines passageways open to external environment; nasal passageways
What 9 cell types are in fibrous connective tissue?
Fibroblasts Macrophages Leukocytes Plasma cells Mast cells Adipocytes Mesenchymal cells Malenocytes Microphages
Characteristics of muscular and nervous tissue
Excitability
Membrane potential
What is excitability?
A characteristic of all living cells
What is membrane potential?
Electrical charge differences that occur across plasma membranes
4 signs of inflammatory response
Swelling
Redness
Heat
Pain
