Tissue Types Flashcards
What are the four basic tissues of the body?
Epithelial, Connective Tissue, Muscle, Nerve
What does epithelial tissue do? (4)
Forms barriers between inside and outside world and between compartments of the body, covers exposed body surfaces, lines hollow organs/ body cavities/ ducts of glands, and forms glands
What does connective tissue do? (4)
Links tissues and organs together, stores energy, forms immune system, provides structural and metabolic support
What does muscle tissue do? (3)
Specialized for contraction, generates force to produce motion of body parts and move substances through blood vessels and hollow organs, and maintains body temp
What does nervous tissue do? (2)
Receives/processes/integrates signals from within the body and from external environment, generates and transmits impulses that control and integrate various functions
What are the characteristics of epithelia? (5)
Avascular, continuous, rest on basal lamina, little ECM, polarized (apical and basolateral surfaces differ)
How are epithelia named? (2 factors)
According to number of layers of cells (1 is simple, and more than 1 is striated)
According to shape of cells in the outermost layer (squamous is flat, columnar, cuboidal)
What is simple squamous epithelium?
Single layer of flat cells (apical-basal distance short)
Lines body cavities (mesothelium)
Lines heart chambers and blood vessels (endothelium)
Lines sites of gas exchange in lungs
What is simple cuboidal epithelium?
Single layer of cells with height equaling width (cuboidal)
Found in areas where secretion or absorption occurs (have room for machinery)
Found in glands and their ducts
Line portions of kidney tubule system
What is simple columnar epithelium?
Single layer of cells, they are taller than they are wide (provide protection)
Line digestive tract, fallopian tubes and excretory ducts such as those from gall bladder
What is stratified squamous epithelium?
Stratified cells, outermost layer is squamous
Found where mechanical stresses are severe
Forms outer layer of skin, lines rectum/ anus/ mouth/ esophagus and vagina
Keratin- dehydration
What is stratified cuboidal epithelium?
Two to three layers of cells, outermost layer has cells of equal height and width
Relatively rare, line ducts of larger exocrine glands
Found in ducts of mammary and sweat glands
What is stratified columnar epithelium?
Multiple layers of cells, outermost layer has cells with greater height than width
Relatively rare- found in large excretory ducts and portions of pharynx, urethra and anus
What is pseudostratified columnar epithelium?
Nuclei appear at multiple levels, all cells touch basal lamina but not many touch luminal surface
Found in respiratory system and male reproductive tract
What is transitional epithelium?
Multiple layers of cells, outermost cells are large and dome shaped
Found only in urinary tract (for expansion and retraction of bladder)
What are glands?
Composed of epithelial cells and form by growth of epithelial cells into underlying connective tissue
Exocrine glands release secretions through ducts onto epithelial surfaces
Endocrine glands lack ducts and secrete hormones into the blood
What happens in the formation of glands?
Epithelial cells grow into underlying connective tissue
Exocrine: secretory cells remain connected to surface by a duct
Endocrine: connecting cells disappear, secretions released into blood vessels
What are the three mechanisms of secretion?
Merocrine: normal exocytosis (vesicles fuse to apical surface and release secretory contents)
Apocrine: apical surface pinched off
Holocrine: entire cell released, cell IS secretory products
What are the three classifications (and 6 subclasses) of connective tissue?
Connective tissue proper (loose and dense)
Fluid connective tissue (blood and lymph)
Supporting connective tissue (cartilage and bone)
What are the characteristics of connective tissue?
Relatively few cells and abundance of ECM
What is in the connective tissue matrix?
Ground substance: highly hydrated gel
Fibres: collagen (form bundles that provide tensile strength), reticular (form branching network that supports cells), elastic (thin branching fibres that function like rubber bands)
What do fibroblasts and macrophages do in the connective tissue structure?
Fibroblasts secrete ground substance and fibres
Macrophages ingest debris and function in immune response
What is the classification of connective tissue based on?
Density of fibers, types of fibers, preponderance of specific cell type
What is mesenchyme?
Connective tissue, found in developing embryo, remains as stem cells in adult tissue
What is loose connective tissue?
Packing material- fills spaces between organs, provide cushioning and support
Abundance of ground substance or cells
Relatively few fibers
3 types: areolar, adipose, reticular
What is areolar connective tissue?
Most common and least specialized connective tissue
Links together other tissues and organs throughout body
Open framework- ground substance and elastic fibers
What is adipose connective tissue
Fat tissue
Forms deposits in specific areas of the body (determined largely by genetics)
Functions in padding, insulation and energy storage
What is dense connective tissue?
Abundance of fibers, relatively little ground substance and few cells
What is dense irregular connective tissue?
Fibers unaligned and run at variety of different angles
Forms dermis of skin, organ capsules, sheaths around bones and muscles and nerves
What is dense regular connective tissue?
Fibers aligned in one direction
Forms tendons (muscles to bones) and ligaments (bone to bone)
What are membranes?
Composed of epithelium and connective tissue
Lines surfaces, cavities, and hollow organs
What are fluid connective tissues?
Blood- composed of cells and plasma, plasma forms fluid matrix
Lymph- composed of lymphocytes and lymph fluid, lymph fluid is a dilute solution of proteins and excess interstitial fluid
What are supporting connective tissues?
Consists of cartilage and bone
Extensive incompressible matrix
Support soft tissues of the body
What are characteristics of muscle tissue?
Elongated cells, specialized to contract and generate force
What are the three types of muscle tissue?
Skeletal- attaches to bones, striated (pattern of bands), voluntary contraction
Smooth- associated with viscera, non-striated, involuntary contraction
Cardiac- only in heart, striated, involuntary contraction
What is skeletal muscle?
Forms long cylindrical multinucleated tubes
Exhibits distinct cross banding patterns
Stabilizes and moves the articulated skeleton
What is smooth muscle?
Cells short, spindle shaped, contain single nucleus, not striated, forms walls of blood vessels and hollow organs, specialized for slow sustained contractions
What is cardiac muscle?
Cells short, branched, striated and contain single nuclei
Specialized for continuous rhythmic contraction in one direction (apical to tubes)
What are the characteristics of nervous tissue?
Highly asymmetrical cells with long cytoplasmic processes
Transmit electrical signals via ionic conductions
Axon, dendrites, cell body, etc
