Tissues Flashcards
Tissue
group of similar cells, in close proximity, organized to perform one of more specific functions.
What are the four classes of tissues?
-epithelial
-connective
-muscle
-nervous
What are the 4 functions of epithelia?
-providing physical protection
-control permeability
-provide sensation
-produce specialized secretions
Three specializations of epithelial cells:
-move fluids OVER the epithelium
-move fluids THROUGH the epithelium
-produce secretions
Microvilli
increase surface area, absorption, and secretion
Cilia
move fluids across the epithelium
Simple epithelium
single layer of cells
Stratified epithelium
several layers of cells
Squamous epithelium
flat shaped
Cuboidal epithelium
square shaped
Columnar epithelium
tall shaped
Mesothelium
simple squamous epithelium that lines body cavities
Endothelium
simple squamous epithelium that lines heart and blood vessels
Simple squamous function
absorption and diffusion
stratified squamous function
protects against attacks
simple cuboidal function
secretion and absorption
stratified cuboidal function
make up sweat and mammary glands
simple columnar function
absorption and secretion
pseudostratified columnar epithelium function
involves cilia movement of mucous
stratified columnar function
protection
Endocrine glands
release hormones into interstitial fluid
does not have ducts
Exocrine glands
produce secretions into epithelial surfaces through ducts
ex: breast milk from mild ducts
Merocrine secretion
-produced in the golgi apparatus
-released by vesicles through exocytosis
ex: sweat glands
Apocrine secretion
-produced in the golgi apparatus
-are released by shedding cytoplasm
ex: mammary gland
Holocrine secretion
-released by cells bursting; killing gland cells
-cells are then replaced by stem cells
ex: sebaceous gland
3 characteristics of connective tissue
-specialized cells
-solid extracellular (protein fibers)
-fluid extracellular (ground substance)
Connective tissue:
-connects epithelium to the rest of the body
-provides structure (bone)
-stores energy (fat)
-transports materials (blood)
-has no contact with the environment
Loose connective tissue
has more ground substance; less fibers
ex: fat or adipose tissue
Dense connective tissue
has more fibers and less ground substance
ex: tendons
Connective tissue proper function
connect and protect
fluid connective tissue function
transport
supportive connective tissue function
structural strength
True or false: Collagen fibers are the most common fibers in connective tissue proper
TRUE
ex: ligaments or tendons
Reticular fibers
network of interwoven fibers that is strong and flexible
resists force in many directions
ex: sheaths around organs
Elastic fibers
contain elastin and return to original length after stretching
ex: elastic ligaments of vertebrae
Ground substance
clear, colorless, and viscous
fills spaces between cells and slows pathagens
Areolar tissue
least specialized elastic fibers
holds blood vessels and capillary beds
Adipose tissue
white fat or brown fat
Reticular tissue
supports fibers that support functional cells and reticular organs
Dense regular connective tissue function
-attachment and stabilization
ex: tendons and ligaments that go in the same direction
Dense irregular connection tissue function
-interwoven networks of collagen fibers
-layered in skin, around cartilage and bones
Fluid connective tissue consists of:
blood and lymph
Cartilage
gel-like ground substance
Bone
calcified and used for structure
Three types of cartilage
elastic, fibrocartilage, hyaline
Fibrocartilage characteristics
-limits movement
-prevents bone to bone contact
-pads knee joints
Bone cells (osteocytes)
arranged around central glands within a matric
Periosteum
covers bony surfaces
Membranes
physical barriers that line or cover portions of the body
-created by epithelium + connective tisssue
Mucous membranes
line passageways that have external connections
Serous membranes
-line cavities and are not open to the outside
-have fluid to reduce friction
Cutaneous membrane
skin on the surface of the body
Synovial membranes
-line moving joint cavities
-produce synovial fluid
-protects the ends of bone
3 types of muscle
-skeletal
-cardiac
-smooth
Skeletal muscle cells in appearance are:
striated, voluntary, and multi-nucleated
Cardiac muscle
-cardiocytes
-form branching networks connected at intercalated disks
-striated, voluntary, and single-nucleated
Smooth muscle
-small and tapered
-can divide and regenerate
-nonstriated, involuntary, and single nucleus
Neural tissue is concentrated in:
the brain and spinal cord
Neurons
-nerve cells
-perform electrical communication
Neuroglia
provide homeostatic, structural and metabolic support of neurons
Cell body of the neuron
contains nucleus and nucleolus
Dendrites of the neuron
-short branches extending from the cell body
-receive incoming signals
Axon of the neuron
-long, thin extension of the cell body
-carries outgoing electrical signals to their destination
