Epithelium and Connective Tissue Flashcards
Describe an epithelial tissue
-forms barriers between the inside and outside world
-also forms between compartments within the body
-it covers exposed body surfaces
-lines organs, cavities and tubes
-not vascularized
Do epithelial cells form all glands of the body?
-yes
Describe connective tissues
-links tissues and organs together
->provides structural and metabolic support
->stores energy
->forms the immune system
What are the characteristics of epithelia
-continuous
-avascular but richly innervated
-they rest on a basal lamina
-little extracellular matrix
-polarized
->organelles are not homgenous
->apical and basolateral surfaces differ in polarity and function
Does epithelia have a high regeneration rate?
-yes
->they reproduce all the time
How do you classify epithelia
-one layer of epithelial cells=simple
-more than one layer=stratified
-shape is determined by the apical membrane layer
->shape of the epithelia determines the function
->for example, the lungs will have simple squamous epithelia for gas exchange
->columnar epithelia increases surface area and is present for villi
Describe a simple squamous epithelium
-single layer of flat cells
-lines body cavities(mesotheliu)
->secretes lubricating substance to reduce friction
-lines heart chambers and blood vessels(endothelium)
->controls vessel permeability
-lines sites of gas exchange in the lungs
->allows material to pass by diffusion
Describe simple cuboidal epithelium
-single layer of cells where height equals width
-it is found in glands and their ducts
-lines portions of the kidney
->where secretion and absorption occurs
Describe pseudostratified columnar epithelium
-nuclei appear at multiple levels
-all cells touch basal lamina but not all reach the apical surface
-they are found in the respiratory system
->function is for protection, secretion(mucus) motolity
Describe the stratified squamous epithelium
-stratified cells and outermost layer is squamous
->found where mechanical stresses are severe
-forms outer layer of skin(keratin to deal with dehydration)
->keratin is also a very hard protein
-lines oral cavity, esophagus, anus and vagina
->provides protection against abrasion, pathogens and chemicals
->anything associated with the outside world
Described the stratified cuboidal epithelium
-two to three layers of cells with outermost layer of cells of equal height and width
-it is relatively rare
->line larger ducts of glands
-found in ducts of sweat and mammary glands
->both of these glands are involved in secretion
Describe the simple columnar epithelium
-single layer of cells that are taller than they are wide
-lines the digestive tract
->provides absorption, protection and can secrete mucus and enzymes
Describe the stratified columnar epitheliym
-two to multiple layers of cells
->height of outer layer of cells greater than the width
-relatively rare intermediate location
->associated with ducts where there is change in function
Describe transitional (urinary) epithelium
-multiple layers of cells
-outermost cells large and dome shaped
-changes appearance with stretching
-these are only found in urinary tract
->expands and protects
Describe the formation of glands
-it forms at the epithelia cells
->it forms in the connective tissue and is usually cuboidal
->the cells in the gland release some sort of secretion
->if the cells are associated with a duct, it will be referred to as an exocrine gland
-if the connecting cells dissapear, secretions are released into blood vessels
->it will be referred to as an exocrine gland
What are the characteristics of connective tissue
-cells are dispersed in abundant ECM
->determines physical property of the tissue
-matrix=fibres(fascia), ground substance(bones), fluid(plasma)
-provides structural and metabolic support to other tissues and organs
-link different tissues together
-link tissues and organs together to generate overall body form(fascie)
-aids with wound repair
-protects body against infection
How do we classify connective tissue
-specific cell types
-types of fibres
-density of fibres
Proper
->many types of cells and fibres in a syrupsy matrix
Fluid
->distinctive p0pulation of cells suspended in a watery matrix
Supporting
->a more homegenous pupulation of cells and matrix
->contains closely packed fibres
What are the basic structures of connective tissue proper
Ground substance
->hydrated gel(provides compression strength)
Fibres
->collagen, elastic, reticular
Adipocyte
->stores lipid reserves
Macrophages
->ingest debris and function in immune response
->all plasma and mast cells are important for immune function
What is the origin of all connective tissue
-mesenchyme
Describe connective tissue proper: loose connective tissue
-packing material
->fills spaces between organs, providing cushioning and support
-relatively dew fibres
-three types
->areolar
->adipose
->reticular
Describes connective tissue proper: adipose connective tissue
-most common and least specialized
->links together other tissues and organs throughout body
->often found with epithelium
Describe CT proper: Adipose connective
-fat tissue
->forms deposits in specific areas of the body
->functions in padding, insulation and energy storage
Describe CT proper: dense connective tissue
-thick layer of tissue with an abundance of fibers
-relatively little ground substance and few cells relative to loose connective tissue
-regular and irregular
Describe dense regular connective tissue
-fibers aligned in one direction
-forms tendons(muscle to bone) and ligaments(bone to bone)
-different from skeletal tissue: nuclei of fibroblasts vs muscle fibers
Describe dense irregular connective tissue
-fibers unaligned and run at a variety of angles
->great for strength-resistance to forces
-forms dermis of skin, organ capsules, sheaths around bones, muscles and nerves
