Lecture 4- Basic Tissues Flashcards
what are the 4 basic tissues?
epithelia
connective tissue
muscle
nervous
where is epithelia located?
covers surfaces
lines cavities and tubes
forms glands
examples of where epithelia is found
skin, mouth, tubes (blood vessels)
what are the 4 important characteristics of epithelia?
attachment (loosely packed cells supported by a basement membrane)
avascularity (contains no blood vessels)
regeneration
polarity (apical and basal)
where does the apical membrane of epithelia face
lumen
where does the basal side of epithelium face
basement of the membrane
what is classification of epithelia based on?
number of cell layers and the shape of cells
simple epithelium
one layer
stratified epithelium
two or more layers
what are the 3 shapes of epithelia
squamous (flat)
cuboidal (cube)
columnar (rectangle)
what are the 6 main types of epithelia?
Simple squamous
Keratinised stratified squamous
Non keratinized stratified squamous
Simple cuboidal
Simple columnar
Pseudostratified stratified columnar with goblet cell
2 features of simple squamous
flat cells- oval shaped nuclei
one layer of cells
what is the major function of simple squamous
exchange of nutrients and gases
where is simple squamous located?
blood vessels and alveoli (smooth flow for less resistance)
3 features of keratinised stratified squamous
-flat surface cells with oval-shaped nuclei
-many layers
-keratin sits on the upper surface of the epithelium
what is the major function of keratinised stratified squamous
protection, barrier, waterproof
where is keratinised stratified squamous epithelium found
skin, gums and hard pallet where more abrasion occurs
2 features of non-keratinised stratified squamous epithelium
flat surface cells with oval-shaped nuclei
-many layers
major function of non keratinised stratified squamous epithelium
protection, barrier
where is non keratinised stratified squamous located
oral cavity, oesophagus
2 features of simple cuboidal epithelium
square cells with round nuclei
one layer
what is the major function of simple cuboidal epithelium
secretion and absorption
where is simple cuboidal epithelium located
glands and kidney tubules
what is microvilli
projections of the cytoplasm increasing the SA for absorption
what are the 2 features of simple columnar epithelium
tall cells with oval, basally located nuclei
one layer
what is the major function of simple columnar epithelium
absorption and secretion
4 features of pseudostratified ciliated columnar epithelium
-tall cells
-appears stratified some cells don’t reach the free surface
-all cells touch the basement membrane
-cilia and goblet cells
what are the functions of pseudostratified ciliated columnar epithelium
mucociliary escalator (mucus from the goblet cells will trap any inhaled particles and the cilia will waft the mucus toward the pharynx)
where is pseudostratified cilitated columnar epithelium found?
trachea and large respiratory airways
what are intercellular junctions
specialised areas of that bind one cell to another
what are the 4 examples of intercellular junction
desmosomes
hemidesmosomes
tight junctions
gap junctions
desmosomes
very strong connections between adjacent cells
-resist stretching and twisting
hemidesmosomes
-attach cells to the basement membrane
-stabilise the position and anchor cell to the underlying tissue
tight junctions
interlocking proteins tightly bind cells together near the apical edge
-prevent the passage of water and solutes between cells (e.g. in digestive tract)
gap junctions
cells held together by an interlocking membrane protein containing a central pore
-allows movement of small molecules and ions between cells -found in cardiac muscle
what are the 6 main functions of connective tissue
-Forms a structural framework for the body
-Supports, surrounds and interconnects other tissue
types
-Protects delicate organs
-Transports fluids and dissolved materials
-Stores energy reserves
-Defends body from microorganisms
what does connective tissue consist of?
cells within an extracellular matrix
what is the main cell type found in connective tissue?
fibroblasts
fibroblasts
synthesize proteins found in the extracellular matrix
what other cells are found in connective tissue?
adipocytes (fat cells)
macrophages (engulf foreign particles)
mast cells (immune response)
what 3 things does the extracellular matrix in connective tissue consist of ?
ground substance
tissue fluid
protein fibers: collagen (most abundant for tensile strength and support) , reticular (type of collagen), and elastic
ground substance
made up of carbs and proteins and binds to water
-main function is hydration
what are the two types of connective tissue
-specialized connective tissue
-connective tissue proper
3 examples of specialized connective tissue
blood, cartiallage and bone
blood as a specialised connective tissue
red blood cells suspended in plasma
-plasma that acts as the extracellular matrix
bone as a specialised connective tissue
bone cells suspended within a background matrix that is hardened with calcium and phosphate
cartilage as a specialised connective tissue
chondrocytes (cartilage cells) in a matrix that is less solid than bone but more fluid than blood
what is the main function of connective tissue proper
packaging and support for other tissues
how is connective tissue proper classified
-according to type, arrangement and abundance of ground fibres, cells and ground substance
what are the 3 connective tissue proper
-loose areolar/ loose irregular
-dense irregular
-dense regular
what does loose areolar connective tissue contain?
-less cells and more ground substance
-few fibres
-variety of cells: fibroblasts, adipocytes and macrophages
where is loose areolar connective tissue found
-under the epithelium that covers and lines the body surfaces
what does dense irregular connective tissue contain?
-little ground substance
-many collagen fibre bundles arranged in all directions ( can handle forces from all directions)
-few cells (many fibroblasts)
function of dense irregular connective tissue
resists excessive stretching and distension
where is dense irregular connective tissue found
the dermis (so the skin can be pulled back)
what does dense irregular connective tissue contain?
-little ground substance
-densely packed bundles of collagen fibers arranged in parallel rows
-few cells (mainly fibroblasts)
where is dense regular tissue found in
tendons and ligaments (handle stress from one direction)
-extend from muscle to the bone
muscle tissue
produces movement and is specialised for contraction
what are the 3 types of muscle tissue
skeletal
smooth
cardiac
3 common features of muscle tissue
-elongated parallel to the axis of contraction
-numerous mitochondria
-contractile elements
3 functions of skeletal muscle
-moves and stabilizes the skeleton
-forms sphincters in the digestive and urinary tract
-involved in respiration
4 features of skeletal muscle
-long, cylindrical cells
-striated (due to arrangement of the contractile filaments)
-multinucleated (nuclei located at the periphery of the cell)
-innervated by the somatic nervous system (voluntary)
where is smooth muscle located
walls of organs, blood vessels and airways
2 functions of smooth muscle
-gastrointestinal movement
-alters the diameter of airways and blood vessels ( needed to reduce flow distally and increase blood pressure proximally)
4 features of smooth muscle
-short fusiform cells (spindle-shaped)
-non-striated
-single, centrally located nucleus
-innervated by autonomic nervous system (involuntary)
where is cardiac muscle located
heart wall
function of cardiac muscle
-helps to circulate blood and to maintain blood pressure
5 features of cardiac muscle
-branched muscle fibres
-striated
- 1-2 central nuclei
-intercalated discs (have gap junctions allowing ions to pass)
-innervated by the ANS
