Lec 3 Cells to Tissues Flashcards
Most cells form tissues - what are the types of tissues, which one is different and why?
muscle tissue nervous tissue epithelial tissue connective tissue connective is odd one out as its many different tissue
what holds cells together?
cell- cell adhesion molecules
extracellular matrix proteins (fibres)
internal external scaffolding
close proximity pressure affects
what are the differences between epithelial and connective tissue
connective tissue is - plentiful extracellular matrix few cells spread within matrix rich in fibres like collagen - matrix bears mechanical stress cells not directly attached
epithelial
cells in tightly bound epithilia sheets
very little extra cellular matrix - just the basal lamia underneath the epithilium
cell-cell adhesion attach cells - bear the mechanical stress
what is the primary cell of connective tissue?
the mesenchymal stem cell (differentiates into all connective tissues)
it produces most extracellular fibers that anchor cells into place
at first it can inter convert between cell types before settling
produces bone, cartilage ect
where do we find epithelial tissue, why ?
line all cavities and free surfaces of the body
specialised junctions between cells help form tissue barriers, to inhibit transfer of water, acids ect
epithelia mostly rest on connective tissue, through a basement membrane.
connective tissue binds epithelia to other tissues to produce an organ
name lateral epithelial cell adherence systems in order
tight junctions adhesion junctions desmosomes gap junctions cell adhesion molecules - intergins
all cell adhesion systems require calcium to function
name basal surface adhesion systems
binds to basal lamina/basement membrane
hemi - desmosomes
focal adhesion
intergrins
proteoglycan
what is a tight junction?
forms a seal and selective barrier
prevents leakage of molecules
prevent pathogens from gaining entry to systems (why we have an epithelial layer)
what is an adherence junction?
joins two actin bundle sin cells together
what is a desmosome?
joins intermediate filaments in two cells
strongest junction
bears mechanical stress
gap junction
allows passge of small molecules / ions ect
for cell communication, ion transport
hemidesmosome
anchors intermediate filaments in the cell (made of keratin) to the basal lamina (which attaches to connective tissue via elastin, fibirillin, collagens)
focal adhesions
anchors actin filaments in the cell to the basal lamina
actin allows for immune patrolling and wound contraction
what is the basal lamina (basement membrane)
A thin, acellular layer to which epithelial cells are anchored
what are integrins used for
Integrins play an important role in basement mebrane– Transmembrane proteins which connect the cell cytoskeleton to the ECM
Physical attachment
Signal transduction
Immune patrolling and cell migration
what is the mucosal membrane ?
it lines the hollow organs - GI tract, urinary tract, respiratory tract.
it secretes mucus, a thick protective fluid with enzymes, immunoglobulins ect
to stop pathogens and dirt from entering the body
prevent loss of water (dehydration) from tissues
lubrication
what makes up the mucous membrane
epithelium
basal lamina
lamina Propecia (smooth muscle for contraction)
outline what the respiratory tract is
for gaseous transport and exchange
made up of a conducting portion (trachea) and a respiratory portion (bronchioles to aveoli)
what is the role of cartilage in the trachea?
hyaline cartialge - C shaped ring to prevent the trachea from collapsing under vaccum.
what is the function of the mucosal membrane in respiratory tract
- secretions (produced by goblet cells full on enzymes) from submucosa provide a block to stop pathogens entering system and cillia on the epithilia. the cillia wave forms the mucocilliary escalotor to move them to the stomach for digestion
What is the function and structure of the urinary tract?
large basal lamina producing mucus to act as a barrier to keep in acidic urine in
tight junctions to prevent urine escape
ureter and bladder have thick muscle layer to maintain pressure, prevent bursting.
essential nutrients are absorbed by kidney
prevention of pathogen entry
removal of waste products
What is the function of the mucosa in the GI tract?
absorb substances from the lumen (large SA to achieve this- folding of mucosa epithilal cells, microvilli and peristaltic actions)
prevent pathogens - lamina propria contains lymphatic tissue to aid this
move contents and expel waste - peristalsis
what are the layers of the gi tract ?
mucosa lines the lumen
muscularis mucosa - thin smooth muscle layer
submucosa - connective tissue layer
muscularis externa - peristalsis - two directions of smooth muscle layers - inwards and along
the serosa - secretes fluid - connective tissue - also stops expansion that would burst the GI
the stomach has rugae - folds that increase SA
jejunum has villii for SA
give examples of specialised structures on the apical domain
microvilli - border in the GI tract - increase SA for adsorption
sterovilli - sensory - inner ear
cilia - form a moving stroke - mucocilliary escalator
what is the structure and function of cells in the stomach (GI tract)
Mucosa - epithilium - the gastric mucosa secrets acid, digestive enzymes
lamina propria,
muscularis mucosae
the submucosa
muscalaris externa - multidirectional, contract for peristalsis
folded into rugae to increase SA
