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Health Disease Therpeutics 1.1 > Epithelial tissues and cell interactions > Flashcards

Epithelial tissues and cell interactions Flashcards

1
Q

What is the difference between exocrine and endocrine gland

A
  • exocrine: secrete prodicct on body surface or body tube

- endocrine: secrete product directly into BS

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2
Q

Examples of exocrine and endocrine glands

A

EX: Intestinal gland (mucus released on GI tract lumen), Sebaceous gland (secretes sebum on skin surface)

END: pituitary gland (secrete hormone in blood capillaries)

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3
Q

What are tight junctions

A

Junction between apical surface and basal surface (stops macromolecules and proteins from getting from BS to AP)

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4
Q

What does laminin do and features

A

consists of 3 chains (a,b,y)

  • contains 2 collagen and 1 cell binding (a) domains
  • helps epithelial attach to basement membrane
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5
Q

Where is basement membranes found

A
  • between epithelial cell and connective tissue

- endothelial lining of capilaries

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6
Q

What do connective tissues contain

A
  • fibroblasts
  • adipocytes
  • mast cells and macrophages
  • collagen and elastin
  • cytoplasm – extracellular matrix
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7
Q

What do extracellular matrix consist of

A

groud substance- water loving proteoglycans (resists compressive forces) that trap water
- ground substance and fibres
-

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8
Q

What are proteoglycans and aggrecans

A

-P consists GAG (glycoamino glycan)– disaccharide units– attract sodium with negative sugars– attract water – viscours– resist compressive forces

AG– 3000 serine rich core protein, 100 chrondroitin sulfate and 30 keratin sulfate, that GAG is attached to

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9
Q

How are collagin tissues made

A

collagen alpha chain- synthesised in fibroblast cytoplasm– diffuse in ER– form triple helix (SV)– exotysosis – triple helix into fibril– collagen fibre

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10
Q

How are elastin made

A

Tropoplastin – collagen alpha chain- synthesised in fibroblast cytoplasm– diffuse in ER– exocytosis– elastin– fibrillin +elastin– elastin fibre

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11
Q

What are the most important cell types in the epidermis

A

keratinocytes >90%

    • found in basal cell layer
    • specialised and can divide into new stem cells
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12
Q

How are cells in the epidermis renewed

A

-kerotinocytes stop dividing- detatch from basement membrane – migrate through epidermis layers – terminal differentiation—->nuclear degradation , aggregation, lamellar bodies, lipid excrusion

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13
Q

What is a cornified envelope

A
  • tough insoluble sack below plasma membrane of keratinocytes – final stage of terminal differentiation
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14
Q

What is the stratum corneum

A
  • flat anuclear keratinocytes
  • epidermal permeability (prevent water loss, protects against microbial invasion)
  • hard for drugs to go through stratum corneum (transappendageal, transepidermal routes)
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15
Q

What are the main stress bearing components in epithelial cells and connective tissues

A

Connective tissues– extracellular matrix

epithelial cell– cell cytoskeleton linked by cell-cell and cell-matrix junctions

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16
Q

What are components of cell-cell and cell- extracellular matrix junctions

A

tight junctions (fence -prevents proteins from apical to BL and barrier- prevents protein from diffusing beween cells)

  • adherans and desmosomes- cell adhesion
  • gap junctions - cell communication to one cell to another

HEMODESMOSOMES AND DESMOSOMES–link cell to basal membrane (adhesion) AND LINK TO keratin intermediate filaments

FOCAL ADHESIONS AND ADHERANS JUNCTIONS– adhesion: AND LINK TO actin microfilaments

17
Q

What are the components of the cytoskeleton and what protein are they made up of

A

IF- maintaining tissue integrety (KERATIN)
Microfilaments- cell migration (ACTIN)
Microtubules- cell devision (TUBULIN)

18
Q

How do intermediate fibres resist stress

A
  • two keratin protein heterodimers
  • resist stress by anchroring cells together (via desmosomes) [cell - cell adhesion]
  • anchoring cells to basement membrane (hemidesmosomes) [cell matrix adhesion to basal lamina surface]
  • important for tissue integrity
19
Q
  • What is pemphigus
A
  • caused by autoantibodies – target adhesion properties of -stops desmogleins from interacting with eachother
    • loss of cell-cell adhesion – loss of epidermal integrety– leads to skin blistering
20
Q

How are actin used in cell migration

A
  • new actin microfilaments formed at leading edge of cell (lamellipodium)
  • actin incorporated into Focal adhesions protein – form new focal adhesion– which anchor lamellipodium to substratum (matrix protein)
21
Q

What are the 3 steps of microfilaments in cell migration

A

protrusion – actin polymerisation pushes out lamellipodium

ATTATCHMENT- new focal adhesions attatching LP to SUBSTRATUM –creates grip at the front

DETATCHMENT – contraction of actin – tension – relieved when FAs at back are degraded – back moves cell forward

– repeated and move cell for cell migration

22
Q

How can actin binding drugs potentially be used to treat cancer

A
  • prevents cell motility and dissemination of tumour cells to distance sites

PHALLOIDIN= prevents microfilament depolymerisation

LATRUNCULLIN= prevents microfilament polymerisation

23
Q

What do microtubules do and what are microtubule binding drugs

A
  • forms the mitotic spindle for cell division
  • Taxol prevents microtubule depolymerisation
    Vinblastine- prevents microtubule polymerisation
    : used as chemotherapy agents (anti mitotic)
    – not specific lose hair
24
Q

What are the features of tight junctions

A
  • prevents paracellular movement (between cells): BARRIER
  • maintain epithelial polarity : FENCE
  • caludin and occudin (tight junction protein domain)
  • also produced by endthelial cell in BBB
25
Q

What can pass through the BBB through the paracellular tight junction route and transcellular pathway

A

Paracellular - passive diffusion of small water molecule
HARD FOR DRUGS TO GET THROUGH PARA ROUTE- tight junctions there

TRANSCELLULAR–

  • passive diffusion of small lipid soluble molecules
  • transporters (glucose, AA, nucleosides)
  • receptor mediated endocytosis (insulin, transferrin)
26
Q

What are some small lipid soluble drugs that can pass through the BBB

A
  • more lipophilic more that it can pass through transcellular route

– morphine, codein, heroine: increasing in lipophilicity

– interact with opoid receptors in the brain

27
Q

What drug is used to treat brain tumours

A
  • small lipophilic molecules such as nitrourea
  • crosses transcellular pathway
  • nitourea – DNA alkylating agent (prevents DNA replication)
28
Q

How is L-DOPA used to treat parkinsons

A
  • dopamine cannot cross BBB
  • L-DOPA resembles tyrosine which crosses BBB (by large amino acid transporter) through transcellular pathway

– L-DOPA crosses by large amino acid transporter – prodrug and is converted to dopamine in brain

29
Q

What are potential strategies for increasing drug delivery across BBB

A
  • Analogues (drug resemblance that can cross)
  • Trogan horse (couple a drug able to cross)
  • administration of drug by ultrasound (creates gap on endothelial cell for drugs to pass through) or osmotic opening

-nanoparticles like liposomes (lipid soluble)

30
Q

What are microfilaments made up of

A
  • Actin microfilaments (F ACTIN)
  • monomers of G actin polymerisation to make F actin
  • microfilament subunit= G actin monomer
  • microfilament- for cell migration

Health Disease Therpeutics 1.1 (9 decks)

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