L4 : Epithelial cells and surface specialisations Flashcards

1
Q

State the characteristics of serous membranes

A
  • Line certain closed body cavities (not open to exterior)
  • envelop internal organs
  • thin layer of connective tissue
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2
Q

What is the fucntion of serous membrane?

A

secrete lubricating fluid : promotes friction free movement of structures

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3
Q

Give examples of serous membranes

A
  • perinoteum : envelops abdominal organs
  • pleural sacs : envelops lungs
  • pericardial sac : envelops heart
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4
Q

What are the outer and inner walls of serous membrane called?

A
  • outer : parietal serosa
  • inner : visceral serosa
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5
Q

Define Epithelium

A
  • Sheets of contiguos cells of varied emryonic origin,
  • cover the external surface of body and
  • line internal surface including blood vessels
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6
Q

What are the surfaces with epithelial linings for exterior, interior opened to exterior and interior not opened to exterior?

A
  • Exterior : Skin
  • I E : respiratory tract, GI tract, urinary tract
  • I x E : peritoneum, pericardial sac, pleural sac
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7
Q

What are the classifications of epithelial cell types?

A

Simple (one cell thick):

  • squamous
  • cuboidal
  • columnar
  • pseudostratified

Stratified (more than oct):

  • squamous
  • cuboidal
  • columnar
  • transitional
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8
Q

State function of simple squamous epithelia

A
  • fast material exchange : respiratory space in lungs
  • barrier to fluids : in brain and CNS
  • tissue lubrication : serous membrane
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9
Q

State function of simple cuboidal epithe.

A
  • Absorbtion and secretion (exocrine glands, thyroid glands, pancreatic duct, collecting duct…)
  • Hormone synthesis
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10
Q

State function of simple columnar epitheli.

A
  • Absorption of nutrients (small intestine, colon)
  • *(some contains microvilli - inc SA)
  • Secretion (stomach lining, small intestine, colon)
  • Lubrication (small intestine, colon)
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11
Q

State the characteristic of pseudostratified epithelia

A
  • All cells make contact with basement membrane
  • not all cells reach epithelial surface
  • nuclei at different levels
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12
Q

State the function of pseudostratified epithelium

A
  • Mucus secretion
  • particle trapping and removal
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13
Q

Where are pseudostratified epithelium located?

A

Lining of nasal cavity, trachea and bronchi

(conduction portion)

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14
Q

State the function of stratified squamous non-keratinised epithelium

A
  • protection against abrasion
  • reduces water loss while remaining moist

Location : oesophagus, vagina, anal canal

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15
Q

What is the key feature of stratified squamous keratinised epithelium?

A

Stratum corneum : consist of outermost cells which are dead, lost their nuclei and cornified.

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16
Q

State the function of stratum corneum

A
  • reduces water loss
  • protect against abrasion
  • barrier towards toxins and microbes
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17
Q

Describe the process of keratinocytes maturing from basal layer to stratum corteum

A
  • Stratified squamous keratinised epithelium made up of keratinocytes
  • keratinoctyes undergo mitosis at basal layer
  • daughter keratinocytes move towards surface, differentiating and losing ability to divide
  • keratinocytes synthesis keratins(provide strength for epidermis)
  • movement of keratinocytes from basal layer to stratum corteum : 28-40 days
18
Q

What are the other cells of the epidermis?

A
  • Melanocytes
  • Langerhans cells
19
Q

What is the function of melanocytes?

A
  • produce melanin - main pigments that give skin its colour
  • * darker skin, more melanin but same number of melanocytes
20
Q

What is the function of langerhans cells?

A
  • present antigens to T lymphocytes
  • mediate immune reactions
21
Q

How are melanin from Mature melanosomes transferred to neighbouring keratinocytes?

A
  • Pigment donation - involve phagocytosis of tips of dendritic processes
22
Q

What is the function of stratified squamous keratinised epith?

A
  • Protection against abration
  • prevent water loss
  • shielding against UV light
  • prevent microbial ingress
23
Q

Where is transitional epithelium found and state its function

A
  • Urinary tract
  • protection of underlying tissue from toxic chemicals
24
Q

List the different types of cell surface specialisations and state each function

A
  • Keratin : protects against abrasion
  • Cilia : controls micro-movement of luminal contents
  • Goblet cells : secretes mucus
  • Clara cells : act as stem cells for respiratory epithelium
  • Microfold cells
  • Stereocilia
25
Q

What causes Cystic Fibrosis?

A
  • Mutation in CFTR gene
  • deficiancy in Cl ions release
  • mucous very sticky
26
Q

What are the effects of cystic fibrosis?

A
  • Airways : clogging and infection of bronchial passage, breathing obstructed
  • Liver : small bile duct blocked - disrupts digestion
27
Q

State the characteristics and functions of clara cells

A

Characteristics

  • on airway side of terminal bronchioles
  • club like apical surfaces
  • no cilia, no basal bodies

Function

  • Protect bronchiolar epithelium - secrete uteroglobin
  • Detoxify harmful substances inhaled into lungs
  • Act as stem cells - regenerate bronchiolar epithelium
28
Q

State the characteristic and functions of Microfold cells

A

Characteristic

  • Found only in small intestine, close to lymphatic nodule
  • Have folded extensions

Function

  • Trap pathogens and present to dendretic cells

*weakness : portal of entry for pathogens

29
Q

State the functions of Stereocilia

A

Inner ear

  • mechanosensing organelles
  • respond to fluid motion for hearing and balance

epididymis and vas deferens

  • facilitate absorption of residual sperm body
30
Q

What are the cell renewal rates of the airway epithelium?

A
  • Clara cells : never
  • Trachea : 1-2 months
  • Goblet cells : 10 days
  • Alveoli : 8 days
31
Q

What is the effect of smoking on lungs at the early stage?

A
  • mucus layer thickens
  • cilia die
  • ciliagenesis : 2-4 days
32
Q

What is the effect of smoking on lungs at the chronic stage?

A
  • goblet cells poliferate
  • clara cells die
  • carcinogens induce mutations
  • fibroblast lay down scar tissue
33
Q

What are the common respiratory conditions related to smoking ?

A
  • Acute bronchitis
  • Chronic bronchitis
  • Emphysema
  • COPD
  • Asthma
34
Q

Describe some of the common respiratory conditions related to smoking

A

1. Emphysema :

shortness of breath - permanent widening of airspaces

2. Asthma :

  • wheeze, shortness of breath, chest tightness and cough.
  • Caused by bronchospasm, obstruction from mucus and narrowing of airways

3. Chronic bronchitis :

  • chronic inflammation of bronchi and bronchioles.
  • Reduced lung function - excess mucus in the lung passage
  • irreparable damage to bronchioles and alveoli
35
Q

Describe the mucocilliary escalator in trachea

A
  • mucous lining trachea traps inhaled particles
  • upward beating of cilia drives debris-laden mucus towards the pharyx
36
Q

What is epithelia metaplasia

A

capacity of epithelial cell to differentiate to another cell

37
Q

What is neoplasia

A
  • Changes that occur in epithelia - give rise to tumour
38
Q

What is adrenocarcinoma?

A

Tumour of epithelial origin

39
Q

How are cross sections of cuboidal and columnar cells differentiated under slide?

A

cuboidal : polygonal

columnar : hexagonal

40
Q
A