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
What causes Cystic Fibrosis?
* Mutation in CFTR gene * deficiancy in Cl ions release * mucous very sticky
26
What are the effects of cystic fibrosis?
* **Airways** : **clogging** and **infection** of **bronchial passage**, **breathing obstructed** * **Liver** : **small bile duct blocked** - disrupts digestion
27
State the characteristics and functions of clara cells
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
State the characteristic and functions of Microfold cells
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
State the functions of Stereocilia
Inner ear * mechanosensing organelles * **respond to fluid motion** for hearing and balance epididymis and vas deferens * **facilitate absorption of residual sperm body**
30
What are the cell renewal rates of the airway epithelium?
* Clara cells : never * Trachea : 1-2 months * Goblet cells : 10 days * Alveoli : 8 days
31
What is the effect of smoking on lungs at the early stage?
* mucus layer thickens * cilia die * ciliagenesis : 2-4 days
32
What is the effect of smoking on lungs at the chronic stage?
* goblet cells poliferate * clara cells die * carcinogens induce mutations * fibroblast lay down scar tissue
33
What are the common respiratory conditions related to smoking ?
* Acute bronchitis * Chronic bronchitis * Emphysema * COPD * Asthma
34
Describe some of the common respiratory conditions related to smoking
**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
Describe the mucocilliary escalator in trachea
* mucous lining trachea traps inhaled particles * upward beating of cilia drives debris-laden mucus towards the pharyx
36
What is epithelia metaplasia
capacity of epithelial cell to differentiate to another cell
37
What is neoplasia
* Changes that occur in epithelia - give rise to tumour
38
What is adrenocarcinoma?
Tumour of epithelial origin
39
How are cross sections of cuboidal and columnar cells differentiated under slide?
cuboidal : polygonal columnar : hexagonal
40