Tissues, Organs and Systems Flashcards

1
Q

From inside to out, what are the layers of the trachea?

A
  • Lumen
  • Mucous membrane made of pseudostratified ciliated columnar epithelium
  • Submucosa, containing seromucous glands
  • Hyaline cartilage ring (horse shoe shape)
  • Adventitia
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2
Q

What is the structure of the mucosa in trachea?

A
  • Epithelial layer is several layers deep
  • Surface covered in cilia (moves debris, dust, bacteria etc. towards mouth)
  • Lamina propria is very thin
  • No muscularis mucosa layer
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3
Q

What is the structure of the submucosa of the trachea?

A
  • The connective tissue layer contains mainly collagen and elastin fibres and many fibroblasts
  • Contains seromucous glands that produce watery mucus that thickens during infections
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4
Q

What are the features of the cartilage in the trachea?

A
  • C-shaped hyaline cartilage ring
  • Made of two distinct layer:
    • perichondrium layer (contains fibroblasts that lay down collagen fibres)
    • chondrogenic (contains chondroblasts which form cartilage)

The cells present can interconvert from chondroblasts to chondrocytes and so can make both hyaline and elastic cartilage

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5
Q

What do secretions are produced from the epithelium and and submucosal glands of the trachea and bronchi?

A
  • Mucins and water (makes sticky mucus)
  • Serum proteins (lubricate the surface)
  • Lysozymes (destroy bacteria)
  • Anti-proteases (inactivate bacterial enzymes)
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6
Q

What makes up the mucociliary escalator?

A

The ‘cilia wave’ and mucous moves materials to oral cavity where it can be swallowed- making the mucociliary escalator

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7
Q

What does cilia contribute to the mucociliary escalator?

A
  • Tracheal mucosa contains approximately 250 cilia/cell

- Cilia beat at 12Hz beneath a moveable, viscoelastic mucus blanket

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8
Q

What does trachea look like in histology?

A
  • Unusually thick basement membrane

- Lamina propria rich in immune cells and contains layers of elastic

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9
Q

What differences in structure are there between primary and secondary/tertiary bronchi?

A
  • ## Histology similar to primary bronchi but cartilage is only present as cresents and not full C-shapes
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10
Q

What features are present in secondary and tertiary bronchi?

A
  • Epithelium made of pseudostratified ciliated columnar cells
  • Bound by smooth muscle
  • Supported by seromucous glands in the submucosa
  • Airway kept open by crescent shaped hyaline cartilage.
  • No layer of outer smooth muscle
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11
Q

How are alveolus connected to capillaries?

A
  • Capillaries are lined with flattened specialised epithelial cells (called endothelium)
  • These cells are attached to fused basal lamina with even thinner specialised cells of the air sac
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12
Q

How are alveoli adapted for their function?

A
  • Folds in basal lamina allow for expansion of the air sacs when air is drawn into the lungs
  • At junctions, small amounts of collagen are present and surrounded by layers of elastin fibres in the mucosa to allow recoil
  • The connective tissue ‘muscle’ layers in the mucosa are created by the collagen and elastin fibres
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