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Respiratory Defences Flashcards

1
Q

The respiratory system is split into 2 zones, Conducting airways (Zone) and Respiratory Airways (Zone):. What are each of these zones comprised of?

A 
Conducting airways (Zone):
Nasal cavity
Trachea
Bronchi
Bronchioles

Respiratory Airways (Zone): :
Respiratory bronchioles
Alveolar ducts and Alveoli

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2
Q

Function of the nose

A

The nose acts to filter large particle (>10μm ;nasal hairs) inspired air.
Warms & humidifies the air-prevents epithelium drying out

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3
Q

Mucosal layer lined with different types of epithelial cells:describe them and what they do

A

Respiratory epithelium-bathed in aqueous viscous& sticky mucus to trap particles.
Ciliated epithelium have a coordinated beat-mucociliary escalator push material towards naso & oropharyrnx

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4
Q

what stimulates irritant receptors & provoke sneezing & coughing to remove material.

A

irritant particles

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5
Q

what is the Lamina propria

A 
\:
Loose connective tissue
Blood vessels and nerves
Secretory glands
Lymphocytes and other lymphoid cells
Rigid components keeping airways open
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6
Q

describe the types of epithelium found in the conducting airways

A 
Pseudostratified with 3 cell types
Ciliated epithelial cells-mucociliary escalator
Goblet cells (secretory, non-ciliated)
Basal cells (act as stem cells, may contribute to structure)

Columnar in nasal cavities, trachea, bronchi; more cuboidal in bronchioles with Club (Clara) cells replacing goblet cells

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7
Q

what is the mucociliary escalator?

A

Mucus overlies the airway epithelium protects the mucosa
Covered with gel phase over a thin sol phase
Creates a semipermeable barrier & allows exchange of nutrients, H2O, and gases & is impermeable to most pathogens.
Cilia coordinated beating transports particles/cellular debris towards mouth.
Mucus from large bronchi to reach pharynx ~40 min
From respiratory bronchi several days.

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8
Q

what can damage the mucociliary escalator?

A

by inflammation, smoking, pollution, infections.

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9
Q

what does mucus contain

A

Anti-proteases e.g. α1-antitrypsin-inhibits proteases released from bacteria & neutrophils
Lysozyme-has anti-bacterial & anti-fungal properties
Anti-microbial properties from Lactoferrin, peroxidases & neutrophil-derived defensins

Above provide non-specific immunity

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10
Q

what productes mucus

A

goblet cells

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11
Q

what makes up mucus and what is its strucure?

A

Main component of airway mucus are mucins, which are high molecular wt glycoproteins

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12
Q

how do mucins affect the nature of goblet cells?

A

they give mucus its gel-like nature

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13
Q

Fluidity & ionic composition of sol phase are cntrolled by what

A

epithelial cells

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14
Q

features of the tract wall nose

A

nous plexus, periosteum, bone

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15
Q

features of the tract wall trachae and bronchioles

A

held open by C-shaped cartilage anterolaterally, smooth muscle (Trachealis) posteriorly

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16
Q

features of the tract wall trachea

A

(generally 16-20) rings of cartilage

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17
Q

features of the tract wall bronchi

A

cartilage plates, smooth muscle, blood vessels of systemic circulation (bronchial arteries)

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18
Q

features of the tract wall bronchioles

A

smooth muscle helical bands

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19
Q

whaat type of cartiage is present in the bronchus?

A

hyaline cartilage.

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20
Q

what type of epithelium lines the bronchus

A

ciliated pseudostratified columnar epithelium

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21
Q

smppthe muscle and goblet cells arent presen tin the bronchus, true or false?

A

false. they are present

22
Q

what dont terminal bronchial have and what does it have

A

doesnt: cartilage, glands
does: smooth muscle

23
Q

describe the eptihelium the the terminal bronchiole

A

Epithelium in initial portion is ciliated columnar, but becomes cuboid with cilia
Final portion un-ciliated

24
Q

what is the pathway from the terminating brioloes

A

Terminal bronchioles lead to respiratory bronchioles, in turn these lead to alveolar ducts, alveolar sacs, as well as individual alveoli

25
where does gas exchange happen?
1st first respiratory alveoli
26
describe the diffusion distance between alveoli and pulmonary capillaries
minimal
27
epithelium in a respiratory bronchiole
has a low simple cuboidal epithelium and a thin coat of interlaced smooth muscle and elastic fibres.
28
what are the thin evaginations in the respiratory bronchiole
It has thin evaginations in its wall: 1st first respiratory alveoli, where gaseous exchange can take place.
29
what are Type I pneumocytes
95% of alveolar surface Highly flattened Simple squamous epithelium Form occluding junctions with one another Barrier to extracellular fluid into alveolus
30
how is are neighbouring alveoli interconnected
by Pores of Kohn
31
what is The Blood-gas interface
Type I cells forms thin diffusion barrier –fused with pulmonary capillary endothelium
32
what is Type II pneumocytes
More numerous; only about 5% of alveolar surface Cuboidal Capable of rapid cell division. Dispersed among type I pneumocytes and form occluding junctions with them Produce surfactant –reduces surface tension prevents alveoli from collapse
33
difference between type 1 and type 2 cells
thicker & produce fluid layer that lines alveoli
34
what does the fluid layer that lines alveoli contain
Fluid contains pulmonary surfactant (phospholipid: dipalmitoyl phosphatidylcholine) in lamellar bodies
35
what is the function of the fluid layer that lines alveoli
Reduces the surface tension within alveoli
36
what does the interstitium contain
reticular & elastic fibres; allows elasticity | lymphoid cells
37
Secreted factors for non-specific defence
A No of factors produced by epithelial cells & other cells or derived from plasma
38
examples of anti-proteases
α1-antitrypsin-inhibits proteases released from bacteria/neutrophils
39
what properties have lysozymes
antifungal & bactericidal properties
40
what are antimicrobial proteins
Lactoferrin, Peroxidases& neutrophil-derived Defensins & Cathelicidins
41
Immune defence mechanisms:
Leucocytes: neutrophils & lymphocytes present in alveoli Neutrophils kill bacteria Alveolar macrophages migrate found throughout the respiratory tract-phagocytose any particles that get this far Macrophages act as antigen presenting cells & products presented to T & B lymphocytes Macrophages secrete Interleukins(ILs), Tumour Necrosis Factor (TNF) & chemokines ILs & TNF activate immune system Chemokines attract white cells to sites of inflammation Mast cells-secrete heparin, Histamine, 5-HT & hydrolytic enzymes involved in allergy & anaphylaxis (IgE) Principal immunoglobulin is IgA.
42
Natural Killer (NK) Cell
Present in lungs & lymphoid organs Contains granules with hydrolytic enzymes 1st line of defence against viruses Secrete interferons & TNFs T & B lymphocytes migrate to lymph nodes, tonsils & adenoids Diffuse patches of bronchus-associated lymphoid tissue (BALT) in lamina propria Antigens presented to T-Lymphocytes by antigen-presenting cells-cascade of cytokines released & a variety of Antibodies produced (Immunoglobulins) Most important are Dendritic cells Specialised mononuclear phagocytes Act as antigen presenting cells
43
what is a cough
Protective reflexes protect lungs & airways from a variety of foreign materials
44
Cough Reflex:
Caused by irritation of respiratory tract by gases, smoke & dust Receptors throughout airways between epithelial cells Rapidly adapting afferent myelinated fibres in vagus In trachea leads to cough; lower airways leads to hyperpnoea Also causes reflex bronchial & laryngeal constrictions Characterised by deep inspiration followed by forced expiration with closed glottis Results in expulsion of irritants from respiratory tract
45
Sneezing Reflex:
Caused by irritation of nasal mucous membrane due to dust particles, debris & excess fluid accumulation Characterised by deep inspiration followed by forced expiration with open glottis Results in expulsion of irritant from airways Irritation of nasal mucous membrane , olfactory receptors & trigeminal nerve endings in nasal mucosa Afferents from trigeminal & olfactory nerves pass to sneezing centre in medulla Efferent fibres pass from medulla via trigeminal, facial, glossopharyngeal, vagus & intercostal nerves. Results in activation of pharyngeal, tracheal & respiratory muscles
46
Swallowing Reflex:
Initiated by stimuli to dorsum of tongue, soft palate & epiglottis During swallowing respiration is inhibited-Deglutition reflex Prevents inhalation of food
47
Stretch Receptors:
Located in smooth muscle of bronchial walls Slowly adapting Afferents ascend via vagus Stimulation results in inspiration being shorter & shallower These receptors responsible for Hering-Breuer inspiratory reflex Lung inflation inhibits inspiratory muscle activity Deflation reflex-augments inspiratory muscle activity Normal breathing weak reflex, more active during exercise when tidal vol >1 L; In neonates-protects against over-inflation
48
Juxtapulmonary (or J )receptors
Located on alveolar & bronchial walls close to capillaries Afferents unmyelinated C-fibres or myelinated nerves in vagus
49
activation of Juxtapulmonary (or J )receptors
apnoea (cessation of breathing) or rapid shallow breathing, HR & BP fall, laryngeal constriction & relaxation of skeletal muscles. J receptors activated by: -Increased alveolar wall fluid -Pulmonary congestion & oedema -Microembolisms -Inflammatory mediators such as Histamine Above associated with lung disease
50
Somatic & Visceral Reflexes
Visceral or somatic pain produce opposite effects on breathing Stretching intestines or distending gallbladder or bile ducts inhibits breathing Somatic pain generally causes rapid shallow breathing Cold H2O on bare skin produces a gasp & increases ventilation rate Face immersion in H2O (especially Cold) the Dive reflex Proprioceptors (position/length sensors) in muscles & joints of respiratory muscles detect load on muscles (not diaphragm) and can respond to increased load by modulating respiration Pain receptors: stimulation often leads to brief apnoea followed by increased breathing Receptors in trigeminal region & larynx: stimulation gives rise to apnoea or laryngeal spasm

Block 2 ALS (3 decks)

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