Respiration Lecture 16: Pulmonary Defensive Reflexes Flashcards Preview

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Flashcards in Respiration Lecture 16: Pulmonary Defensive Reflexes Deck (51)
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1
Q

4 pulmonary defensive reflexes

A

1) cough
2) sneeze
3) diving response (prevents H2O from entering airway)
4) laryngeal chemoreflex

2
Q

dysphagia

A

disordered swallow

3
Q

dystussia

A

disordered cough

4
Q

cause and result of impaired airway defense

A

most neurological disorders. Result = dysphagia and/or dystussia

5
Q

T or F: no therapy exists for impaired cough

A

T

6
Q

Causes of enhanced airway defense

A

upper airway cough syndrome, asthma, gastroesophageal reflex disease, bronchitis, bronchiectasis, ACE inhibitor therapy side effect

7
Q

Manifestation of enhanced airway defense

A

cough

8
Q

One of the most common reasons why sick patients visit physicians in US

A

coughing. (Manifestation of many disorders)

9
Q

Fx of cough/sneeze

A

removal of mucus or foreign matter from the nasal or pulmonary systems via generation of large expiratory airflows. Large inspiration followed by large expiration.

10
Q

Sneeze vs. cough

A

soft palate lowers in sneeze to divert airflow out the nose

11
Q

3 stages of typical cough

A

1) inspiratory phase (negative airflow)
2) Compression phase (0 airflow, intrathoracic P increasing behind closed airway)
3) Expiratory phase (positive airflow)

12
Q

which muscles are active during inspiratory phase of cough?

A

diaphragm, chest wall, laryngeal dilators

13
Q

Which muscles are active during compression phase of cough?

A

laryngeal constrictors, expiratory muscles

14
Q

Which muscles are active during expiratory phase of cough?

A

expiratory abdominal and chest wall muscles

15
Q

General reflex pathway for cough

A

Receptors in Larynx/lungs/airways stimulate brainstem cough generator —> respiratory muscles

16
Q

C fibers and their effect on generating cough

A

pain/sensory receptors in lungs, esp. for chemical stimuli. Controversial influence on cough

17
Q

Slowly adapting receptors and effect on generating cough

A

stretch receptors that monitor lung volume. Contribute to but are NOT sufficient to stimulate cough alone (passive role)

18
Q

Rapidly adapting receptors and effect on generating cough

A

have strong influence via vagus nerve to generate cough

19
Q

laryngeal receptors relay through which nerve to cause cough?

A

superior laryngeal n.

20
Q

How is diving response stimulated?

A

Via nasal/facial receptors that communicate to brain through trigeminal n.

21
Q

Effects of diving response

A

vasoconstriction, bradycardia, lung apnea via sympathetic nerves

22
Q

advantage of diving response

A

Allows for reduction of metabolic rate/consumption of oxygen so you can stay submerged for longer periods of time. More pronounced in aquatic animals

23
Q

laryngeal chemoreflex induced by:

A

larynx –> superior laryngeal n. –> brain

24
Q

effects of laryngeal chemoreflex

A

laryngospasm, bradycardia, lung apnea

25
Q

laryngeal chemoreflex

A

prevents aspiration of foreign matter. Common in neonates. Can be elicited via mechanical or electrical stimuli

26
Q

Fx and distribution of smooth muscle in airway

A

Fx: controls diameter of airways. Present from trachea down to alveolar ducts

27
Q

bronchospasm/bronchoconstriction

A

increased contractile activity of airway smooth muscle

28
Q

bronchodilator

A

drug that relaxes airway smooth muscle

29
Q

bronchomotor tone

A

baseline contractility of airway smooth muscle under normal conditions

30
Q

local control of airway smooth muscle

A

relaxation or contraction of airways by release of various chemicals. Pro-inflammatory chemicals (serotonin, histamine, prostaglandin, leukotrienes) are released from mast cells eosinophils, and neutrophils in the airways. Norepinephrine causes relaxation

31
Q

Where is norepinephrine released?

A

adrenal gland, sympathetic innervation

32
Q

What do steroidal asthma meds inhibit?

A

Parasympathetic innervation to airway so they remain open

33
Q

Parasympathetic control of airway

A

leads to bronchoconstriction via release of Acetylcholine

34
Q

What do sensory C fibers release in response to chemical irritants or inflammatory mediators from mast cells, eosinophils, or neutrophils?

A

pro-inflammatory tachykinins

35
Q

What is mucus composed of?

A

Glycoproteins (aka mucins)

36
Q

Where is mucus formed/secreted?

A

Epithelial goblet and serous cells (small airways) and submucosal glands (large airways)

37
Q

Where are submucosal glands found?

A

large airways

38
Q

3 main functions of mucus

A

1) insulates airway from irritants
2) antibacterial
3) entrapment of particles

39
Q

Factors that determine amount of mucus present in airways (4)

A

1) rate of secretion
2) rate of absorption by epithelium
3) ciliary transport
4) cough transport

40
Q

Negative consequences of mucus accumulation

A

1) airflow obstruction
2) enhanced deposition of inhaled particulates
3) dilutes surfactant

41
Q

Cystic fibrosis etiology

A

thickened mucus layer, thinned/dehydrated serous layer due to hyperactive Na channels and transfer of Na and H2O from serous to epithelial layer. Cilia therefore less able to clear pathogens.

42
Q

parasympathetic control of mucus secretion

A

Brainstem preganglionics stimulate airway ganglia to release Acetylcholine, which stimulates mucus secretion

43
Q

C fiber control of mucus secretion

A

C fibers directly innervate goblet cells and mucus secreting glands. They release tachykinins/mediators from inflammatory cells, which induces release of mucus.

44
Q

Where are cilia found?

A

trachea to respiratory bronchioles. NOT in alveoli

45
Q

Where do cilia “beat” to?

A

towards oropharynx

46
Q

Where is cilia movement the greatest?

A

large airways

47
Q

Fx of cilia

A

move mucus from distal airways to larger airways and ultimately out of resp. system

48
Q

2 strokes of cilia

A

Effective stroke (actively pushes mucus layer towards oropharynx; requires more energy) and Recovery stroke (bends and moves away from oropharynx in serous layer in preparation for next stroke upward; requires less energy)

49
Q

epiphase =

A

mucus layer

50
Q

hypophase =

A

serous layer

51
Q

Which layer is more viscous, epiphase or hypophase?

A

Epiphase. Floats on top of hypophase in “mucus flakes” and reduces forces needed to cough and move mucus up and out airway

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