Respiration Lecture 16: Pulmonary Defensive Reflexes Flashcards Preview

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

4 pulmonary defensive reflexes

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

2

dysphagia

disordered swallow

3

dystussia

disordered cough

4

cause and result of impaired airway defense

most neurological disorders. Result = dysphagia and/or dystussia

5

T or F: no therapy exists for impaired cough

T

6

Causes of enhanced airway defense

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

7

Manifestation of enhanced airway defense

cough

8

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

coughing. (Manifestation of many disorders)

9

Fx of cough/sneeze

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

Sneeze vs. cough

soft palate lowers in sneeze to divert airflow out the nose

11

3 stages of typical cough

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

12

which muscles are active during inspiratory phase of cough?

diaphragm, chest wall, laryngeal dilators

13

Which muscles are active during compression phase of cough?

laryngeal constrictors, expiratory muscles

14

Which muscles are active during expiratory phase of cough?

expiratory abdominal and chest wall muscles

15

General reflex pathway for cough

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

16

C fibers and their effect on generating cough

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

17

Slowly adapting receptors and effect on generating cough

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

18

Rapidly adapting receptors and effect on generating cough

have strong influence via vagus nerve to generate cough

19

laryngeal receptors relay through which nerve to cause cough?

superior laryngeal n.

20

How is diving response stimulated?

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

21

Effects of diving response

vasoconstriction, bradycardia, lung apnea via sympathetic nerves

22

advantage of diving response

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

laryngeal chemoreflex induced by:

larynx --> superior laryngeal n. --> brain

24

effects of laryngeal chemoreflex

laryngospasm, bradycardia, lung apnea

25

laryngeal chemoreflex

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

26

Fx and distribution of smooth muscle in airway

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

27

bronchospasm/bronchoconstriction

increased contractile activity of airway smooth muscle

28

bronchodilator

drug that relaxes airway smooth muscle

29

bronchomotor tone

baseline contractility of airway smooth muscle under normal conditions

30

local control of airway smooth muscle

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

Where is norepinephrine released?

adrenal gland, sympathetic innervation

32

What do steroidal asthma meds inhibit?

Parasympathetic innervation to airway so they remain open

33

Parasympathetic control of airway

leads to bronchoconstriction via release of Acetylcholine

34

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

pro-inflammatory tachykinins

35

What is mucus composed of?

Glycoproteins (aka mucins)

36

Where is mucus formed/secreted?

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

37

Where are submucosal glands found?

large airways

38

3 main functions of mucus

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

39

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

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

40

Negative consequences of mucus accumulation

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

41

Cystic fibrosis etiology

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

parasympathetic control of mucus secretion

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

43

C fiber control of mucus secretion

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

44

Where are cilia found?

trachea to respiratory bronchioles. NOT in alveoli

45

Where do cilia "beat" to?

towards oropharynx

46

Where is cilia movement the greatest?

large airways

47

Fx of cilia

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

48

2 strokes of cilia

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

epiphase =

mucus layer

50

hypophase =

serous layer

51

Which layer is more viscous, epiphase or hypophase?

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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