Respiration Lecture 16: Pulmonary Defensive Reflexes

Question 1

4 pulmonary defensive reflexes

Answer 1

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

Question 2

dysphagia

Answer 2

disordered swallow

Question 3

dystussia

Answer 3

disordered cough

Question 4

cause and result of impaired airway defense

Answer 4

most neurological disorders. Result = dysphagia and/or dystussia

Question 5

T or F: no therapy exists for impaired cough

Answer 5

T

Question 6

Causes of enhanced airway defense

Answer 6

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

Question 7

Manifestation of enhanced airway defense

Answer 7

cough

Question 8

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

Answer 8

coughing. (Manifestation of many disorders)

Question 9

Fx of cough/sneeze

Answer 9

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

Question 10

Sneeze vs. cough

Answer 10

soft palate lowers in sneeze to divert airflow out the nose

Question 11

3 stages of typical cough

Answer 11

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

Question 12

which muscles are active during inspiratory phase of cough?

Answer 12

diaphragm, chest wall, laryngeal dilators

Question 13

Which muscles are active during compression phase of cough?

Answer 13

laryngeal constrictors, expiratory muscles

Question 14

Which muscles are active during expiratory phase of cough?

Answer 14

expiratory abdominal and chest wall muscles

Question 15

General reflex pathway for cough

Answer 15

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

Question 16

C fibers and their effect on generating cough

Answer 16

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

Question 17

Slowly adapting receptors and effect on generating cough

Answer 17

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

Question 18

Rapidly adapting receptors and effect on generating cough

Answer 18

have strong influence via vagus nerve to generate cough

Question 19

laryngeal receptors relay through which nerve to cause cough?

Answer 19

superior laryngeal n.

Question 20

How is diving response stimulated?

Answer 20

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

Question 21

Effects of diving response

Answer 21

vasoconstriction, bradycardia, lung apnea via sympathetic nerves

Question 22

advantage of diving response

Answer 22

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

Question 23

laryngeal chemoreflex induced by:

Answer 23

larynx –> superior laryngeal n. –> brain

Question 24

effects of laryngeal chemoreflex

Answer 24

laryngospasm, bradycardia, lung apnea

Question 25

laryngeal chemoreflex

Answer 25

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

Question 26

Fx and distribution of smooth muscle in airway

Answer 26

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

Question 27

bronchospasm/bronchoconstriction

Answer 27

increased contractile activity of airway smooth muscle

Question 28

bronchodilator

Answer 28

drug that relaxes airway smooth muscle

Question 29

bronchomotor tone

Answer 29

baseline contractility of airway smooth muscle under normal conditions

Question 30

local control of airway smooth muscle

Answer 30

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

Question 31

Where is norepinephrine released?

Answer 31

adrenal gland, sympathetic innervation

Question 32

What do steroidal asthma meds inhibit?

Answer 32

Parasympathetic innervation to airway so they remain open

Question 33

Parasympathetic control of airway

Answer 33

leads to bronchoconstriction via release of Acetylcholine

Question 34

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

Answer 34

pro-inflammatory tachykinins

Question 35

What is mucus composed of?

Answer 35

Glycoproteins (aka mucins)

Question 36

Where is mucus formed/secreted?

Answer 36

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

Question 37

Where are submucosal glands found?

Answer 37

large airways

Question 38

3 main functions of mucus

Answer 38

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

Question 39

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

Answer 39

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

Question 40

Negative consequences of mucus accumulation

Answer 40

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

Question 41

Cystic fibrosis etiology

Answer 41

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.

Question 42

parasympathetic control of mucus secretion

Answer 42

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

Question 43

C fiber control of mucus secretion

Answer 43

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

Question 44

Where are cilia found?

Answer 44

trachea to respiratory bronchioles. NOT in alveoli

Question 45

Where do cilia "beat" to?

Answer 45

towards oropharynx

Question 46

Where is cilia movement the greatest?

Answer 46

large airways

Question 47

Fx of cilia

Answer 47

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

Question 48

2 strokes of cilia

Answer 48

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)

Question 49

epiphase =

Answer 49

mucus layer

Question 50

hypophase =

Answer 50

serous layer

Question 51

Which layer is more viscous, epiphase or hypophase?

Answer 51

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