Respiratory responses to irritation and invasion

Question 1

What are the adaptations present in the URT to protect against irritation and invasion?

Answer 1

Hair/ ciliated epithelium?
Goblet cells producing mucous
Diameter of passageways limits what can pass through

Question 2

What is the adaptation present in the conducting airways (trachea to terminal bronchioles) to prevent irritation and invasion?

Answer 2

Mucociliary escalator
Cilia beat cranially to move mucus towards pharynx
Causes swallowing

Question 3

What adaptation is there in the respiratory zone (lung parenchyma) to prevent irritation and invasion? Where do these drain into?

Answer 3

Alveolar macrophages

Drain into pulmonary lymphatic system

Question 4

What are the 3 classes of sensory airway receptors?

Answer 4

Rapidly adapting receptors (RARs)
Slowly adapting receptors (SARs)
C fibres

Question 5

Where are rapidly adapting receptors (RAR) found? What do they respond to?

Answer 5

Intrapulmonary airways 
Mechanical stimuli (ones in URT more mechanical, ones in LRT more chemical)

Question 6

When are rapidly adapting receptors more active?

Answer 6

When rate and volume of lung inflation increases (during normal respiration)

Question 7

What do rapidly adapting receptors cause if they detect mechanical or chemical stimuli? What NS pathway is responsible for this?

Answer 7

Reflex bronchoconstriction
Mucous secretion

Parasympathetic pathway

Question 8

Where are slowly adapting receptors found and what do they detect?

Answer 8

Around bronchioles and alveoli

Mechanical stimulation

Question 9

When does the activity of slowly adapting receptors increase? When does their activity decrease?

Answer 9

Increase during inspiration Decrease during expiration

Question 10

What are the afferent fibres of the slowly adapting receptors responsible for?

Answer 10

Hering-Breur reflex

Question 11

What do C-fibres detect? What directly activities them?

Answer 11

Noxious chemical/mechanical stimuli

Bradykinin and capsaicin

Question 12

Are C-fibres involved in normal respiration?

Answer 12

No - only during irritation or invasion

Question 13

What efferent effects do C-fibres cause after stimulation?

Answer 13

Bronchoconstriction
Mucous secretion
Apnoea and shallow breathing
Coughing

Question 14

Name 3 reflexes caused by irritation or invasion

Answer 14

Sneeze reflex
Cough reflex
Nasopulmonary reflex

Question 15

What is the purpose of the cough reflex? Which receptor types are involved?

Answer 15

To remove excess mucus or agents from the respiratory types
All 3 (RARs, SARs, C-fibres)

Question 16

Where are all three receptors concentrated?

Answer 16

Tracheal bifurcation

Question 17

Is the coughing reflex under conscious control?

Answer 17

Automatic

Degree of concious control = psychogenic coughing

Question 18

Where is the cough centre found?

Answer 18

Medulla oblongata and pons

Question 19

What afferent nerve supplies the coughing reflex? Where does the efferent nerve go to and which nerve?

Answer 19

Afferent: vagus nerve
Efferent:
Diaphragm (phrenic nerve)
Abdominal and respiratory muscles (somatic spinal nerves)
Larynx ( vagus and recurrent laryngeal nerve)

Question 20

What are the 3 phases to coughing?

Answer 20

Inspiratory phase
Compression phase
Expiratory phase

Question 21

Where are the receptors for the sneeze reflex and what stimuli do they detect?

Answer 21

Nasal mucosa

Mechanical and chemical

Question 22

What afferent nerve supplies the sneezing reflex?

Answer 22

Trigeminal nerve

Question 23

Where is the sneezing centre located?

Answer 23

Medulla oblongata

Question 24

Describe the process that takes place during sneezing

Answer 24

Eyes shut 
Inspiration 
Glottis closes
Increased thoracic pressure
Expiration through nose and mouth

Question 25

What is the efferent pathway for sneezing?

Answer 25

Poorly understood but similar to coughing
Phrenic nerve - diaphragm
Somatic spinal nerve - abdominal and thoracic muscles
Vagus and recurrent laryngeal - larynx

Question 26

What stimulates sneezing?

Answer 26

Irritation 
Invsaion 
Bright light 
Full stomach 
Any stimulation of trigeminal  (plucking eyebrows)
Psychogenic (for attention) 
Arousal

Question 27

What is the nasopulmonary reflex? Give an example

Answer 27

Reflex bronchoconstriction due to irritant/invasion

Breathing through nose on a cold day

Question 28

What happens if the nasopulmonary reflex results in longterm bronchoconstriction?

Answer 28

Hypoxia and hypercapnia

Question 29

What afferent nerve and efferent nerve supply the naeopulmonary reflex?

Answer 29

Afferent - trigeminal

Efferent - vagus