Control of Lung Function

Question 1

What is the dorsal respiratory group the main location for?

Answer 1

Generation of the rate and rythm of breathing - Control of Inspiration

Question 2

Where is the dorsal respiratory group located?

Answer 2

Dorsomedial medulla in the ventrolateral nucleus of the solitary tract

Question 3

What is the ventral respiratory group responsible for?

Answer 3

Voluntary forced expiration control

Inhibition of the apneustic centre

Question 4

Where is the ventral respiratory group located relative to the dorsal respiratory group?

Answer 4

Ventral to it

Question 5

When is the ventral respiratory group inactive?

Answer 5

During quiet breathing

Question 6

Where is the apneustic centre located?

Answer 6

Lower part of the pons

Question 7

Where is the pneumotaxic centre located?

Answer 7

Upper part of the pons

Question 8

What effect does the pneumotaxic centre have on the dorsal respiratory group?

Answer 8

Inhibitory

Question 9

What effect does the apneustic centre have on the dorsal respitatory group?

Answer 9

Stimulatory

Question 10

What effect does the dorsal respiratory group have on the ventral respiratory group?

Answer 10

Inhibitory

Question 11

What effect does the ventral respiratory group have on the DRG and AC?

Answer 11

Inhibitory

Question 12

Do action potentials at a low frequency stimulate the AC or the PC?

Answer 12

AC (apneustic)

Question 13

When the action potentials fire at a higher frequency, are the AC or PC stimulated?

Answer 13

PC

Question 14

What effect does the PC have on the action potentials and what is this effect followed by?

Answer 14

Causes a cessation (stop)

Follwed by a period of latency before the AC then stimulates the DRG again to increase the action potential frequency.

Question 15

Which spinal nerves form the phrenic nerve?

Answer 15

C3, C4, C5

Question 16

What motor and sensory innnervation does the phrenic nerve provide?

Answer 16

Motor innervation to the diaphragm

Sensation to the central tendon aspect of the diaphragm

Question 17

What action do the external intercostal muscles contribute to?

Answer 17

Inspiration

Question 18

What action do the internal intercostal muscles contribute to?

Answer 18

Expiration

Question 19

If there are gaps in the capillaries of normal circulation, then why are they described as ‘continuous’?

Answer 19

Because these gaps between capillary endothelial cells are filled with H20.

Question 20

What is the blood brain barrier and why is it important?

Answer 20

The purpose of the blood-brain barrier is to protect against circulating toxins or pathogens that could cause brain infections, while at the same time allowing vital nutrients to reach the brain.

Question 21

Why is the blood brain barrier considered to have continuous capillaries?

Answer 21

Because they have tight junctions between capillary endothelial cells formed by nervous cells to prevent unnecessary leakage of molecules.

Question 22

Can charged molecules pass the lipid bilayer?

Answer 22

Not without transporters

Question 23

Is dissolved carbon dioxide able to pass through the lipid bilayer and therefore the blood brain barrier (BBB)?

Answer 23

Yes

Question 24

How does this CO2 that is now in the CSF as it crossed the BBB from the capillaries, initiate activation of the DRG?

Answer 24

CO2 reacts with water to form a carbonate ion (HCO3-) and a proton.
Protons will enter the MO and interact with the afferent fibres.
These take the signal straight to the DRG to be able to determine what type of rate and rhythm should be created.

Question 25

Where are irritant receptors found?

Answer 25

Embedded within and beneath airway epithelium (larynx, trachea, bronchi, and intrapulmonary airways)

Question 26

What is the role of the irritant receptor?

Answer 26

Detects foreign mattter. Leads to cough which involves forceful expiration against a closed glottis with sudden glottal opening and high velocity expulsion of air.

Question 27

Where are pulmonary stretch receptors found?

Answer 27

Past the secondary bronchi

Question 28

How are these stretch receptors activated?

Answer 28

Excessive inflation of lungs

Question 29

What do the stretch receptors do once they are activated?

Answer 29

They send afferent signals to respiratory centres and stimulate pneumotaxic + VRG Inhibit inspiration and stimulate expiration

Question 30

Where are J-receptors found?

Answer 30

Alveolar walls in close proximity to the capillaries

Question 31

What is the role of a J-receptor?

Answer 31

Respond to chemicals in pulmonary circulation, distention of the pulmonary capillary walls and accumulation of interstitial fluid (oedema). Increases breathing frequency as a response to these factors - send APs via vagus nerve leading to bronchoconstriction and increased RR

Question 32

What happens when you reach the CO2 threshold for breathing?

Answer 32

Accumulation of H+ beyond BBB activates the DRG - the struggle phase

Question 33

What happens to the 3D structure of proteins if the level of acidity of the blood is not tightly regulated enough?

Answer 33

It is altered

Question 34

Is a base anioic or cationic?

Answer 34

Anionic, also a molecule that reversibly binds to protons

Question 35

Why does an acid have a low pH compared to a base?

Answer 35

It dissociates with H+, which creates a decreased pH as the higher the concentration of H+, the lower the pH. Whereas a base binds to the H+ and would decrease the concentration.

Question 36

What is the formula for calculating pH and what is the formula for then converting pH into H+ concn.?

Answer 36

-log10 [H+]

Question 37

What is the difference between alkalaemia and alkalosis?

Answer 37

Alkalaemia - higher-than-normal blood pH, | Alkalosis - describes circumstances that will decrease [H+] and increase pH

Question 38

What is meant by a ventilatory disturbance?

Answer 38

Minor change in breathing that changes pH which is then corrected by the kidneys which are slow responses.

Question 39

What is meant by a metabolic disturbance?

Answer 39

Any non-lung cause of a change in the pH that is subsequently corrected for by the lungs which are fast responses.

Question 40

What type of reaction is needed to correct an acidosis?

Answer 40

Alkolitic response

Question 41

Where are the peripheral chemoreceptors found?

Answer 41

Bifurcation of carotid arteries in region called carotic and aortic bodies in the aortic arch. Found very close to the baroreceptors.

Question 42

What is the role of the peripheral chemoreceptors?

Answer 42

Stimulate breathing in response to hypoxia

Question 43

Which part of the brain is responsible for the emotional responses?

Answer 43

Limbic system

Question 44

How can the movement of a muscle lead to an increase in breathing?

Answer 44

Efferents from pirmary motor cortex to skeletal muscles partly innervate MO by sending volitional instructions to it as it will inevitably be necessary. Proprioceptive afferents from muscle spindles and golgi tendon organs also innervate MO on way to brain.

Question 45

Why is there a cold shock ventilator response?

Answer 45

Immersion in cold water (<10 degrees Celsius) causes a large and fast fall in skin temperature, detected by the superficial sensory nerve endings in the skin which evokes muscle spasms and hyperventilation.