Week 8- Control of Lung Function

Question 1

What are the 4 centres found in the medulla oblongata?

Answer 1

Dorsal respiratory group
Ventral respiratory group
Apneustic center
Pneumotaxic centre

Question 2

What are the inspiratory and expiratory groups? What acronym can be used to remember them?

Answer 2

DIVE: dorsal inspiratory, ventral expiratory

Question 3

What is the role of the dorsal respiratory group?

Answer 3

Inspiratory centre, controls inspiration and sets the rate

Question 4

What is the role of the ventral respiratory group?

Answer 4

Expiratory centre, inactive during quiet breathing

Question 5

What is the role of the pneumotaxic centre?

Answer 5

Its the inspiratory off switch, regulates depth and frequency

Question 6

What does the pneumotaxic centre inhibit/stimulate?

Answer 6

Inhibits the dorsal respiratory group

Question 7

What does the apneustic centre inhibit/stimulate?

Answer 7

Stimulates the dorsal respiratory group

Question 8

What does the dorsal respiratory group inhibit/stimulate?

Answer 8

Inhibits the ventral respiratory group

Question 9

What does the ventral respiratory group inhibit/stimulate?

Answer 9

Inhibits the dorsal respiratory group and the apneustic centre

Question 10

When are the apneustic and pneumotaxic centres active during an action potential when theres quiet breathing?

Answer 10

Apneustic: at the bottom of the sloping line (start of AP)
Pneumotaxic: at the top of the sloping line (end of AP)

Question 11

What respiratory muscles do motor nerves innervate?

Answer 11

Intercostal muscles

Question 12

What respiratory muscles do sympathetic nerves innervate?

Answer 12

The spine

Question 13

What respiratory muscles do parasympathetic nerves innervate?

Answer 13

Of the pulmonary plexus

Question 14

What common molecule can cross the blood brain barrier and why?

Answer 14

Co2 as its lipid soluble

Question 15

What does Co2 enter after crossing the blood brain barrier?

Answer 15

CSF

Question 16

What happens to Co2 after it has crossed the blood brain barrier and is in the CSF?

Answer 16

It combine with water to form carbonic acid, which then dissociates, the H+ formed then enters the medulla and goes to the dorsal respiratory nucleus

Question 17

Why is it helpful that Co2 can cross the blood brain barrier?

Answer 17

It is an indicator of metabolism, so the vol of H+ that reaches the medulla/dorsal respiratory nuclei can indicate to the brain how much metabolism is occurring in the body

Question 18

What 3 receptors in the pulmonary system affect ventilation?

Answer 18

Irritant receptors
Stretch receptors
J receptors

Question 19

Where are irritant receptors found?

Answer 19

In and underneath the epithelial lining of the trachea

Question 20

Where are stretch receptors found?

Answer 20

In the bronchi, deeper in the airway

Question 21

Where are J receptors found?

Answer 21

At the alveoli

Question 22

What is the function of irritant receptors?

Answer 22

To cause coughs

Question 23

What is the function of stretch receptors? How do they do this

Answer 23

To increase expiration and reduce inspiration during excessive inflammation of the airways. They do this by inhibiting DR group and apneustic centre and stimulating VR group and pneumotaxic centre in the medulla oblongata

Question 24

What is the function of J receptors?

Answer 24

To increase breathing frequency in the case of pulmonary capillary engorgement and oedema

Question 25

What ions enter RBCs to maintain resting potential?

Answer 25

Chloride

Question 26

What transporter do chloride ions enter RBCs through?

Answer 26

AE1 transporter

Question 27

How does blood react to changes in pH?

Answer 27

It has enormous buffering capacity and can react almost immediately to pH imbalances

Question 28

What is the equation used for calculating conc of H+ from pH?

Answer 28

10 to the negative power of the pH

Question 29

What is the equation used for calculating pH from conc of H+ ?

Answer 29

-log base 10 [H+]

Question 30

Define alkalaemia

Answer 30

A higher than normal blood pH

Question 31

Define acidaemia

Answer 31

A lower than normal blood pH

Question 32

Define alkalosis

Answer 32

Circumstances that will decrease pH and reduce [H+]

Question 33

Define acidosis

Answer 33

Circumstances that will reduce pH and increase [H+]

Question 34

What stimulates a slow response to an increase/decrease in pH?

Answer 34

Changes in HCO3- and H+ retention/secretion in the kidneys

Question 35

How is blood pH altered rapidly?

Answer 35

Changes in ventilation stimulate rapid compensatory responses changing Co2 elimination

Question 36

Where are peripheral chemoreceptors located

Answer 36

Near baroreceptors

Question 37

What do efferents from the primary motor cortex to skeletal muscle partially innervate?

Answer 37

The medulla

Question 38

What do proprioreceptive afferent and golgi tendon organs innervate on the way to the brain?

Answer 38

The medulla

Question 39

How does skin effect breathing?

Answer 39

Cold temperature (eg immersion in water) trigger hyperventilation

Question 40

Is acidosis or alkalosis induced after hypoventilation?

Answer 40

Acidosis

Question 41

Is acidosis or alkalosis induced after hyperventilation?

Answer 41

Alkalosis

Question 42

Why is acidosis induced after hypoventilation?

Answer 42

Less fresh air reaches the lungs, this increases co2 conc in alveoli, reduces conc gradient, increases co2 conc in post alveolar blood, co2 combines with water to form carbonic acid, carbonic acid dissociates more to H+ ions, increased conc of H+ reduces pH and induces respiratory acidosis

Question 43

Why is alkalosis induced after hyperventilation?

Answer 43

More fresh air reaches lungs, co2 in alveoli decreases, conc gradient increases, less co2 in post alveolar blood, less co2 combines with water, less carbonic acid synthesis and dissociation, cons of H+ falls

Question 44

Describe how partial compensation of respiratory acidosis is achieved

Answer 44

Acute phase: excess co2 enters RBCs and combines with water to form bicarbonate, this is excreted via AE1 transporter, increased bicarbonate shifts the carbonic acid equilibrium left reducing the conc of H+ and increasing pH Chronic phase: increased bicarbonate reabsorption in the kidney

Question 45

How many stages to partial compensation are there after respiratory acidosis? What are they called?

Answer 45

2- acute first and then chronic

Question 46

How many stages to partial compensation are there after respiratory alkalosis? What are they called?

Answer 46

1- no acute is present, only chronic

Question 47

Describe partial compensation after respiratory alkalosis

Answer 47

Chronic phase: increased reabsorption of bicarbonate in the nephrons, increased secretion of bicarbonate from renal collecting ducts

Question 48

Describe what happens to pH during pre, under compensation, partial compensation and full compensation of respiratory acidosis

Answer 48

Pre: normal range Under comp: pH is low Partial comp: pH gradually increases Full comp: pH is normal rage again

Question 49

Describe what happens to p [co2] during pre, under compensation, partial compensation and full compensation of respiratory acidosis

Answer 49

Pre: normal range Under comp: co2 conc is high Partial comp: co2 remains high Full comp: co2 conc remains high

Question 50

Describe what happens to base excess during pre, under compensation, partial compensation and full compensation of respiratory acidosis

Answer 50

Pre: normal range Under comp: normal range Partial comp: high Full comp: high

Question 51

Describe what happens to pH during pre, under compensation, partial compensation and full compensation of respiratory alkalosis

Answer 51

Pre: normal range Under comp: pH is high Partial comp: pH gradually decreases Full comp: pH is normal rage again

Question 52

Describe what happens to p [co2] during pre, under compensation, partial compensation and full compensation of respiratory alkalosis

Answer 52

Pre: normal range Under comp: co2 conc is low Partial comp: co2 remains low Full comp: co2 conc remains low

Question 53

Describe what happens to base excess during pre, under compensation, partial compensation and full compensation of respiratory alkalosis

Answer 53

Pre: normal range Under comp: normal range Partial comp: low Full comp: low