Control of Lung Function

Question 1

What are the four centers in the brain that control lung function called?

Answer 1

1. Dorsal Respiratory Group
2. Ventral Respiratory Group
3. Apneustic Center
4. Pneumotaxic Center

Question 2

What is the Dorsal Respiratory group responsible for?

Answer 2

Main controller of inspiration

Question 3

Which group in the medulla sets the rate for inspiration?

Answer 3

The dorsal respiratory group

Question 4

Which group in the medulla is the expiratory center?

Answer 4

The ventral respiratory group

Question 5

What does the ventral respiratory group Inhibit?

Answer 5

The dorsal and apenustic

Question 6

What does the apneustic center do?

Answer 6

Stimulates the dorsal respiratory group

Question 7

What is the pneumotaxic center known as?

Answer 7

The inspiratory off switch

Question 8

What does the pneumotaxic center do?

Answer 8

Regulates depth and frequency of breathing

Question 9

What does the pneumotaxic center inhibit?

Answer 9

The dorsal respiratory group

Question 10

Why is the pneumotaxic center especially important?

Answer 10

Prevents pulmonary damage and over inflation of the lungs

Question 11

Which two centers make up the pontine respiratory group?

Answer 11

The apnuestic center and the pneumotaxic center

Question 12

Which muscles does the dorsal respiratory group innervate?

Answer 12

The external intercostals

Question 13

Which muscles are involved with expiration?

Answer 13

Internal intercostals

Question 14

Which muscles are involved with inspiration?

Answer 14

External Intercostals

Question 15

Aside from the external intercostals, what else is involved with inspiration?

Answer 15

• The diaphragm
• It moves down during inspiration to reduce pressure in the lungs, which allows the flow of air into the lungs

Question 16

Aside from the internal intercostals, what else in involved with inspiration?

Answer 16

Accessory respiratory muscles

Question 17

Which anatomical structure(s) create the primary drive to breathe?

Answer 17

Specialised medullary/pontine nuclei

Question 18

What inhibits the apneustic center?

Answer 18

Pulmonary afferents

Question 19

What type of gap junctions do normal capillaries have?

Answer 19

H2O-filled gap junctions

Question 20

What type of junctions are found in the Blood Brain Barrier?

Answer 20

Tight junctions

Question 21

Why can charged or large molecules not pass through the blood brain barrier?

Answer 21

Due to the presence of tight junctions

Question 22

Why can Carbon Dioxide pass the Blood Brain Barrier?

Answer 22

CO2 is highly lipid soluble and therefore can pass the blood brain barrier

Question 23

Why are the tight junctions found in the brain?

Answer 23

Certain nervous cells like astrocytes pack the H2O filled junctions which make them tight junctions

Question 24

What does CO2 and H2O do to affect our drive to breathe?

Answer 24

• CO2 can cross into the CSF where it reacts with H2O to form carbonic acid, which dissociates into H+ and bicarbonate
• H+ interacts with afferent fibres in the medulla which send signals to the dorsal respiratory group to determine rate and rhythm of breathing

Question 25

Levels of oxygen are sensed by what on the surface on the medulla oblongata?

Answer 25

Central Chemoreceptors

Question 26

Where are central chemoreceptors found?

Answer 26

In the medulla oblongata

Question 27

What do central chemoreceptors respond to?

Answer 27

Hydrogen ion concentration from the dissociation of CO2 within the surrounding tissue and the CSF, NOT BLOOD

Question 28

Why do central chemoreceptors not response to changes in the blood?

Answer 28

The diffusion of the ions such as H+ and HCO3- from the blood is poor due to the tight junctions between the cells which forms the blood brain barrier

Question 29

Where are peripheral receptors located?

Answer 29

Around the aortic arch and the carotid sinus (Aortic and Carotid Bodies)

Question 30

Afferent neurones from the peripheral chemoreceptors are via which two nerves?

Answer 30

Glossopharyngeal and the Vagus nerve

Question 31

What enzyme is responsible for converting H2O and CO2 into H2CO3 and then H+ and HCO3-?

Answer 31

Carbonic anhyrase

Question 32

What happens when central chemoreceptors found in the medulla detect a reduced blood pH?

Answer 32

They cause the respiratory centers to increase the rate and depth of breathing

Question 33

How does the partial pressure of Carbon Dioxide change going from Rest into Exercise?

Answer 33

Does not change

Question 34

Why does the transition from rest to exercise not impact the partial pressure of CO2?

Answer 34

The overall affect is no change

Question 35

What are irritant receptors?

Answer 35

Afferent receptors found within and beneath the airway epithelium

Question 36

What does activation of irritant receptors lead to?

Answer 36

Cough

Question 37

What does a cough involve?

Answer 37

* Forceful expiration against a closed glottis * Sudden glottal opening and high velocity expulsion of air

Question 38

What does excessive inflation of the lungs activate?

Answer 38

Pulmonary Stretch Receptors

Question 39

What does activation of the stretch receptors do?

Answer 39

Inhibits inspiration and stimulates expiration

Question 40

When stretch receptors are activated, which centers are activated and which are inhibited?

Answer 40

* Apneustic and dorsal are inhibited * Ventral is stimulated

Question 41

What are J receptors sensitive to?

Answer 41

Pulmonary capillary engorgement (high pressure) and oedema

Question 42

What does stimulation of the J receptors lead to?

Answer 42

Increased breathing frequency as oedema and engorgement affect the lungs' ability to ventilate

Question 43

What is Volitional Apnoea?

Answer 43

Cessation of breathing which decreases arterial oxygen and increases CO2

Question 44

What stimulates the medulla to breathe in?

Answer 44

Accumulation of H+ beyond the blood brain barrier when holding breath

Question 45

Describe the emotional change to ventilation

Answer 45

* Special senses and higher brain centres (e.g. limbic system) elicit an emotional response * This can affect the respiratory control centre

Question 46

How are nerves distributed so that exercise can affect breathing?

Answer 46

* A branch of the efferents that go from the primary motor cortex to gross skeletal musculature also innervate the medulla * This tells the brain to start breathing during exercise * Proprioceptive afferents from muscle spindles and golgi tendon organs innervate the medulla on the way to the brain

Question 47

What is meant by chloride shift?

Answer 47

Where one chloride ion is exchanged into red blood cell for one bicarbonate ion out the red blood cell

Question 48

What is an acid

Answer 48

A proton donor

Question 49

A greater H+ concentration refers to what in terms of pH?

Answer 49

A low pH

Question 50

Why must the acidity of the blood be tightly regulated?

Answer 50

marked changes will alter the 3D structure of proteins (enzymes, hormones, protein channels)

Question 51

What transporter is involved in chloride shift?

Answer 51

AE1 Transporter

Question 52

Whatis the ability of the blood to react to changes in H+ ion conc known as?

Answer 52

buffering capacity

Question 53

What is meant by alkaemia?

Answer 53

A higher than normal pH of blood

Question 54

What is meant by acidaemia?

Answer 54

A lower than normal pH of blood

Question 55

What is alkalosis?

Answer 55

Circumstances that will decrease [H+] and increase pH

Question 56

What is acidosis?

Answer 56

Describes circumstances that will increase [H+] and decrease pH

Question 57

What stimulates a rapid compensatory response to affect pH?

Answer 57

Changes in ventilation

Question 58

What stimulates a slow compensatory response to affect pH?

Answer 58

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

Question 59

What is needed to correct an acidaemia?

Answer 59

Alkalosis

Question 60

What are baroreceptors?

Answer 60

Receptors which are sensitive to changes in blood pressure

Question 61

What receptors are involved in the control of alveolar ventilation during exercise?

Answer 61

Central chemoreceptors

Question 62

What triggers the change in ventilation due to emotional change?

Answer 62

The respiratory control center

Question 63

Efferents from primary motor cortex to gross skeletal musculature partly innervate what?

Answer 63

the medulla

Question 64

What innervates the medulla on the way to the brain during exercise?

Answer 64

Proprioceptive afferents from the muscle spindles and golgi tendon organs

Question 65

What effect does cycling someones legs have and what does this show?

Answer 65

* Increases ventilation * Shows that the afferent nerves from muscles and tendons also innervate the medulla on the way to the brain * As the shortening and lengthening of the muscle fibres is enough to create an increase in ventilation

Question 66

What effect does immersion in cold water have on ventilation?

Answer 66

Results in an inspiratory gasp and hyperventilation

Question 67

What pH range is the blood pH tightly regulated between?

Answer 67

7.35 and 7.45

Question 68

What do peripheral chemoreceptors do?

Answer 68

They respond to changes in blood molecule concentrations (like oxygen and carbon dioxide) and help maintain cardiorespiratory homeostasis

Question 69

Why does the partial pressure of carbon dioxide and oxygen not change during normal exercise?

Answer 69

use of oxygen increases and prouction of CO2 increases, however this is compensated for by corresponding increases in ventilation such that blood gas levels remain in normal limits

Question 70

In what circumstance might the partial pressure of oxygen or carbon dioxide change?

Answer 70

During strenuous exercise, when the production of lactic acid results in an acideamia