Control of Lung Function

Question 1

What is the dorsal respiratory group?

Answer 1

•Inspiratory centre
•Main ‘controller’ of inspiration
•Set the ‘rate’
-Stops Ventral

Question 2

What is a ventral respiratory group?

Answer 2

•Expiratory centre
•Inactive during quiet breathing
-Inhibit apneustic centre
-Stops Dorsal

Question 3

What is the apneustic centre?

Answer 3

•Stimulates activity in DRG
•Inhibited by pulmonary afferents
-Encourgaes D

Question 4

What is the penumotaxic centre?

Answer 4

•The ‘inspiratory off switch’
•Regulates depth & frequency
-Stops D

Question 5

What forms the phrenic nerve?

Answer 5

• C3, C4, C5, (primary drive to breath)

- Bilateral, innervates the diaphragm

Question 6

What do respiratory muscles have?

Answer 6

Motor neurons as skeletal muscle

Question 7

What are the external intercostals?

Answer 7

• Supplementary inspiratory musculature
• Need innervation to inertial intercostal for expiratory efforts
• Lots of innervation for rectus abdomens

Question 8

What is in BBB?

Answer 8

• tight junctions are also supplemented by glial cells to keep them in place
• proton concentration in CNS to provide stimulus to breathe
• Proton conc is proportional to CO2 conc
• H+ Cant dissolve through but CO2 can move and this combines with water to form H+ and bicarbonate

Question 9

What do the protons in the CSF do?

Answer 9

• Tasted by chemoreceptors neurones in medulla
• Medulla sampling blood which regulates way acting
• Projections to dorsal respiratory nucelus

Question 10

What can pass the BBB?

Answer 10

-Charged/large molecules cannot pass BBB
-CO2 is highly lipid soluble
-Useful a proton conc reflect CO2 conc and CO2 conc reflects metabolism so if change breathing we want to change proportional to what is required
so if one of outputs of energy production is CO2 then gives
Real time indicator as to what metabolism in body is like

Question 11

What are the irritant receptors?

Answer 11

• Afferent receptors embedded within and beneath airway epithelium
• Leads to cough: which involves forceful expiration against a closed glottis with sudden glottal opening & high velocity expulsion of air

Question 12

What are the stretch receptors

Answer 12

• Excessive inflation of lungs activates pulmonary stretch receptors
• Afferent signals to respiratory centres inhibit DRG and apneustic centre and stimulate pneumotaxic VRG
• Inspiration inhibited & expiration stimulated

Question 13

What are J receptors?

Answer 13

• Sensitive to oedema and pulmonary capillary engorgement

* Increases breathing frequency

Question 14

What is an acid?

Answer 14

An acid is any molecule that has a loosely bound H+ ion that it can donate
H+ ions are also called protons (because an H atom with a +1 valency has no electrons or neutrons)

Question 15

What is a base?

Answer 15

A base is an anionic (negatively charged ion) molecule capable of reversibly binding protons (to reduce the amount that are ‘free’)

Question 16

What is the paradox?

Answer 16

A greater concentration of H+ ions refers to a lower pH (discussed later)
The acidity of the blood must be tightly regulated, marked changes will alter the 3D structure of proteins (enzymes, hormones, protein channels)

Question 17

What is the acid base homeostasis?

Answer 17

This relationship is in an equilibrium. Increasing something on one side will push the equation in the opposite direction

Question 18

What is the buffering capacity in the blood?

Answer 18

The buffering capacity of the blood was first identified by Pitts and Swan
The blood has an ENORMOUS buffering capacity that can react almost IMMEDIATELY to imbalances

Question 19

What is alkalaemia?

Answer 19

Refers to high-than-normal pH of blood

Question 20

What is acideamia?

Answer 20

Refers to lower-than-normal pH of blood

Question 21

What is alkalosis?

Answer 21

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

Question 22

What is acidosis?

Answer 22

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

Question 23

What do changes in ventilation stimulate?

Answer 23

Changes in ventilation can stimulate a RAPID compensatory response to change CO2 elimination and therefore alter pH

Question 24

What do changes in HCO3- and H+ retention/secretion in the kidneys stimulate?

Answer 24

Changes in HCO3- and H+ retention/secretion in the kidneys can stimulate a SLOW compensatory response to increase/decrease pH

Question 25

What does an acidosis need?

Answer 25

An acidosis will need an alkalosis to correct

Question 26

What does an alkalosis need?

Answer 26

An alkalosis will need an acidosis to correct

Question 27

Where are peripheral chemoreceptors?

Answer 27

Positioned near the carotid baroreceptors (sensitive to changes in blood pressure)

Question 28

What is breathing during excecise?

Answer 28

1. Efferents from primary motor cortex to gross skeletal musculature partly innervate medulla
2. Proprioceptive afferents from muscle spindles & golgi tendon organs innervate medulla on way to brain

Question 29

Can skin affect breathing?

Answer 29

• Thermoreceptors have afferents

- Cold shock 80-90% immersion