Lecture 22: Respiration 1

Question 1

Why do you need to breath?

Answer 1

acquire oxygen and remove waste (CO2)
maintain blood pH
match metabolism
temperature regulation

Question 2

What is the oxygen cascade?

Answer 2

ventilation -> pulmonary diffusion -> circulation -> tissue diffusion -> tissue metabolism

Question 3

What are the three phases of respiration?

Answer 3

inspiration, post-inspiration and late expiration

Question 4

What happens during inspiration?

Answer 4

diaphragm contracts and expands the thoracic cavity
abductor muscles of the upper airways contract resulting in dilation of the upper airways
subglottal pressure decreases

Question 5

What happens during post-inspiration?

Answer 5

diaphragm starts to relax and volume of the thoracic cavity decreases
adductor muscles of the upper airways contract resulting in constriction of the upper airways
significant increase in subglottal pressure

Question 6

What happens during late expiration?

Answer 6

diaphragm is relaxed and volume of the thoracic cavity is compressed
muscles of the upper airways are relaxed and the upper airways are opened up a little bit more
subglottal pressure is decreased

Question 7

What does the phrenic nerve innervate?

Answer 7

the diaphragm

Question 8

What does the hypoglossal nerve innervate?

Answer 8

the genioglossus muscle

Question 9

What does activity of the recurrent laryngeal nerve lead to during inspiration?

Answer 9

contraction of the abductor muscles of the upper airway to reduce resistance and increase airflow

Question 10

Where is the ventral respiratory group located?

Answer 10

in the medulla

Question 11

What do brainstem regions produce synchronised respiratory output to?

Answer 11

the spinal cord

Question 12

What is pre-BötC sufficient for?

Answer 12

generating respiratory rhythm

Question 13

What would happen if you destroyed pre-BötC neurons?

Answer 13

this would lead to a decrease in respiratory frequency and amplitude of motor output

Question 14

What is the function of pre-BötC neurons?

Answer 14

pre-inspiratory or early inspiratory function

little to no expiratory function

Question 15

What do pre-BötC neurons express?

Answer 15

NK1-receptor, somatostatin and Dbx-1 transcription factor

Question 16

What type of neuron are pre-BötC neurons?

Answer 16

glutamatergic

there is a subset that is glycinergic

Question 17

What is the endogenous ligand for the NK1-receptor?

Answer 17

substance P

Question 18

Why type of receptor is NK1?

Answer 18

G-protein coupled receptor which is internalised following stimulation by substance P
attached ligand is also internalised

Question 19

What is saporin?

Answer 19

a ribosomal inactivating protein (RIP) which inhibits protein synthesis and initiates cell death

Question 20

What is required for saporin to enter the cell?

Answer 20

needs to be bound to a chaperone

Question 21

Are NK1-R expressing cells in pre-BötC actually required for normal breathing rhythm generation?

Answer 21

yes

Question 22

What did destruction of NK1-receptor expressing neurons in the pre-Botzinger complex result in?

Answer 22

irregular breathing with large periods of apnea

Question 23

What did silencing of the pre-Botzinger complex by the insect peptide allatostatin after transfection with AAV result in?

Answer 23

cessation of breathing

Question 24

What do experiments in destruction and silencing of pre-Botzinger complex neurons serve to demonstrate?

Answer 24

pre-Botzinger complex is essential and necessary for respiratory rhythm generation

Question 25

What are the properties of pre-Botzinger neurons?

Answer 25

action potentials continue to fire even when all synaptic transmission is inhibited

Question 26

What allows for intrinsic bursting in pre-Botzinger neurons?

Answer 26

persistent sodium current

Question 27

What are two important factors in generation of bursts in pre-BötC neurons?

Answer 27

Ca2+ activated nonselective cationic current AND persistent sodium currents

Question 28

How does intra-alveolar pressure and intra-pleural pressure change during inspiration?

Answer 28

intra-alveolar pressure decreases then increases

intra-pleural pressure decreases

Question 29

How does intra-alveolar pressure and intra-pleural pressure change during post-inspiration?

Answer 29

intra-alveolar pressure increases then slightly decreases

intra-pleural pressure increases

Question 30

How does intra-alveolar pressure and intra-pleural pressure change during late expiration?

Answer 30

intra-alveolar pressure decreases

intra-pleural pressure increases

Question 31

How does airflow change during respiration?

Answer 31

inspiration: air flow in
post-inspiration: air flow out
late expiration: air flow out