RESPIRATION 16

Question 1

1) What modifies breathing?
2) What is the primary stimulus for changes in ventilation
3) Which other two factors play lesser roles?

Answer 1

1) Sensory inputs
2) CO2
3) Oxygen and plasma pH

Question 2

Ventilatory response to CO2

Name the two factors measured?

Answer 2

Respiratory rate 
Tidal Volume ( mL)

Question 3

What is Hypercapnia?
What is the normal level?
What is the high level?

Answer 3

Abnormal high level of CO in blood.
40mmHg
45mmHg

Question 4

What is Hypocapnia?

What is the low level?

Answer 4

Abnormal low level of blood CO2

35mmHg

Question 5

What mediates CO2 chemosensitivity?

Answer 5

Oxygen

Question 6

Central CO2 chemoreceptors 1) Location

2) What does it monitor?

Answer 6

1) Medulla

2) H+ in cerebro-spinal fluid and arterial circulation

Question 7

Peripheral chemoreceptors

1) Structures?
2) What does it monitor?

Answer 7

1) Carotid and aortic bodies

2) Arterial level of oxygen and CO2/H+

Question 8

How CO2 Chemoreceptors work?

Answer 8

1) Proton-sensing G-protein coupled receptor 4 ( GPR4) in RTN
2) Sense extra-ceullar pH lower than 7

Question 9

1) What are medullary raphe and what do they do?
2) Are they chemosensitive?
3) These neurons are?

Answer 9

1) Serotoninergic neurons
2) Yes
3) Closed to vessels and capillaries

Question 10

In terms of respiratory chemosensitivity and sleep, What is breathing dependent on?

Answer 10

Metabolic (CO2 and O2) control in Non-REM sleep

Question 11

Clinical focus: sleep apnea

1) What is sleep apnea?
2) List 4 different forms of apneas.

Answer 11

1) Cessation of airflow without respiratory effort
2) Chyne-Stoked breathing
Idiopathic central apnea
Naroctic or anaglesic -induced apnea
Hypoventilation syndrome (Ondine’s curse)

Question 12

25-40% of patients with sleep apnea also have?

Answer 12

Heart failure

Question 13

Clinical focus: Cheyne-Stokes breathing (periodic breathing)

1) Description
2) Causes (3)

Answer 13

1) Waxing and waning of breathing

2) Can be due of heart failure, low sensitivity to CO2 or damage to respiratory centers

Question 14

Clinical focus: Congenital Central Hypoventilation Syndrome

1) Aka
2) What leads to respiratory arrest?
3) Marked by?
4) Cause

Answer 14

1) Ondine’ curse
2) Hypoventilation
3) Reduction of ventilatory and arousal responses to CO2
4) Mutation of Phox2B gene

Question 15

What is Phox2B?

Where is the Phox2B protein found?

Answer 15

1) A gene coding for transcription factor in autonomic nervous system
2) At the level of the RTN

Question 16

Treatments:

1) Patients do not respond to: Congenital Central Hypoventilation Syndrome
2) What is require adequate ventilation, at least during sleep.
3) What is used during the 1st years of life?
4) What is used later in life

Answer 16

1) Ventilatory stimulants
2) Mechanical ventilation
3) Positive-pressure ventilation (PPV)
4) Bi-level psotive airway pressure ventilation continous negative extrathoracic pressure ventilation and diaphragm pacing

Question 17

1) How does Phox2B required for?

2) How does a Phox2b mutation affect it breathing?

Answer 17

1) Development of several neuron types in the central and peripheral nervous systems
2) Genetic elimination of the RTN severely abolishes CO2 sensitivity in constitutive

Question 18

O2 Mediated CO2 chemosensitivity:
What do the following levels indicate:
1) 37 mmHg
2) 47 mmHg
3)  110 mm Hg

Answer 18

1) Severe hypoxia
2) Mild Hypoxia
3) Normoxia

Question 19

Oxygen chemosensitivity:

1) Hypercapnia
2) Normocapnia
3) Hypocania

Answer 19

1) 48.7 mm Hg
2) 43.7 mmHg
3) 35. 8 mmHg

Question 20

What is Hyperoxia?
What is the normal level?
What is too high?
What is hypoxia?
Low level of O2

Answer 20

Abnormal high level of oxygen in blood
= 100-110mmHg
> 110 mmHg
Abnormal low level of blood O2 
< 50 mmHg

Question 21

Central oxygen chemoreceptors ( List the three)

Answer 21

1) The locus coeruleus
2) The thalamus
2) The preBotzinger Complex

Question 22

1) Which receptors play a lesser role in hypoxia?

2) What does the prebotzinger complex do?

Answer 22

1) Central oxygen chemoreceptors

2) The site generating respiratory rhythm

Question 23

Cartoid bodies

1) Contain
2) Detect

3) Unique trait

Answer 23

1) Glomus cells
2) Detect low oxygen (mainly), high CO2 and low pH
3) Highest blood flow of all tissues in the body

Question 24

Clinical focus: tumors of carotid bodies: 3 different types

Answer 24

1) Familial
2) Sporadic
3) Hyerplastic

Question 25

What activated carotid bodies?

Answer 25

Low blood oxygen

Question 26

Cellular mechanisms mediating oxygen sensing (1-7 steps)

Answer 26

1) Low PO2
2) K+ Channels closes
3) Cell depolarizes
4) Voltage gated Ca2+ channels closes
5) Ca 2+ entry
6) Exocytosis of dopamine-containing vesicles
7) Signal to medullary centers to increase ventilation