PL3 - control of breathing :: brain stuff and chemoreceptors

Question 1

What area regulates volitional and emotional control of breathing?
Someone is having an anxiety attack and is hyperventilating which area is most likely causing this?

Answer 1

The supra-pontine sites

Located above the pons – can surpass the respiratory areas in the pons and the medulla and act on the muscles directly

Question 2

Hyperventilation
Hypoventilation

Answer 2

Hyperventilation – breathing in excess of metabolic needs

Hypoventilation – Breathing thats insufficient to meet metabolic needs

Question 3

What is the nucleus tractus solitarius closely associated with?

Answer 3

The dorsal respiratory group (DRG)

Question 4

What are the main respiratory areas in the pons and the medulla?

Answer 4

Medulla – pneumotaxic and apneustic center
Pons – DRG and Ventral Respiratory Group (VRG)

Question 5

What are the pneumotaxic and apneustic center responsible for?

Answer 5

Pneumotaxic – consists of parabrachial neurons. – helps with the transition from inspiration to expiration – inhibits inspiration so expiration can begin

Apneustic center – Responsible for prolonged inspiration (apneusis)

Question 6

What are the structures associated with the DRG and the VRG and what is their role in respiration?

Answer 6

DRG:
- Nucleus tractus solitarius – receives info from a variety of receptors and sends signals to trigger inspiration.

VRG:
- Botzinger complex: controls expiration

• Pre-botzinger complex: Consists of pacemaker neurons. Sets the normal respiratory rate (eupnea = 12-16 bpm)
• Nucleus retroambiguus: Contains both inspiratory and expiratory neurons
• Nucleus Ambiguus: Responsible for inspiration. controls soft palate+uvula+some pharynx and larynx muscles
• Parafacial respiratory group (pFRG): Responsible for expiratory control especially during forced expiration
• RTN: Principle chemosensitive site
• Post inspiratory complex (PiCO) : located in ventromedial pons — involved in post-inspiratory rhythm generation

Question 7

What is the function of the pontine respiratory group (PRG)?

Answer 7

Fine tune respiration and important in laryngeal motor control

Question 8

What is the negative feedback control of the respiratory system dependent on?

Answer 8

Oxygen and acid-base homeostasis

Question 9

_____________ can be adjusted on a breath-by-breath basis in tune with whole-body metabolism

Answer 9

Alveolar ventilation can be adjusted on a breath-by-breath basis in tune with whole-body metabolism

Question 10

True or false:
The supra-pontine sites can surpass the respiratory centers when regulating control.

Answer 10

True – they can directly act on the muscles thru the motor neuron pathways

Question 11

Hyperpnoea

Answer 11

Hyperpnoea – Increased breathing that matches metabolic needs such as during exercise

Question 12

Tachypnoea

Answer 12

Tachypnoea – Increased resp rate above normal (12-20 breaths pm) often rapid and shallow

Question 13

Dyspnea

Answer 13

Dyspnoea - Labored breathing (its a symptom with multiple causes)

Question 14

Apnoea

Answer 14

Apnoea - Absence of airflow due to lack of respiratory effort or airway obstruction

Question 15

When do abdominal muscles contribute to breathing?

Answer 15

They play a role during active breathing
– They contribute during the late expiratory phase

Question 16

What are the 3 main oscillators that regulate respiration

Answer 16

1. preBötzinger complex [preBötC],
2. post-inspiratory complex [PiCo]
3. parafacial respiratory group [pFRG]

Question 17

Muscles modulating airway resistance during respiration and when do they fire during quiet breathing?

Answer 17

Located in the larynx:
- Posterior cricoarytenoid (dilation of airways)
- Thyroarytenoid (constriction of airways)

PCA fires in the inspiratory phase
TA fires in the post-inspiratory phase

Question 18

Which resp. group (DRG/VRG) consists of:
- Only inspiratory neurons
- Both inspiratory and expiratory neurons

Answer 18

• DRG
• VRG

Question 19

Which region in the brain is responsible for the following:
- Sets the inspiration rate
- Putative rhythm post-inspiratory generator
- drives active expiration
- Contains pacemaker neurons
- Fine tune respiration and are important in laryngeal motor control
- Principal chemosensitive site
- expiratory control especially during hypercapnia
- primary integrative site

Answer 19

• Prebotzinger complex
• PiCo (post-inspiratory complex)
• pFRG (parafacial respiratory group)
• Prebotzinger complex
• PRG (pontine respiratory group)
• RTN (retrotrapezoid nucleus)
• pFRG
• NTS (nucleus tractus solitarius) - (DRG)

Question 20

Btozinger complex

Answer 20

expiratory complex

Question 21

Pre-botzinger

Answer 21

Inspiratory
Principal rhythm generator
– has pacemaker neurons
– Sets principal inspiratory rate

Question 22

PiCO

Answer 22

Post inspiratory complex
– post-inspiratory
– putative rhythm generator

Question 23

RTN (retrotrapezoid nucelus)

Answer 23

principal chemosensitive site (for CO2 chemoreception)

Question 24

PRG

Answer 24

Pontine respiratory group
– fine tunes respiration
– important in laryngeal motor control during breathing

Question 25

pFRG

Answer 25

Parafacial respiratory group -- Main center in active respiration -- Quiescent rhythm generator -- active especially during hypercapnia

Question 26

Inspiratory phase is critical for _________ . Activates obligatory and accessory muscles. Upper airway dilation facilitates airflow. Early expiratory (post-inspiratory) phase is critical to the ________________. ____________ protects FRC. Late expiratory phase is essential to ___________ ________________________ facilitates large tidal volume.

Answer 26

Inspiratory phase is critical for ventilation. Activates obligatory and accessory muscles. Upper airway dilation facilitates airflow. Early expiratory (post-inspiratory) phase is critical to the “braking” of expiratory flow. Laryngeal narrowing protects FRC. Late expiratory phase is essential to active breathing. Abdominal muscle recruitment facilitates large tidal volume.

Question 27

_______ is a nexus in central CO2 chemosensitivity

Answer 27

RTN

Question 28

What do central chemoreceptors respond to?

Answer 28

- Local increases in H+ conc. - Increases in PCO2 ----> IN THE CEREBROSPINAL FLUID

Question 29

What do peripheral chemoreceptors respond to?

Answer 29

Changes in PO2, PCO2 and pH (blood acidosis by metabolites)

Question 30

Which chemoreceptors account for the majority of the ventilatory response to hypercapnia?

Answer 30

the central chemoreceptors (account for 70%) While peripheral accounts for 10-30%

Question 31

acidaemia

Answer 31

Blood acidosis

Question 32

What are the 2 peripheral chemoreceptors - where located? Which one is more important? Which nerves do they send signals via?

Answer 32

- Carotid bodies and aortic bodies - In carotid artery at dilation - carotid sinus - In aortic arch -- carotid bodies more important carotid - glossopharyngeal Aortic -- vagus

Question 33

When is alveolar ventilation greater - sleep or awake? how does this affect PCO2?

Answer 33

Awake - increases Pco2

Question 34

Alveolar hypoventilation results in a respiratory _______ Alveolar hyperventilation results in a respiratory _______

Answer 34

acidosis alkalosis

Question 35

primary mechanism for defending the airway from aspiration of liquids?

Answer 35

The laryngeal chemoreflex

Question 36

When is the laryngeal chemoreflex especially powerful? What is its response to liquid in larynx? What could it lead to?

Answer 36

in early-life Central apnea and laryngeal adduction are key features of this reflex in response to liquid in the airways. Can lead to fatal-apneoa -- (sudden death syndrome)

Question 37

Laryngeal chemoreflex?

Answer 37

- Defends airway against aspiration of liquids - Causes laryngeal adduction and central apnoea

Question 38

Laryngeal chemoreflex?

Answer 38

- Defends airway against aspiration of liquids - Causes laryngeal adduction and central apnoea

Question 39

Thermoreceptor, mechanoreceptor and chemoreceptor afferent feedback is relayed centrally via which nerves?

Answer 39

Trigeminal, vagus and glossopharyngeal

Question 40

Which reflex prevents lungs from over inflating and signals start of expiration?

Answer 40

Hering-breuer reflex

Question 41

Which receptors are triggered by fluid accumulation in the lungs/oedema?

Answer 41

The J-receptors

Question 42

Answer 42

Question 43

Answer 43

Question 44

Answer 44

Question 45

What is the result of a muscle reflex activated due to increased exercise on breathing? What is this reflex activated by?

Answer 45

Hyperpnea -- increased breathing to match metabolic needs. Stimulus: stretch of muscles, tendons, movement of joints Sensors: GTO, Spindles, proprioreceptors.