control of breathing

Question 1

where is the respiratory centre of the brain?

Answer 1

the medulla and pons in the brainstem

Question 2

what is the function of the respiratory centre of the brain?

Answer 2

produces uninterupted rhythmic breathing activity

Question 3

Describe the dorsal respiratory group

Answer 3

• located in the dorsal region of the medulla
• recieves afferent signals from glossopharyngeal & vagus nerve
• dorsal respiratory group (DRG) primarily fire
  during inspiration and have input to the spinal motor neurons
  that activate respiratory muscles involved in inspiration—the
  diaphragm and inspiratory intercostal muscles

Question 4

Describe the ventral respiratory group

Answer 4

• located on the ventral region of the medulla
• control expiration
• expiratory neurons appear to be important during exercise/strenous physical activity

Question 5

what is the pre-botzinger complex in the upper part of VRG?

Answer 5

it is the respiratory rhythm generator

Question 6

where do the repetitive bursts of action potentials travel to?

Answer 6

the diaphragm and inspiratory muscles

Question 7

what are the 3 key areas in the medullary respiratory centre?

Answer 7

1. dorsal respiratory group
2. ventral respiratory group
3. pre-botzinger complex upper part of ventral respiatory group

Question 8

Describe the neural generation of rhythmical breathing

Answer 8

• the groups of neurons have the properties of periodic firing & are responsible for the basic rhythm of ventilation
• they generate repetitve bursts of AP’s going to the respiratory muscles
• during inspiration, the AP’s increase creating a ‘ramp-like’ pattern and increasing the inspiratory muscle activity
• expiration occurs as the elastic lung recoils

Question 9

what is the diaphragm innervated by?

Answer 9

the phrenic nerve

Question 10

where is the apneustic centre located?

Answer 10

the pons

Question 11

what is the effect of the apneustic centre?

Answer 11

• the impulses of this centre have an excitatory effect on the inspiratory area of medulla
• they prolong the ramp action of AP’s

Question 12

what is the function of the pneumotaxic centre in the pons?

Answer 12

• inhibits inspiration
• modulates the apneustic centre in the pons
• finetunes the transition from inspiration to expiration

Question 13

what is inspiration initiated by?

Answer 13

Inspiration is initiated by a burst of action potentials in the
spinal motor neurons to inspiratory muscles like the diaphragm.

Question 14

what is the primary inspiratory muscle at rest?

Answer 14

the diaphragm

Question 15

what type of cells is the respiratory rhythm generator (pre-botzinger complex) made up of?

Answer 15

pacemaker cells and a complex network of neurons that act together to set the basal respiratory rate

Question 16

what occurs when the inspiratory neurons stop firing?

Answer 16

the inspiratory muscles relax which allows passive expiration

Question 17

Describe is an example of a cut off signal for inspiration?

hint - its a reflex

Answer 17

• the pulmonary stretch receptors which are ativated by a large inflation during inspiration
• AP’s in the afferent nerve fibres in the stretch receptors travel to the brain & inhibit the activity of the medullary inspiratory neurons
• called the hering-breuer reflex

Question 18

how do chemoreceptors alter the rate of breathing?

Answer 18

• they have important inputs to the respiratory centre eg the rate of inspiration / expiration can be increased or decreased when the** levels of arterial oxygen decrease** or when the** levels of arterial CO2 increase**

Question 19

what are the peripheral chemoreceptors and where are they located?

Answer 19

• peripheral receptors - ie below the CNS
• they are located high in the neck
• eg carotid bodies and aortic bodies

Question 20

where is the central chemoreceptors located and what does it respond to?

Answer 20

• located in the medulla
• responds to increased H+ concentration in the brain ECF

Question 21

what is hyperventilation?

Answer 21

breathig in excess of the metabolic needs

Question 22

what is hyperpnoea?

Answer 22

increased breathing that matches the metabolic needs

Question 23

what is tachypnoea?

Answer 23

increased brathing above normal (more than 20 per minute), often rapid and shallow breathing

Question 24

what is hypoventilation?

Answer 24

breathing that is **insufficient to meet the metabolic needs **

Question 25

what is apnoea?

Answer 25

an absence of airflow due to a lack of respiratory effort or airway obstruction