Cardio 3.3

Question 1

what does breathing maintain?

Answer 1

Pa(O2) and Pa(CO2)

Question 2

what part of the brain stem normally controls the breathing?

Answer 2

medulla and pons

Question 3

what three groups of neurons in the brain stem normally control involuntary breathing ?

Answer 3

-Medullary respiratory center
-apneustic center
-pneumotaxic center
(latter two are in the pons)

Question 4

medullary respiratory center contains what neurons?

Answer 4

Dorsal Respritory group (DRG)

Question 5

The DRG is mainly responsible for what?

Answer 5

inspiration and generation of the basic rhythm for breathing

Question 6

what provides input to the DRG and what do they do?

Answer 6

CN X- inputs info from the peripheral chemoreceptors and mechanorecperores

CN IX- inputs information from peripheral chemoreceptors

Question 7

by what means does output from the DRG travel?

Answer 7

The phrenic nerve

Question 8

the medullary group contains what neurons?

Answer 8

Ventral respiratory Group (VRG)

Question 9

What does the VRG control?

Answer 9

-primarily responsible for experiration

However, is not active during normal breathing, only during active breathing

Question 10

how does normal respiration occur?

Answer 10

activation and deactivation of the DRG (active when inspiring, inactive when expiring)

Question 11

where is the apneustic center located?

Answer 11

lower pons

Question 12

what does the apneustic center controle?

Answer 12

Prolonged stimulation of inspiration (excites respritory center in medulla prolonging action potentials in the phrenic nerve)

Question 13

where is the pneumotaxic center located?

Answer 13

in the upper pons

Question 14

what function does the pneumotaxic center play

Answer 14

inhibits inspiration and limits the burst of action potential in the phrenic nerve (limits the size of the Tidal volume)

Question 15

true or false, the cerebral cortex can overide the brainstem in order to cause hyper or hypo ventalation

Answer 15

true

hyperventalation can raise pH by decreasing Ps(CO2)

Question 16

where are central chemoreceptors found?

Answer 16

bilaterally in the ventrolateral medulla

Question 17

where are the peripheral chemoreceptors found?

Answer 17

The aortic arch and carotid arteries

Question 18

what stimulii increases the Breathing rate?

Answer 18

Central chemoreceptors
    Lower pH
    Increased P(CO2)
Peripheral
    decreased P(O2)
    Increased P(CO2)
    decreased pH

Question 19

what is the most closely controlled chemical influencing respiration?

Answer 19

CO2 (Normally around 40mmHg, and regulated +/-3mmHG)

Question 20

what does a decrease in pH in the CSF induce?

Answer 20

An increased breathing rate

Question 21

what crosses the blood brain barrier more easily

H+ of CO2

Answer 21

CO2

Question 22

what are peripheral chemoreptor most sensitive to?

Answer 22

arterial O2 (only has a slight inlfuence on ventilation, O2 must be below 60)

Question 23

What is hypoxic drive

Answer 23

when CO2 is retained due to pulminary disease, thus receptors adapt, and do not react to this stimuluse. declining O2 is the driving force behind respiration

Question 24

Is it a good idea to give someone with hypoxic drive O2?

Answer 24

NO, this will decrease their breathing

Question 25

what are three non-chemical factors that conribute to breathing

Answer 25

• lung stretch receptors
• irritant receptors
• joint and muscle receptors

Question 26

what is the purpose of the stretch recpetors

Answer 26

it is a protective reflex to prevent over-expansion of the lung

Question 27

where are irritant receptors found

Answer 27

between epithelial cells lining the airways (constrict branchial smooth muscle)