Respiratory System 2

Question 1

Respiratory muscles = _____ muscles and are controlled by ___ neurons.

Answer 1

• skeletal muscles

- motor neurons

Question 2

What two components are important for inspiration? What do they control?

Answer 2

• phrenic nerve: diaphragm

- External intercostal nerve: external intercostal muscles

Question 3

What component is important for expiration? What does it control?

Answer 3

internal intercostal nerve: internal intercostal muscles

Question 4

Name 6 components that generate the breathing rhythm.

Answer 4

• Phrenic nerve
• Internal and external intercostal nerves
• Inspiratory and expiratory neurons
• Respiratory control centers of medulla
• Respiratory control centers of pons
• Central pattern generator

Question 5

Name the 3 components of the brainstem respiratory centre.

Answer 5

• inspiratory neurons
• expiratory neurons
• mixed neurons

Question 6

Inspiratory neurons ____ during inspiration.

Answer 6

depolarize

Question 7

Expiratory neurons _____ during expiration.

Answer 7

depolarize

Question 8

Mixed neurons have properties of:

Answer 8

both inspiratory and expiratory neurons

Question 9

What are the 2 respiratory control centres that are located on each side of the medulla?

Answer 9

• ventral respiratory group (VRG)

- dorsal respiratory group (DRG)

Question 10

Describe the ventral respiratory group (VRG).

Answer 10

nucleus ambiguous = mostly expiratory

Question 11

Describe the dorsal respiratory group (DRG).

Answer 11

nucleus tractus solitaries = mostly inspiratory

Question 12

In the medulla, inspiratory neurons are hypothesized to:

Answer 12

control motor neurons to inspiratory muscles

Question 13

In the medulla, expiratory neurons are hypothesized to:

Answer 13

control motor neurons to expiratory muscles and/or inhibit inspiratory neurons

Question 14

Pontine respiratory group contains ____, ____, and ____ neurons.

Answer 14

inspiratory, expiratory, and mixed neurons

Question 15

Pontine respiratory group may regulate:

Answer 15

transitions between inspiration and expiration

Question 16

Central pattern generator (CPG) mechanism is:

Answer 16

• unknown

- possibly through pacemaker type of activation

Question 17

Name 7 peripheral inputs to respiratory centres.

Answer 17

• Chemoreceptors
• Pulmonary stretch receptors
• Irritant receptors
• Muscle and joint proprioceptors
• Baroreceptors
• Thermoreceptors
• Nociceptors

Question 18

Breathing is also affected by what 3 things?

Answer 18

• limbic system
• hypothalamus
• cerebellum

Question 19

What are the 2 types of chemoreceptors that control ventilation?

Answer 19

• peripheral chemoreceptors

- central chemoreceptors

Question 20

Where are peripheral chemoreceptors found?

Answer 20

in carotid and aortic bodies

Question 21

Describe peripheral chemoreceptors.

Answer 21

• Detect levels of CO2 and O2 in the CSF and the blood
• pH changes when PCO2 changes or directly by H+ ions
• Low PO2 increases chemoreceptor sensitivity to PCO2
• PO2 not really a factor
• pH is the primary factor
• more rapid response

Question 22

Where are central chemoreceptors found?

Answer 22

central surface of medulla

Question 23

Describe central chemoreceptors.

Answer 23

• H+ ions from CO2 in blood and from increased brain activity or decreased blood flow to the brain
• H+ ions directly (and thus, pH)
• Indirectly respond to PCO2
• Cannot respond to increased H+ in the blood because they cannot cross the blood brain barrier

Question 24

Central chemoreceptors respond to:

Answer 24

changes in pH of the CSF

Question 25

Central chemoreceptors are not directly responsive to ___, instead they respond indirectly to it via ____.

Answer 25

- CO2 | - pH

Question 26

Increased CO2 ______ pH.

Answer 26

decreases

Question 27

Central chemoreceptors are not responses to changes in -___.

Answer 27

O2

Question 28

Normal blood pH =

Answer 28

7.4 (range 7.38 –7.42)

Question 29

____ and ___ systems regulate blood pH.

Answer 29

respiratory and renal systems

Question 30

Small changes in pH have what effect?

Answer 30

large physiological effects

Question 31

What is acidosis?

Answer 31

- blood pH < 7.35 | - CNS depression

Question 32

What is alkalosis?

Answer 32

- blood pH > 7.45 | - CNS over-excitation

Question 33

Name 2 buffers.

Answer 33

- hemoglobin | - bicarbonate

Question 34

Describe how hemoglobin is a buffer.

Answer 34

deoxyhemoglobin has a greater affinity for H+

Question 35

At the tissues, hemoglobin does what?

Answer 35

can release O2 and bind H+ (Bohr effect)

Question 36

How is pH regulated by CO2 levels?

Answer 36

- respiratory acidosis (caused by increased CO2) | - respiratory alkalosis (caused by decreased CO2)

Question 37

Why does bronchoconstriction and bronchodilation occur?

Answer 37

- Smooth muscle innervated by ANS | - SNS vs PSNS response

Question 38

At rest, only ___% of pulmonary capillary capacity.

Answer 38

~33%

Question 39

Those not participating in gas exchange (alveoli near non-conducting capillaries – nearest to apex at rest) are considered:

Answer 39

physiological dead space

Question 40

What is exercise-induced arterial hypoxemia (EIAH)?

Answer 40

- decreased transit time - Up to 15% desaturation below resting values may occur- O2 diffusion is reduced (from alveoli to the blood) - occurs near maximal exercise - Compound effect due to right shift of O2/Hb curve – increased temp during exercise (1.5 – 3 celcius) and pH (< 7.25)

Question 41

In EIAH, for every 1% decrease in O2 saturation, VO2 max decreases by:

Answer 41

1.5-2%

Question 42

Respiratory muscle work accounts for ____% of VO2.

Answer 42

10-16%

Question 43

The diaphragm fatigues at __% VO2.

Answer 43

80%

Question 44

What is respiratory muscle training?

Answer 44

Reduces the reflex response that redistributes blood away from exercising muscle to the respiratory muscles

Question 45

Why can respiratory muscle fatigue have a negative impact on performance?

Answer 45

reductions in blood flow to the working muscles

Question 46

How is pressure affected when exercising at altitude?

Answer 46

Partial pressures drop so less oxygen is available at the alveoli Decreased arterial PO2 = hypoxemia Decreased tissue oxygen levels = hypoxia

Question 47

What response happens when exercisign at altitude?

Answer 47

- Stimulates a reflexive response that increases ventilation, but as a consequence, decreases PCO2, impacting chemoreceptors - Result is a shift of the oxyhemoglobin curve to the left and more O2 is loaded at the lungs (less at tissues) - Also: 2, 3 DPB/BPG stimulated and EPO