L22: Respiratory System III

Question 1

CO2 is ___ soluble in body fluids than O2

Answer 1

more

Question 2

in what ways is CO2 transported in the blood?

Answer 2

1) dissolved in the blood (7%)
2) as a bicarbonate ion (70%)
3) binds to hemoglobin - HbCO2 (23%)

Question 3

the rapid conversion of CO2 into bicarbonate ion depends on the presence of __

Answer 3

carbonic anhydrase (CA)

Question 4

carbonic anhydrase (CA) is found in __

Answer 4

in red blood cells

Question 5

effects of O2 affinity changes upon __

Answer 5

Hb loading and unloading

Question 6

conversion of CO2 to H+ and HCO3- continues until

Answer 6

equilibrium is reached

Question 7

to keep the reaction going, the products __

Answer 7

must be removed from the cytoplasm

Question 8

what are the ways of removing free H+ and HCO3- from RBCs?

Answer 8

1) an antiport protein exchanges HCO3- for Cl- in a process known as chloride shift
2) Deoxyhemoglobin within the RBC acts as a buffer and binds H+ in the reaction:
H+ + Hb -> HbH

Question 9

how does CO2 bind to hemoglobin?

Answer 9

when O2 leaves its binding sites on the Hb molecule, CO2 binds with free Hb at exposed amino groups

Question 10

what is formed when CO2 binds to Hb?

Answer 10

HbCO2 carbaminohemoglobin

Question 11

most of the HCO3- __

Answer 11

moves out of the erythrocytes into the plasma in exchange for chloride ions

Question 12

as venous blood flows through lung capillaries, __

Answer 12

blood P(CO2) decreases because of the diffusion of CO2 out of the blood into the alveoli, and the reactions are reversed

Question 13

most of H+ generated in the erythrocytes from carbonic acid

Answer 13

binds to deoxyhemoglobin because deoxyhemoglobin formed as oxygen unloads from oxyhemoglobin, has a higher affinity for H+

Question 14

as the blood flows through the lung capillaries

Answer 14

H+ bound to deoxyhemoglobin is released and combines with HCO3- to yield carbon dioxide and water

Question 15

diaphragm and intercostal muscles are

Answer 15

skeletal muscles

Question 16

skeletal muscles do not contract without

Answer 16

stimulation by motor neurons

Question 17

breathing depends entirely upon

Answer 17

cyclical respiratory muscle excitation by the motor nerves

Question 18

inhibition or destruction of motor nerves results from

Answer 18

paralysis of the respiratory muscles and death unless artificial respiration is instituted

Question 19

when action potentials cease

Answer 19

the inspiratory muscles relax, and expiration occurs as the elastic lungs recoil

Question 20

inspiration is initiated by

Answer 20

a burst of action potentials in the spinal motor nerves to inspiratory muscles like the diaphragm

Question 21

in active expiration,

Answer 21

both inspiration and expiration are facilitated by a burst of action potentials

Question 22

the integrating center for the control of breathing is located in

Answer 22

the medulla oblongata

Question 23

the medullary respiratory center is located in

Answer 23

reticular formation

Question 24

the components of medullary respiration center

Answer 24

a small group of pacemaker cells in the pre-Botzinger complex located on either side of the medulla

Question 25

these neurons fire ___

Answer 25

rhythmically and produce rhythmic discharges in phrenic motor neurons

Question 26

what regulates contraction of inspiratory and expiratory muscles?

Answer 26

complex interactions within the medulla oblongata

Question 27

inspiratory and expiratory neurons in the medulla show

Answer 27

reciprocal inhibition

Question 28

during increases in breathing, the inspiratory and expiratory motor nerves and muscles are

Answer 28

not activated at the same time, rather alternate in function

Question 29

__ fine tunes the transition between inspiration and expiration

Answer 29

the Pontine respiratory group (PKG) of the Pons

Question 30

the actions of the pons and medualla are modulated by

Answer 30

the cortex (voluntary control) and sensory input

Question 31

__ provide regulatory input to the medullary inspiratory neurons

Answer 31

peripheral (arterial) and central chemoreceptors

Question 32

peripheral chemoreceptors location

Answer 32

close to the baroreceptors involved in reflex control of blood pressure

Question 33

peripheral chemoreceptors functions

Answer 33

P(O2), pH, P(CO2)

Question 34

peripheral chemoreceptors types

Answer 34

carotid bodies and aortic bodies

Question 35

carotid bodies monitor

Answer 35

O2 supply, predominant

Question 36

central chemoreceptors location

Answer 36

medulla oblongata

Question 37

central chemoreceptors provide __

Answer 37

excitatory synaptic input to the medullary inspiratory neurons

Question 38

central chemoreceptors are stimulated by

Answer 38

an increase in the H+ concentration of the brain ECF

Question 39

why does H+ concentration in the brain's ECF change?

Answer 39

changes in blood P(CO2)

Question 40

___ in the carotid and aortic bodies are activated by ___

Answer 40

specialized glomus cells, a decrease in P(O2) or pH or an increase in P(CO2)

Question 41

glomus cells trigger __

Answer 41

a reflex increase in ventilation

Question 42

oxygen is ___ factor in regulating ventilation

Answer 42

not usually an important

Question 43

to what level P(O2) should fall to trigger the ventilation reflex?

Answer 43

to less than 60 mm Hg

Question 44

when is O2 important in glomus cells reflex?

Answer 44

extreme conditions, high altitude, pathologies, chronic obstructive pulmonary disease (COPD)

Question 45

any condition __ will activate carotid and aortic glomus cells and increase ventilation

Answer 45

that reduces plasm pH or increases P(CO2)

Question 46

central chemoreceptors set __

Answer 46

the respiratory pace by providing continuous input into the control network

Question 47

the central chemoreceptors are located on

Answer 47

the ventral surface of the medulla

Question 48

the central chemoreceptors respond to

Answer 48

pH changes in the CSF, they are not directly responsive to CO2