L22: Respiratory System III Flashcards

1
Q

CO2 is ___ soluble in body fluids than O2

A

more

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2
Q

in what ways is CO2 transported in the blood?

A

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

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3
Q

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

A

carbonic anhydrase (CA)

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4
Q

carbonic anhydrase (CA) is found in __

A

in red blood cells

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5
Q

effects of O2 affinity changes upon __

A

Hb loading and unloading

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6
Q

conversion of CO2 to H+ and HCO3- continues until

A

equilibrium is reached

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7
Q

to keep the reaction going, the products __

A

must be removed from the cytoplasm

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8
Q

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

A

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

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9
Q

how does CO2 bind to hemoglobin?

A

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

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10
Q

what is formed when CO2 binds to Hb?

A

HbCO2 carbaminohemoglobin

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11
Q

most of the HCO3- __

A

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

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12
Q

as venous blood flows through lung capillaries, __

A

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

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13
Q

most of H+ generated in the erythrocytes from carbonic acid

A

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

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14
Q

as the blood flows through the lung capillaries

A

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

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15
Q

diaphragm and intercostal muscles are

A

skeletal muscles

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16
Q

skeletal muscles do not contract without

A

stimulation by motor neurons

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17
Q

breathing depends entirely upon

A

cyclical respiratory muscle excitation by the motor nerves

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18
Q

inhibition or destruction of motor nerves results from

A

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

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19
Q

when action potentials cease

A

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

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20
Q

inspiration is initiated by

A

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

21
Q

in active expiration,

A

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

22
Q

the integrating center for the control of breathing is located in

A

the medulla oblongata

23
Q

the medullary respiratory center is located in

A

reticular formation

24
Q

the components of medullary respiration center

A

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

25
Q

these neurons fire ___

A

rhythmically and produce rhythmic discharges in phrenic motor neurons

26
Q

what regulates contraction of inspiratory and expiratory muscles?

A

complex interactions within the medulla oblongata

27
Q

inspiratory and expiratory neurons in the medulla show

A

reciprocal inhibition

28
Q

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

A

not activated at the same time, rather alternate in function

29
Q

__ fine tunes the transition between inspiration and expiration

A

the Pontine respiratory group (PKG) of the Pons

30
Q

the actions of the pons and medualla are modulated by

A

the cortex (voluntary control) and sensory input

31
Q

__ provide regulatory input to the medullary inspiratory neurons

A

peripheral (arterial) and central chemoreceptors

32
Q

peripheral chemoreceptors location

A

close to the baroreceptors involved in reflex control of blood pressure

33
Q

peripheral chemoreceptors functions

A

P(O2), pH, P(CO2)

34
Q

peripheral chemoreceptors types

A

carotid bodies and aortic bodies

35
Q

carotid bodies monitor

A

O2 supply, predominant

36
Q

central chemoreceptors location

A

medulla oblongata

37
Q

central chemoreceptors provide __

A

excitatory synaptic input to the medullary inspiratory neurons

38
Q

central chemoreceptors are stimulated by

A

an increase in the H+ concentration of the brain ECF

39
Q

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

A

changes in blood P(CO2)

40
Q

___ in the carotid and aortic bodies are activated by ___

A

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

41
Q

glomus cells trigger __

A

a reflex increase in ventilation

42
Q

oxygen is ___ factor in regulating ventilation

A

not usually an important

43
Q

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

A

to less than 60 mm Hg

44
Q

when is O2 important in glomus cells reflex?

A

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

45
Q

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

A

that reduces plasm pH or increases P(CO2)

46
Q

central chemoreceptors set __

A

the respiratory pace by providing continuous input into the control network

47
Q

the central chemoreceptors are located on

A

the ventral surface of the medulla

48
Q

the central chemoreceptors respond to

A

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