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Physiology Test 4 > Gas diffusion and transport-handout 5 > Flashcards

Gas diffusion and transport-handout 5 Flashcards

1
Q

Describe how oxygen diffusion works

A

the partial pressure of oxygen in the alveoli is 100mmHg the circulatory system is only 40mmHg, the blood picks up the difference and drops off oxygen in the tissues where the partial pressure is even lower than 40mmHg

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2
Q

Describe carbon dioxide diffusion

A

The partial pressure of carbon dioxide is greater than 46 mmHg in the peripheral tissues, the carbon dioxide goes into the alveoli where the pressure in only 40mmHg from carbon dioxide

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3
Q

What is the diffusion barrier

A

pneumoxyte basement membrane-endothelium

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4
Q

Which law explains passive diffusion

A

Ficks law

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5
Q

Which law is this
J=D(P(O2A)- P(O2a) A/d

Describe the parameters

A

Ficks law

J- rate of gas transfer
D-diffusion coefficient, depends on molecular size
PO2A-PO2a- alveolar and arterial blood parial pressure (oxygen tension)
A- area of exchange
d- diffusion distance or thickness of diffusion barrier

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6
Q

At what point is blood fully oxygenated, how fast is that

A

with in a fourth of a second; the red blood cells are usually fully oxygenated befor they reach the end of lung capillaries

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7
Q

What can oxygen diffusion be impaired by

A
  1. decrease in the area of diffusion (A)- # of alveoli in emphysema or capillaries in pulmonary embolism
  2. decrease in oxygen tension gradient- hypoventilation high altitude

low barometric pressure= low partial pressure of oxygen

  1. thickening of diffusion barrier- pulmonary edema, alveolar wall fibrosis
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8
Q

How is oxygen transported in the blood

A
  1. physically dissolved oxygen

2. hemoglobin (Hb) bound oxygen

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9
Q

What is henry’s law

A

amount of dissolved gas= partial gas pressure X gas solubility in the fluid

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10
Q

What is the partial pressure of oxygen in the alveoli and how much oxygen is dissolved in the blood

A

100mmHg

there is 100mL of blood contained in 20mL of oxygen

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11
Q

How is 97-98% of blood carried inside the body

A

by hemoglobin

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12
Q

Describe the hemoglobin structure

A

composed of four protein globin chains surrounding a central heme group; most adult hemoglobin have two alpha chains and two beta chains

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13
Q

What type of iron binds the oxygen molecule

A

ferrous containing pigment can reversely bind oxygen molecules

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14
Q

Describe the structure of heme

A

a porphyrin ring with an iron atom in the center; ferrous iron (reduced form)

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15
Q

What is loading

A

combining of four oxygen molecules with one hemoglobin molecule-makes oxyg

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16
Q

Describe unloading

A

release of oxygen from oxyhemoglobin molecule at tissue level -forms deoxyhemoglobin

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17
Q

What is affinity

A

force of attract between the oxygen and hemoglobin-increases upon binding the first oxygen molecule

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18
Q

What is the force that underlies loading of oxygen and its binding to hemoglobin

A

high partial pressure of oxygen in the alveoli “loads” erythrocytes with oxygen

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19
Q

Describe loading and unloading through the diagram

A

the oxygen moves from the alveolus into the arterial blood where it mostly binds to the red blood cell (more than 98%), transport of cells in plasma and the oxygen goes into the cells to be used for cellular respiration

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20
Q

What is the level of saturation of two molecules of oxygen and what is the highest level of saturation

A

50%

and 100% if four molecules

Note: normal saturation of arterial blood at sea level is 97-99%, venous blood more than 70%

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21
Q

What in normal rbc count for males and females

A

for males its 4.7-6 mln/mcl
for femals its 4.2-5.4 mlm/mcl

mln/mcl- million per microliter

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22
Q

What is the normal level of hemoglobin

A

males its 13.8-17.2 g/100mL

femals its 12.1-15.1 grams/100mL

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23
Q

What is oxygen content and what does it depend on

A

the total amount of oxygen in blood from dissolved oxygen in plasma and molecules bound to hemoglobin

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24
Q

What is the result of high partial pressure in alveoli

A

loads erythrocytes with oxygen and increases saturation of hemoglobin

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25
Q

Define henrys law

A

when a mixture of gases is in contact with liquid the gas will dissolve in liquid in proportion to its partial pressure gradient

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26
Q

Describe the gas solubility of carbon dioxide and nitrogen

A

carbon dioxide is two times more soluble in water than oxygen and nitrogen is not soluble

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27
Q

What is the oxygen hemoglobin dissociation curve, describe its two parts

A

it at first has a sigmoidal shape (tissue portion where there is low partial pressure of oxygen and hemoglobin loses oxygen, the resting cell has a partial pressure of 40mmHg after the partial pressure goes above this there is a hemoglobin loading phase and then there is a plateau part, and the partial pressure in the lungs is 100mmHG, the load percent gets close to 100%

28
Q

What allows the oxygen to unload from the red blood cells into the tissues

A

the low partial oxygen pressure in tissues leads to unloading of oxygen from red blood cells

29
Q

Explain what happens in very high mountains to gas transport and diffusion

A

the partial pressure of oxygen in lungs drops from 100mmHg to 28mmHg at that pressure red blood cells will carry 50% the maximum load of oxygen
Therefore, low oxygen partial pressure, low hemoglobin saturation and oxygen content in blood

30
Q

What is the saturation lvl of hemoglobin in the arterial blood and venous blood (person is at rest)

A

98% in the arteries

75% in the venous blood @ rest due to release of oxygen to tissues

31
Q

What will cause the saturation of venous blood to go down

A

but during exercise the hemoglobin saturation of venous blood can further decrease

32
Q

At what partial pressure of oxygen is hemoglobin saturated and what does that mean

A

100mmHg the arterial blood will be saturated which means that oxygen is bound to all four heme groups

33
Q

At what partial pressure of oxygen is hemoglobin 75% saturated

A

at 40mHg (venous blood) hemoglobin is 75% saturated

34
Q

At what partial pressure oxygen is hemoglobin 50% saturated

A

25mmHg

35
Q

What is the main factor that determines the affinity of oxygen and hemoglobin

A

partial pressure is the main factor that determines affinity of oxygen and hemoglobin (and its saturation)

36
Q

What other factors affect affinity

A

temperature
partial pressure of carbon dioxide
hydrogen concentration
2.3 DPG

37
Q

If any of the factors that affect affinity increase what does that mean for the oxygen hemoglobin curve? what about if they decrease?

A

the increase means more metabolic activity of tissues, an increase demand for oxygen and the graph will shift to the right

a decrease will shift the curve to left

38
Q

What is the effect of temperature on the oxygen hemoglobin curve

A

high temperature means a high partial pressure is needed for the same level of hemoglobin saturation- affinity is lower at higher temperature

39
Q

In the lungs what will shift the dissociation curve to the left, increasing affinity between oxygen and hemoglobin

A

the temperature of blood
hydrogen concentration
partial pressure of carbon dioxide
2,3 DPG

40
Q

What is the effect of carbon dioxide on the oxygen-hemoglobin curve

A

a decrease in partial pressure of carbon dioxide shifts the dissociation curve to the left, increases the binding of oxygen

41
Q

What is the effect of pH/ Bohr effect on the oxygen-hemoglobin curve

A

increasing the pH shifts the curve to the left, or less H+

42
Q

What is the effect of 2,3 DPG-BPG on oxygen hemoglobin curve

A

less 2.3 DPG shifts curve to left

43
Q

What is the difference between the structure of fetal and adult hemoglobin and how does this affect the affinity seen in the oxygen-hemoglobin curve

A

the two beta chains of fetal hemoglobin are substituted by two gamma chains which increase the affinity for oxygen and shifts the hemoglobin curve to the left

44
Q

How does the difference in fetal Hb help the baby during development

A

higher affinity of the fetal hemoglobin increases the binding power and allows oxygen to transfer from maternal red blood cells to the erythrocytes of the baby

45
Q

Describe embryonic blood flow and refer to diagram

A

embryonic blood flows from umbilical arteries (no oxygen) to the placenta and back by the umbilical vein (oxygenated) it is separated from maternal circulation.

The maternal arterioles feed into the open intervillous space where oxygenated blood surrounds fetal blood vessels and both oxygen and carbon dioxide is exchanged.

46
Q

What does carbon monoxide do to oxygen in blood

A

diminished oxygen carrying capacity (oxygen content) of blood

47
Q

What is carbon monoxide and why is it dangerous

A

odorless, colorless, poisonous gas formed from incomplete combusion of carbon

48
Q

What does carbon monoxide do to RBC/Hb

A

its affinity for hemoglobin is 200 times greater than oxygen and it can bind to form carboxyhemoglobin, which lower oxygen carrying capacity of red blood cells and oxygen content of the blood

49
Q

Does carbon monoxide affect partial pressure of oxygen

A

not really

50
Q

What does the diagram show in regards to adding CO to hemoglobin

A

carbon monoxide lowers the oxygen content of blood

51
Q

What sickle cell anemia

A

congenital defects in hemoglobin proteins (abnormal hemoglobin type S)

52
Q

What is thalassemia

A

insufficiency and congenital defects in hemoglobin protein production

53
Q

What is methhemoglobinemia

A

formation of methhemoglobin (altered iron status) after radiation of drug administration (local and thru inhalation anesthetics, nitrites)

54
Q

What cyanosis

A

the greenish black blood was found after anesthsia induction

55
Q

When ever we is cyanotic-looking blood what is usually the cause

A

dyshemoglobinemia-hemoglobin in the reduced or deoxygenated state; blood gas measurement, however, showed that partial oxygen is high 135mmHg

56
Q

What is methhemoglobin

A

its cynosis due to oxidation of hemoglobin; also sulfhemoglobin when an sulfur atom is incorporated into the porphyrin ring of the heme group

57
Q

what happens to the patients oxygen carrying capacity

A

the oxidation of ferrous iron into ferric iron (2+) by oxidizing agents like nitrites and anesthetics alters hemoglobin into the methhemoglobin form and makes it unable to use oxygen for transport-oxygen carrying capacity is lowered-anemia hypoxia

58
Q

What is a suspected agent of methhemoglobin as seen in the pharmacy news article

A

toxic aniline or carbon compounds

59
Q

Whats high risk for methhemoglobinemia

A 
prilocaine
benzocaines
sulfonamides
nitrates/nitrites 
ciprofloxacin
60
Q

Whats low risk for methhemoglobnemia

A

inhalation anesthetics

61
Q

Describe the differences between ferric and ferrous heme

A

ferric has a charge of 3+ and ferrous a charge of 2+ it is altered

62
Q

How can methhemoglobinemia be treated

A

by the methylene blue electron donor which gets iron back to the ferric state

can be seen because MetHb will be brown and OxyHb will be red

63
Q

How is carbon dioxide transported in blood

A
  1. physically dissolved in plasma
  2. combined with protein portion of hemoglobin-carbamino hemoglobin
  3. as the bicarbonate ion
64
Q

What is the percentage breakdown of the different types of transport of carbon dioxide in blood

A

physically in plasma-5-7%
combined with Hb- 7-23%
bicarbonate ion 70% or more

65
Q

Explain the path of the bicarbonate ion

A

rbc’s that pass through tissue capillaries, the partial pressure of carbon dioxide is high—> carbon dioxide and water are converted into hydrogen ion and bicarbonate ion by carbonic anhydrase.

The bicarbonate will exchanged by rbc for a chloride ion

in the lungs the reverse happens

Physiology Test 4 (6 decks)

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