HLB - Gas Exchange and Gas Transport

how many ml of oxygen combines with each gram of haemoglobin

1.34

how many grams of haemoglobin are present per liter of blood

150g/l

what is the partial pressure of oxygen in arterial blood at atmospheric pressure with an oxygen saturation of 97%

13kPa

an oxygen partial pressure below what value (in kPa) causes respiratory failure

below 8kPa

what is 2.3-DPG

2,3 diphosphoglycerate

what does an increased concentration of 2,3-DPG cause in terms of the oxygen haemoglobin dissociation curve

right shift

if the oxygen haemoglobin curve is right shifted what does this mean

oxygen is released from haemoglobin into cells

in the alveoli what type of shift in the oxygen haemoglobin dissociation curve results from an increase of 2,3 DPG, and what does this mean for affinity

a left shift, with increased haemoglobin affinity for oxygen

what does the oxygen cascade refer to

the falling pressure of oxygen from the air to the mitochondria

what is FIO

the fraction of inspired oxygen

what is the FIO in air

0.21

what does PIO stand for

the partial pressure of oxygen within the inspired air

what does Patm stand for and what is its value

atmospheric pressure, which is 101kPa

how is PIO calculated

FIO x Patm

what is the approximate value of PIO

20kPa

what is a normal oxygen saturation value between

94 and 98%

what is oxygen saturation

a measure of the percentage of haemoglobin that is fully saturated with oxygen

what is the alveolar gas equation used for

to calculate the partial pressure of oxygen in the alveolus

what is the alveolar gas equation

PAO = FIO (Patm - Ph20) - (PaCO/R)

what is PAO

the partial pressure of oxygen in the alveolus

what is Ph20

the measure of pressure of water vapor

what is PaCO

the partial pressure of carbon dioxide

in the alveolar gas equation, what does R stand for and what is its value

the respiratory quotient, which is 0.8

what is the conversion ratio of mmHg to KPa

1 : 133.32

what is DO2

oxygen delivery

what is CO, and what is it equal to

cardiac output, it is equal to heart rate times the stroke volume

how is oxygen delivery calculated

cardiac output multiplies by the arterial oxygen content

what is VO2

oxygen consumption

what is VO2 equal to

the amount of oxygen consumed in a minute

what is VO2 at rest

250ml/min

at rest in a healthy person, which is greater, their oxygen consumption, or their oxygen delivery

oxygen delivery

how much more soluble is carbon dioxide in plasma than in oxygen

20%

what percentage of carbon dioxide is carried as carbaminohaemoglobin

30%

what percentage of carbon dioxide is dissolved in plasma

10%

what percentage of carbon dioxide is transported in the blood as bicarbonate ions

60%

what is chloride shift

when chloride ions diffuse into red blood cells

when does chloride shift occur

when there is a high hydrogen ion concentration in red blood cells, causing chloride ions to diffuse in to maintain electrical neutrality

why cant hydrogen ions diffuse out of red blood cells in relation to chloride shift

the membrane is impermeable to them

what causes an excess of hydrogen ions in red blood cells in terms of chloride shift

the action of carbonic anhydrase

what can occur when the partial pressure of oxygen rises in the haldane

haemoglobin releases carbon dioxide into the lungs

what can occur when the partial pressure of oxygen falls, in the haldane effect

haemoglobin binds to carbon dioxide in the tissues

what does the haldane affect make the oxygenation of haemoglobin dependent of in the alveoli

carbon dioxide release

in terms of the haldane affect, what can haemoglobin take up more of when deoxygenated

carbon dioxide

in arterial blood, what range must pH be maintained between

7.35 and 7.45

transport of what into the plasma is critical in acid base regulation of the blood

carbon dioxide

what are two important buffers in the blood that bind to and release carbon dioxide

bicarbonate and deoxygenated haemoglobin

what type of respiratory failure can result in respiratory acidosis

type two respiratory failure

how does type two respiratory failure cause respiratory acidosis

it causes an increase in carbon dioxide levels, increasing hydrogen ions, so lowering the pH

what is the respiratory quotient

the ratio of carbon dioxide production to oxygen consumption

what does metabolising carbohydrates produce in terms of the volume of carbon dioxide

a volume of carbon dioxide equal to the volume of oxygen used

what does ventilation correlate with

the rate of carbon dioxide production

what is an acinus

a unit of respiratory function, distal to the terminal bronchioles

what is an acinus comprised of

bronchioles, alveolar ducts, and alveoli

what do many acinar together form

the pulmonary lobule

what are pulmonary lobules separated by

septae

what does the structural independence that acinar provide prevent

the collapse of an individual unit

how many alveoli does an adult male have

approximately 300 million

what does the number of alveoli depend on

an individuals height

what does the size of the alveoli depend on

the volume of air in the lungs

what is the shape and size of the alveolar

an irregular polyhedron that is between 0.1 and 0.2 micrometers in diameter

what are club cells/ bronchiolar exocrine cells

cells that produce glycosaminoglycans in alveolar fluid

what are pneumocytes

Specialised epithelial cells lining the alveoli

where are type 1 pneumocytes found

resting on the basement membrane, interfacing closely with the capillary membrane

what is the alveolar epithelium comprised of

type 1 pneumocytes and the basement membrane

what is the interstitial space

the space between the alveolar epithelium and capillary endothelium

what is the alveolar capillary unit

the alveolar epithelium, interstitial space, and capillary endothelium

where are type 2 pneumocytes found

at the junction between alveoli

what do type 2 pneumocytes produce

surfactant

what is the function of surfactant

to reduce surface tension

what is the interstitium

the microscopic space between the alveoli and pulmonary capillary wall

how thick is the interstitium

0.5 micrometers

does a higher or lower molecular weight increase speed of diffusion

lower molecular weight

does a higher or lower solubility of gas in a membrane increase diffusion speed

higher solubility

what is TLCO

the transfer factor of the lung for carbon monoxide

what can TLCO help to estimate

the movement of oxygen across the capillary membrane

what is the single breath method

a method used to determine the amount of carbon monoxide transferred across the alveolar capillary membrane per minute

what two conditions reduce TLCO

emphysema and pulmonary fibrosis

how does emphysema reduce TLCO

it affects the surface area available for gas exchange

how does pulmonary fibrosis affect TLCO

it affects the thickening of the membrane

when is carboxyhaemoglobin formed

when carbon monoxide binds to haemoglobin

how is carbon monoxide poisoning managed

by hyperbaric oxygen

when is methaemoglobin produced

when the iron component is haemoglobin is oxidised so that it is in its ferric state (Fe3+)

why is MetHb damaging

it cannot bind to oxygen so cannot participate in oxygen transport

how is MetHb managed

though oxygen therapy and methylene blude

what are the main causes of pathological increase in MetHb

congenital, idiopathic, exposure to chemicals, specific antibiotics

what is meant by idiopathic

of unknown cause

what are examples of chemicals that can cause a pathological increase in MetHb conc

anesthetics or nitrobenzene

what are examples of specific antibiotic that can cause a pathological increase in MetHb conc

dapsone, chloroquine or nitrites