Lecture 10 - Energy production and oxygen consumption Flashcards Preview

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Flashcards in Lecture 10 - Energy production and oxygen consumption Deck (28)
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1

Partial pressure =

fractional concentration x pressure
fractional conc of O2 (0.2094) x 101.32 (atmospheric at seal level)

2

What is the first step in the oxygen cascade

humidification in the airway through water vapour
reduces partial pressure of inspired air from 21 kPa to 19.9 lPa

3

What is the 2nd step in the oxygen cascade

alveolar gas

4

step 3 in oxygen cascade

alveolar-capillary diffusion - cross between alveolar and capillaries
not much difference

5

What are the biggest PO2 drops in the cascade?

between humid air and alveolar gas and between arterial and venous blood

6

step 4 of oxygen cascade

ventilation-perfusion mismatch and shunt
deoxygenated blood fusing with oxygenated blood to form arterial blood
shunting - when blood isnt oxygenated - bypasses
we all have around 2.5% of shunting

7

Step 5 of oxygen cascade

tissue diffusion

8

Step 6

diffusion within cell

9

Describe the krogh model

This unit structure implies that each section of capillary is responsible for the supply to a corresponding cylindrical section of surrounding tissue.
lethal corner - venule end of capillary - cells at this end will be the first to become hypoxic
o2 tissue diffusion
all arteriole to venule - pressure drops
all cells have exposure to different O2 levels.

10

Oxygen delivery calculation
amount of o2 leaving the heart in one minute

= O2 carried by haemoglobin + dissolved oxygen
approx 1000 ml/min

11

What is oxygen consumption

amount of blood used by the body in one minute
approx 250 ml/min

12

basal metabolic rate

VO2 at rest

13

Normal values of VO2 at rest

Normal values - 200 ml/min
Relative to body size:
BMR = 45 Wm/-2
VO2 = 4.8 min/kg

14

what is vo2

measure of oxygen consumption

15

What are the factors affecting VO2

1. age - peak at age 0-2 years then falls for rest of life
2. temperature - metabolic rate doubles with every 10 degrees celcius
3. exercise

16

What happens in anaemia

1. Increased DPG shifts O2-Hb curve to the right
2. reduced blood flow to non-essential organs - eg. skin, bowel
3. increased O2 extraction from blood
4. increase in cardiac output

17

CO2=

(SO2 x [Hb] x 1.39) + 0.3

18

DO2=

CO2 X CO (multiplied by amount of blood leaving heart)

19

What is respiratory exchange ratio

the ratio of co2 production to o2 consumption

20

normal RER =

1

21

what is RER affected by?

acid base balance
hyperventialtion
metabolic fuel

22

compare RER of carbs, fatty acids and proteins

more in carbs, least in Fatty acids
1, 0.7, 0.8

23

What are the functions of oxygen

Glycolysis
Tricarboxylic acid cycle
Oxidative phosphorylation

24

What is glycolysis

occurs in the cytoplasm
glucose to pyruvate or lacate in the presence of or absence of oxygen
however no oxygen is required in the process
2ATP molecules are produced per gluocse

25

what is the function of oxygen in the TCA cycle (Krebs)

Occurs most in the mitochondria
Acetyl CoA from glycolysis is converted to CO2
38 ATP molecules per glucose

26

What happens in oxidative phosphorylation

occurs in the mitochondria
NADH provides H+
H+ combines with O2 to produce water
ATP produced

27

What are the main causes of fundamental hypoxia

Anoxic (lack of O2) - respiratory failire
stagnant (Lack of blood supply) - Angina
anaemic (lack of Hb) - Angina and low Hb

28

Normal arterial PO2

13.5 kPa