Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MD3001resp > Ventillation And Diffusion > Flashcards

Ventillation And Diffusion Flashcards

1
Q

Describe the structure of the conducting airways?

A

Made of cartilage, few smooth muscles
- will rarely collapse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is alveolar ventilation?

what is pulmonary ventilation?

A
  • Alveolar ventilation is the exchange of gas between the alveoli and the external environment
  • Pulmonary ventilation is the process of air flowing into the lungs during inspiration (inhalation) and out of the lungs during expiration (exhalation) – about 500ml of air inhaled and expired on each breath
  • Pulmonary ventilation includes the gas used in gas exchange, and the anatomic dead space air that fills up the respiratory system, but isn’t used in gas exchange
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the structure of the respiratory and alveolar ducts?
Are the susceptible to collapse??

A
  • no cartilage, lots of smooth muscle
  • susceptible to collapse during expiration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How much air is there in anatomical dead space?

At what generation does the dead space turn into respiratory area?

A

250mls
Generation 17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How much alveoli do humans have?
&
Across what surface area?

A

Humans have around 300 million alveoli in a cross sectional area that increases from 2.5cm2 at trachea to around 100m2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why does airflow velocity decrease?

At what number of airway generations/divisions does aggregate cross-sectional area start to rapidly increase?

Where will this area be around?

A
  • Airflow velocity decreases to allow adequate time for diffusion once the air reaches the capillaries
  • At about 12-14 airway generations/divisions, the aggregate cross-sectional area starts to rapidly increase
  • The area will be around the respiratory bronchioles, as this area is where alveoli start to appear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the primary functions of the respiratory and cardiovascular systems?

A
  • transport O2 from the lungs to all tissues in the body.
  • remove CO2 from the tissues to the lungs
  • lungs will expire this CO2 to the atmosphere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are Oxygen and CO2 able to move by diffusion?

Where is Oxygen and CO2 partial pressure high and low?

How does partial pressure change affect diffusion of gas?

What is this principle the basis of?

A
  • Oxygen and CO2 can diffuse (passive) as both gases move by diffusion down their partial pressure gradients (also down their concentration gradients)
  • Oxygen partial pressure is high in the air, and low in the tissues
    CO2 partial pressure is high in the tissues and low in the air
  • These both allow the gases to move down their partial pressure gradient
  • If the partial pressure in the liquid becomes greater than in the air, the gas will diffuse out of the liquid, and vice versa, due to gases flowing down partial pressure gradients
  • This is the basis for O2 moving into the blood from the lungs, whereas C02 moves out of the blood into the lungs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the movement in concentration gradient for both CO2 and O2

A

Both gases move down their concentration gradient.

O2 goes down concentration gradient as it moves from air to the tissues

CO2 moves down the concentration gradient as it moves from tissues to air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is Daltons Law?

A

“Total pressure (Ptotal) of a mixture of gases is the sum of their individual partial pressures (Px)”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the value for atmospheric pressure?

A

atmospheric pressure at sea level is 760mmHg or 101.325 kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

if atmospheric pressure changes …

is proportion of gas changes …

A

if atmospheric pressure changes then partial pressure changes

is proportion of gas changes its partial pressure changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is Henry’s law?

A
  • states that the concentration of O2 dissolved in water (O2(dis)) is proportional to the partial pressure (PO2) in the gas phase

(O2) dis= s x PO2

where s = solubility of O2 in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How soluble is CO2, O2, and N2 in blood at atmospheric pressure?

Why do we need haemoglobin?

A
  • CO2 is the most soluble in blood plasma
  • O2 is about 1/20th as soluble as CO2
  • This means the blood can carry far more dissolved CO2 than O2
  • This is why we need haemoglobin as a special oxygen carrier, otherwise we wouldn’t have enough oxygen in the blood
    N2 is barely soluble in blood at atmospheric pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens to alveolar air?

Why is this important?

How is this affected on a cold day?

A
  • Alveolar air is warmed and humidified by adding water vapour to it
  • This is important alveolar cells are sensitive to pressure/temperature
  • When the air is cold, the humidity in the air is decreased, so the air becomes dry
  • There is not enough time to warm this air, so it dries out the respiratory system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the partial pressure for water vapour?

A

Water vapour also has a partial pressure, so when we breath gases in and add water vapour, we have to subtract the partial pressure of water vapour from the partial pressure of these gases that make up atmospheric pressure

The partial pressure of water vapour is 47mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is s for blood plasma?
(s= solubility of O2 in water)

A

s= 0.0013 mM/mmHg at 37 degrees celsius so

so (O2)dis= 0.0013 x 100 mmHg = 0.13 mM (arterial blood)

(O2) dis = 0.0013 x 40 mmHg = 0.05 mM (mixed venous blood)

18
Q

Is oxygen or co2 more soluble?

A

CO2 is the most soluble, O2 is about 1/20th as soluble and N2 is barely soluble at atmospheric pressure.

19
Q

for there to be gas exchange between alveolar and blood, what does O2 have to do?

A

O2 has too:
- dissolve in an aqueous environment
- diffuse across the membranes
- enter the blood

20
Q

what is the equation for flow?

A
21
Q

what is the rate of difussion proportional to?

A
  • partial pressure difference
  • solubility area
  • solubility (D, diffusion coefficient)
  • molecular mass
  • inversely proportional to tissue thickness (T)
22
Q

describe the surface structure/size of the lungs?

A
  • surface area of lungs is large (50-100m2)
  • large number of alveoli (around 500million)
  • thin walls (0.2-0.5um)
23
Q

what is the concentration gradient across the lungs?

A

PO2 alveolar air= 100mmHg
PO2 of venous blood = 40mmHg

diffusion is rapid
(molecular mass is insignificant, but solubility is very important, with CO2 diffusing 20x more rapidly than O2

24
Q

what is the difference between rest and exercise for the time is takes for blood to pass through the capillaries?

A

at rest = 0.75-1 second for blood to pass through pulmonary capillaries

  • O2 equilibrium only takes about 0.25 secs (so not normally diffusion limited)

in exercise, capillary transit time can be reduced to as little as 0.3 secs (so not it is diffusion limited)

This can decrease how saturated each blood cell is with oxygen, leading to an incomplete O2 equilibrium.

25
Q

describe the direction of movement of CO2 in the blood capillary?

across what concentration gradient?

A

CO2 moves in the opposite direction to O2 from blood capillary into alveoli

  • against smaller concentration gradient:
  • alveolar PCO2 is 40mmHg
  • venous PCO2 is 45 mmHg

however, there is a greater solubility, so CO2 will diffuse 20x more rapidly than O2 as the same amount of gas moves.

26
Q

when are there diffusion limitations?

A
  • in oedema
  • emphysema
  • pulmonary fibrosis
  • mucus, inflammation of airway, tumours, reduced gas entry (gas exchange reduced)
27
Q

how does edoema effect flow?

A

because T (thickness of barrier) increases
- the transit time through capillary may not be suffiecnt to complete full gas exchange, therefore
- gas exchange is reduced
- more marked effect on O2 than CO2, due to greater solubility of CO2

28
Q

how does emphysema effect flow?

A

in emphysema, A is reduced (breakdown of tissue in alveolar sac)
- gas exchange will be reduced

29
Q

how does pulmonary fibrosis effect flow?

A

in pulmonary fibrosis, T is increased due to deposition of fibrotic tissue
- gas exchange is reduced

30
Q

what is the effect of altitude?

A
  • at a high altitude, atmospheric pressure will be reduced, hence PO2 is reduced
31
Q

what is the effect on partial pressure by simple being in Denver Colorado?

A

Denver is 1620m above sea level.
- Pb is 632 (down from 760mmHg)
- inspired PO2is 125 (down from 149 mmHg)
- alveolar PO2 is 84 (down from 104 mmHg)
- alveolar PCO2 is 34 (down from 40mmHg

32
Q

what are the 2 physiological adaption to altitude?

A

acute hypoxia
adaptive hypoxia

33
Q

acute hypoxia?

A
  • hypoxia is sensed by peripheral chemoreceptors
  • ventilatory drive increases initially but blunted by central chemoreceptors that respond to decreased PaCO2 due to increased ventilation
  • CO increases due to suppression of the cardioinhibitory centre
34
Q

adapt hypoxia?

A
  • central chemoreceptors adapt so ventilation rate continuous to increase
  • PaCO2 drops leading to respiratory alkalosis, kidneys compensate by reducing acid excretion blood Ph normalises
  • alkalosis stimulates 2,3 DPG production leading to righforward shift of O2 dissociation curve
35
Q

what happens to the:

blood
vasculature
cardiopulmonary system

during acclimation

A

Blood:
- erythropoietin release stimulated
- Hb concentration increases to 200 g/L from 150 g/L

Vasculature:
- hypoxia stimulates angiogenesis
- capillary density increases throughout the body

Cardiopulmonary system:
- vascular and ventricular remodelling
- smooth muscle growth increases vascular wall thickness
- right ventricle hypertrophies

36
Q

what happens to the atmospheric pressure while diving?

what are the effects of depth?

A

it will increase by 760 mmHg (1atmosphere) every 10m depth.

effects of depth:
- increase in partial pressure, N2 and O2 dissolve into blood at lethal excess
- volume decreases

37
Q

how can gas become toxic during diving?

A
  • N2 narcosis = partial pressure of N2 (40m and below) rises and starts to dissolve in body tissues

*02 poisoning = tightly regulated at sea level and system essentially saturated

  • at higher pressure O2 dissolves in blood in excess of the buffering capacity of the Hb
  • helix = N2 replaced by helium and percentage of O2 is tailored to reduce harm
  • helium is less readily dissolved in body tissues and less narcotic.
38
Q

In what 3 steps is N2 narcosis caused?
How can N2 narcosis be avoided?

A

N2 narcosis steps:
1) At 40m of depth and below, the partial pressure of N2 rises, which leads to N2 dissolving into the blood and distributed into the circulation, preferentially partitioning in fat tissue

2) If we resurface too quickly, the high N2 partial pressure that forced N2 into the blood returns to normal, and the N2 comes out of the blood too quickly, which forms pure N2 bubbles

3) The presence of bubbles in the blood stream causes decompression sickness, or “the bends. – a painful process

N2 narcosis can be avoided by resurfacing slowly, which allows N2 partial pressure to slowly equilibrate and N2 to move out of the blood slowly

39
Q

What is oxygen toxicity/poisoning?

How is it normally caused?

How does it affect the lungs?

How soon can it appear?

How is O2 poisoning at depth caused?

A
  • Oxygen toxicity/poisoning is organ system/tissue damage that occurs from breathing in too much extra (supplemental) oxygen
  • Extended exposure to above-normal oxygen partial pressures, or shorter exposures to very high partial pressures, can cause oxidative damage to cell membranes, leading to the collapse of the alveoli in the lungs.
  • Pulmonary effects can present as early as within 24 hours of breathing pure oxygen
  • At higher atmospheric pressures due to depth, partial pressure of oxygen increases, which forces more oxygen to dissolve in the blood, causing hyperoxia
  • This O2 dissolves in blood in excess of the buffering capacity of Hb, leading to blood alkalosis
40
Q

How can N2 Narcosis and oxygen poisoning be avoided?

A
  • N2 narcosis and oxygen poisoning can be avoided by replacing N2 with helium and tailoring the oxygen to reduce harm
  • This mixture is known as Heliox (Helium and Oxygen)
  • Helium (He) less readily dissolves in body tissues and is less narcotic

MD3001resp (41 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions