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Human Phiology Y4 > 2 Respiratory System > Flashcards

2 Respiratory System Flashcards

1
Q

Define gas exchange

A

CO2 and O2 exchange between pulmonary capillaries and alveoli = external respiration

CO2 and O2 exchange between systemic capillaries and surrounding cells = internal respiration

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2
Q

What are the 4 factors affecting EXTERNAL respiration?

A

Lipid solubility of gases = to allow passing through membranes via simple diffusion

Perfusion and rate of flow = compatible alveolar airflow and pulmonary capillary blood flow

Partial pressure gradients

Surface area, thickness and structure of respiratory membranes

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3
Q

What does it mean to have lipid soluble gases?

A

They rely on partial pressure gradients to simply diffuse

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4
Q

How to calculate partial pressure?

A

Atmospheric pressure (760 mmHg) x fraction of gas in the atmosphere (fixed proportion %)

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5
Q

Explain the connection between atmospheric pressure and partial pressures?

A

Combined partial pressure of gasses = atmospheric pressure

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6
Q

What happens to partial pressure at high altitude?

A

Atmospheric pressure decreases

Therefore partial pressure of each gas decreases with increasing altitude

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7
Q

What is Henry’s Law?

A

How much gas can dissolve in a liquid at a given temperature

Depends on partial pressure and solubility of the gas

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8
Q

What happens to partial pressure in a closed system?

A

Partial pressure gradient is lost because everything would equilibrate

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9
Q

What occurs when partial pressure is increased in an open system that has reached equilibrium?

A

At equilibrium, the pressure of oxygen in the air is the same as that in the liquid with equal diffusion in both direction

Increasing partial pressure leads to increase diffusion INTO the liquid until new equilibrium is reached

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10
Q

Why at the same pressure and temperature, does more CO2 dissolve into liquid than O2?

A

CO2 has greater SOLUBILITY than O2

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11
Q

How does humidification of inhaled air occur?

A

Air moving along the airways gets humidified

Picks up water molecules and increases the partial pressure of water

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12
Q

If ventilation is decreased, what happens to lung pCO2?

A

The pCO2 in the lungs will increase so diffusion of CO2 from blood to alveolus would decrease because gradient could reverse

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13
Q

What factors are required for diffusion across alveoli?

A

Diffusion only occurs if alveoli are

VENTILATED

PERFUSED

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14
Q

Define perfusion

A

Volume of blood flowing through alveoli

Gas exchange occurs when blood perfuses capillary

No blood flow = no gas exchange

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15
Q

Why is the rate of blood flow important in gas exchange?

A

Alveolar gases take time to diffuse and equilibrate with blood

Different gases = different rates

If rate is too fast = not enough time for gas exchange to occur (can occur as exercise)
If rate is too slow = gas exchange stilted

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16
Q

What occurs in the 0.25s buffering time to full oxygenation of blood?

A

pO2 of blood reaches alveolar pO2 in 0.25s

17
Q

What is the importance of the 0.25s buffering time?***

A
18
Q

What are the factors affecting INTERNAL respiration?

A

Metabolic rate of tissue

Rate of blood flow

Partial pressure gradients

Surface area in various tissues

19
Q

What happens if there is imperfect ventilation-perfusion coupling in the lungs?

A

pO2 of blood entering systemic capillaries is lower than alveolar

Gas exchange only occurs at the cell-capillary interface when a new equilibrium is reached where O2 is delivered into tissue and CO2 is removed through the blood

20
Q

What factors are needed for good ventilation?

A

Good air flow
Space to ventilate

21
Q

What can cause there to be a decrease in ventilation?

A

Constricting airway = due to external or allergic reaction

Obstructing airways

Reduced airspace for ventilation = severe pneumonia lungs fulled with debris, mucus, etc

22
Q

Define pulmonary ventilation

A

Process of air exchange between lungs and the atmosphere

23
Q

What does Boyle’s Law state?

A

In a closed system, with fixed temp and pressure

The pressure is solely based on volume

24
Q

Explain the muscles needed for inspiration and expiration

A

Contract diaphragm and external intercostal muscles increase volume and decrease pressure below atmospheric pressure = inspiration

Relax diaphragm and external intercostal muscles decreases volume, increases pressure above atmospheric pressure = expiration

25
Q

Explain the muscles needed for DEEP inspiration and expiration

A

Deep inspiration and expiration is an ACTIVE process

Requires contraction of internal intercostal muscle and more forceful contraction of diaphragm and external intercostal muscles = to bring about GREATER VOLUME CHANGE

26
Q

What is intrapleural pressure?

A

Pressure within the pleural cavity = filled with pleural fluid

The thin space between the visceral pleura (lining the lungs) and the parietal pleura (lining the chest wall)

27
Q

What is the value of intrapleural pressure?

A

Usually negative to intrapulmonary and atmospheric pressure

28
Q

What is the function of pleural fluid?

A

Acts as suction to keep lungs inflated

29
Q

What factors affect intrapleural pressure?

A

Surface tension of alveolar fluid = inward

Elasticity of lung = inward

Elasticity of thoracic wall = outward

30
Q

What happens to intrapleural pressure during inspiration and expiration?

A

Thoracic wall moves outward, increasing volume and decreasing intrapleural pressure
More negative pressure allows lungs to expand during inspiration

Thoracic wall recoils inward, decreasing volume and returning intrapleural pressure to -4mmHg relative to atmospheric pressure = allowing lungs to recoil

31
Q

When does intrapleural pressure become positive?

A

During forceful expiration

32
Q

What can cause excess pleural fluid to expand the pleural space?

A

Pleural effusion = serous fluid leaking from capillaries with increased hydrostatic pressure

Hemothorax = blood leaking from injured vessels

33
Q

What can cause excess air to expand the pleural space?

A

Pneumothorax = from puncture of lung, causing lung to collapse

Human Phiology Y4 (7 decks)

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