Lecture 9 - 10 Flashcards by Wroe B

List some of the anatomy involved in the Respiratory System

Mouth
Trachea
Lungs
Bronchi
Alveoli
Pleura
Thorax

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What happens in the Alveolar region?

Oxygen uptake and CO2 removal

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Where does gas exchange take place?

Alveoli and Bronchioles

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What is the role of the Bronchi?

Responsible for the movement and guidance of air

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List the 2 fixed parameters of gas exchange

1) Surface area
2) Short diffusion distance

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Explain the Surface Area parameter

If there is a large surface area, there is a lot of area to facilitate gas exchange

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Explain the Short Diffusion Distance parameter

The shorter the distance, the easier it is for the gases to travel that distance

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What is Boyle’s law?

P1V1=P2V2
- Product of pressure and volume is constant

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What is ventilation and list the formula?

Exchange of air between the atmosphere and alveoli
Air Flow (F)= Pressure Difference (∆P) / Resistance (R)

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What happens during Inspiration?

Palv is LOWER than Patm
- Volume of the lungs increases – Palv drops – driving airflow into the lung

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What happens during Expiration?

Palv is HIGHER than Patm
- Volume of the lungs decreases – Palv rises – driving airflow out of the lung

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Finish the formula: ∆P=

Alveolar Pressure (Palv) – atmospheric pressure (Patm)

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Is Inspiration an Active or Passive process?

Active process
- Inspiration requires energy

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Is Expiration an Active or Passive process?

Passive process
- Usually doesn’t require contraction of muscles

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What is Transmural pressure?

The pressure difference across the wall of a structure — between the inside and the outside

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What is the formula for Transmural Pressure?

Ptp = Palv - Pip

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What affects how much lungs can expand for a given change in Ptp?

Lung stretchability / lung compliance

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What happens when Ptp increases?

Lungs expand

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What happens when Ptp decreases?

Lungs recoil

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During inspiration the intrapleural pressure (Pip) becomes ____ than than atmospheric pressure (Patm) and alveolar pressure (Palv) becomes ____than Patm

Lower; Lower

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What is Lung Compliance?

Determines the ability of a lung to add and remove air

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What does Lung Compliance determine?

How much the lungs can expand depending on ∆V for a given change in Ptp (∆Ptp)

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What is a contributing factor of Lung Compliance?

Fluid (water) covers lung surfaces

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High surface tension= ?

Low Lung Compliance

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Low surface tension= ?

High compliance

What are Surfactants produced and secreted by?

Type II alveolar cells

What is the role of Surfactants?

- Forms a layer between water and air - Reduces interaction between H2O molecules - Reduces surface tension of the water

What happens with Small **Increases** in Compliance?

- Lung can expand easier - less stiff - Easier to breath - less work of breathing

What happens with Small **Decreases** in Compliance?

- Lung expansion is more difficult - stiffer - More difficult to breath - more work to breath

What condition is an Extensive increase in lung compliance?

Emphysema

What condition is an Extensive **decrease** in lung compliance?

Pulmonary fibrosis- restrictive lung disease

What is Airway Resistance?

How easy air can move in and out of the lungs

What does Airway Resistance depend on?

Radius of airway tubes (radii)

In normal situations, is Airway Resistance Low or High?

Low

What are the Physical Factors affecting Airway Resistance?

- Ptp - Elastic connective tissue - Mucus

What are the Neuroendocrine Factors affecting Airway Resistance?

- Norepinephrine - Acetylcholine - Leukotrienes - Histamine

What do Parasympathetic Nerves do to airways?

Broncho**constriction**

What do Sympathetic Nerves do to airways?

Broncho**dilation**

What are the 2 important measures of Pulmonary function?

1) VC- Volume of air expired with maximum effort, capacity 2) FEV1- Forced expiratory volume in 1 sec, resistance

What do healthy individuals expire of VC?

80% in 1 second

What is Restrictive lung disease?

- VC reduced - FEV1 normal

What is Obstructive lung disease?

- VC normal - FEV1 <80% (Asthma, COPD)

What is Minute Ventilation?

Tidal volume (mL/breath) x respiratory rate (breaths/min) - ⩒E = Vt x f

What is Alveolar Ventilation?

(Tidal Volume - Dead space) x Respiratory rate - ⩒A = (Vt –VD) x f

What is Dead Space?

Volume of inspired air that does not take part in gas exchange - VD = ~150 ml

What are some dental issues with CPAP?

- Tooth movements - loose teeth - Jaw shifting - Dry mouth

What is the overall goal of gas exchange in the body?

Get O₂ into the blood and CO₂ out of the blood

What is the normal respiratory quotient (RQ) for a mixed diet?

0.8

How does **hypo**ventilation affect alveolar PO₂ and PCO₂?

PO₂ decreases PCO₂ increases

What does the oxygen-haemoglobin dissociation curve show?

Non-linear relationship: binding of one O₂ molecule increases Hb's affinity for more O₂

How is CO₂ transported in blood?

- 10% dissolved in plasma - 25-30% bound to carbaminohemoglobin (HbCO2) - 60-65% converted to bicarbonate (HCO3-)

How does **hyper**ventilation affect blood gases?

Lowers PCO₂

What neural centres control breathing?

- Pons (pneumotaxic and apneustic centers) - Medulla (DRG and VRG)

What is hypoxic hypoxia?

Low arterial PO₂ due to high altitude or lung disease

Name two protective reflexes of the respiratory system

1) Sneezing (nasal irritation) 2) Coughing (laryngeal irritation)

What happens during anaphylaxis?

Sudden allergic reaction causing airway narrowing and shock; treat with adrenaline

What is the Respiratory Quotient (RQ) for a carbohydrate-rich diet?

RQ = 1.0

What is the Respiratory Quotient (RQ) for a fat-rich diet?

RQ = 0.7

What happens to alveolar PO₂ and PCO₂ during hyperventilation?

PO₂ increases PCO₂ decreases

What does Dalton’s Law state?

Total pressure of a gas mixture equals the sum of the partial pressures of each individual gas

In which direction does gas diffusion occur?

From high partial pressure to low partial pressure

What is the homeostatic response if an alveolus has low airflow?

Pulmonary capillary blood flow decreases

What is the homeostatic response if an alveolus has low blood flow?

Airflow to the alveolus is reduced

What is cooperativity in hemoglobin binding?

Binding of one O₂ molecule increases the affinity for additional O₂ molecules

Why is the plateau phase (70–100 mmHg) of the O₂-Hb curve important?

Acts as a safety factor maintaining O₂ saturation even if lung function declines

What enzyme catalyzes the conversion of CO₂ + H₂O to H₂CO₃?

Carbonic anhydrase

How does hyperventilation cause respiratory alkalosis?

By lowering arterial PCO₂ and thus lowering H⁺ concentration

What is the role of the Dorsal Respiratory Group (DRG)?

Controls inspiration by stimulating the diaphragm and external intercostals

What is the role of peripheral chemoreceptors?

Detect changes in PO₂ and to a lesser extent

What is stagnant hypoxia?

Reduced blood flow to tissues despite normal oxygen content

What is histotoxic hypoxia?

Tissues cannot use oxygen properly (e.g. cyanide poisoning)

Why is sneezing important?

Removes irritants from nasal passages using high-velocity airflow

What happens during a cough reflex?

A powerful expiration occurs after a deep inspiration against a closed glottis

How does epinephrine treat anaphylaxis?

- Vasoconstriction (increases BP) - Bronchodilation (opens airways)

How does hypoventilation cause respiratory acidosis?

By increasing arterial PCO₂ and thus increasing H⁺ concentration

Lecture 9 - 10 Flashcards

(75 cards)