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BIOM2012 (4 & 7) > 7 Respiratory > Flashcards

7 Respiratory Flashcards

1
Q

What is the lung parenchyma and how does it function?

A

Lung parenchyma is connective tissue comprised of cells and extracellular matrix of collagen and elastic fibres. The parenchyma is the main determinant of the lung’s mechanical properties such as compliance and elastic recoil

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2
Q

Which cells comprise the pseudostratified epithelium?

A
  • Ciliated cells
  • Goblet cells
  • Basal Cells
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3
Q

What are the two types of cells found in the alveolar and briefly state their roles

A

Type 1: the site of gas exchange within the alveolar

Type 2: cells that secrete surfactant to decrease surface tension within the alveolar

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4
Q

What are the 3 components that make up the pleura?

A
  • Visceral Pleura: membrane covering the lung
  • Parietal Pleura: membrane lining the wall of the thoracic cavity
  • Pleaural Fluid: viscous liquid filling the space between the membrane allowing friction free gliding
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5
Q

Name 3 functions of the respiratory system besides gas exchange

A
  • Acid-Base balance
  • Phonation
  • Filtration
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6
Q

Explain the mechanisms of negative pressure breathing

A
  • during inspiration the diaphragm and intercostal muscles contract, expanding the thoracic cavity and increasing lung volume
  • As volume is increase pressure is decreased (according to Boyle’s Law)
  • The pressure gradient between the thoracic cavity and the atmosphere causes air to rush into the lungs
  • Upon exhalation, the lungs recoil to force the air out of the lungs. The intercostal muscles relax, returning the chest wall to its original position. During exhalation, the diaphragm also relaxes, moving higher into the thoracic cavity.
  • This increases the pressure within the thoracic cavity relative to the environment.
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7
Q

Explain positive pressure breathing and when this would be necessary

A
  • Positive pressure breathing involves increasing air pressure at the nose and mouth to be greater than that of the alveolar
  • This will cause air to move down pressure gradient into the lungs
  • This is used in patients who cannot breathe effectively through negative pressure breathing such as those with sleep apnea
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8
Q

Explain transpulmonary pressure

A

The difference between intra-alveolar pressure and intra-pleural pressure

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9
Q

What is hysteresis

A

The difference in pressure of inspiration and the pressure of expiration

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10
Q

What is pulmonary surfactant and explain its role

A

A fluid mixture of lipids and proteins produced by Type 2 alveolar cells. It coats the interior of the alveolar to lower surface tension in order to increase the compliance of the lung. This decreases the difficulty to breath and prevents the tiny alveolar from being squished during exhalation

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11
Q

What are two examples of respiratory impairments caused by surfactant?

A
  • Neonatal Respiratory Distress Syndrome: lack of surfactant in premature babies
  • Acute Respiratory Distress Syndrome: inactivation of surfactant by edema components
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12
Q

What is the difference between obstructive and restrictive pulmonary disorders?

A
  • Obstructive Pulmonary Disease: increased airway resistance (e.g. chronic asthma, cystic fibrosis, chronic emphysema)
  • Restrictive Pulmonary Disease: reduction in total lung capacity from structural or functional changes (e.g. interstitial lung disease, sarcoidosis, pulmonary fibrosis)
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13
Q

What is FEV1 and FVC?

A

FEV1 = Forced expiratory volume. The amount of air exhaled in the first second of maximum expiration

FVC = Forced Vital Capacity. The amount of air that can be expired forcefully after max inspiration

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14
Q

What is the FEV1/FVC ratio and what is a normal value?

A

The ratio between maximum amount of air expired and how much is expired in the first second. The average person can expel 80% within the first second

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15
Q

What is residual volume and why is it necessary?

A

The volume of air left in lungs are forced expiration. This helps prevent the lungs collapsing and ensures continuous gas exchange.

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16
Q

List 4 factors effecting ventilation

A
  • Pressure relationships
  • surfactant
  • compliance
  • resistance to air flow
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17
Q

What is compliance and give the formula for compliance

A

Compliance is the ability of the lung to stretch and expand and reflects the elastic resistance of chest wall. It can be expressed as C = ∆V/∆P

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18
Q

What are 3 factors influencing airway resistance and give the formula for resistance

A

Raw = Resistance of airways is influenced by

  • physical obstructions (e.g. mucus)
  • Viscosity of air
  • Diameter of airways (due to vasoconstriction/dilation)

Given by formula: F = ∆P/Raw

19
Q

Explain Ventilation Perfusion Coupling

A

Ventilation (V) is the gas which reaches the alveoli. Perfusion (Q) is the blood which reaches the alveoli. Both are tightly regulated to ensure efficiency.

Changes in either one of these alters the V/Q ratio.

Increases in V/Q = local hyperoxia = vasodilation

Decreases in V/Q = local hypoxia = vasoconstriction

20
Q

Explain the role of haemoglobin and its structure

A

Haemoglobin is required as an oxygen transporter as the amount of O2 that can be dissolved in plasma is too small for the metabolic demands of the body. It is found exclusively in RBC’s and is comprised of 4 chains (2 alphaglobins & 2 betaglobins) and 4 heme groups (which the oxygen binds to). Hemoglobin also acts as a vasoconstrictor.

21
Q

What are two indications that O2 Therapy could be required?

A

Tissue hypoxia with arterial hypoxemia

  • ventilation perfusion mismatch
  • alveolar hypoventilation
  • right to left shunting

Tissue hypoxia without arterial hypoxemia

  • myocardial infarction
  • low cardiac output states
  • CO poisoning
  • Chronic lung disease
22
Q

What are some of the detrimental effects of O2 therapy ?

A

Hyperoxia can result in:

  • depression of ventillation
  • rentinopathy of prematurity
  • bacterial infection associated with humidifiers
  • oxygen toxicity
23
Q

Name the 3 major ways that CO2 is transported through the body

A
  • Dissolved (7%)
  • Bound to hemoglobin (23%)
  • Bicarbonate ions (70%)
24
Q

Explain Bohr’s Effect

A

The effect by which the presence of CO2 decreases the affinity of Hb for O2 which increases the offloading of O2 to tissue

25
Q

Explain Haldane Effect

A

Oxygenation of blood in the lungs displaces carbon dioxide from haemoglobin which increases the removal of carbon dioxide

26
Q

Causes of Metabolic Acidosis

A
  • diabetic ketoacidosis
  • diarrhoea
  • renal failure
  • aspirin OD
  • sepsis
  • shock
27
Q

Causes of Metabolic Alkalosis

A
  • loss of gastric secretions
  • overuse of antacids
  • K+ wasting in diuretics
28
Q

Causes of Respiratory Acidosis

A
  • hypoventilation
  • COPD
  • airway obstruction
  • drug OD
  • chest trauma
  • pulmonary edema
  • neuromuscular disease
29
Q

Causes of Respiratory Alkalosis

A
  • hyperventilation
  • hypoxia
  • anxiety
  • high altitude
  • pregnancy
  • fever
30
Q

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

A

The DRG receives input from the peripheral sensory receptors. The DRG contains primarily inspiratory neurons and is involved in the generation of rhythm

31
Q

What is the role of the Ventral Respiratory Group (VRG)?

A

Receives sensory input from the the DRG and contains predominantly motor-neurons controlling the pharynx and larynx.
The VRG is split into 3 sections:
- Rostral VRG: (Bötzinger Complex) which drives expiratory activity
- Intermediate VRG: control larynx and pharynx and contains respiratory rhythm generator
- Caudal VRG: expiratory premotor neurons

32
Q

What is the PONS responsible for?

A
  • smooth transition from inspiration to expiration
  • helps terminate respiration
  • modifies rhythm by sending signals to both DRG and VRG
  • adapts breathing to situations such as sleeping talking and exercising
33
Q

What mechanisms allow voluntary control of breathing?

A

The motor cortex in the cerebral cortex of the brain are responsible. The cortex sends an impulse down the corticospinal tract to respiratory neurons in spinal cord for events such as talking, blowing candles, or holding breath.

This can be overridden at what is called the breaking point when the partial pressure of CO2 gets too high

34
Q

How do peripheral chemoreceptors act to control breathing?

A

There are peripheral chemoreceptors found near the carotid bifurcation and near aortic bodies which both contain islands of Type I and Type II cells surrounded by sinusoidal capillaries.

The type I (glomus) cells are the chemosensors and are surrounded by endings of afferent nerves. Glomus cells contain catecholamines that are released upon exposure to hypoxia and cyanide

35
Q

How to central chemoreceptors act to control breathing?

A

They are housed in the medulla behind the blood brain barrier and sense changing PCO2 levels (and H+). Dissolved CO2 crosses BBB into CSF where it is converted to carbonic acid.

36
Q

Explain how peripheral and central chemoreceptors are integrated to control ventilation

A

Central chemoreceptors account for 70-80% of drive to breath, and are activated by CO2 (respiratory acidosis) whereas peripheral chemoreceptors are solely driven by hypoxia. Together they are able to control ventilation

37
Q

Why are children more vulnerable to air pollution than adults?

A

Children breath more than adults do relative to size and hence the more they breath the more they are exposed.

Also children’s lungs are still growing and air pollution can potentially causes problems with proper lung growth, which can lead to increased risk of other diseases

38
Q

What effects does obstructive sleep apnea have on the body?

A
  • decreased oxygen saturation
  • decreased blood pressure
  • decreased heart rate
  • rib cage and abdominal muscles are not active, but respiratory efforts still continue
39
Q

List the effects that anaesthesia has on respiration

A
  • decreased functional residual capacity
  • decreased compliance
  • decreased respiratory drive to hypoxia
  • increases resistance of respiratory tract
  • increase ventilation/perfusion mismatch
  • increased ventilation in upper lung
  • increased perfusion in lower lung
40
Q

What respiratory events occur when acclimatising to altitude?

A
  • ventilation slowly increases
  • decreases PCO2 and increased PO2 in arteries
  • increased haemoglobin concentrations
  • increases in plasma erythropoietin
  • increase in blood pH (due to hyperventilation)
41
Q

Explain what ‘bends’ (or caisson disease) is when diving

A

The volume of gasses decreases with depth, due to changes in pressure. When a diver resurfaces quickly this can cause decompression, which is when dissolved gasses in the body expand and come out of solution in bubbles, effecting most organs including the brain and heart.

42
Q

What is the role of 2,3-Bisphosphoglyceric acid (2,3 BPG)?

A

It binds with greater affinity to deoxygenated haemoglobin than it does to oxygenated haemoglobin

it decreases the affinity for oxygen and allosterically promotes the release of the remaining oxygen molecules bound to the haemoglobin; therefore it enhances the ability of RBCs to release oxygen near tissues that need it most.

43
Q

Where is the pneumotaxic centre located?

A

The pneumotaxic centre is located in the upper part of the pons

BIOM2012 (4 & 7) (2 decks)

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