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Dentistry Biological Science > Respiration 1 > Flashcards

Respiration 1 Flashcards

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1
Q

What are the 5 stages of respiration?

A
  1. Ventilation: Exchange of air between atmosphere and alveoli
  2. Exchange of O2 and CO2 between alveolar air and blood in lung capillaries by diffusion
  3. Transport of O2 and CO2 through pulmonary and systemic circulation by bulk flow
  4. Exchange of O2 and CO2 between blood in tissue capillaries and cells in tissues by diffusion
  5. Cellular utilisation of O2 and production of CO2
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2
Q

What parts make up the upper and lower respiratory tract?

A

Upper: nasal cavity, nostril, mouth, pharynx, larynx
Lower: Trachea, lungs, bronchi, diaphragm

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3
Q

Explain the structure of the trachea&bronchi

Bronchioles?

A

trachea&bronchi = low resistance pathway for air flow, C-shaped bands of rigid cartilage keep airways open, trachealis muscle spans between ends of cartilage bands (contracts to aid expulsion of blockages - when coughing and sneezing)

bronchioles = no cartilage, smooth muscle bundles, these are normally relaxed (allowing air to reach alveoli), contraction prevents irritants and particles from entering alveoli

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4
Q

How many division are there of the bronchi in humans?

A

up to 8 divisions

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5
Q

What are the conducting zones?

A

Region of the lower respiratory tract which carries air to the alveoli. It has too many layers for gas exchange to occur.

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6
Q

Give features of bronchioles

A

No cartilage.
Smooth, muscle bundles - normally air to reach alveoli.
Contraction prevents irritants and particles from entering alveoli.

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7
Q

What forms the respiratory zone?

A

Respiratory bronchioles
Alveolar ducts
Alveoli

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8
Q

What are the functions of the lower respiratory tract?

A

Gas Exchange:

Respiratory bronchioles:
Minimal actual gaseous exchange. They branch into individual alveoli or alveolar ducts.

Alveolar duct and sacs:
Site of gaseous exchange. Extensive blood supply, surrounded by blood capillaries.

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9
Q

What two things in the lungs maximise gas exchange?

A
  • High surface area

- Very thin walls

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10
Q

What are the two types of alveolar cells and give details on each?

A

Both pneumocytes

Type 1 flattened epithelium (for gaseous exchange)
Type 2 thicker cells (secrete surfactant).

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11
Q

What is the purpose of the pores between alveoli?

A

Allow entry of air even if alveolar ducts are blocked.

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12
Q

What are the 4 main functions of the lungs?

A
  • Provide oxygen and remove carbon dioxide
  • Form speech sounds
  • Protection from microbes and other foreign matter
  • Regulates blood hydrogen ion concentration
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13
Q

Define each of these lung volume:

  1. Tidal volume
  2. Inspiratory reserve volume
  3. Expiratory reserve volume
  4. Residual volume

Give approx male values

A
  1. In normal steady breathing, the volume of air breathed in per breath
  2. Maximum amount that lung volume can be increased above tidal volume
  3. A further maximal exertion of the expiratory muscles after tidal volume
  4. Even after maximal expiratory effort, the volume of air left in the lungs
  5. 500ml
  6. 3000ml
  7. 1200ml
  8. 1200ml
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14
Q

What is the functional residual volume?

A

What is left in the lungs after a normal breath

- expiratory reserve & residual volume

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15
Q

What are lung capacities?

Give some examples of them

A

Sum of two or more volumes

Inspiratory capacity = tidal volume + inspiratory reserve
Vital capacity = inspiratory reserve volume, tidal volume, expiratory reserve
Functional Residual capacity = expiratory reserve + reserve volume

Sum of inspiratory reserve, expiratory reserve, tidal volume and residual volume = total lung capacity.

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16
Q

Explain what ventilation is and hence minute ventilation calculation

How is this different from alveolar ventilation?

A

Ventilation is exchange of air between the atmosphere and the alveoli.

Minute ventilation - total ventilation per minute
This is respiratory rate X tidal volume.

Alveolar Volume = volume of fresh air reaching alveoli per minute.
This is different because gaseous exchange occurs primarily in alveoli and minimally in respiratory bronchioles, while pharynx and conducting zone do not contribute. Alveolar V will be less as less air is getting to the alveoli than is breathed in.

17
Q

What is the volume from the top of the pharynx down to the terminal bronchioles called?

What is this fixed value for humans?

Where is anatomical dead space found?

A

Anatomical dead space

150ml

Conducting zone

18
Q

Work out alveolar ventilation knowing tidal volume is 500ml and dead space is 150ml

Respiratory rate is 12

A

500-150=350ml reaching alveoli

Tidal volume = alveolar ventilation and alveolar dead space

Alveolar vent = minute ventilation - dead space ventilation

(500x12) - (150x12) = 4200ml/min

19
Q

What is alveolar dead space and hence physiological dead space?
Are they fixed?

A

Alveolar dead space = alveoli are poorly perfused with blood, then no gas exchange occurs in those areas.

Physiological dead space = anatomical dead space + alveolar dead space

Anatomical dead space is fixed (150ml) but physiological dead space is not as alveolar dead spaces changes.

20
Q

Explain how and why ventilation occurs

What is the equation for flow of air?

A

Air moves from a region of high pressure to a region of low pressure.
Flow = difference in pressure / resistance

The pressures here are atmospheric pressure - alveolar pressure (the difference between pressure inside and outside lung).

21
Q

What pressure changes causes air to move into and out of the lungs?

When is there no pressure change?

A

Atmospheric pressure is higher than alveolar pressure means airs move in.

Vice versa for air to move out.

In between breaths.

22
Q

How does Boyles law explain air flow?

A

Pressure in a gas is inversely proportional to volume.

Diaphragm goes down in inspiration, increases volume, decreasing pressure so air flows into lungs as pressure is lower in lungs.

23
Q

What is occurring in the lung at functional residual capacity?

A

at the end of normal breathing out…

respiratory muscles are relaxed and inward recoil of lungs is balanced by outward recoil of chest wall

24
Q

What are the two pressures in the lung?

What is the difference between the two?
When is this value higher?

A

Intrapleural (pressure between two membranes. This is usually slightly negative as lungs recoil inwards and chest wall recoils outwards)

Alveolar pressure

Difference: alveolar - intrapleural is called trans- pulmonary pressure.

Higher after breathing in as intrapleural pressure decreases.

25
Q

Give the 5 events in inspiration

A
  1. Nerves stimulate diaphragm and other inspiratory muscles to contract, expanding the chest wall
  2. Intrapleural pressure falls – (becomes more negative -0.7 kPa)
  3. Alveoli are expanded (due to increased PTP causing increased pressure difference across alveoli)
  4. Pressure in Alveoli falls (Boyles Law)
  5. Increased pressure difference from mouth to alveoli - air flows into lungs
26
Q

What are the sequences of events in normal expiration?

What happens in forced expiration?

A
  1. Nerves decrease firing to diaphragm and intercostals, muscles relax
  2. Expanded chest wall recoils inwards
  3. Intrapleural pressure goes back towards pre-inspiration level. Transpulmonary pressure decreases to inspiration level.
  4. Expanded lungs which have a greater elastic recoil, decrease in size
  5. Air in alveoli gets compressed (Boyles Law)
  6. Air flow out of lungs

Forces expiration: abdominal muscles increases recoil of diaphragm and speed shrinkage of chest wall and lungs. Intrapleural pressure may be positive.

27
Q

What happens to the pressures during inspiration?

A

Expanding chest wall lowers intra-pleural pressure, making transpulomary pressure more positive. This expands the lung and makes alveolar pressure negative and results in inward airflow.

28
Q

What happens to the pressures during expiration?

Between breaths?

A

Lung is collapsing, alveolar pressure is higher than atmospheric causing air outflow.

Chest wall isnt expanding. Alveolar pressure is the same as atmospheric pressure so there is no airflow.

29
Q

What causes resistance in the upper and lower airways?

A

Upper = congestion in nose, pharynx and larynx

Lower = middle order bronchi mainly cause this. Bronchioles have a smaller diameter but there are more of them so total resistance is very low.

30
Q

Explain the difference in air flow in quiet breathing and high ventilation

A

Quiet - flow is usually laminar: gas particles move parallel to the walls with a higher velocity at centre of tube

High - turbulent, noisy flow

31
Q

Explain how obstructive lung disease (asthma or bronchitis) affects air flow

A

Narrowing of lumen, airway resistance increased, airflow decreased, decreased gaseous exchange

Asthma: smooth muscle is hypersensitivity to constrictors, causes thickening and inflammation

Chronic bronchitis: glands produce excess mucus, with inflammation

32
Q

How does resistance affect air flow?

What other things affect radius of bronchi?

A

Flow = difference in pressure / resistance.

Resistance is inversely proportional to the 1/r^4.
Radius of tube has the most affect on resistance of the airflow.
A small change in radius gives us a large change in resistance.

  • Chemical and neural factors (dilators and constrictors)
  • Physical factors.
    Beginning of inspiration (lateral traction exerted by connective tissue increases airway radius, aiding lung expansion).
    Forced expiration (dynamic compression of airways increases resistance considerably).
33
Q

What is lung compliance?

A

Change in lung volume / change in trans-pulmonary pressure.

It measures how easily lungs are expanded by a given change in pressure which determines the amount of work that has to be done by reparatory muscles.

Trans-pulmonary pressure cannot be measured directly. Subject needs to inhale in step and hold breath at each step and the volume each time inspired is measured.

34
Q

What determines lung compliance?

A

Forces that inspiratory muscles have to overcome to make lungs expand

1.Resistance of tissues to stretch influenced by composition of extracellular matrix. Elastin is stretchable, but requires work, collagen is not Too much = fibrosis (low compliance). (amount of elastin affecting the expansion of alveoli)
Not enough = emphysema (high compliance)

  1. Resistance due to Surface Tension at air/water interface in alveoli
35
Q

What does a decreased compliance suggest?

Increased compliance?

A

Work of breathing increased.
Suggests lung fibrosis (restrictive lung disease)

Suggests lung emphysema. Tissue destruction causes alveoli to fuse forming large air-sacs. Bronchioles tens to collapse more easily upon expiration.

36
Q

How does surface tension affect lung compliance?

A

Surface tension is caused by water molecules attracting each other.

Wall tension is a fixed value so if pressure changes, radius has to change also.
Different alveoli have different radius and hence different pressure.

37
Q

A small alveoli next to a large one will tend to collapse. How is this prevented?

A

Surface tension is the same in both.
Higher pressure in smaller one so air flow from smaller to larger will collapse smaller.

Surfactant changes the surface tension so the pressure difference is normalised and air will not flow from smaller to larger alveoli,
More surfactant in smaller alveoli to prevent the collapse. Tension is reduced more in smaller alveoli. Prevents the difference in pressure.

38
Q

What things can be seen in obstucture and resistive dieases?

A

Obstructive - unable to force out 75% volume but lung volume is okay.

Restrictive - may force out more than 75% but unable to expand lung in all.

Dentistry Biological Science (88 decks)

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