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Function & Dysfunction > Respiration > Flashcards

Respiration Flashcards

1
Q

Why is the left lung smaller (2 lobes) than the right lung (3 lobes)

A

You need to have space for the heart

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2
Q

What are the lungs important for?

A

External respiration, O2, CO2​
Route for water loss and heat elimination​
Maintenance of acid base balance​
Respiratory pump, enhances venous return​
Forms speech​ (need air going through vocal folds)
Defends against inhaled foreign matter​
Removes, inactivates blood clots​

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3
Q

acid based balance

A

Lungs, kidney and in blood (bicarbonate, phosphate, citrate which acts as buffers)

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4
Q

What is the respiratory quotient RQ?

A

RQ = CO2 produced​ / O2 consumed​

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5
Q

Which ventilation is active
What happens in expiration
Describe breathing mechanism

A

*Inspiration or forced expiration (when blowing up a balloon)
*elastic recall of the lungs

When you inhale:
the intercostal muscles contract, pulling the ribcage upwards and outwards
the diaphragm contracts, pulling downwards, volume of the thorax increases and the pressure inside decreases
air is drawn into the lungs down a pressure gradient.

When you exhale:
the intercostal muscles relax pulling the ribcage downwards and inwards, the diaphragm relaxes, doming upwards,
volume of the thorax decreases and the pressure inside increases
air is pushed out of the lungs.

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6
Q

What muscles do we use when we expire at rest?

A

None

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7
Q

What is the most important muscle in inspiration?

A

Large sheet of skeletal muscle, the diaphragm

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8
Q

What are the inspiratory muscles
What happens in forced expiration​​

A

*Diaphragm, External intercostals​ (lift ribcage), Sternocleidomastoids​ (lifts sternum), Anterior serrati (lifts several ribs) and Scalenes (lifts first 2 ribs)​

*Abdominal (pulls lower ribs down & compresses abdomen upwards). Internal intercostals​ (lowers ribcage)

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9
Q

What is a goblet cell?
What are cilia?

A

*They are modified epithelial cells that secrete mucus on the surface of mucus membranes of organs, particularly those of the lower digestive tract and airways

*Finger like projections that help to remove mucus, trap dirt.
Smoking damage cilia so often have lots of mucus
mucolytics can be given to break down mucus.

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10
Q

Describe 3 functions of trachea

A

*Provide a safe, sturdy passageway for air to travel from the mouth or nose to the lungs.
*Prevent the passage of foreign objects into the respiratory system.
*Regulate the temperature and humidity of air passing into the lungs.

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11
Q

What are alveolar cells (Pneumocytes)​

A

Type 1 alveolar cells​
Support​
Flattened​
Few organelles​

Type 2 (5% SA, 60% number)​
Surfactant​ (prevent alveoli from collapsing and lowers surface tension).makes breathing easy.
Phospholipoprotein​

Alveolar macrophage​
Housekeeping​
Phagocytic​

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12
Q

Vasculature​ (circulations)

A

Alveolar (take deoxygenated blood to the lung to get oxygenated.
bronchial circulation​ (lung itself needs its own O2)

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13
Q

Why is there an extremely thin blood gas barrier​ in capillaries

A

Air to blood is typically <0.5 micrometre
in the capillaries red blood cells bend. The benefit of this is to decrease the distance further. red blood cells are 7 micrometers in diameter and these run in single file.

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14
Q

Does oxygen decrease on a mountain?

A

The percentage of air on a mountain is still 21%, the molecules on a mountain spaces out so density of air gases decreases. There is less molecules in general.

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15
Q

What is partial pressure?
What is atmospheric pressure at sea level?
What is the partial pressure of oxygen?
What is the partial pressure of CO2?

A

*pressure a specific gas would exert in isolation in the same volume
*760mm Hg (millimetres of mercury)
*21% (in air) of 760 =160 mmHg
*4% of 760=30.4mm Hg

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16
Q

What four main factors that affect the diffusing capacity (DLCO or TLCO)?​

A

Membrane thickness
surface area
pressure difference (gradient of gases across membrane​)
Diffusion coefficient of gas​.

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17
Q

What is Fick’s law of diffusion​?
What is Henry’s law?

A

*Lungs ideally suited to gaseous exchange​
‘the rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane’.​

*Gases will diffuse from a gas mixture with a high partial pressure into a liquid until the partial pressures of the gas in the gas mixture and liquid are in equilibrium. Or vice versa - from liquid with high partial pressure into a gas mixture with a low partial pressure
-alveolar PO2 and PCO₂ will have a direct effect on arterial PO₂ and PCO2 →The quantity of a gas that will be dissolved in a liquid is proportional to the partial pressure of the gas and its solubilitycoefficient

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18
Q

What is the Pleura​

How does air get into the lungs?

A

A pleura is a serous membrane that folds back on itself to form a two-layered membranous pleural sac.
Pleural sac separates lung from wall of thorax​​
Pleural cavity filled with intrapleural fluid​
Parietal pleura lines the thorax​
visceral pleura, lines the lungs​.
This is important in terms of pressure (transmural pressure gradient).

For air to enter the lung, P(alv) has to be – ve. Inspiratory muscles stretch the lung, so P(pleural) goes more –ve, this causes P(alv) to go to – 1 mmHg and air is sucked in. ​
​– 1 mmHg pressure change is enough to move 500 ml of air (VT).​

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19
Q

What is (Vt)

A

Tidal volume

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20
Q

What happens with pressure as we breath?

A

1, end of expiration, Patm and Palv are equal, no air flow​

​2, chest expanding, P(pl) pressure lower, increase in transpulmonary pressure, lung expands, Palv negative, inward airflow​

​3. lung size not changing, glottis open to the atmosphere, Palv, Patm, equal, no air flow RM relax, passive collapse of lungs and chest wall, elastic recoil​

​​4. Mid expiration, lungs collapse, compress alveolar gas, Palv higher than Patm, outward air flow​

​

21
Q

Summary of inspiration and expiration​

A

Inspiration
Diaphragm and inspiratory intercostals contract Thorax Expands Pip (The peak inspiratory pressure ) becomes more subatmospheric ↑ Transpulmonary pressure Lungs Expand Palv becomes subatmospheric Air flowsintoalveoli

Expiration
Diaphragm and inspiratory intercostals stop contracting, Chest wall Recoils inward, Pip moves back toward pre-inspiration value. Transpulmonary pressure moves back toward pre-inspiration value, Lungs Recoil toward pre-inspiration size Air in alveoli becomes compressed Palv becomes greater than Patm Air flowsoutoflungs

22
Q

Summary

A

Command to breathe (neural)​
Air enters, Palv increases​
Greater recoil (PL) causes air to exit​
Muscle contraction​
Ppl goes more -ve​
Causes Palv to go -ve​
Cycle starts again​

23
Q

What is the transpulmonary pressure (PL) difference between Palv and Ppl.​

A

The transpulmonary pressure (PL) difference between Palv and Ppl.​
PL = Palv – Ppl​
PL is also called the recoil pressure and is a measure of the forces that tend to collapse the lung.​

24
Q

Pneumothorax abolishes transmural pressure gradient​

A

Intra-alveolar pressure greater than intrapleural pressure​
Penetrating pneumothorax, equalises pressure difference, lung collapse​
Disease induced pneumothorax, spontaneous​

25
Q

What is lung compliance​

A

*Ability of lungs to stretch​
*Elasticity​
*Surface tension​
*Change in lung volume produced by change in transpulmonary pressure​
*Greater compliance, easier to expand lungs, inverse of stiffness​
*Decreased compliance, shallow, rapid breathing​

Compliance (change in) Lung volume / (change in) (Palv -Pip)
same as
(change in) V / (change in) Ptp

26
Q

What does idiopathic?

A

Unknown cause

27
Q

What is emphysema?
What happens to compliance?​

A

Destruction of structures supporting the alveoli, often due to smoking, causing loss of elasticity.
It increases, as the pressures needed for the same volume are less due to loss of elastic tissue.​ like a paper bag can’t recoil.

28
Q

What is lung fibrosis?
what happens to compliance?​

A

In lung fibrosis (often occurring in interstitial lung disease/occupational lung disease)
Very stiff and hard alveoli.

It decreases, as the pressures needed for the same volume are greater.​
Patient needs lots of energy to take a breath

29
Q

What happens to ribcage and lungs in a dead person

A

The lungs are like a rubber balloon
The chest is like a spring

The ribcage springs out but the lungs collapse
The chest wall is energetically more happy at a higher volume hence they expand out.

30
Q

FRC

A

Functional residual capacity
pressure between lung and chest wall is balanced (equal and opposite). It is the volume in lungs when you breath out before breathing in.

you can artificially change FRC for short period of time but it messes up the balance. Makes it energy inefficient

31
Q

Surfactant & Compliance​

A

Surfactant = lipids and proteins secreted by type II alveolar cells​
Lowers alveolar surface tension​
Increases compliance​
Reduces recoil​
Prevents alveoli collapsing​
infant/other Respiratory distress syndrome​ (near drowning can cause this-it can wash out surfactant)

all detergents lower surface tension

32
Q

Discuss H2O relationships with alveoli

A

When water forms a surface layer with air, the surface H2O molecules have a strong attraction e.g. needle/rain drop, though not with detergent.​

In alveoli, H2O attracts other H2O molecules & they force out air and attempt to collapse the alveolus.​

33
Q

What is LaPlace’s law?

A

Have to use La Place’s Law to help us. This tells us the pressure needed to keep a sphere open is: ​

P = pressure​
P = 2 x T / radius T = surface tension​
r = sphere radius​
P is equal and opposite to the collapsing pressure. ​

34
Q

Describe how the size of alveoli is important linking it to pressure and LaPlace’s law

why don’t alveoli collapse?

A

This would be a disaster for the lungs at low lung volumes (especially for premature neonates), as all the alveoli would collapse.​

To reopen them would take a great amount of pressure (as r would be very small).​

But this does not occur in reality, otherwise every breath would take a tremendous effort.​
surfactant works better in smaller alveoli

The reason this doesn’t happen is that:​
Alveoli share common septal walls​
Surfactant gets more concentrated in smaller alveoli, therefore​
PA = 2 x 15 ​/ 1= 30 (same as B)​

35
Q

Pulmonary ventilation​

A

(Minute volume, VE) ​= tidal volume x respiratory rate​
Minute volume approximately 6L, can increase to 200L​
Alveolar ventilation is more important than pulmonary ventilation​
(Tidal volume – dead space) x respiratory rate​

​Quiet breathing = (500-150)x 12 = 4200 ml/min​
Deep slow breathing = (1200-150)x 5 = 5250​
Shallow rapid breathing = (150-150)x 40 = 0​

ventilation=tidal volume X frequency

36
Q

How could we quickly test for lung disease?

A

Using lung volumes

37
Q

Blood divert oxygen to areas with good blood flow

A

Local controls match ventilation with perfusion​
Hypoxic pulmonary vasoconstriction – hypoxia causes​
vasoconstriction in the pulmonary vasculature, so blood can go to ​better ventilated alveoli (systemic opposite – vasodilation)​
less O2, less blood, vessels constricts

38
Q

List some factors which can alter VQ ratios?​

A

*Space/microgravity​
*G forces​
*Exercise​
*Body position​
*Disease​

39
Q

Ventilation perfusion ratios​?

A

Gravity causes regional differences in ventilation and perfusion​
Hydrostatic pressure affects blood pressure and flow​
Blood flow decreases from base to apex​
Gravity alters intrapleural pressure – apex more expanded​
Ventilation higher at base than apex ​
Ventilation perfusion ratio is higher in apex than base.​

40
Q

Delivery of oxygen to tissues

A

*O2 moves down a concentration gradients from:
–> atmospheric–>alveoli–>plasma–>erythrocytes–>plasma–>interstitial fluid–>cells

41
Q

Gas transport
Name the shape of an S shape curve

A

sigmoidal curve

42
Q

*Haemoglobin​

*what affects haemoglobin dissociation curve to the right

A

Low partial pressure of oxygen in muscle capillaries​
Haemoglobin READILY gives up O2 to Myoglobin​
Lungs - high partial​

pressure of oxygen, so Hb takes up O2​
A steep Hill slope allows Hb to efficiently take up O2, then transfer it to Mb in the muscle​

​Sigmoid plot suggests +ve​
co-operativity​

*more H+
more CO2
Higher temperature
More BPG

43
Q

What is BPG

A

biophospho glycerate

Shift to right
1)increased hydrogen ions
2)increased CO2
3)Increased temperature
4)increased BPG

This can be caused by exercise
released by red blood cells exposed to hypoxia

44
Q

CO2 transport in the blood​

A

Most of it combining with water to form bicarbonate and some binding on to hydroxy haemoglobin and some being dissolved.
CO2 has 3 methods of being transported in the blood
Deoxygenated Hb, increases capacity to carry CO2​

Deoxygenated Hb binds H+ well.​
Haldane effect ‘For any given PCO2, the CO2 content of deoxygenated blood is greater than that of oxygenated blood’.​

Likewise, Oxygenated Hb, decreases capacity to carry CO2​

45
Q

Describe what CO can do

A

CO has 210 x more affinity for HB​ than O2. It is a colourless, odourless gas.​
Carbon monoxide has a high affinity to haemoglobin. High levels of CO can be dangerous.
incomplete combustion

46
Q

Acid base balance​

A

Henderson-Hasselbach equation:​
CO2 + H2O <–>H2CO3-<–>HCO3- + H+​
pH ∞ log [HCO3-]/[PCO2] ​
If ratio remains constant, pH 7.4​
Hypercapnia (high PCO2) due to hypoventilation will decrease HCO3-/PCO2 ratio, and pH, respiratory acidosis​

47
Q

Why do we need control?​

A

Want to breathe enough to ensure Hb gets close to full saturation.​
Don’t want to breathe more than needed (keep WB minimum).​

Want to regulate CO2 quite carefully, as changes can vary pH. Double VE causes arterial pH to rise to 7.6, half it pH falls to 7.2.​
7.4 is normal
We sometimes have to ‘override’ automatic reflex control e.g. blowing, breath holding, swimming, speech etc.​

48
Q

There is a synergistic relationship between PO2 and PCO2​

A

When the effect of PO2 is investigated independently at constant PCO2, ventilation doesn’t change until PO2 falls below 8kPa.​
The effects are increased if PCO2 is raised.​

49
Q

Neural respiratory centres​

A

Found in brainstem (bilaterally in medulla oblongata & pons):​
Dorsal respiratory group (DRG) – inspiratory​
Ventral respiratory group (VRG) – inspiratory & expiratory​
Pneumotaxic centre - rate & pattern of breathing​

Function & Dysfunction (19 decks)

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