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PA10309 > Respiration > Flashcards

Respiration Flashcards

1
Q

What factors can effect pulmonary compliance?

A

Increase - Surfactant and Emphysema (loss of elastic tissue so its easier to stretch)

Decrease - Pulmonary fibrosis (scar tissue is harder to stretch)

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2
Q

Name the receptors that detect H+, CO2 and O2, and where they’re found

A

Central Chemoreceptors - [H+] and PCO2

Peripheral Chemoreceptors - PO2

These are found in the carotid and aortic bodies

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3
Q

What is the parenchyma?

A

The functional unit of the lungs, and where gaseous exchange takes place

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4
Q

List the differences in the muscles used during inspiration and expiration during exercise

A

Inspiration - External intercoastals

Diaphragm

Expiration - Internal intercoastals

Abdominal muscles

Diaphragm

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5
Q

What stimulates the development in lung epithelium in babies?

A

Corticosteroids

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6
Q

How are the lungs emptied of fluid during birth?

A

There is a surge of steroids and catecholamines which activate Epithelial Sodium Channels (ENaC) These cause Na+ to leave the lungs, and take the water with them

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7
Q

What is meant by the neuronal control of breathing?

A

The automatic control by respiratroy centres in the brainstem

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8
Q

The lungs have various metabolic functions. What is one of the major functions in terms of the kidneys?

A

It activates Angiotensin 1 –> 2

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9
Q

Is gas exchange done in the upper or lower respiratory tract?

A

Lower

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10
Q

What role can adrenaline have on smooth muscle?

A

Cause it to contract/constrict

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11
Q

Describe Slowly Adapting myelinated fibres

A

These are stimulated by stretch receptors in smooth muscle (in the airways)

They causes various reflexes such as shortened inspration, the Hering-Breuer Reflex, and bronchodialation

Hering-Breuer Reflex = the promotion of exhalation after inflation (to prevent over-inhalation)

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12
Q

What are pleural membranes?

A

A double membrane that surrounds each lung, containing serous fluid (as a lubricant)

They act as a seal to ensure that if one lung collapses, the other will be ok

The fluid also allows the lungs to stick to the inside of the thorax

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13
Q

Explain what is meant by Ventilation-Perfusion matching

A

For gas exchange to be as good as possible, the ventilation of the alveoli must equal the blood perfusion

If the ratio is not equal to 1, then we need to decrease the blood flow (if one lung is not working) via vasoconstriction

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14
Q

Describe rapidly adapting stretch receptors (myelinated)

A

These are stimulated by sudden, sustained inflation, as well as irritant receptors

They causes reflexes such as coughs, bronchodialation and mucus secretion

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15
Q

What is the difference between Exogenous and Endogenous stimuli?

A

Exogenous - Noxious agents from the air

Endogenous - Inflammatory agents that are generated by the body

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16
Q

Describe the fluctuations in PCO2 during exercise

A

Ventilation increase before exercise starts, so PCO2 decreases to start with

The PCO2 then increases slowly as more CO2 is produced from exercise

Once exercise stops, PCO2 spikes due to a drop in ventilation

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17
Q

What are the downsides of a lung transplant?

A

There is a loss of lung-brain innervation

So there is a loss of the Hering-Breuer Reflex and cough stimulation

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18
Q

Explain how Acetazolamide, Doxapram and Caffeine work

A

Acetazolamide - Inhibits carbonic anhydrase to create mild acidosis –> increasing the ventilation rate

It can also lower EPO production and haematocrit

Doxapram - Closes K+ channels in the glomus cells to increase the repsiration rate

Caffeine - Stimulates non-specific parts of the CNS, including the respiratory system

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19
Q

Name one way in which the specilaisation of cells change as you move down lung airways

A

Less ciliated cells are present They also get smaller

20
Q

What is meant by “binding is co-operative” in terms of haemoglobin?

A

As each of the 4 molecules of oxygen binds, it becomes easier for the next oxygen to bind

21
Q

How do you calculate the Partial Pressure of a gas?

Also how do you calculate the RQ

A

P = Barometric pressure x Fraction of the gas

RQ = CO2/O2

A usual value of 0.8 represent 0.8 CO2 is used for every 1 O2

22
Q

Sensory (afferent) nerves innervate epithelial cells to the brain, but what type of innervation occurs from the autonomic fibres?

A

Parasympathetic branches of the vagus nerve This can be both inhibitory and excitatory

23
Q

List the differences between the Pulmonary and Bronchial Circulations

A

Pulmonary - Low [oxygen] Has a high flow rate and is complient –> so it has a large blood capacity Passes around the alveoli Blood flows from the right ventricle Its job is to allow gaseous exchange to occur and return the oxygenated blood back to the left heart

Bronchial - High [oxygen] Supplies the cells of the conducting airways with oxygen and nutrients Has a low flow rate but high pressure Blood flows from the aorta (left ventricle)

24
Q

Explain the importance of the respiratory centres in the brain stem

A

Medulla - Contains both inspiratory and expiratory centres which stimulate intercoastal muscles

It recieves information from the periphery and Pons

The Exipratory centre is only used when exercising

Pons - Contains both the Pneumotaxic and Apeneustic Centres

The Pneumotaxic centre modifies signals in the medulla to control breathing rate and its pattern

25
Q

How do coughs occur?

A

Irritant receptors are stimulated, which send sensroy nerve signals to the medulla, which sends motor nerve signals to the skeletal muscles

This causes the glottis to close, and intercoastal muscles to contract rapidly

The pressure increase causes the glottis to open –> causing the cough

26
Q

What are the roles of mechanoreceptors and chemoreceptors in the lungs?

A

Mechanoreceptors detect muscle movement in the lungs (when they’re stretched)

Chemoreceptors detect a change in pH, which is dependent on the [CO2]

27
Q

What is surfactant? And where is it made?

A

A solute that when dissolved in solution reduces surface tension, mainly in the alveloi –> preventing their collapse They are made in Type 2 epithelial cells Theyre made up mainly of lipid (mostly phospholipid)

28
Q

What is the purpose of the Pre-Botzinger Complex?

A

It creates spontaneous discharge that causes rythmic stimulation of motor nerves –> causing the contraction of the diaphragm

The more stimulation, the greater the ventilation rate, so its very important in the removal of CO2

29
Q

What is the difference between static and dynamic compliance?

A

Static - the compliance at a flow of zero (end of inspiration/expiration)

Dynamic - the compliance during active flow

30
Q

Explain the changes is air resistance as you go down the respiratory system

A

To start with there is high resistance due to passages getting lower (the conducting zones)

The resistance slowly decreases to a very low number (in the capillaries)

The number gets smaller as when the total resistance is added up, the capillaries total resistance has very little contribution to the overall resistance in the system

31
Q

Where in the brain controls voluntrary breathing?

A

Cerebral Cortex

32
Q

Describe the sensory afferent unmyelinated fibres

A

These are the pulmonary and bronchial fibres

They bring about much slower responses due to the lack of myelination

These cause bronchconstriction and mucus secretion

33
Q

What do the somatic motor nerves innervate? And what nerve innervates the diaphragm?

And what do the automonic nerves innervate?

A

Somatic - Innvervate skeletal muscle in the thorax

The diaphagm is innervated by the Phreic Nerve –> which causes hiccoughing when irritated

Automonic - Innverate the bronchials, as well as smooth muscles and their secretory cells

34
Q

Explain how the uptake of oxygen occurs in the capillary

A

At the arterial end of the capillary the blood from the alveoli moves into the blood quickly due to a large oxygen concentration gradient

This concentration gradient decreases as you move towards the venous end as an equilibrium is reached

35
Q

Does PCO2 or [H+] have a greater effect on ventilation?

And why?

A

PCO2

This is because H+ cannot pass through the blood brain barrier (BBB), but CO2 can

So CO2 enters the brain, forming carbonic acid, before dissociating into H+ and HCO3-, which is detected by central chemoreceptors

So more CSF PCO2 –> The lower the pH

36
Q

Explain how those with low haemoglobin concentrations have adapted to live at high altitudes

A

They have an increased ventilation rate

They also have an increases pulmonary perfusion rate, so more blood can be oxygenated

More myoglobin is present to ensure that oxygen transport and use is efficient

37
Q

Define Hypoxaemia and Hypercapnia

A

Hypoxaemia - Low oxygen

Hypercapnia - High CO2

38
Q

Is exhalation, at rest, a passive or active processes?

And why?

A

Passive

This is due to the elastic nature of the lungs

Eg, once full it will automatically push the air out again

39
Q

Explain how O2 binding to haemoglobin affects CO2

A

The more oxygen that is bound to haemoglobin, the less carbaminohaemoglobin that can be formed due to the Hb becoming more acidic

The excess H+ binds to carbonate to form carbonic acid –> releasing CO2

40
Q

How does a glomus cell work?

A

When oxygen falls K+ channels close, causing depolarisation –> which stimulates dopamine release –> which stimulates afferent fibres

The signals are sent to the medulla

41
Q

Describe the difference between Type 1 and Type 2 alveolar epithelial cells (pneumocytes)

A

Type 1 - Has a very large surface area

Squamous cells

Where Gas exchange occurs

Type 2 - Secrete surfactant

Cubodial cells

They are the precursors for Type 1 cells

42
Q

What is myoglobin?

A

A molecule that is found in skeletal and cardiac muscle

It has a single binding site for oxygen, but it has a very high affinity for it, so it will attract the oxygen off of haemoglobin

43
Q

List, from top to bottom, the ways in which CO2 can be transported

A

HCO3- –> when CO2 production increases

Carbaminohaemoglobin

Dissolved in plasma

44
Q

Does water vapour have a partial pressure in the upper respiratory tract?

A

Yes - 47mmHg at body temperature

45
Q

How do you calculate the Alveolar Oxygen Pressure?

A

O2 inspired - (CO2 produced/RQ)

46
Q

What are 4 sources of H+ gains?

A

Hypoventilation (keeping CO2)

Production of non-volatile acids

Due to loss of HCO3- via diarrhoea and urine

47
Q

What are the 4 souces of H+ loss?

A

Utilization in metabolism

Loss in vomit and urine

Hyperventilation (excessive loss of CO2)

PA10309 (9 decks)

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