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Medicine yr1 > RESP-breathing in special circumstances > Flashcards

RESP-breathing in special circumstances Flashcards

1
Q

what happens to the respiratory system in old age?

A
  • Decreased elastic recoil of lung tissues and chest wall compliance
  • Decreased strength in the respiratory muscles
  • Increased residual volume, decreased vital capacity and decreased FEV 1
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2
Q

what happens to the respiratory system in obesity?

A
  • Upper airway restriction and lung volume reduction = decreased functional residual capacity (volume in lungs after normal exhalation)
  • Increases risk of atelectasis (collapsed alveoli = example of shunting)
  • Alveoli have little volume - V/Q mismatching (shunt - alveoli stops gas exchange)
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3
Q

what are the respiratory changes seen in fear?

A
  • The hypothalamus sends signals once stress is perceived
  • Sympathetic NS stimulates adrenal medulla to secrete adrenaline/noradrenaline – increases alertness, blood flow to muscles, respiration rate and cardiac output
  • Stimulation of corticotrophs (by CRH) causes release of ACTH which stimulates release of cortisol from the adrenal cortex – increasing glucose metabolism and suppressing the immune system
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4
Q

what are the 3 ways breathing is initiated in infancy?

A
  • mechanical
  • chemical
  • sensory
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5
Q

describe how breathing is initiated mechanically

A

The compression from the vaginal canal forces any remaining fluid out of the neonate’s lungs

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6
Q

describe how breathing is initiated chemically

A

-Cutting of the umbilical cord results in asphyxia (CO2 increase, O2 decrease, pH decreases = acidosis). This acidotic state is detected by chemoreceptors and respiratory centres in the medulla initiate breathing

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7
Q

describe how breathing is initiated sensorily

A

Decrease in temperature, stimulation of nerve endings in the skin, experiencing light and sound in the extrauterine environment all stimulate breathing

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8
Q

how does the position of the diaphragm change during birth?

A

moves up by 4cm

increase vol

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9
Q

how does the position of ribs change during birth?

A

ribs flare out-A=P dimension

increase vol

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10
Q

how does tidal volume change during birth and what does this cause?

A

increase by 200ml

  • > results in 5% increase in VC
  • > and 20% in residual vol
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11
Q

how does the respiratory rate change during birth?

A

it doesn’t

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12
Q

what is the end result for ventilation during birth?

A
  • > increase in ventilation
  • > decrease in PaCO2
  • > PaO2 essentially unchanged
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13
Q

what is the normal range for arterial blood gas pH?

A

pH= 7.35-7.45

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14
Q

what is the normal range for arterial blood gas pCO2?

A

pCO2= 35-45mmHg

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15
Q

what is the normal range for arterial blood gas HCO3-?

A

HCO3-= 22-26EQ/L

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16
Q

how would you describe the overall state of pregnancy in accordance to arterial blood gases?

A

compensated respiratory alkalosis

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17
Q

describe the change in blood gases seen during pregnancy

A
  • > decrease in PaCO2=more bicarb=alkalosis
  • > to compensate for change=decrease in HCO3- ions
  • > allows pH to remain unchanged during pregnancy (hence compensated)
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18
Q

how do the partial pressures of air change with increasing altitude?

A

-all decrease (at same rate)

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19
Q

what is the effect of falling PaO2 at higher altitude?

A
  • reduces partial pressure gradient
  • driving O2 uptake
  • caused hypoxia
  • causing sensory and cognitive functions to decline
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20
Q

what can the body’s responses to increased altitude be?

A
  • acute
  • adaptive
  • acclimation
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21
Q

describe the acute response during altitude change

A
  • Hypoxia sensed by peripheral chemoreceptors (in aortic arch) and the respiratory centre responds by increasing ventilatory drive which increases oxygen uptake and carbon dioxide emission
  • Respiratory centre also suppresses the cardioinhibitory centre – increasing heart rate/cardiac output and hence increasing oxygen uptake by pulmonary perfusion
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22
Q

how long does the acute response during altitude change take to occur?

A

within minutes

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23
Q

how long does the adaptive response during altitude change take to occur?

A

days-weeks

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24
Q

describe the adaptive response during altitude change

A
  • The central chemoreceptors adapt slowly allowing ventilation rates to climb to address altitude-induced hypoxia
  • This decreases PaCO 2 causing respiratory alkalosis
  • Kidneys compensate by decreasing acid secretion and blood pH renormalizes
  • Alkalosis also stimulates 2,3-DPG production
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25
Q

what is the effect of 2,3-DPG on Hb’s O2 affinity?

A

-2,3-DPG decreases Hb’s O₂ affinity, causing O₂ Hb dissociation curve to shift to the right and this enhances O₂ unloading to tissues

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26
Q

how long does the acclimation response during altitude change take to occur?

A

months to years

27
Q

describe the acclimation response during altitude change

A
  • Hypoxia will stimulate erythropoietin to be released from kidneys ->increase amount of Hb → increases blood’s O2 carrying capacity by 50%
  • Hypoxia stimulates angiogenesis → capillary density and perfusion will increase
28
Q

how does pressure with increased water depth?

A

pressure rises quickly

water is denser than air

29
Q

how does increased water depth affect the alveoli?

A

compresses gas within alveoli = increase partial pressure of gases but decreases alveolar volume

30
Q

what are the 2 issues with diving and the pressure involved?

A

1-At sea level, only O2 and CO2 can dissolve in blood to any significant extent. Depth increases the partial pressures of all gases – so other gases will now be able to dissolve leading to potentially lethal effects

2-Pressurising a gas decreases its volume – when a diver resurfaces this can cause severe damage to the tissues that contain the gas

31
Q

describe what nitrogen narcosis is

A

At a depth of ≥40m, Pa(N2) rises so that it is able to dissolve in cell membranes → this disrupts ion channel function. (worsens with depth and causes loss of function below 80m)

32
Q

describe what oxygen poisoning is

A

Oxygen is inherently toxic due to its tendency to form free radicals. Usually, Hb acts as a buffer as it closely regulates the amount of O2 delivered to the tissues. High Pa(O2) will eventually exceed the buffering capacity of Hb

33
Q

which gases is air principally made up of?

A

N2 (78%) and O2 (21%)

34
Q

what is the problem with inhaling N2 and O2 under pressure?

A

both are toxic when inhaled under pressure

35
Q

what substance do divers who work at depth breathe and why?

A

-helium/oxygen (heliox) mix

-Helium replaces N2 because it dissolves in the body tissues less readily
Inhaling Heliox reduces airway resistance and decreases the work of breathing.

36
Q

outline how decompression sickness arises

A
  • As the diver ascends, Pa(N2) decreases and comes out of solution.
  • It forms pure bubbles of N2 that enter the blood stream and eventually, form a mass in major vessels that cause ischaemia.
  • The dependent tissues experience pain. If serious, will result in death.
37
Q

how can decompression sickness be avoided?

A

Managed by slowing the rate of ascent to give more time for the gas to diffuse out of tissues and into the lungs.

38
Q

how can decompression sickness be treated?

A

If ascent occurs too quickly, there are specialised decompression chambers for divers to help them acclimate.

(hyperbaric chambers)

39
Q

With regards to the initiation of breathing; cutting the umbilical cord will result in what?

A-Acidotic state
B-alkalosis
C-increased cardiac output
D-decreased cardiac output

A

A

40
Q

Which of the following is Not a change that occurs for respiration at birth?

A-tidal volume increases by 200ml
B-20% increase in residual volume
C-diaphragm moves up by 4cm
D-decrease in PaCO2

A

B

41
Q

Decrease in PaCO2
In the adaptive response to altitude change, the alkalosis state of the body will stimulate the production of what?

A-erythropoetin
B-blood vessels (angiogenesis)
C-2,3-DPG

A

C

42
Q

outline the acid/ base equation

A

CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO-

43
Q

which receptors in the medulla detect changes in H+ in the CSF?

A

Central chemoreceptors

44
Q

what does hyperventilation cause?

A

decrease in CO2

45
Q

how is hyperventilation compensated?

A

kidneys excrete bicarbonate

46
Q

what does hypoventilation cause?

A

increase in CO2=acidosis

47
Q

what do the kidneys do in response to hypoventilation?

A

resorb bicarbonate

48
Q

where are the 2 types of peripheral chemoreceptors found?

A
  • > carotid chemoreceptors found at bifurcation of common carotid artery
  • > aortic arch chemoreceptors
49
Q

what do carotid chemoreceptors detect?

A

Detect change in: PCO2, PO2 and pH

50
Q

what do aortic arch chemoreceptors detect?

A

detect changes in PCO2 and PO2

51
Q

the change in which molecule is the most important?

A

CO2 is the most important; it drastically changes H+ in CSF

O2 is only relevant when very/chronically low

52
Q

how can you tell if the blood gas abnormality is respiratory or metabolic?

A

Is the imbalance being caused by the lungs or the kidneys

HCO3-=kidney (metabolic)
CO2=lungs (respiratory)

53
Q

how can you tell if the blood gas abnormality is compensated or uncompensated?

A

Has the body worked to bing the imbalance back to normal

54
Q

what do these blood gas results show?

pH: 7.25
pCO2: 85
HCO3-: 25

A

uncompensated respiratory alkalosis

55
Q

what do these blood gas results show?

pH: 7.25
pCO2: 55
HCO3-: 20

A

uncompensated mixed acidosis

56
Q

what do these blood gas results show?

pH: 7.41
pCO2: 27
HCO3-: 23

A

23

57
Q

why are vaccines important?

A
  • This is the only type of medical intervention that is able to eradicate a disease.
  • It is also one of the most cost-effective public health interventions
58
Q

name the 5 types of vaccines

A
  • active
  • passive
  • polysaccharide (PS)
  • conjugate-PS
  • adjuvant
59
Q

describe active vaccination

A

Administration of an antigen (either a modified infectious agent or a toxin of it) resulting in active adaptive immunity (long term)

60
Q

describe passive vaccination

A

Administration of an antibody-containing serum (short term)

61
Q

describe passive vaccination

A
  • Immune response is induced by polysaccharide antigens which are T-Cell independent (polysaccharides cannot bind to MHC complexes to be presented to T-Cells).
  • They activate B-Cells directly, but without the T-Cell activation, no memory B-Cells can be made.
62
Q

describe conjugate-PS vaccination

A
  • In a conjugate-PS vaccine, there is a carrier protein attached to the PS. Polysaccharides alone cannot be loaded onto the MHC of an APC alone, since MHCs can only bind to proteins.
  • However, in a conjugate-PS, there is now a carrier protein which can bind and activate MHCs on APCs such as T-Cells.
  • This results in T and B Cell activation 🡪 memory cells are produced, and long-term immunity is achieved.
63
Q

what is adjuvant?

A
  • a chemical added to any vaccine in order to help the vaccine work better.
  • The adjuvant acts to activate immune cells (e.g. dendritic cells) by binding to toll-like receptors (TLRs), which results in a stronger immune response

Medicine yr1 (55 decks)

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