respiratory > Physiology > Flashcards

Physiology Flashcards

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1
Q

what does medulla rhythmicity control?

A

basic level control
inspiratory (DRG) and expiratory areas (VRG)

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2
Q

what is the pneumotoaxic area?

A

helps coordinate the transition between inspiration and expiration

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3
Q

what is the apneustic group?

A

sends impulses to inspiratory area that activate it and prolong inspiration and inhibit expiration

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4
Q

what is the dorsal respiratory group?

A

input from IX and X nerves into medulla
input ends inspiration

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5
Q

what is ventral respiratpry group?

A

inactive in normal/ quiet breathing as DRG is active
expiration is passive
activity increases with exercise, dyspnoea, lung disease

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6
Q

what is the function of respiratory control?

A

maintain homeostasis - gases/ pH
maximises mechanical activity for efficiency
adapts to needs
speech, coughing, exercise, disease

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7
Q

what does cortical control include?

A

brainstem control - pons medulla
ventilatory pump - resp muscles
sensors - chemoreceptors/ mechanoreceptors

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8
Q

what is the function of cortical control?

A

negative feedback
modifies amount and type of breathing
modifies chemical and mechanical state

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9
Q

where are the two higher centres responsible for rhythm control?

A
  1. cerebral cortex
  2. hypothalamus and limbic system
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10
Q

what does the cerebral cortex do in relation to rhythm control?

A

voluntarily changes breathing patterns, overridden by stimuli of increased arterial [H+] and [CO2]
- if you hold breathing then faint, normal breathing continues - kids who hold breath, brainstem will override

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11
Q

what does the hypothalamus and limbic system do in relation to rhythm control?

A

emotional changes

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12
Q

how does ventilation rate and depth increase?

A
  • Voluntary hyperventilation by cerebral cortex
  • Anticipation of activity via stimulation of limbic system (behaviour and emotion)
  • Increase in arterial [H+] above 40mmHg, dramatic decrease in O2 detected by central and peripheral chemoreceptors
  • Increase in sensory impulses from proprioceptors in muscles and joints and increase in motor impulses from motor cortex
  • Decrease in blood pressure detected by baroreceptors
  • Increase in body temp
  • Prolonged pain
  • Stretching and sphincter
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13
Q

how does ventilation rate and depth decrease by?

A
  • Voluntary hypoventilation controlled by cerebral cortex
  • Decrease in arterial [H+]
  • Decrease in sensory impulses from proprioceptors (movement receptors) in muscles and joints and decrease in motor impulses
  • Increase in Bp detected by baroreceptors
  • Severe pain (nociceptors) causes apnoea
  • Irritation of pharynx/ larynx by touch/ chemicals causes apnoea followed by coughing/ sneezing
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14
Q

what are the two types of peripheral chemoreceptors?

A

carotid and aortic

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15
Q

what is the role of the peripheral chemoreceptors?

A

send signals via glossopharyngeal (carotid) and aortic (vagus)
respond by altering firing rate
negative feedback mechanism
respond to O2, pH and hypercapnia

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16
Q

how does the peripheral chemoreceptor’s respond to oxygen?

A

respond to PaO2 - drop must be very dramatic so it doesn’t interact with daily breathing
hypoxia potentiates other responses

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17
Q

how does peripheral chemoreceptors respond to arterial pH?

A

more sensitive response
more [H+] - acidosis - more firing for more ventilation
less [H+] - alkalosis - decreased ventilation

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18
Q

how does peripheral chemoreceptors respond to CO2?

A

can respond to hypercapnia but fairly insensitive

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19
Q

describe the carotid bodies?

A

both small nodules (2mg), highest blood flow in any tissue
very high metabolic rate
type I glomus cells - chemosensitizer cells of carotid
can detect hypoxia - only peripheral chemoreceptor which can

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20
Q

what effect does the aortic chemoreceptors have?

A

systemic
can lower blood flow - affected by anaemia, sepsis, hypotension

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21
Q

what is the role of central chemoreceptors?

A

main source of tonic drive (slow/ graded) quiet breathing - eupenic control
powerful influence on respiratory centre - primary source for feedback for assessing ventilation effectiveness

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22
Q

what do central chemoreceptors primarily respond to?

A

PaCO2 - changes to CSF pH
insensitive to hypoxia

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23
Q

what is chronic hypercapnia?

A
  • Respiratory acidosis
  • Bicarbonate compensations return the brain pH back to normal so central chemoreceptors are less sensitive to further changes in PaCO2
  • Central chemoreceptors drive depressed – minute ventilation depends on hypoxia via carotid bodies
  • If pure O2 given – depresses carotid response and will reduce hypoxic ventilation drive
  • Could depress ventilation, increase PaCO2, induce come (CO2 narcosis)
  • Increase in partial pressure above 45mmHg
  • Causes – COPD, lung diseases, renal impairment – decompensation
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24
Q

what does chronic hypercapnia do to ventilation?

A

chemoreceptor adaptation and depressed ventilation

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25
how does the parasympathetic NS control respiration?
slows breathing rate down causes bronchial tubes to narrow and pulmonary vessels to widen
26
how does sympathetic NS affect respiration?
increases breathing rate causes bronchial tubes to widen and pulmonary blood vessels narrow
27
what do sensors within airways do?
detect lung irritants sensory trigger sneezing/ coughing chemoreceptors
28
what is central sleep apnoea?
brain temporarily stops sending muscles needed to breathe
29
what is hypoxemia?
low oxygen levels within the blood
30
what is hypoxia?
low oxygen levels within tissues
31
what can cause hypoxemia?
ventilation/ perfusion mismatch diffusion impairments - emphysema, scarring of the lungs hypoventilation low oxygen environments right to left shunting
32
what is partial pressure?
pressure of single type of gas within a mixture
33
what is daltons law?
behaviour of gases when they come into contact with liquid conc of gas in a liquid is directly proportional to the solubility and partial pressure of that gas
34
what is ventilation?
movement of air in and out the lungs
35
what is perfusion?
flow of blood in the pulmonary capillaries
36
what factors are important for good gas exchange?
pressure gradient - allows the movement thin capillary membrane and thin alveoli alveoli have large surface area
37
what occurs during times of poor ventilation?
body redirects blood flow in alveoli to areas of better ventilation - constricts bronchioles to direct arteries serving alveoli with good ventilation will vasodilate - greater blood flow
38
what is external respiration?
occurs at alveoli
39
what is internal respiration?
gas exchange at tissues
40
what do central chemoreceptors detect?
detect change in CO2/ H+ within brain
41
what do peripheral chemoreceptors detect?
faster detection responds to changes in PO2 and PCO2 sense hypoxia
42
what can acute exacerbations of asthma be triggered by?
resp viruses. Can be bacterial infections, allergens, pollutants and occupational exposure
43
which sex is more likely to develop asthma during childhood?
male
44
which sex is more likely to have persistent asthma into adulthood?
female
45
when is asthma worse during the day?
diurnal - at night or early morning
46
what resp conditions could be potential differential diagnoses?
bronchiectasis, COPD, fibrosis, PE, infection (pertussis and TB), lung cancer
47
what is a differential diagnosis GI related for asthma?
gastro-oesophageal reflux
48
what is a cardiac differential diagnose for asthma?
HF
49
why would a sputum sample be useful for asthma diagnosis?
blood clots bacterial infection - green
50
what FEV1/FVC score would indicate asthma?
<70%
51
what decrease in FEV1 between no treatment and then bronchodilator would indicate asthma?
improving by 12%
52
what is the use of fractional exhaled NO?
confirms eosinophil inflammation within asthma
53
what should be included within an annual asthma reveiw?
symptoms/ control, smoking status, inhaler technique and adherence. PEFR and vaccination status (should be up to date). Lifestyle – smoking cessation and healthy BMI promoted
54
what would you put inside an inhaler?
- Inhalers: lowest possible dose of inhaled steroid – escalate as appropriate 1. Symptomatic asthma – short acting beta 2 agonist (SABA) as required 2. Add low dose of inhaled corticosteroid (ICS) 3. Add long acting beta 2 agonist (LABA)/ trial of leukotriene receptor antagonist (LTRA) 4. Increase dose of ICS or trial TTRA 5. ICS increased to high and specialist 6. Specialist – theophylline/ biologic agents
55
what are complications of asthma?
pneumonia, collapse and pneumothorax, resp failure, status asthmaticus
56
what is status asthmaticus?
emergency - asthma exacerbation
57
what happens if the pressure drops across the lungs?
lung will collapse
58
what is intrapleural pressure?
pressure in pleural cavity (less than atmospheric – more negative). Pressure between parietal and visceral. It does change during different phases of breathing
59
what is intra-alveolar pressure?
pressure within alveoli, which changes depending on phases of breathing. Alveoli are connected to atmosphere via tubing or airways. The interpulmonary pressure of alveoli always equalised with atmospheric pressure
60
what is transpulmonary pressure?
difference between intrapleural and alveolar pressure. A higher transpulmonary lung would indicate a larger lung
61
what is more soluble in water O2 or CO2?
Carbon dioxide is more soluble in water than oxygen - Oxygen is mainly bound to haemoglobin - Carbon dioxide is primarily bicarbonate
62
define pneumonia
infection triggering inflammation which causes capillaries to leak hence the fluid. It is characterised by consolidation
63
how is diffusion defined by Ficks Law?
by Fick’s Law: gas flow, diffusion area, thickness, diffusion constant sol-das solubility and gas molecular weight.
64
what fluid lines alveoli?
surfactant - Layer of fluid lining alveoli – some mucus. Not thick and helps with O2 diffusion
65
what happens with more fluid gathers around alveoli?
- Pathology is when this fluid thickens – extra fluid or more mucous build up – caused by infection, fibrosis
66
what is bulk flow?
process used by small lipid- insoluble proteins to cross capillary walls - Alongside diffusion this is responsible for most gas transport
67
does anaemia effect diffusion with gas exchange?
- Diffusion of gases will be affected by condition of alveolar membrane and increases with blood flow and decreases with anaemia (diffusion is dependent on blood supply)
68
what is the oxygen dissociation curve?
Oxygen dissociation curve – the haemoglobin affinity for oxygen
69
why would the oxygen dissociation curve shift to the right?
- Shift to right: reduced affinity - gives up oxygen more easily – high CO2, lower pH, higher temp (in fever, haemoglobin gives up oxygen more easily to help keep tissues perfused)
70
why would the oxygen dissociation curve shift to the left?
- Shift to left: higher affinity – prevents oxygen leaving haemoglobin – lower CO2, higher pH, lower temp
71
what are the 4 things contributing to hypoxaemia?
1. Hypoventilation – less oxygen getting in – reduced resp rate 2. Diffusion – gas exchange issues eg fluid (pneumonia) or NO (anaesthetic) 3. Shunt – blood supply has been redirected 4. Ventilation – perfusion mismatch: the amount of oxygen going to alveoli doesn’t match the blood supply to remove the oxygen
72
what occurs in left to right pulmonary circulation shunt?
- Left -right shunts: true anatomical – blood form bronchial circulation joins pulmonary vein. Some coronary venous blood drains into LV. Disease – shunting can be greater
73
describe the apex of the lung in terms of ventilation
- More negative intrapleural pressure – more pulling - Alveoli have larger volume - Smaller compliance – less elastic - Less ventilation
74
describe the base of the lung in terms of ventilation?
- Less negative intrapleural pressure - Alveoli with smaller volume and more of them - Larger compliance – more elastic - More ventilation There is more blood flow and the base of the lung
75
can hypoxia vasoconstriction help with severity of mismatch?
yes can redirect blood to areas of better match
76
what can regions of lower V/Q result in?
in constriction of airways, inflammation and secretion
respiratory
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