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PHA112 > Respiratory System 2 > Flashcards

Respiratory System 2 Flashcards

1
Q

what is daltons law of partial pressures?

A
  • air we breathe made of n2, o2, h2o, co2
  • there = diff % of each gas in air
  • each gas makes up diff proportion of total mixture
  • sum of pp = total pressure of air
  • pp of various gases = imp in establishing gradients which drives gases through system
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2
Q

how is the pCO2 in peripheral tissues higher than in arteries returning from lungs?

A

CO2 = end product of cellular respiration

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3
Q

how is the pO2 lower in tissues than in arterial blood?

A

O2 continuously used by cells

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4
Q

what are the gradients of o2 and co2?

A

o2 - from blood to tissues

co2 - from tissue to blood

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5
Q

following internal respiration, what happens to o2 and co2?

A

o2 unloads to tissues

co2 uptake into blood

po2 in venous blood dec to 40 mmHg

pco2 in venous blood inc to 45mmHg

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6
Q

following ventilation, what happens to o2, co2?

A

po2 in alveoli inc

pco2 dec

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7
Q

what are the pressure gradients of o2 and co2?

A

o2 - lungs to blood

co2 - blood - lungs

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8
Q

what is a Hb mol composed of?

A

4 globin chains surrounding central haem group

2 alpha + 2 beta chains

4 o2 per Hb

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9
Q

saturated haemoglobin

A

when all 4 haems of mol bound to oxygen

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10
Q

partially saturated haemoglobin

A

when 1 to 3 haems bound to oxygen

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11
Q

the rate that haemoglobin binds + releases oxygen is regulated by …

A
  • po2
  • temp of blood
  • pco2
  • conc of BPG (2,3-bisphosphoglycerate)
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12
Q

in haemoglobin saturation, what happens if oxygen levels drop?

A
  • more oxygen dissociates from haemoglobin + is used by cells
  • resp rate / cardiac output don’t inc
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13
Q

co2 is transported in the blood in 3 forms

what are these?

A
  • dissolved in plasma
  • chemically bound to proteins
  • bicarbonate ions in plasma
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14
Q

describe internal respiration at tissues using (formula)?

A
  • co2 diffuses into RBC
  • high conc of co2 equation to shift to right
  • combines with water to = carbonic acid
  • h2co3 dissociated into h+ + hco3-
  • hydrogen ions attach to one of 4 haem mol knocking off one o2
  • o2 travels down conc gradient to tissues
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15
Q

what is the chloride shift?

A

counterbalances the out rush of neg bicarbonate ions from RBCs

cl- ions move from plasma into erythrocytes

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16
Q

describe external respiration using (formula)?

A
  • reaction shifts to left
  • bicarbonate ions move into RBC + bind with h+ to make carbonic acid
  • carbonic acid split into co2 + h20
  • co2 levels rise
  • co2 diffuses from blood into alveoli along conc gradient
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17
Q

what other factors can influence haemoglobin saturation?

A
  • inc in temp, h+, pco2, BPG —> inc o2 uploading from haemoglobin
    curve SHIFTS RIGHT

dec in these will shift curve left

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18
Q

dorsal respiratory group / inspiratory centre

A
  • located near root of nerve IX
  • excites inspiratory muscles + sets eupnoea
  • becomes dormant during expiration
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19
Q

what is the ventral respiratory group (VRG) involved in?

A

forced inspiration + expiration

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20
Q

what is depth of breathing determined by?

A

how actively respiratory centre stimulates respiratory muscles

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21
Q

what is rate of breathing determined by?

A

how long inspiratory centre = active

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22
Q

pulmonary irritant reflexes

A

irritants promote reflexive constriction of air passages

23
Q

inflation reflex (hering-breuer)

A

stretch receptors in lungs stimulated by lung inflation

24
Q

upon inflation, what happens?

A

inhibitory signals sent to medullary inspiration centre to end inhalation + allow expiration

25
Q

hypothalamic controls act through …

A

limbic system to modify rate + depth of respiration

26
Q

rise in body temp acts to ….

A

inc resp rate

27
Q

cortical controls are …

A

direct signals from cerebral motor cortex that bypass medullary controls

28
Q

changing pco2 levels are monitored by …

A

central chemoreceptors of brain stem

co2 in blood diffuses into cerebrospinal fluid

29
Q

what does hypercapnia result in (inc in pco2)?

A
  • inc in h+ conc in medulla
  • stimulates DRG to inc depth + rate of breathing
  • allows body to remove co2
30
Q

depth + rate of breathing : pco2

process

A
  • inc in arterial pco2
  • dec ph in cerebrospinal fluid
  • central chemo receptors in medulla mediate response

—> afferent impulses —> medulla respiratory centres

—> efferent impulses —> respiratory muscles

inc ventilation

arterial pco2, ph return to normal

31
Q

what is the arch of the aorta?

A

main vessel originating from heart

32
Q

what is the carotid sinus?

A

main artery of neck

33
Q

where are the peripheral chemoreceptors located ?

A
  • arch of aorta

- carotid sinus

34
Q

decrease in po2 will stimulate DRG to…

A

inc resp rate

35
Q

hypoventilation occurs when…

A

pco2 levels = abnormally low

body slows resp rate

36
Q

what is a simple way to overcome hypoventilation?

A

holding breath/breathing slow and shallow

will cause co2 levels to rise in blood

as co2 levels rise, chemoreceptors triggered to stimulate DRG to inc ventilation

37
Q

what may occur until pco2 levels rise?

A

apnoea (breathing cessation)

38
Q

hyperventilation occurs when …

A

co2 removed from blood quickly

occurs in response to hyercapnia (high co2 in blood)

regulated by h+ conc in brain

39
Q

what does hyperventilation reduce?

A

H+ (acid)

40
Q

hypoventilation pushes reaction to …

A

right

41
Q

respiratory alkalosis has a ph of ..

A

> 7.35

42
Q

what are arterial oxygen levels monitored by?

A

aortic + carotid bodies

43
Q

what is a hypoxic drive?

A

when po2 levels become principle respiratory stimulus

44
Q

what are the causes of hypoxia?

A

reduced levels of oxygen in blood

45
Q

hypoxic hypoxia

A

due to not enough pulmonary gas exchange

  • high altitudes, drowning, aspiration, CO poisoning etc
46
Q

ischaemic hypoxia

A

inadequate circulation

  • diabetes mellitus, atherosclerosis
47
Q

anaemic hypoxia

A

anaemia

  • diet, internal bleed
48
Q

histotoxic hypoxia

A

metabolic poison

cyanid poisoning

49
Q

what are the signs of cyanosis?

A
  • blueness of skin, lips, finger nail clubbing
50
Q

quick travel to altitudes above 8000 feet may produce symptoms of acute mountain sickness

give eg of some symptoms?

A
  • headaches
  • shortness of breath
  • nausea
  • dizziness
51
Q

how does acclimatisation to high altitudes occur?

A

chemoreceptors = more responsive to pco2 when po2 declines

decline in blood o2, stimulates kidneys to acerbate prod of EPO (erythropoietin)

52
Q

what are common features of homeostatic imbalance?

A
  • COPD
  • history of smoking
  • dyspnoea (laboured breathing)
  • coughing + frequent pulmonary infections
  • hypoventilation with respiratory acidosis
53
Q

what is emphysema?

A

destruction of alveolar walls, loss of lung elasticity, air trapping

PHA112 (37 decks)

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