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Respiratory > Physiology > Flashcards

Physiology Flashcards

1
Q

State the 3 laws and what they state

A

Boyle’s Law: as vol of gas inc, pressure exerted by gas dec
LaPlace’s Law: the smaller the radius of the alveolus, the more likely the alveolus is to collapse
Henry’s Law: the amount of O2 dissolved in blood is proportional to its partial pressure

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2
Q

what is an easy way of remembering what partial pressure is?

A

the number of molecules going in

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3
Q

what 4 steps are involved in external respiration?

A
  1. Ventilation
  2. Exchange of gases between air and blood
  3. Transport of gases
  4. Exchange of gas between blood and tissue
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4
Q

what 2 types of ventilation are there and what do they consist of?

A

Pulmonary Ventilation: vol of air breathed in and out per min. TV x RR
Alveolar Ventilation: vol of air exchanged between atmosphere and alveoli. has anatomical dead space.
TV (-dead space) x RR

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5
Q

What is dead space?

A

Area that can’t undergo gas exchange.

Areas that are ventilated but not perfused.

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6
Q

TRUE/ FALSE:

Ventilation is the rate of blood that passes through lungs

A

FALSE
this is perfusion. ventilation is the rate of gas that passes through lungs.
they differ between apex and base of lung.

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7
Q

What happens in areas that are perfused but not ventilated?

A

CO2 inc, O2 dec > airways dilate, vessels contract > airflow inc, blood flow dec

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8
Q

TRUE/FALSE:

Inc in respiratory rate (RR) is more effective in inc Pulmonary Ventilation

A

FALSE

inc in TV is more effective.

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9
Q

Give a description of the 4 factors that affect rate of Gas Exchange and how

A
  1. Partial Pressure: pressure that 1 gas exerts in a mixture of gases. As this inc, rate of gas transfer inc.
  2. Diffusion co-efficient: this is greater for CO2 and so it is more soluble in cell membrane therefore taken up more readily than O2.
  3. Large surface area: lungs, pulmonary capillaries
  4. Thin walled Alveoli (1 cell thick)
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10
Q

What is the equation for partial pressure

A

P= KH x C

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11
Q

In what 2 forms is O2 transported around the blood?

A
  1. Bound to Hb

2. Physically Dissolved

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12
Q

How many haem groups does Hb have and what do they do?

A

4, reversibly bind to 1 O2 molecule

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13
Q

When is Hb considered saturated?

A

When Hb is carrying its max load of O2

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14
Q

What shape does the Hb dissociation curve have and why?

A

Sigmoidal, each O2 that binds inc Hb’s affinity for O2

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15
Q

Why does it plateau?

A

All sites become occupied

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16
Q

True/False:

Bohr Effect shifts curve to the left due to inc release of O2 because of disease

A

False:

shifts curve right

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17
Q

In what 3 forms is CO2 transported in the blood?

A

Solution, Bicarbonate, carbamino compound

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18
Q

True/ False:

Most CO2 is transported as carbamino compound

A

False:

As Bicarbonate

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19
Q

How come CO2 is transported in solution?

A

Due to diffusion co-efficient- CO2 is 20 times soluble in solution that O2.

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20
Q

How is Bicarbonate formed and where?

A

RBCs

CO2 + H2O → H2CO3 → HCO3- + H+

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21
Q

What enzyme is needed for this reaction (bicarbonate formation)?

A

Carbonic Anhydrase

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22
Q

True/ False:
The Haldane Effect states that removing O2 from Hb dec affinity of Hb for CO2 hence shifting CO2 dissociation curve to the right.

A

False:

removing O2 INC affinity of Hb for CO2

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23
Q

Why are the Haldane and Bohr effects important?

A

facilitate O2 liberation and CO2 uptake in lungs

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24
Q

Name the 3 pressures in the lung

A

Atmospheric, Intra-Alveolar, Intra-Pleural

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25
Q

Atmospheric pressure has a value of…

A

760mmHg

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26
Q

What is an important point relating partial pressure in gas phase (lungs) and in solution

A

As PP in gas phase inc, the concentration of gas in liquid inc proportionally

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27
Q

What 3 things are closely monitored and kept within narrow limits

A

CO2, O2 and pH

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28
Q

True/False:

Hypercapnia is elevated CO2 meaning the system is responsive to CO2

A

True

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29
Q

How is Hypercapnia detected and how is it controlled

A

CO2 generated H+ through central chemoreceptors

30
Q

What detects a lack of O2 (Hypoxia)

A

Peripheral chemoreceptors

31
Q

How is pH regulated and what detects it

A

Peripheral CRs. The buffer system (CO2 + H2O → H2CO3 → HCO3- + H+) controls pH as more H+ in blood (inc pH) causes and inc in CO2 via this system.

32
Q

How is the buffer system intensified and what is responsible for this

A

PCRs cause hyperventilation. This inc breathing rate hence inc CO2 elimination hence less H+ (as CO2 generates H+)

33
Q

What is Hypoxic Drive

A

Acute or chronic changes due to low PiO2

34
Q

When is hypoxic drive important/ occurs

A

Patients with chronic CO2 retention (COPD) or high altitudes

35
Q

What are the Acute and Chronic responses?

A

Acute: headache, flushed face, nausea, hyperventilating, inc CO
Chronic: inc RBCs, new capillaries, more mitochondria

36
Q

What is inspiration caused by

A

Expansion of lungs due to respiratory muscles being contracted

37
Q

Is inspiration active or passive

A

Active

38
Q

What specific respiratory muscle is involved with inspiration

A

Flattening of the diaphragm

39
Q

What 2 things cause linkage between thorax and lungs (i.e. pleura)

A

Intra-pleural Fluid Cohesiveness: strong attraction between water molecules
-ve IP pressure: this causes a pressure gradient to form causing lung expansion and chest to move inward

40
Q

How do the airways dilate during inspiration

A

IP pressure falls due to inc in volume in chest so airways are pulled open by expanding thorax

41
Q

The rhythm of breathing is controlled by 2 control systems…

A

Neural and Chemical

42
Q

True/ False:

The medulla is the main rhythm generator

A

True

43
Q

What is the dorsal resp system and how does it work

A

Normal Respiratory System
Pre-botzinger complex neurones are excited which excite dorsal neurones causing them to fire in bursts which causes excitation of inspiratory neurones. When firing stops, passive expiration occurs

44
Q

How does the pneumotaxic centre modify breathing

A

stops inspiration

45
Q

How does the apneustic centre modify breathing

A

prolonged inspiration

46
Q

What happens if pneumotaxic centre isn’t present?

A

Apneusis- prolonged breathing

47
Q

How is breathing involuntarily modified…

A

Stretch Receptors, Joint Receptors, Cough reflex

  • Stretch Receptor: activated during insp, prevents hyperinflation of lungs
  • J receptors: impulses from moving limbs reflexly inc breathing
  • Cough reflex: clears airways
48
Q

What is involved in chemical control of inspiration?

A

Blood gas tensions detected by chemoreceptors:
PCR: CO2, O2, H+
CCR: H+ presence in cerebral spinal fluid

49
Q

What is expiration (4 points)

A
  • Caused by relaxation of inspiratory muscles
  • Passive
  • Lung recoil makes IA pressure rise
  • Air molecules in small volume so move down pressure gradient (out of alveoli) until IA= A pressure
50
Q

How do lungs recoil?

A

Due to the presence of elastic connective tissue

51
Q

How do airways contract during expiration?

A

Chest recoils (expels air) so IP pressure rises closing airways

52
Q

When does dynamic air compression occur?

A

During expiration due to an inc in IP pressure

53
Q

What occurs in dynamic airway compression

A

The alveoli and airways are compressed (as alveoli push air out going down its conc. gradient)

54
Q

Why is dynamic airway compression dangerous for patients with Obstructive Lung Disease

A

Pressure change is lost due to obstruction, decreased elastic recoil

55
Q

What causes active expiration and why

A

Ventral resp system is responsible- inc firing of dorsal neurones excites ventral group which activates insp muscles

56
Q

When does active expiration usually occur

A

During hyperinflation

57
Q

True/ False:

The Apneustic and Ventral res groups are part of the Pons Respiratory Control Group

A

False:
Apneustic is & Penumotaxic
Ventral & Dorsal part of medulla res group

58
Q

Name the 4 volume types & describe…

A

Tidal Vol: Vol of air entering/leaving lungs in 1 breath
Inspiratory reserve: extra vol of air breathed in on top of TV
Expiratory reserve: extra vol of air breathed out on top of TV
Residual: min air left in lungs after max expiration

59
Q

Name 4 capacities & describe…

A

Vital: TV + IV + EV
Inspiratory: max vol of air that can be inspired after normal expiration
Total lung: tot vol of air that lungs can hold
Functional residual: vol of air left in lungs after exp

60
Q

What is spirometry used for?

A

Reduced FVC indicates Obstructive LD

61
Q

Peak Flow Meter shows what?

A

Assesses airway function. May also suggest presence of Obstructive LD.

62
Q

True/ False:

Peak flow result is the best out of 3

A

True

63
Q

What is pulmonary compliance and how is it measure?

A

Measure of effort that goes into stretching lungs

Vol change per unit of pressure change

64
Q

What does it mean if you have less compliant lungs?

A

More effort to produce inflation

65
Q

What pathology decreases pulmonary compliance?

A

Oedema, lung collapse, pulmonary fibrosis as bigger pressure change needed to produce sufficient change in volume

66
Q

What pathology increases pulmonary compliance?

A

Emphysema due to more energy needed to expel air due to hyperinflation

67
Q

When do lungs operate at more than half full (norm)?

A

Exercise, airway resistance, dec pulmonary compliance, loss of elastic recoil

68
Q

Is resistance in lungs normally low or high?

A

Low

69
Q

What causes alveolar collapse?

A

If there are too many water molecules on alveolus surface then tension can be too strong hence alveoli collapse

70
Q

How is alveolar collapse prevented?

A

Surfactant: secretion that creates gaps between water molecules lowering surface tensions
- RDS is pathology of this
Alveolar Interdependence: alveoli stretch and recoil exerting expansion forces causing collapsed alveoli to open

Respiratory (19 decks)

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