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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
Atmospheric pressure has a value of...
760mmHg
26
What is an important point relating partial pressure in gas phase (lungs) and in solution
As PP in gas phase inc, the concentration of gas in liquid inc proportionally
27
What 3 things are closely monitored and kept within narrow limits
CO2, O2 and pH
28
True/False: | Hypercapnia is elevated CO2 meaning the system is responsive to CO2
True
29
How is Hypercapnia detected and how is it controlled
CO2 generated H+ through central chemoreceptors
30
What detects a lack of O2 (Hypoxia)
Peripheral chemoreceptors
31
How is pH regulated and what detects it
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
How is the buffer system intensified and what is responsible for this
PCRs cause hyperventilation. This inc breathing rate hence inc CO2 elimination hence less H+ (as CO2 generates H+)
33
What is Hypoxic Drive
Acute or chronic changes due to low PiO2
34
When is hypoxic drive important/ occurs
Patients with chronic CO2 retention (COPD) or high altitudes
35
What are the Acute and Chronic responses?
Acute: headache, flushed face, nausea, hyperventilating, inc CO Chronic: inc RBCs, new capillaries, more mitochondria
36
What is inspiration caused by
Expansion of lungs due to respiratory muscles being contracted
37
Is inspiration active or passive
Active
38
What specific respiratory muscle is involved with inspiration
Flattening of the diaphragm
39
What 2 things cause linkage between thorax and lungs (i.e. pleura)
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
How do the airways dilate during inspiration
IP pressure falls due to inc in volume in chest so airways are pulled open by expanding thorax
41
The rhythm of breathing is controlled by 2 control systems...
Neural and Chemical
42
True/ False: | The medulla is the main rhythm generator
True
43
What is the dorsal resp system and how does it work
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
How does the pneumotaxic centre modify breathing
stops inspiration
45
How does the apneustic centre modify breathing
prolonged inspiration
46
What happens if pneumotaxic centre isn't present?
Apneusis- prolonged breathing
47
How is breathing involuntarily modified...
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
What is involved in chemical control of inspiration?
Blood gas tensions detected by chemoreceptors: PCR: CO2, O2, H+ CCR: H+ presence in cerebral spinal fluid
49
What is expiration (4 points)
- 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
How do lungs recoil?
Due to the presence of elastic connective tissue
51
How do airways contract during expiration?
Chest recoils (expels air) so IP pressure rises closing airways
52
When does dynamic air compression occur?
During expiration due to an inc in IP pressure
53
What occurs in dynamic airway compression
The alveoli and airways are compressed (as alveoli push air out going down its conc. gradient)
54
Why is dynamic airway compression dangerous for patients with Obstructive Lung Disease
Pressure change is lost due to obstruction, decreased elastic recoil
55
What causes active expiration and why
Ventral resp system is responsible- inc firing of dorsal neurones excites ventral group which activates insp muscles
56
When does active expiration usually occur
During hyperinflation
57
True/ False: | The Apneustic and Ventral res groups are part of the Pons Respiratory Control Group
False: Apneustic is & Penumotaxic Ventral & Dorsal part of medulla res group
58
Name the 4 volume types & describe...
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
Name 4 capacities & describe...
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
What is spirometry used for?
Reduced FVC indicates Obstructive LD
61
Peak Flow Meter shows what?
Assesses airway function. May also suggest presence of Obstructive LD.
62
True/ False: | Peak flow result is the best out of 3
True
63
What is pulmonary compliance and how is it measure?
Measure of effort that goes into stretching lungs | Vol change per unit of pressure change
64
What does it mean if you have less compliant lungs?
More effort to produce inflation
65
What pathology decreases pulmonary compliance?
Oedema, lung collapse, pulmonary fibrosis as bigger pressure change needed to produce sufficient change in volume
66
What pathology increases pulmonary compliance?
Emphysema due to more energy needed to expel air due to hyperinflation
67
When do lungs operate at more than half full (norm)?
Exercise, airway resistance, dec pulmonary compliance, loss of elastic recoil
68
Is resistance in lungs normally low or high?
Low
69
What causes alveolar collapse?
If there are too many water molecules on alveolus surface then tension can be too strong hence alveoli collapse
70
How is alveolar collapse prevented?
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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