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Physiology Flashcards

1
Q

How is most oxygen transported in the blood?

A

Bound to haemoglobin

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2
Q

What is the primary factor in determining the percentage saturation of haemoglobin with oxygen?

A

PO2, if partial pressure is normal haemoglobin will be saturated

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3
Q

What factors can impair oxygen delivery to tissues?

A

Decreases in partial pressure of inspired oxygen
Respiratory disease
Anaemia
Heart failure

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4
Q

What factors move the oxyhaemoglobin dissociation curve to the right?

A 
hypercapnia
hyperthermia
Acidosis
Increased 2,3 DPG
sickle cell disease exercise
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5
Q

What are the three methods by which carbon dioxide is transported in the blood?

A

In solution
As bicarbonate
As carbamino compounds

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6
Q

How is most carbon dioxide transported in the blood?

A

As bicarbonate

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7
Q

Describe the Haldane effect.

A

Removing oxygen from Hb increases the ability of Hb to pick up carbon dioxide and carbon dioxide generated hydrogen ions.

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8
Q

Does oxygen move the carbon dioxide-haemoglobin dissociation curve to the left or right?

A

right

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9
Q

Which part of the brainstem acts as the major rhythm generator in control of respiration?

A

Medulla

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10
Q

What is the name given to the network of neurones responsible for generating breathing rhythm?

A

Pre-botzinger complex

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11
Q

Which neurones are excited by the rhythm generated by the pre-botzinger complex?

A

Dorsal respiratory group neurones in the medulla

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12
Q

When does expiration occur?

A

When the firing of dorsal respiratory group neurones stops.

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13
Q

How does hyperventilation occur?

A

There is increased firing in the dorsal neurones. This excites the ventral respiratory group neurones, which in turn leads to contraction of the accessory muscles of respiration leading to forced expiration.

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14
Q

Which part of the body can modify the respiratory rhythm generated in the medulla?

A

The pons

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15
Q

What mechanism prevents apneusis (prolonged inspiratory gasps with brief expiration)?

A

The pneumotaxic centre in the pons is stimulated when the dorsal respiratory neurones fire, terminating inspiration.

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16
Q

Which mechanism prevents over-inflation of the lungs during exercise?

A

Hering-Breuer

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17
Q

What receptors mediate the Hering-Breuer mechanism?

A

Pulmonary stretch receptors

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18
Q

Where are the peripheral chemoreceptors located?

A

Aortic and carotid bodies

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19
Q

What stimulus do central chemoreceptors respond to?

A

Hydrogen ion concentration in the cerebrospinal fluid

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20
Q

What receptors mediate hypoxic drive?

A

Peripheral chemoreceptors

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21
Q

Describe the chronic adaptations to high altitude hypoxia.

A 
Increased RBC production
Increased 2,3 DPG
Increased capilaries
Increased mitochondria
Kidneys conserve acid
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22
Q

What is internal respiration?

A

The intracellular mechanisms which consume oxygen and produce carbon dioxide.

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23
Q

What is external respiration?

A

The sequence of events that lead to the exchange of oxygen and carbon dioxide between the external environment and the cells of the body.

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24
Q

What are the four steps involves in external respiration?

A

Ventilation
Gas exchange between alveoli and blood
Gas Transport
Gas exchange at tissue level

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25
What is Boyle's Law?
At any constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas i.e. as volume increases, pressure decreases
26
How does the body decrease intra-alveolar pressure during inspiration?
The chest wall and lungs are stretched by the muscles of inspiration. The increase in the size of the lungs decreases the intra-alveolar pressure as the air is contained in a greater volume. The air then enters the lungs down the pressure gradient until intra-alveolar pressure=atmospheric pressure
27
What type of cells secrete surfactant?
Type II alveolar cells
28
How does surfactant work to lower alveolar surface tension?
Alveolar surface tension is cause by the attraction between water molecules at liquid air interface. Surfactant intersperses between the water molecules lining the alveoli, preventing alveolar collapse.
29
Why do premature babies sometimes present with respiratory distress syndrome of the newborn?
Developing foetal lungs are unable to synthesise surfactant until late in the pregnancy. If a baby isn't producing enough surfactant, it has to over come the high surface tension to inflate its lungs.
30
What is alveolar interdependence?
If an alveolus starts to collapse, the surrounding alveoli are stretched and the recoil, exerting expanding forces on the collapsing alveoli to reopen it.
31
What is tidal volume?
The volume of air entering or leaving the lungs during a single breath.
32
What is inspiratory reserve volume?
Extra volume of air that can be maximally inspired over and above the typical resting tidal volume.
33
What is inspiratory capacity?
Maximum volume that can be inspired at the end of a normal quiet inspiration. IC = IRV + TV
34
What is expiratory reserve volume?
Extra volume of air that can be actively expired by maximal contraction beyond normal volume of air after a resting tidal volume.
35
What is residual volume?
Minimum volume of air remaining in the lungs even after a maximal expiration.
36
What is functional residual capacity?
Volume of air in the lungs at the end of a normal passive expiration. FRC = ERV + RV
37
What is vital capacity?
Maximum volume of air that can be moved out during a single breath following a maximal inspiration. VC = IRV + TV + ERV
38
What is total lung capacity?
The maximum volume of air that the lungs can hold. | TLC = VC + RV
39
What is spirometry a measure of?
Dynamic lung volumes
40
What is the primary determinant of airway resistance?
Radius of the conducting airway.
41
Does pulmonary compliance increase or decrease with age?
Increase.
42
What wave on an ECG is associated with atrial depolarisation?
P wave
43
The QRS complex occurs when which heart chambers depolarise?
Ventricles
44
What takes up most of the time between the start of the P wave and the start of the QRS complex?
AV nodal delay
45
How many small squares does a QRS complex usually last for?
3 small squares (0.12s)
46
When does contraction of the ventricles occur on an ECG?
ST segment
47
What are the lateral leads on an ECG?
I, aVL, V5 and V6
48
What are the inferior leads on an ECG?
II, III and aVF
49
What are the anterior leads on an ECG?
V1-4
50
In which intercostal space are leads V1 and V2 placed for an ECG?
4th
51
How many leads are in a standard ECG?
12
52
What is autorhythmicity?
The ability of the heart to beat rhythmically in the absence of external stimuli.
53
Where does excitation of the heart usually originate from?
SA node
54
The movement of which ions is responsible for the pacemaker potential?
Decrease in potassium influx Funny current (slow sodium and potassium influx) Transient calcium influx
55
The rising phase of the pacemaker action potential is due to influx of which ion?
Calcium
56
What is the resting membrane potential in atrial and ventricular myocytes?
-90mV
57
The rapid upstroke during Phase 0 of the AP in cardiac myocytes is due to influx of which ion?
Sodium
58
Which ions are responsible for the plateau phase of the action potential in cardiac myocytes?
Calcium
59
The inactivation of which channels results in the refractory period?
Sodium channels
60
Why is the refractory period important?
It prevents another action potential from being initiated until the cell has repolarised.

Year 1 (5 decks)

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