Physiology Flashcards
1
Q
What is internal respiration?
A
Gas production by cells
2
Q
What is external respiration?
A
O2 and CO2 exchange between environment and body cells
3
Q
What is LaPlace’s Law + how to alter it?
A
Tension on a vessel wall depends on the thickness of the wall + tension is decreased by increasing thickness and vice versa
4
Q
What is Henry’s Law?
A
PP of a gas is proportional to the amount dissolved in a liquid
5
Q
What is Boyle’s Law + increased …. means decreased …?
A
PP of a gas is inversely related to its volume + volume and pressure
6
Q
Normal atmospheric pressure?
A
760 mm Hg
7
Q
Normal intrapleural pressure?
A
756 mm Hg
8
Q
Normal intrapulmonary pressures at different breathing stages?
A
760 mm Hg, 759 mmHg then 761 mmHg
9
Q
What are the main muscles of inspiration and what is their nerve supply?
A
Diaphragm (C3,4,5) and external intercostals (T1-11)
10
Q
2 ways in which the thorax expands with the lungs?
A
- Water molecules in pleura resist being pulled apart
- Transmural pressure gradient keeps lungs and thorax separate
11
Q
Explain the transmural pressure gradient?
A
Intrapulmonary pressure (760) pushes out against the intrapleural pressure (756) + the pressure across the thorax (760) pushes in against the intrapleural pressure (756)
12
Q
Role of surfactant?
A
Lowers the surface tension of smaller alveoli
13
Q
What produces surfactant?
A
Type II alveoli (mainly) + component from Club/Clara cells
14
Q
Explain alveolar interdependence?
A
- Membranes of outer alveoli are stretched in towards a collapsed alveoli
- They then recoil and pull the membrane of collapsed alveoli with them
15
Q
2 key factors that control lung contraction?
A
Elasticity of connective tissue + alveolar surface tension
16
Q
Is airway resistance low or high in healthy people?
A
Low
17
Q
What key thing determines airway resistance?
A
Airway radius
18
Q
Explain how upper airways are kept open during expiration?
A
- Intraplural presure rises and puts pressure on lower airways
- Increased pressure upstream keeps airways open
19
Q
Explain why people with OLDs are prone to a collapsed airway?
A
- During expiration the increased intrapleural pressure keeps upper airways open
- In OLDs the pressure gradient is lost over obstruction and airways collapse
20
Q
What is pulmonary ventilation and how do you calculate it + normal value?
A
- Volume breathed in/out per min
- TV X RR
- 6
21
Q
What is alveolar ventilation and how do you calculate it + value?
A
- Volume exchanged between alveoli and atmosphere
- TV - dead space X RR
- 4.2
22
Q
What is the main determinant of pulmonary ventilation?
A
The tidal volume
23
Q
Is pulmonary or alveolar ventilation the smallest and why?
A
Alveolar due to dead space
24
Q
What is anatomical dead space?
A
Part of the airway that are non-conducting
25
What is alveolar dead space?
Alveoli that are well ventilated but not perfused
26
2 variable factors that affect gas exchange at different areas of the lung?
Ventilation (V) and perfusion (Q)
27
Is V/Q mismatch normal?
Yes- V/Q normally varies between regions of the lung
28
Effect of increased O2 on pulmonary vs systemic arterioles?
Vasodilation vs vasoconstriction
29
Effect of decreased O2 on pulmonary vs systemic arterioles?
Vasoconstriction vs vasodilation
30
Forced expiration muscles and their nerve supply?
Internal intercostals (T1-11) + abdominal muscles (intercostal nerves)
31
Forced inspiratory muscles and nerve supply?
Sternocleidomastoid + scalenus (both spinal accessory CNXI)
32
3 main factors affecting alveolar gas exchange?
- PP of a gas
- Fick's Law (membrane thickness/area)
- Diffusion coefficient
33
Does O2 or CO2 have a greater PP or diffusion coefficient?
O2 has greater PP and CO2 has greater diffusion coefficient
34
Normal tidal volume?
500 ml
35
Normal total lung capacity?
57000 ml/5.7 litres
36
Term for normal volume of air breathed in and out?
Tidal volume (VC)
37
Term for extra forced air breathed in?
Inspiratory reserve volume (IRV)
38
Term for IRV + TV?
Inspiratory capacity (IC)
39
Term for extra forced air breathed out?
Expiratory reserve volume (ERV)
40
Term for volume of air that cannot be expelled from lungs?
Residual volume (RV)
41
Term for ERV + RV?
Functional residual capacity (FRC)
42
Term for volume inhaled + exhaled at force?
Vital capacity (VC)
43
What 2 things form the total lung capacity?
VC + RV
44
Name for pores between alveoli?
Pores of Kohn
45
The main determinant of Hb% saturation is?
The pO2
46
Oxygen dissociation curve shift to the left means a ... in O2 delivered to tissue?
Decreased
47
Oxygen dissociation curve shift to the right means a ... in O2 delivered to tissue?
Increase
48
6 factors that shift the oxygen dissociation curve left?
HbF, low CO2, low H, low temperature, low 2,3-DPG and carboxyhaemoglobin (CO)
49
Why does CO shift the oxygen dissociation curve to the left?
When CO binds Hb to form carboxyhaemoglobin it increases Hb affinity for O2
50
4 factors that shift the oxygen dissociation curve to the right?
High CO2, high H, high temperature and high 2,3-DPG
51
pO2 is determined by O2 dissolved + O2 bound to Hb? True or False?
False - pO2 is only determined by O2 dissolved in the blood
52
Explain the Bohr effect and a region of the body it takes place?
- Increased CO2/H decreases Hb affinity for O2 + decreased CO2/H increased Hb affinity for O2
- Takes place at metabolically active cells when CO2/H displaces O2 from Hb
53
Explain the Haldane effect and a region of the body it takes place?
Increased O2 decreases Hb affinity for CO2/H + decreased O2 increases Hb affinity for CO2/H
- Takes place in the lungs when incoming O2 displaces CO2 from Hb so it can be expelled
54
Hb structure + graph shape?
2 alpha, 2 beta subunits + sigmoidal curve
55
HbF structure + function?
2 alpha, 2 gamma subunits + higher O2 affinity allows foetus to receive O2 even if mother's pO2 is low
56
Mb structure + function + graph shape?
One subunit, short term skeletal/cardiac muscle O2 storage + hyperbolic curve
57
Main 2 factors affecting pO2?
Pressure of inspired air (750 mm Hg) + proportion of O2 in inspired air
58
Main way CO2 is transported?
As HCO3/bicarbonate
59
10% of CO2 is transported as this?
Dissolved CO2
60
30% of CO2 is transported as this + example?
Carbamino compunds + carbaminohaemoglobin
61
Give the chemical reaction of CO2 in red blood cells + what happens to the products?
- CO2 + H2O H2CO3 (carbonic acid) HCO3 (bicarbonate) + H
| - H is absorbed by Hb and HCO3 leaves the cell via chlorine exchange to buffer the blood
62
How does Hb act as a buffer?
Absorbs hydrogen ions
63
Main site of breathing rhythm generation?
Pre-Botzinger complex in the medulla
64
Controls normal respiration?
Dorsal respiratory group
65
Controls forceful expiration?
Ventral respiratory group
66
Controls inhibition of of inspiration + where it is located + what happens if it is damaged?
Pneumotaxic centre + in the pons + breathing is in long gasps called apneusis
67
Controls prolonged inspiration?
Apneustic centre
68
Important respiratory reflex + function + sensors/control centre?
Hering-Breuer + prevents overinflation of the lungs + pulmonary baroreceptors signal to the medulla
69
The PP of which gas controls breathing under normal conditions?
PCO2
70
Normal MAP of pulmonary arteries + pulmonary hypertension value?
12-20 mm Hg + > 25 mmHg
71
Where are central chemoreceptors found and what do they mainly detect?
In the medulla + CO2/H/pH of CSF
72
Where are peripheral chemoreceptors found and what do they mainly detect?
In the aortic/carotid bodies + pO2 of arteries
73
Peripheral chemoreceptors drive increased respiration when pO2 falls below?
60 mm Hg
74
Can CO2 + H cross the BBB + what this means for arterial changes?
Yes + no + central chemoreceptors mainly respond to CSF but if responding to arterial components it can only respond to CO2
75
Enzyme involved in the Hb CO2 reaction?
Carbonic anhydrase
76
Target SaO2% in healthy people?
94-98%
77
Target SaO2% in people with underlying disease?
88-92%
78
SaO2% that requires ABGs to be taken?
< 92%
79
Which 2 places is blood taken for an ABG?
Radial or femoral artery
80
3 step summary of interpreting an ABG?
- Look at H+ to see if it is alkalosis or acidosis
- Look at HCO3 and PCO2 and whichever has the biggest change will be the type (metabolic or respiratory)
- Look to see if there is a change in the value of the other measurements for compensation
81
3 causes of respiratory acidosis?
OLDs, RLDs and hypoventilation (many causes)
82
What is FEV1?
Volume of forced air expelled in 1 second
83
What is FVC?
Total volume of forced air expelled
84
FEV1 of a healthy vs unhealthy person?
> 80% vs < 80%
85
FEV1/FVC of a healthy vs unhealthy person?
> 0.7 vs < 0.7
86
What is pulmonary compliance + a decreased value means?
Effort needed for lungs to stretch and recoil + more effort to inflate
87
OLDs have a .... pulmonary compliance and .... elastic recoil?
Increased and decreased
88
RLDs have a .... pulmonary compliance and .... elastic recoil?
Decreased and increased
89
Anemic hypoxia is caused by?
Less Hb to carry oxygen
90
Circulatory hypoxia is caused by?
Reduced blood flow to tissue
91
Hypoxic hypoxia is caused by + example?
Low pO2 causing low SaO2% + high altitudes
92
Toxic hypoxia is caused by + 2 examples?
Poisoning + CO and cyanide
93
Low value of pO2 and high value of pCO2 that stimulates chemoreceptors ( + which ones) to affect the respiratory centre in the medulla?
pO2 < 60 mm Hg (peripheral) and pCO2 > 70-80 (central)
94
VIP and NO released by parasympathetic fibres cause?
Smooth muscle relaxation
95
OLDs move the flow volume loop to the left or right + why + shape of top half?
Left + air trapping causes increased volume + slope
96
RLDs move the flow volume loop to the left or right + why + shape of loop?
Right + reduced lung volume due to fibrosis + smaller version of normal
97
Physiological dead space = .... + ...?
Anatomical dead space + alveolar dead space
98
Dalton's law of partial pressures?
Total pressure of a gas mixture is the sum of the PPs of the individual gases
99
Sympathetic innervation only affects what 2 things in the airways?
Blood vessels and goblet cells
100
Where are M1, M2 and M3 in airways + role?
M1 (ganglia) allow rapid Ach action on nicotinic receptors, M2 (postganglionic neurone) inhibit Ach, M3 (SM cell) allow contraction
