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foundations of medicine 3 > physiology > Flashcards

physiology Flashcards

(107 cards)

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1
Q

what are the 5 components needed for effective gas exchange / respiration

A
  • controller
  • ventilatory pump
  • gas exchanger
  • cardiovasc system
  • enough haemoglobin
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2
Q

what is the role of the respiratory controller

A

determines the rate and depth of breathing via efferent signals sent to the resp muscles from resp centres

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3
Q

where are the respiratory centres found

A

in the brain stem

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4
Q

what is respiration modified by

A

inputs from the pons

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5
Q

where is respiratory rhythm generated

A

medulla

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6
Q

what is the role juxtapulmonary receptors

A

protect against hyperinflation

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7
Q

where are peripheral chemoreceptors found

A

carotid bodies - at the bifurcation of the common carotid arteries
aortic bodies - along the aortic arch

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7
Q

what happens to ventilation in response to decreased blood pressure

A

increased rate of ventilation

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8
Q

what is the role of peripheral chemoreceptors

A

sense tension of oxygen and carbon dioxide and [H+] in the blood

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9
Q

where are central chemoreceptors found

A

near the surface of the medulla of the brainstem

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10
Q

what do central chemoreceptors respond to

A

the [H+] of CSF

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11
Q

what is the most potent stimulant of respiration

A

arterial PCO2 acting through central chemoreceptors
(increased [H+] in CSF)

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12
Q

which part of the respiratory system is activated in hypoxic drive

A

peripheral chemoreceptors

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13
Q

when is hypoxic drive clinically important (2)

A

in patients with chronic CO2 retention
high altitudes

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14
Q

give an example of a condition which causes chronic CO2 retention

A

COPD

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15
Q

what happens when peripheral chemoreceptors are stimulated by increased [H+]

A

hyperventilation to increase the elimination of CO2 from the body

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16
Q

name some factors that can affect the ventilatory pump of respiration

A

neuromuscular weakness
decreased compliance
loss of pressure gradient
increased airway resistance

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17
Q

what condition can cause a loss of pressure gradient across the lungs

A

pneumothorax

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18
Q

name 2 conditions which can cause increased airway resistance

A

asthma, COPD

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19
Q

what is the bucket handle mechanism

A

external intercostal muscle contraction lifts the ribs and moves out the sternum

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20
Q

how is the volume of the thorax increased vertically during inspiration

A

contraction of the diaphragm

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21
Q

what nerve is involved in contraction of the diaphragm

A

phrenic nerve from C3,4 and 5

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22
Q

what are the major muscles of inspiration

A

external intercostal and diaphragm

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23
Q

what are the accessory muscles of inspiration

A

sternocleidomastoid
scalenus

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24
what are the muscles of active expiration
internal intercostal muscles abdominal muscles
25
what happens to pressure in the lungs during inspiration
intra-alveolar drops below atmospheric intrapleural becomes more negative
26
which forces keep alveoli open
transmural pressure gradient pulmonary surfactant alveolar interdependence
27
which forces promote alveolar collapse
elasticity of stretched pulmonary connective tissue fibres alveolar surface tension
28
what does parasympathetic stimulation of the airways cause
bronchoconstriction
29
what does sympathetic stimulation of the airway cause
bronchodilation
30
what is the main determinant of airway resistance
radius of the conducting airway
31
what happens to intrapleural pressure during expiration
rises
32
when does dynamic airway compression occur
during forced expiration
33
who do we worry about with dynamic airway compression
people with obstructive lung disease
34
what can be the clinical sign of dynamic airway compression in obstructive lung disease
wheeze or prolonged expiration
35
what is the consequence of dynamic airway compression in a patient with obstructive lung disease
airway collapse
36
what can also make dynamic airway compression worse
decreased elastic recoil
37
what is pulmonary compliance
the measure of effort that has to go in to stretching the lungs
38
what does the wall of an alveolus consist of
single layer of flattened type I alveolar cells
39
name conditions which reduce the surface area for gas exchange
emphysema lung collapse
40
what is cardiac output
the volume of blood pumped by each ventricle per minute
41
what is the equation for cardiac output
stroke volume x heart rate
42
what is stroke volume
the volume of blood ejected by each ventricle per heartbeat
43
what is the equation for stroke volume
end diastolic volume - end systolic volume
44
how are changes in stoke volume brought about
changes in the diastolic length of myocardial fibres
45
what is diastolic length of myocardial fibres determined by
end diastolic volume
46
what is cardiac preload
the extent to which the left ventricular wall stretches at the end of diastole, or before systole starts
47
what determines the end diastolic volume
venous return
48
what does left sided heart failure cause
pulmonary capillary congestion and pulmonary oedema
49
what is the primary factor which determines the percent saturation of haemoglobin with O2
PO2
50
effect of anaemia on oxygen saturation curve
normal shape but doesn't reach maximum oxygen saturation
51
what is tidal volume
the volume of air entering or leaving the lungs during a breath
52
what is inspiratory reserve volume
the extra volume of air that can be maximally inspired above the tidal volume
53
what is inspiratory capacity
tidal volume + inspiratory reserve volume the maximum volume of air that can be inspired at the end of normal expiration
54
what is expiratory reserve volume
extra volume of air that can be breathed out after tidal volume
55
what is residual volume
the minimum volume of air left in the lungs after maximum expiration
56
what is functional residual capacity
the volume of air in the lungs at the end of normal passive expiration
57
what is vital capacity
the maximum volume of air that can be moved out during a single breath following maximal inspiration
58
what is total lung capacity
the maximum volume of air that the lungs can hold
59
what is forced expiratory volume
volume of air that can be expired during the first second of expiration
60
what is FEV1:FVC ratio normally
>75%
61
what is FEV1:FVC ratio in an asthmatic patient
<75%
62
how do we identify the difference between FEV1:FVC ratio in a patient with COPD compared to asthma
asthmatic patients will respond to a bronchodilator
63
what classification is used to assess airflow limitation in COPD
GOLD (1-4)
64
FEV1:FVC ratio in restrictive lung disease
normal as both are low
65
why do people complain of tingling during anxiety/hyperventilation
hyperventilation causes respiratory alkalosis this causes decreased ionised calcium - as it binds to albumin if pH increases decreased ionised calcium results in increased nerve excitability
66
what does a low pO2 cause the lungs to do
pulmonary vasoconstriction
67
why can't we give excessive oxygen to COPD patients with chronic CO2 retention
can lead to hypercapnic respiratory failure
68
what happens to pulmonary compliance in a patient with emphysema
increases
69
why do lungs collapse in pneumothorax
increased intrathoracic pressure abolishes the transmural pressure gradient
70
physical sign of a pneumothorax
hyperresonant percussion and decreased/absent breath sounds
71
how do we calculate oxygen delivery index
oxygen content of arterial blood x cardiac index
72
which 2 factors determine O2 content of arterial blood
haemoglobin concentration and its saturation with oxygen
73
what is homeostasis
maintaining near constant internal environment
74
what is the primary type of homeostatic control mechanisms in the human body
negative feedback
75
how do negative feedback mechanisms work
oppose initial changes in environment
76
what is the importance of negative feedback loops in the body
promote stability by regulation of variables within a narrow range
77
what are the 3 main components of a negative feedback mechanism
sensor, control centre and effectors
78
what happens to thermoregulation in fever
a cold response raises the body temp to a new set point
79
where can we take an indirect estimate of core body temperature
ear drum
80
normal temperature range
36-37.5
81
fever range
38-40
82
hyperthermia range
>40
83
where can we take a direct estimate of core body temperature (2)
rectum or oesophagus
84
hypothermia range
<35
85
name the 4 ways in which the body can lose heat
radiation conduction convection evaporation
86
name the 3 ways in which the body can gain heat
radiation convection conduction
87
name some hormones which can increase BMR
adrenaline, noradrenaline, thyroxine
88
where is the control centre for thermoregulation
hypothalamus
89
where are central thermoreceptors mostly found
hypothalamus, abdominal organs
90
where are peripheral thermoreceptors found
in the skin
91
what are the effectors in thermoregulation (3)
skeletal muscles skin arterioles sweat glands
92
what part of the hypothalamus is activated by cold
posterior hypothalamic centre
93
which part of the hypothalamus is activated by warmth
anterior hypothalamic centre
94
how is set point raised in a fever
chemicals from macrophages act as endogenous pyrogens stimulate the release of prostaglandins from the hypothalamus hypothalamus initiates mechanisms to heat the body e.g. shivering temp increases to reach the new set point
95
what is the response of skeletal muscles to warmth
decreased tone
96
what is a motor unit
a single alpha motor neuron and all the skeletal muscle fibres it innervates
97
what is the functional unit of a muscle
sarcomeres
98
what is the name of the thin muscle filament
actin
99
what is the name of the thick muscle filament
myosin
100
what are actin and myosin arranged into
sarcomeres
101
what is a segment of actin and myosin called
myofibril
102
where is calcium released from in muscle contraction
lateral sacs of the sarcoplasmic reticulum
103
what causes calcium release during muscle contraction
action potential in the T tubules
104
what is the role of calcium in muscle contraction
binds to troponin on actin filaments causes tropomyosin to be moved out the wat to uncover cross-bridge binding sites on actin
105
what is the neurotransmitter at the NMJ
acetylcholine
106
when is ATP needed in muscles
during contraction to power cross bridges during relaxation to release cross bridges and pump calcium back into the SR

foundations of medicine 3 (6 decks)

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