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Physiology wk7 Flashcards

1
Q

what is the primary purpose of the respiratory system

A

maintain arterial blood-gas homeostasis

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2
Q

how is arterial blood-gas homeostasis maintained

A
  1. Pulmonary ventilation
  2. Alveolar gas exchange
  3. Gas transport
  4. Systemic gas exchange
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3
Q

what are epiglottis

A

these are what seperates the upper and lower respiratory tracts

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4
Q

what is the membrane surrounding the lungs called

A

pleura

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5
Q

what is special about the pleura

A

intrapleural pressure < atmospheric pressure, and this prevents alveoli from collapsing

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6
Q

how many airway generations are there

A

there are 23

conduction zone:
traechea
bronchi
bronchioles
terminal brinchioles

respiratory zone:
respiratory bronchioles
alevolar ducts
alveolar sacs

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7
Q

where in the bronchi is the conduction zone

A

from the main bronchi (Z1) to the terminal bronchioles (Z16)

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8
Q

where does gas exchange occur in the lungs

A

in the ‘respiratory zone’ (Z17-23)
between respiratpry bronchioles and alveoli sacs

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9
Q

where does pulmonary gas exchange occur

A

pulmonary capillary

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10
Q

how does o2 and co2 move between air and blood

A

through simple diffusion (H to L)

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11
Q

what are the two types of alveolar cell (pneumocytes)

A
  1. Type 1 cells cover 95%, internal surface of the alveolus, critical for gas exchange
  2. type 2 cells release surfactant, this lowers surface tension
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12
Q

what is ficks law of diffusion

A

(surface area / thickness) x diffusion coefficent x (alveolar pressure - arterial pressure)

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13
Q

what are the 5 layers that gas needs to pass to enter blood

A
  1. surfactant
  2. alveolar epithelium - EP
  3. interstitium - IN
  4. capillary endothelium - EN
  5. plasma

SAICP

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14
Q

what are the 3 different mechanics of breathing

A
  • Contraction Length = change in volume
  • Contraction Velocity = change in flow
  • Contraction Force = change in pressure
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15
Q

what is inspiration

A

when the volume of thoracic cavity increases as muscles contract to lower pressure and allow air in

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16
Q

what is the bucket handle motion

A

ribs increases transverse (lateral) diameter of thorax in inspiration (they get wider)

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17
Q

what is the pump handle motion

A

the ribs increases the anteroposterior diameter of the thorax
chest pumps out

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18
Q

what is the diaphragm responsible for at rest

A

pulmonary ventilation (expiration is passive)

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19
Q

what happens to the diaphragm during exercise for inspiration

A

it is assisted by the external intercostal muscles, scalenes, sternocleidomastoid and this increases ventilation 10-20-fold above resting levels

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20
Q

how does expiration become an active process

A

by contraction of the rectus abdominis, internal intercostals and external obliques (RIE)

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21
Q

what is ohm’s law

A

Current = voltage/resistance, applied to breathing
Airflow is dependant upon a pressure gradient and airway resistance

volume per unit of time = (pressure 1 - pressure 2 )/ resistance

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22
Q

what is poiseuille’s law

A

Resistance is dependant upon the length and radius of the tube
Radius is raised to the fourth power, making it the major determinant of airway resistance

resistance = 8nl / (pie x r^4)

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23
Q

what is the formula for volume per unit of time

A

v = tidal volume x breathing freq

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24
Q

what is the formula for alveolar ventilation

A

(tidal volume - dead space) x breathing freq

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25
what is dead space
air that doesnt participate in gas exchange, 150ml in healthy personal, doesn’t change during exercise
26
what are the effects of COPD
Higher end expiratory lung volume Increased work of breathing Increased breathing discomfort
27
what do the words volume and capacity refer to when looking at breathing frequency graph
volume = one segment capacity = two segments
28
The ventilatory response to constant load steady state exercise occurs in 3 phases, what are they
1. Immediate increase in Ventilation 2. Exponential increase in ventilation 3. Plateau
29
what is hyperpnoea
PaCO2 regulation due to proportional changes in alveolar ventilation (V^A) and metabolic rate (VCO2) PaCO2 = (resistance x T? x VCO2) / alveolar ventilation
30
what happens to ventilation during incremental exercise
Ventilation increase linearly with intensity/workload until the ventilatory threshold (lactate/anaerobic threshold), this occurs at 50-75% of peak workload After the threshold ventilation increases exponentially resulting in hyperventilation
31
what is exercise induced arterial hypoxaemia (EIAH)
reduction in PaO2 of >= 10mmHg from rest, occurs in highly trained males during heavy exercise and majority of females occurs when ventilatory demand exceeds capacity
32
what are causes of EIAH
* Limitation of diffusion * Volume/cardiac output mismatch * Relative hypoventilation
33
what influences ventilation during onset of exercise
ventilation changes are largely chieved by increasing tidal volume
34
what influences ventilation change during heavy exercise
tidal volume plateaus and further increases in ventilation are caused by increasing breathing frequency
35
what is the formula for work
force x volume (in breathing, work = pressure x volume)
36
what if the formula for total work
sum of elastic, flow-resistive and inertial forces
37
what is oesophageal pressure (poes)
an estimate of pleural pressure, used to calculate mechanical work of breathing
38
what does the respiratoryy control centre rcc do
controls ventilation
39
where are respiratory central pattern generators located
within the brainstem (pons and medulla)
40
what are the three main groups of neurons
1. Ventral respiratory group (inspiratory and expiratory) 2. Dorsal respiratory group (inspiratory) 3. Pontine respiratory group (modulatory)
41
what is the central controller
brainstem (medulla and pons)
42
what are the motor outputs
* resistance muscles (cricoarytenoid) * pump muscles (diagram)
43
what are the feedback inputs
* peripheral chemoreceptors, * central chemoreceptors
44
what are the feedforward inputs
* muscle afferents (peripheral neurogenic) * co2 flow, (peripheral neurogenic) * central command (central neurogenic)
45
where are peripheral chemoreceptors located
in the aortic arch and cartoid body
46
what do peripheral chemoreceptors do
relay sensory information to the medulla via vagus and glossopharyngeal nerves, change in PaO2 = increase in ventilation
47
what stimulates peripheral chemoreceptors
temp adrenalin co2 o2
48
where are central chemoreceptors located
are in the ventral surface of the medulla, known as the retrotrapezoid nucleus (RTN)
49
what is the RTN sensitive to
change in paCO2 and h+ io s
50
what does an increase in paCO2 lead to
increase in ventilation
51
what is the steps for chemoreceptor feedback
1. detect error signals (disturbance to blood-gas homeostasis) 2. central and peripheral chemoreceptors increase afferent input to brainstem 3. premotor neurons in the dorsal respiratory group are activated 4. inspiratory muscles contract, increase in ventilation 5. increased ventilation causes changes to: PaO2, PaCO2 and pH. 6. Blood-gas homeostasis is restored
52
what is the difference between ventilatory response to o2 and co2
o2 is curvlinear and co2 is linear
53
what do peripheral chemoreceptors do
fine tune breathing
54
what happens during exercise above threshold
metabolites accumulate including: H+ and K+ which can stimulate breathing. PaCO2 actually falls and therefore inhibits breathing
55
what chronic trainind adaptions improve aerobic capacity
* Lower metabolite accumulation * Lower afferent feedback * Lower ventilatory drive
56
what are 5 examples where pulmonary system limits performance
1. Exercise-induced arterial hypoxaemia 2. Exercise-induced laryngeal obstruction 3. Expiratory flow limitation 4. Respiratory muscle fatigue 5. Intrathoracic pressure effects on cardiac output
57
what is daltons law
total pressure of a gas mixture is equal to the sum of pressure that each gas would exert independently P air = PN^2 + PO2 + PCO2
58
what is the formula for partial pressure
Pgas = Fgas x Pbar
59
what are the steps for pulmonary circulation
1. Pulmonary artery carries deoxygenated blood from right ventricle to the lungs 2. Gas exchange between the alveoli and pulmonary capillaries occurs 3. Oxygenated blood is returned to the left atrium via the pulmonary vein 4. Oxygenated blood is pumped around the systemic circulation to systemic cells
60
what are two features that help pulmonary circulation
low pressure = low resistance thin walled little smooth muscle
61
what are the perfect conditions for gas exchange
ideal that ventilation matches bloodflow
62
what does underperfused refer to
when ventilation is higher than blood flow
63
what does overperfused refer to
when blood flow is higher than ventilation
64
why does gas exchange improve during exercise
increased tidal volume increased pulmonary artery pressure
65
in what two forms is o2 carried
dissolved - 2 combined with HB - 98
66
what is henrys law
amount dissolved is proportional to the partial pressure
67
formula for total conc of o2 within the body
1.34 x Hb x saturation/100 + (0.003 x PO2)
68
what is the bohr effect
causes a shift to the righ in how much o2 is released into the cells, caused by change in pH, co2 and body temp
69
what is myoglobin and its function
o2 binding protein found in skeletal muscles * Provides intramuscular o2 storage * Shuttles o2 from muscle cell membrane to mitochondria
70
what are the 3 ways that co2 is carried
1. Dissolved – 10 2. Bound to Hb – 20 3. Bicarbonate – 70
71
how does the cell maintain neutrality
Hco3- leaves the cell and CL- moves in
72
how is carboamino Hb formed
H+ binds to Hb to form HHB which binds to Co2
73
what are the muscles of inspiration
diaphragm external intercostal scalnes sternaclosamastoid
74
muscles in expiration
rectus abdominis internal intercostal external oblique
75
what is the ventillation-perfusion ratio
gas exchange requires a matching of ventilation to blood flow
76
what do you want to ventillation-perfusion ratio to be
1 >1 = underperfused (more air than blood) 1> = overperfused (less air than blood)
77
why is blood flow lower in the apex (top) than in the base
due to gravity it is disproportionate
78
why does the V/Q ratio improve during exercise
increased tidal volume imcreased pulmonary artery pressure could worsen during high intensity exercise
79
what is the structure of the respiratory system
nose nose cavity pharynx larynx trachea brochus brochiole terminal brochiole
80
what is COPD
increased airway resistance and reduced FEV/FVC

Physiology (13 decks)

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