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The respiratory system Flashcards

1
Q

Respiratory quotient

A

Ratio of CO2: O2 - depends on food consumed

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2
Q

Trachea and bronchi

A

Rigid tubes - rings of cartilage avoid collapse

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3
Q

Bronchioles

A

No cartilage, smooth muscle walls, sensitive to some hormones/chemicals

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4
Q

Alveoli

A

Thin walled inflatable sacs
Pulmonary capillaries around each alveolus for good blood supply
Large SA and thinner - efficient gas exchange 0.5 microm

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5
Q

Type I alveolar cells

A

1 cell layer thick - flattened

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6
Q

Type II alveolar cells

A

Secrete surfactant (phospholipid)

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7
Q

Alveolar macrophages

A

Guard lumen to prevent infection

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8
Q

Pores of Kohn

A

Airflow between neighbouring alveoli - collateral ventilation
Lined with ciliated epithelia and bathed in mucous - much-ciliatory escalator

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9
Q

Pleural sac

A

Double-walled, closed sac separating from thoracic wall
Pleural cavity = interior
Intracellular sac secreted by pleura surfaces - lubrication, protection

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10
Q

Diaphragm

A

Skeletal muscle separating thoracic and abdominal cavity

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11
Q

Function of respiratory system

A

Exchange of gases in air/blood, homeostatic regulation of pH, defence against inhaled pathogens, vocalisation, thermoregulation, water loss

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12
Q

Pressures in the respiratory system

A 
Atmospheric (barometric) pressure
Intra-alveolar pressure (intrapulmonary)
Intrapleural pressure (intrathoracic)
Alveolar pressure  atmospheric = air out of lungs
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13
Q

Boyle’s Law

A

Any constant temperature, the pressure exerted by a gas varies inversely with the volume of gas

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14
Q

Lung mechanics

A

No muscles, relies on difference in pressure (transpulmonary pressure = Palv - Pip) and compliance (stretch)
Respiration muscles attached to chest wall and contract and real to change chest dimensions, causing TP change

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15
Q

Inspiration

A

Diaphragm domed -> phrenic nerve -> contracts and flattens
Intercostal muscles -> intercostal nerve
Expansion of thoracic cavity decrease in intrapleural pressure - increasing ling volume and lowers intra-alaveolar pressure than atmospheric so air enters

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16
Q

Expiration

A

Relaxation of inspiratory muscles - diaphragm and chest wall muscles decrease chest cavity size
Intrapleural pressure increases, compresses lungs, intra-alveolar pressure increases - above atmospheric -> air out
Contraction of expiration muscles -> abdominal wall and internal intercostal

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17
Q

Elastic recoil of alveoli

A

Highly elastic connective tissue, alveolar surface tension

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18
Q

Lung compliance

A 
Effort to stretch lungs
Change in volume to given force/pressure = change in V/Change in P
Ease with with volume can be changed
Reciprocal of elastane
High compliance = easy chest expansion
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19
Q

Law of LaPlace

A

Surface tension P=2T/R
P in large alveolus > smaller - small may collapse
Sufacant lowers surface tension o liquid lining alveoli so pressure to hold alveoli open = reduced

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20
Q

Airway resistance, R

A

R proportional to Ln/r^4
Upper airways diameter constant
Mucus accumulation can increase resistance
Bronchioles - collapsible tubes increase R
Bronchoconstriction (asthma) and dilation can occur

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21
Q

Tidal volume, TV

A

Volume of air/breath

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22
Q

Inspiratory reserve, IRV

A

Extra volume that can be maximum inspired

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23
Q

Inspiratory capacity, IC

A

= IRV + TV

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24
Q

Expiratory reserve, ERV

A

Extra volume that can be expired by max contraction beyond normal

25
Residual volume, RV
Minimal volume remaining in lungs after max expiration
26
Functional residual capacity, FRC
Volume of air in runs after normal expiration | = ERV + RV
27
Vital capacity, VC
Max volume of air in single breath maximum inspired | IRV + TV + ERV
28
Total lung capacity, TLC
Mac volume lungs can hold | VC + RV
29
Forced expiratory volume in 1 second, FEV
Volume of air during first second of expiration in VC determination
30
Anatomical dead space
Conducting airways, no gas exchange occurs ~150ml
31
Physiological dead space
Anatomical dead space + alveolar dead space | Alveolar dead space = non-functioning alveoli e.g. absence of blood flow
32
Minute ventilation
Volume breathed in per min
33
Pulmonary ventialton
Tidal volume x respiratory rate
34
Alveolar ventialtion
TV-dead space x respiratory rate
35
Pulmonary circulation
Conc O2 + CO2 in arterial blood is contents, O2 in same rate as consumers, CO2 out same rate as produced
36
Gas exhange
Simple diffusion of O2/CO2 down partial pressure gradients pp exerted by each gas in mixture = total pressure x fractional composition of gas in mixture Diffusion gradients in lungs and tissue affected by conc grad, SA and permeability
37
Dalton's law
P total = P1 + P2.... | Air --- becomes moist ---> alveoli --> water vapour reduced N2/O2 levels
38
Establishment of gradients
P(air) = PN2, PO2, PH2O, PCO2 | Air through conducting zone - humidified to saturation
39
Solubility of gases
Any pp cones of dissolved gases differ - some more soluble
40
Henry's law
C = kP (pp in atmosphere)
41
Air flows down conc gards
Air -> alveoli PO2 down PCO2 down Due to continuous gas exchnage alveoli/capillaries, air mixes with alveoli air, alveoli air saturated water vapour
42
Exchange of O2 and CO2
In alveoli = rapid In tissue = diffusion grads. PCO2 depends on metabolic activity and blood flow to tissue. Large grads = more exchange Venous blood active tissue, down PO2 and up PCO2 Venous blood right atrium mixed PCO2 and PO2 average
43
Determinants of alveolar PO2 and PCO2
PO2 and PCO2 in inspired air, minute ventilation, rate respiration tissue consumes O2/produces CO2 - alveolar ventilation exceeds demands of tissue: PO2 up and PCO2 down
44
Matching ventilation to perfusion
Ratio alveolar ventilation to pulmonary blood flow (Va/Q - 0.8 av) Upright = gravity increases pulmonary arterial hydrostatic pressure at base than apex - alveolar ventilation varies in same direction as blood flow Ventilated alveoli close to perfused capillaries ideal for gas changes. Top blood flow not as good - middle = best Airway obstruction - V/Q = 0 no ventilation Vascular obstruction - V/Q = infinity = no perfusion
45
Perfusion
Delivery of blood to tissue
46
Haemoglobin
``` Hb + O2 HbO2 - each carries 4 O2 molecules PO2 100mgHg (normal) = Hb 98% sat ```
47
O2/Hb dissociation curve
ppO2 high (lungs) sat high ppO2 low (tissue) sat low - dissociation Plateau where ppO2 high - lungs Steep - systemic Hb unloads O2 to tissues Sigmoidal curve 1O2 bound increase affinity for Hb for next O2 O2 binding = conformational changes Lower affinity shifts curve right - higher pO2 to achieve saturation Higher affinity shift to left - lower PO2 to achieve sat Temp increase - to right pH acidity up, affinity down, to left
48
Myoglobin
O2 binding protein in skeletal muscle - higher affinity for O2 than Hb Low pO2 50% saturated Liberates O2 when pO2 to 10mmHg
49
Foetal Hb
PaO2 20mmHg low sat - 60% sat
50
Co2 combined with water
Bicarbonate ion -> carbonic acid
51
Hypoventilate
PCO2 and H+ ions up, lower pH, inc HCO3- respiratory acidosis - kidneys conserve HCO3- PO2 down stimulates increase in breaths and depth
52
Hyperventilate
PCO3 and H+ ions down, higher pH, decrease in HCO3- - respiratory alkalosis - renal compensation excretes HCO3 APO2 up - reduced lack of CO2 - decrease breaths and depth
53
'Black box' control of breathing
Respiratory neurons in medulla inspiration and expiration Neurons in pons modulate ventilation Rhythmic pattern breathing Ventilation modulated chemical factors and higher brain centres
54
What controls breathing rhythm
Medulla oblongata Dorsal respiration group - in region in nucleus tracts solitairus (NTS) Vagus nerve and higher brain centres alter DRG/VRG
55
Chemoreceptors
Monitor PO2, PCO2, in carotid and aortic bodies
56
Type I peripheral chemoreceptors
Contact blood - afferent nerves - NT
57
Type II peripheral chemoreceptors
Glial cell like - repair and nutrient supply
58
Central chemoreceptors
Ventral surface medulla - H+ ions stimuli pH change cerebrospinal fluid H+ don't cross, CO2 does
59
Chemoreceptor reflex
Central and peripheral respond PCO2 changes

Physiology (9 decks)

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