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Physiology > The respiratory system > Flashcards

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
Q

Residual volume, RV

A

Minimal volume remaining in lungs after max expiration

26
Q

Functional residual capacity, FRC

A

Volume of air in runs after normal expiration

= ERV + RV

27
Q

Vital capacity, VC

A

Max volume of air in single breath maximum inspired

IRV + TV + ERV

28
Q

Total lung capacity, TLC

A

Mac volume lungs can hold

VC + RV

29
Q

Forced expiratory volume in 1 second, FEV

A

Volume of air during first second of expiration in VC determination

30
Q

Anatomical dead space

A

Conducting airways, no gas exchange occurs ~150ml

31
Q

Physiological dead space

A

Anatomical dead space + alveolar dead space

Alveolar dead space = non-functioning alveoli e.g. absence of blood flow

32
Q

Minute ventilation

A

Volume breathed in per min

33
Q

Pulmonary ventialton

A

Tidal volume x respiratory rate

34
Q

Alveolar ventialtion

A

TV-dead space x respiratory rate

35
Q

Pulmonary circulation

A

Conc O2 + CO2 in arterial blood is contents, O2 in same rate as consumers, CO2 out same rate as produced

36
Q

Gas exhange

A

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
Q

Dalton’s law

A

P total = P1 + P2….

Air — becomes moist —> alveoli –> water vapour reduced N2/O2 levels

38
Q

Establishment of gradients

A

P(air) = PN2, PO2, PH2O, PCO2

Air through conducting zone - humidified to saturation

39
Q

Solubility of gases

A

Any pp cones of dissolved gases differ - some more soluble

40
Q

Henry’s law

A

C = kP (pp in atmosphere)

41
Q

Air flows down conc gards

A

Air -> alveoli PO2 down
PCO2 down
Due to continuous gas exchnage alveoli/capillaries, air mixes with alveoli air, alveoli air saturated water vapour

42
Q

Exchange of O2 and CO2

A

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
Q

Determinants of alveolar PO2 and PCO2

A

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
Q

Matching ventilation to perfusion

A

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
Q

Perfusion

A

Delivery of blood to tissue

46
Q

Haemoglobin

A 
Hb + O2  HbO2 - each carries 4 O2 molecules
PO2 100mgHg (normal) = Hb 98% sat
47
Q

O2/Hb dissociation curve

A

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
Q

Myoglobin

A

O2 binding protein in skeletal muscle - higher affinity for O2 than Hb
Low pO2 50% saturated
Liberates O2 when pO2 to 10mmHg

49
Q

Foetal Hb

A

PaO2 20mmHg low sat - 60% sat

50
Q

Co2 combined with water

A

Bicarbonate ion -> carbonic acid

51
Q

Hypoventilate

A

PCO2 and H+ ions up, lower pH, inc HCO3- respiratory acidosis - kidneys conserve HCO3-
PO2 down stimulates increase in breaths and depth

52
Q

Hyperventilate

A

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
Q

‘Black box’ control of breathing

A

Respiratory neurons in medulla inspiration and expiration
Neurons in pons modulate ventilation
Rhythmic pattern breathing
Ventilation modulated chemical factors and higher brain centres

54
Q

What controls breathing rhythm

A

Medulla oblongata
Dorsal respiration group - in region in nucleus tracts solitairus (NTS)
Vagus nerve and higher brain centres alter DRG/VRG

55
Q

Chemoreceptors

A

Monitor PO2, PCO2, in carotid and aortic bodies

56
Q

Type I peripheral chemoreceptors

A

Contact blood - afferent nerves - NT

57
Q

Type II peripheral chemoreceptors

A

Glial cell like - repair and nutrient supply

58
Q

Central chemoreceptors

A

Ventral surface medulla - H+ ions stimuli pH change cerebrospinal fluid
H+ don’t cross, CO2 does

59
Q

Chemoreceptor reflex

A

Central and peripheral respond PCO2 changes

Physiology (9 decks)

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