respiration Flashcards

1
Q

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 is the epiglottis

A

separates upper and lower respiratory tracts

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4
Q

what are the lungs enclosed within

A

membranes called pleura
the intrapleural pressure is less than in the atmosphere preventing alveoli from collapsing

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5
Q

how many airway generations are there?

A

23
main bronchi is Zi conducting zone extending to the terminal bronchioles Z16
gas exchange in the respiratory zone Z17-23

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6
Q

how many alveoli in the lungs

A

300-500 million in each 1/3mm in diameter

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7
Q

where does pulmonary gas exchange take place

A

pulmonary capillary
oxygen an carbon dioxide move between air and blood through diffusion from high to low pressure

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8
Q

what is Ficks low of diffusion

A
  • volume of gas passing through sheet is dependant on:
    1. SA
    2.thickness
    3. diffusion coefficient
    4. pressure gradient
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9
Q

what is the blood-gas barrier

A
  • thin and has a vast SA
  • ideal for gas exchange
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10
Q

what are the mechanics of breathing?

A
  • movement of air into and out of lung by changes in pressure, flow and volume
  • inspiration = volume of thoracic cavity increases at respiratory muscles contract
  • ribs increase transverse diameter of thorax during inspiration (bucket handle motion)
  • ribs increase anteroposterior diameter of thorax during inspiration (pump handle motion)
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11
Q

what muscles are used at rest

A
  • diaphragm contraction is responsible for majority of pulmonary ventilation and expiration is passive
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12
Q

what muscles are used during exercise?

A
  • diaphragm assisted by external intercostals muscles, scalenes sternocleidomastoid increase pulmonary ventilation 01-20 fold above resting levels
  • expiration active by contraction on rectus abdomens, internal intercostals and external oblique
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13
Q

what is ohms law

A
  • current = voltage/resistance applied to breathing
  • airflow dependent on pressure gradient and airway resistance
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14
Q

poiseullies law

A
  • resistance dependant on length and radius of a tube
  • raised to fourth power thus major determinant of airway resisitance
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15
Q

resistance to airflow is determined by what

A

airway diameter - asthma and COPD are conditions negatively impacting the ventilatory response to exercise

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16
Q

the ventilatory response to constant load steady-state exercise occurs in 3 phases:

A
  1. immediate increase in Ve
  2. exponential increase in Ve
  3. plateau
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17
Q

what is exercise hyperpnoea

A
  • PaCO2 regulation due to proportion changes in alveolar ventilation and metabolic rate
18
Q

what is incremental exercise

A
  • ventilation increases linearly with exercise intensity and workload until a point referred to as the ventilatory threshold
  • after Tvent Ve increases resulting in hyperventilation
  • highly training endurance athletes will develop EIAH
19
Q

what is EIAH

A
  • exercise-induced arterial hyperaemia
  • reduction in PaO2 of >10mmHg from rest
  • occurs because ventilatory demand exceeds capacity
  • causes are diffusion limitation, V/Q mismatch and relative hypoventilation
20
Q

changes in breathing patterns during exercise

A

onset: Ve changes largely due to increasing Vt
heavy exercise: Vt plateau increasing Vw due to increased Fb
arterial PO2 and PCO2 and pH well maintained until heavy exercise

21
Q

what is the equation for work

A

work = force (pressure) x volume

22
Q

what is the respiratory control centre

A
  • neural control
  • respiratory central pattern generators located in brainstem
23
Q

what are the 3 main gropes of neurons in control centre

A
  1. ventral respiratory group (inspire and expire)
  2. dorsal respiratory group (inspire)
  3. pontine respiratory group (modulates)
24
Q

describe the model for controlling ventilation

A
  • sensors are the input (chemoreceptors, lungs)
  • inputs into central controller (pons and medulla)
  • outputs to effectors (respiratory muscles)
25
Q

describe peripheral chemoreceptors

A
  • located at aortic arch and carotid body detecting change sin Po2 of blood
  • relay sensory info to medulla via vagus and glossopharyngeal nerves
  • increases Ve
  • activate peripheral chemoreceptors like temp adrenaline and co2
26
Q

describe central chemoreceptors

A

-Pco2 sensors
- located in ventral surface of medulla in RT nucleus
- RTN sensitive to chang ein PaCO2/H+
- increase in Ve

27
Q

what is the order of chemoreceptors feedback

A
  1. detect error signals like disturbances to blood-gas homeostasis
  2. central and peripheral CRs increase afferent input to brainstem in reposted to increase paCO2 or decreasing PaCO2 or pH
  3. premotor neurons in dorsal respiratory group activated
  4. inspiratory muscle contracts increasing Ve
  5. changes in Ve elicit changes in paO2 PaCO2 and pH restoring blood-gas balance
28
Q

ventilatory control during mod intensity exercise and heavy

A
  • no change in mean PaCO2 during mod exercise = primary exercise stimulus must be the feedforward origin
  • in heavy metabolites accumulate stimulating breathing. PaCO2 falls inhibiting breathing
29
Q

effects of endurance training

A
  • Ve is 20-30% over during submaximal exercise in trained versus untrained individuals
  • reduce metabolite accumulation, afferent feedback and ventilatory drive
30
Q

do lungs adapt to exercise training

A
  • no
  • respiratory muscles become stronger and more fatigue resistant
31
Q

what does daltons load state

A
  • total pressure of gas mixture is equal to sum of pressure that teach gas would exert Independently
32
Q

partial pressures of gases

A

O2 = 159mmHg
CO2 = 0.3mmHg
- oxygenated inspired air miss in lung with deoxygenated air from venous blood
- O2 consumed, co2 produces by tissues causes venous po2 to decrease to 40mmHg and venous pco2 increase to 46mmHg

33
Q

explain pulmonary circulation

A
  1. pulmonary artery carries deoxygenated blood from right ventricle to lungs
  2. gas exchange between alveoli and pulmonary capillaries
  3. O2 blood returned to left atrium via pulmonary vein
  4. O2 blood pumped round systemic circulation to systemic cells
34
Q

what are characteristics of the pulmonary circuit

A
  • low pressure and low resistance
    mean artery pressure is 15mmHg but systemic is 100mmHg
  • thin walls with little smooth muscle - no redistribution of blood flow. vascular resistance decreases during exercise due to recruitment of capillaries
35
Q

ventilation-perfusion relationships

A

gas exchange requires a matching of ventilation to blood flow
in upright lung, blood flow increases disproportionately more than ventilation from top to bottom of lung due to gravity
exercise improves the matching due to an increased tidal vol, and increased pulmonary artery pressure

36
Q

what are the 2 forms oxygen is carried in the blood

A
  1. dissolved (2%)
  2. with haemoglobin (98%)
37
Q

describe dissolved o2

A
  • amount os dissolved o2 is 0.003mL blood/mlHg
  • arterial PO2 of 100mmHg = 0.3ml o2/100mL blood
38
Q

describe haemoglobin transport

A
  • chemically bound to the blood
  • concentration of o2 carried in blood is20.3mL O2/100mL blood
39
Q

O2Hb dissociation core effects on exercise

A
  • causes an increase in H+, CO2 and core body temp causing a rightward shift in ODC = Bohr effect
    effect facilitates unloading of O2 to active tissue
40
Q

oxygen transport in muscle

A
  • myoglobin is an o2 binding protein in skeletal muscle
  • has high O2 affinity unloading at very low PO2
  • shuttles O2 from muscle cell membrane to mitochondria for aerobic respiration
  • intramuscular O2 storage
41
Q

co2 transport in blood

A
  • carried dissolved (10%)
  • carried bound to haemoglobin (20%)
  • carried bicarbonate (70%)
  • co2 is 20x more soluble than O2
  • HCO3- leaves cell and Cl moves into cell to maintain neutrality
  • H+ binds to Hb to form HHb binding to CO2 creating carboamino Hb
42
Q
A