week 11- respiratory Flashcards

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1
Q

what do RBC transport

A

Transport O2 to, and CO2 from, peripheral
tissues

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2
Q

what is the concentration of oxygen in arterial blood

A

20ml o2 per 100ml of blood

98.5% O2 bound to haemoglobin (Hb)
* 1.5% (0.3 mL) dissolved in plasma

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3
Q

what is haemoglobin

A

4 globin protein chains, each with a haem group
* Haem (with iron/Fe in the centre) attaches to O2

1 RBC has 280 million Hb molecules
* Each Hb can bind to four O2 molecules
* Binding to haemoglobin is a reversible reaction
* Oxyhemoglobin (HbO2)Deoxyhaemoglobin (HHb)

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4
Q

when is Oxygen saturation 100%

A

When all four haems are attached to O2

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5
Q

what does saturation depend on

A
  • partial pressure of O2
  • affinity of haemoglobin to bind O2
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6
Q

Effect of pH on oxygen affinity and dissociation

A

Tissues have higher CO2 therefore higher acidity
* lower pH
* Lower O2 binding affinity

*higher pH
* Higher O2 binding affinity
* Therefore, O2 dissociates when blood reaches tissues

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7
Q

transport of co2 chemical reaction

A

CO2 + H2O ⇔ H2CO3 ⇔ H+ + HCO3-

moves to right in muscles. moves to left in the lungs

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7
Q

Effect of temperature on haemoglobin affinity and dissociation

A
  • higher Temperature
  • Lower O2 binding affinity
  • lower Temperature
  • Higher O2 binding affinity
  • Effect significant in active tissues generating large amounts of heat
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8
Q

what is co2 carried as in the plasma and what percentage

A
  • 70% carried as bicarbonate ion

this is bc of Carbonic anhydrase (CA) enzyme

7% dissolved in plasma

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9
Q

what is co2 carried as in the haemoglobin and what percentage

A

23% bound to haemoglobin
* Binds to the globular proteins
* Forming carbaminohaemoglobin (HbCO2)

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10
Q

Which gas controls the respiration rate

A
  • Respiration controlled by high PCO2 or low PO2
  • Stimulus to breathe once PCO2 > 40 mm Hg
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11
Q

Hypercapnia- blood pco2, equation, main causes and consequences

A

– Blood PCO2> 45 mmHg
–increase CO2 + H2O-> increase H2CO3-> HCO3- +increase H+
–Main causes
* Hypoventilation - Inadequate O2 delivery and CO2 removal
* Lung disease - Decreased gas exchange
–Consequences
* Respiratory acidosis
* ↓ CNS activity
* Lethargy, coma and death

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12
Q

Hypocapnia- blood pco2, equation, main causes and consequences

A

– Blood PCO2 < 40 mm Hg
* No breathing until level reaches PCO2 ≥ 40 mm Hg
– decrease CO2 + H2O-> decrease H2CO3-> HCO3-decrease H+
– Main cause
* Hyperventilation - Increased CO2 removal
– Consequences
* Respiratory alkalosis
* ↑ CNS activity
* ‘Pins and needles’, dizziness

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13
Q

pH balance in the body

A
  • 7.35 – 7.45
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14
Q

Compensation for acidosis/alkalosis by

A

Chemical buffers in seconds
* Respiratory changes in minutes
* Hydrogen ion excretion and bicarbonate synthesis by kidneys in hours/days

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15
Q

tidal volume- def, volume

A

def: amount of air inhaled during a normal breath
volume: o.5L

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16
Q

expiratory reserve volume- def, volume

A

def- amount of air that can be exhaled after a normal exhalation
volume- 1.2L

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17
Q

inspiratory reserve volume- def, volume

A

def- amount of air that can be inhaled after a normal inhalation
volume- 3.1L

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18
Q

residual volume(RV)- def, volume

A

def- air left in the lungs after a forced exhalation
vol- 1.2L

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19
Q

inspiratory capacity (IC)-def, volume, equation

A

def- volume of air that can be inhaled in addition to a normal exhalation
vol- 3.6L
equation- TV+IRV

20
Q

vital capacity- def, volume, equation

A

def- maximum amt of air that can be moved in or out of the lungs in a single respiratory cycle
vol- 4.8L
equation- EVR+TV+IRV

21
Q

functional residual capacity- def, volume, equation

A

def- volume of air remaining after a normal exhalation
volume- 2.4L
equation- EVR+RV

22
Q

total lung capacity- def, volume, equation

A

def- total volume of air in the lungs after a maximal inspiration
vol- 6L
equation- RV+ERV+TV+IRV

23
Q

forced expiratory volume (FEV1)- def, volume,

A

def- how much air can be forced out of the lungs over a specific time period, usually one second
vol- 4.1-5.5L

24
Q

Respiratory minute volume (RMV)- def, equation

A

defined as the total amount of air moving into the respiratory passages each minute
equation- Tidal volume (TV) × breathing rate (BR = number of inspirations per minute).
From subchapter 3.1 you know that at rest:

TV = 500 mL
BR = 12/min

25
Q

Alveolar ventilation equation

A

(Tidal volume − Anatomic dead space) × Breathing rate

26
Q

Tiffeneau index:

A

FEV1/(F)VC x 100 [%]

27
Q

anatomic dead space

A

air in the conducting zone is not available for gas exchange

28
Q

Alveolar air participating in gas exchange with each breath is:

A

350ml

29
Q

what is the energy cost of breathing at rest and at intense exercise

A

At rest - less than 5% of the total energy expenditure
During intense physical activity: 50-fold increase! * to ensure adequate ventilation

30
Q

Factors affecting airflow

A
  1. diameter of airways
    ans control
  2. airflow during inhalation vs exhalation
  3. turbulent vs laminar flow
31
Q

parasympathetic control of the bronchiole diameter

A
  • Cranial nerve X (vagus)
  • Neurotransmitter
    Acetylcholine
  • Receptors
    Muscarinic cholinergic receptors in smooth muscle cells (SMC)
  • Result
    Bronchial smooth muscle contractionbronchoconstriction
32
Q

parasympathetic control of the bronchiole diameter- non direct

A
  • Stimulates Adrenal medulla to release hormones into the blood
    Noradrenaline + adrenaline
  • Receptors
    β2 adrenergic receptors in SMC in bronchioles
  • Result
    Bronchiolar smooth muscle relaxation-> bronchodilation
33
Q

Bronchoconstriction in asthma

A
  1. Contraction of smooth muscle cells in airway wall
  2. Oedema of the walls of the airways
  3. Accumulation of mucus (usually in the
    lumens of bronchioles)
34
Q

Resistance and flow during normal inspiration ventilation

A
  • Positive pressure in airways increases diameter of the lumen
    -> Decreased resistance
    -> Increased flow
35
Q

Resistance and flow during normal expiration ventilation

A
  • Lower pressure in airways decreases diameter of lumen
    -> Increased resistance
    -> Decreased flow
36
Q

laminar flow

A

low resistance

37
Q

turbulent flow

A

increase resistance

38
Q

The respiratory centres

A

(1) Dorsal respiratory group (DRG)
* medulla
* mainly inspiration
(2) Ventral respiratory group (VRG)
* medulla
* mainly expiration
(3) Pneumotaxic centre
* pons
* mainly controls the rate and depth of breathing

39
Q

Dorsal respiratory group (DRG)

A
  • Neurons in the DRG are connected to motor neurons of the inspiratory muscles
  • C3, 4, 5 keep the diaphragm alive!!!
  • Phrenic nerve (C3–C5)
40
Q

Pneumotaxic centre

A

Inhibits DRG and inspiration may take 0.5 sec only
* Strongly active - shallow, superficial breathing
* Less active - low frequency but deep breathing

41
Q

Ventral respiratory group (VRG)

A

inactive during quiet breathing
* Active during heavy exercise

41
Q

Quiet breathin

A

DRG active – inhalation (2 sec)
DRG inactive – exhalation (3 sec)

42
Q

Forced breathing

A

DRG active – inhalation
VRG active – exhalation

Dorsal group - Does the job
Ventral group - Variable but mainly Venting

43
Q

Respiratory reflexes-Chemoreceptors

A
  1. Peripheral chemoreceptors
    * Located at the aortic and carotid bodies
    * Stimulation of the dorsal respiratory group
    * Monitor the composition of arterial blood
    * Stimulated by lack of oxygen (hypoxia)
    * BloodPO2<60mmHg
    * Causes: inadequate gas exchange, ischemia, anaemia
  2. Central chemoreceptors
    * Located in the medulla oblongata
    * Monitor the composition of CSF
    * Highly sensitive to hypercapnia and acidosis
    * ↑[CO2]inblood=↑[CO2] inCSF
    * CO2 converted to carbonic acid, which dissociates
    to H+andbicarbonate
    * ↑ [H+] = ↑activity of central chemoreceptors
44
Q

Respiratory reflexes- Baroreceptors

A
  1. Baroreceptors (carotid sinus and aortic arch)
    * Respiratory rate increases with low BP
    * Respiratory rate decreases with high BP
    *increase or decrease BP affects breathing rate and tidal volume
45
Q

Respiratory reflexes- Mechanoreceptors

A

Hering-Breuer (inflation) reflex
* Mechanoreceptors detect stretch n the lungs
* Stretched lungs overexpand
* The reflex terminates inspiration
* decrease Tidal volume + increase breathing rate

46
Q

VOLUNTARY CONTROL OF BREATHING

A

Respiration can be voluntarily inhibited
* Overridden when arterial CO2 too high and/or O2 too low

47
Q

Describe the major age-related changes in the respiratory system

A

Arthritic changes in the costovertebral joints and costal cartilages stiffening the thorax and decreasing compliance during inspiration.
Elastic tissue is replaced by scar tissue reducing lung compliance and vital capacity.
Emphysema destroys alveolar surfaces and reduces surface area available for gas exchange with ageing, particularly in smokers.