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Phase 1 Med > Respiratory > Flashcards

Flashcards in Respiratory Deck (119)
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1
Q

What makes up the respiratory pump?

A

Collection of thorax, muscle, nerves, airways and pleura involved in respiration

2
Q

What muscles are involved in inspiration?

A
  • Diaphragm

- External intercostal

3
Q

When are accessory muscles used in respiration and name some

A

During laboured breathing i.e. asthma attack or exercise.

  • Scalene muscle: In neck, lifts ribs.
  • Sternocleidomastoid muscle: Sternum and clavicle to mastoid process, lifts ribs
  • Trapezius: In shoulders, pulls scapula to expand thorax
4
Q

Describe inspiration

A
  • Diaphragm contracts and moves down
  • External intercostal muscles contract to lift rib cage
  • Causes increase volume so decrease in pressure
  • Pleural cavity decreases in pressure, increasing transpulmonary pressure
  • When alveolar pressure < atmospheric pressure, air moves into lungs
5
Q

Describe expiration

A
  • Passive process due to lungs’ elasticity
  • Diaphragm and external intercostal muscles relax, diaphragm moves up, rib cage moves back down
  • Causes decrease in volume so increase in pressure of thorax
  • Pressure increases in pleural cavity, so decreases in tranpulmonary.
  • When alveolar pressure > atmospheric pressure, air moves out of lungs.
6
Q

Which nerves are involved in respiration?

A
  • Motor:
    Phrenic (C3, 4, 5) for diaphragm
    Thoracolumbar nerve roots for external intercostal
7
Q

Describe the pleura of the lungs

A
  • Parietal pleura on outside
  • Visceral pleura on inside
  • Pleural cavity filled with fluid in between
8
Q

Describe the role of the pleura in respiration

A
  • Lubrication for smooth movement when expanding/relaxing
  • Decrease pressure in inspiration to increase transpulmonary pressure
  • Increase pressure in expiration to decrease transpulmonary pressure
9
Q

What respiratory sensors are in the pons?

A

Pneumotaxic centre, apneustic centre

10
Q

What respiratory sensors are in the medulla?

A

Dorsal respiratory groups and ventral respiratory groups

11
Q

What is the role of the pneumotaxic centre?

A

Inhibits apneustic centre to promote expiration

12
Q

What is the role of the apneustic centre?

A

Stimulates DRG

13
Q

What is the role of the dorsal respiratory groups?

A

Fires in bursts to cause respiratory muscle contraction. When stops = passive expiration

14
Q

What is the role of the ventral respiratory groups?

A

Active in forced breathing. Initially stimulated when DRG activates accessory muscles, then VRG takes over at this point.

15
Q

What do peripheral chemoreceptors respond to?

A
  • Hypoxia (decreased pO2)
  • Hypercapnia (increased pCO2)
  • Some detect pH of blood
16
Q

What are the sensors in the upper airway and where are they found?

A
  • Nose, nasopharynx, larynx: Chemo and mechanoreceptors

- Pharynx: Receptors activated by swallowing (to stop respiration)

17
Q

Where are slowly adapting stretch receptors (SASR) found?

A

Smooth muscle of airways

18
Q

What are slowly adapting stretch receptors (SASR) activated by?

A

Lung distension

19
Q

What is the response of slowly adapting stretch receptors (SASR) when activated?

A

Inhibition of respiration

20
Q

Where are rapidly adapting stretch receptors (RASR) found?

A

Between airway epithelial cells

21
Q

What are rapidly adapting stretch receptors (RASR) activated by?

A
  • Lung distension

- Irritants

22
Q

What is the response of rapidly adapting stretch receptors (RASR) when activated?

A

Bronchoconstriction

23
Q

What are C fibres J receptors activated by?

A

Increase in interstitial fluid

24
Q

What response do C fibres J receptors have when activated?

A
  • Rapid, shallow breathing

- Bronchoconstriction

25
Q

What has a larger effect on respiratory drive?

A
  • pCO2
26
Q

Describe gas exchange at alveoli

A
  • O2 rich air is breathed in and travels down to alveoli
  • O2 from alveoli diffuses into blood of capillaries surrounding alveoli (as this blood has low O2 conc.)
  • CO2 from blood diffuses into alveoli (as they have a low CO2 conc.) to be expired
27
Q

What are the 7 layers the oxygen must pass through?

A
  • Alveolar epithelium
  • Interstitial fluid
  • Capillary endothelium
  • Plasma layer in capillary blood flow
  • RBC membrane
  • RBC cytoplasm
  • Hb binding site
28
Q

What is perfusion?

A

Blood supply to the lungs

29
Q

What is a V/Q mismatch?

A

Perfusion of blood in capillaries doesn’t match ventilation of alveoli

30
Q

What is anatomical dead space?

A

Volume of inhaled air that doesn’t reach alveoli before expiration

31
Q

What is physiological dead space?

A

Volume of inhaled air which does not undergo exchange due to a V/Q mismatch meaning alveoli are too poorly perfused

32
Q

What does the steep drop on the oxygen dissociation curve mean?

A

That a small drop if pO2 means a large amount of O2 can be unloaded from Hb for respiring tissue

33
Q

What causes the oxygen dissociation curve to shift right?

A

Increased temperature or pH

34
Q

What causes the oxygen dissociation curve to shift left?

A

Decreased temperature or pH

35
Q

What does it mean if the oxygen dissociation curve shifts left?

A

Tighter binding so less readily dissociates

36
Q

What does it mean if the oxygen dissociation curve shifts right?

A

Decreased affinity for O2, so dissociates more readily

37
Q

What is Bohr’s Law?

A

An increase in pH/[H+] will cause an oxygen dissociation curve to shift to the right and therefore have a decreased affinity for O2, so dissociates more readily.

38
Q

What is Boyle’s Law?

A

Pressure of a gas in a closed container is inversely proportional to the container’s volume. P1V1 = P2V2

39
Q

What is Dalton’s Law?

A

Each gas in a mixture exerts its own force, as if the other gasses were not present.

P(total) = P1 + P2 + P3 etc

40
Q

What is Henry’s Law?

A

The amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas when at equilibrium with the liquid

41
Q

What is Laplace’s Law?

A

P = 2T/r

Where P = Pressure
T = Surface tension
r = Radius

of an alveolus

42
Q

What is surface tension and where is it present?

A

Molecules at the surface of a liquid adhere closely together to form a ‘film’. Present on surface of alveoli.

43
Q

Where is surfactant produced?

A

By type 2 pneumocytes (alveolar cella)

44
Q

List 3 roles of surfactant?

A
  • Reduce surface tension of alveoli to prevent collapse during expiration.
  • Reduce surface tension to prevent air moving from smaller to larger alveoli (Laplace’s Law)
  • Reduce surface tension to increase compliance of lungs (as can expand more easily)
45
Q

What is the acid/base dissociation equation?

A

CO2 + H2O H2CO3 HCO3- + H+

46
Q

What is the Henderson-Hasselbalch equation when applied to the blood?

A

pH = 6.1 + log ([HCO3-]/0.03*pCO2)

47
Q

What must the ratio in the Henderson-Hasselbalch equation be equal to and why? What happens if it is not?

A

Must be equal to 1.3 to maintain optimum blood pH of 7.4. If changes = acidosis or alkalosis

48
Q

What is hypoxia? List 2 causes.

A

Oxygen deficiency. Caused by V/Q mismatch or hypoventilation.

49
Q

What is hypercapnia? List 3 causes.

A

Elevated CO2 levels. Caused by V/Q mismatch or increased CO2 production, hypoventilation.

50
Q

What is peak expiratory flow (PEF)?

A

The maximum airflow that can be achieved during forced expiration

51
Q

What is forced expiratory volume (FEV1)?

A

The maximum amount of air that can be forcibly expired within a second.

52
Q

What is total lung capacity?

A

Total volume of air the lungs can hold.

53
Q

What is vital capacity?

A

The maximum volume of air the can be expired after maximal inspiration.

54
Q

What is functional residual capacity?

A

The volume of air remaining in lungs after passive expiration

55
Q

What is expiratory reserve volume?

A

The additional volume of air that can be forcibly expired after tidal volume.

56
Q

What is inspiratory reserve volume?

A

The additional volume of air that can be forcibly drawn in to lungs after normal tidal volume.

57
Q

What is tidal volume?

A

The volume of air expired during passive expiration or taken in during normal inspiration.

58
Q

What is residual volume?

A

The amount of air which will always remain in lungs, even after maximal expiration.

59
Q

What is airway obstruction?

A

Impediment to inspiratory/ expiratory flow

60
Q

What is airway restriction?

A

Diminished lung capacity (lungs restricted from full expansion)

61
Q

What changes occur in an ageing lung?

A
  • Decreased elastic recoil, compliance, immune function and gaseous exchange.
  • Decreased response to hypoxia and hypercapnia
62
Q

What additional changes occur at birth other than those mentioned in CV?

A
  • Fluid forced out of lungs by birthing process
  • Adrenaline increases surfactant production and so decrease in surface tension
  • O2 is inhaled causing vasodilation of pulmonary arteries
63
Q

Compare systemic and pulmonary arteries

A

Systemic - Thinner walls and minor muscularisation

Pulmonary - Thicker walls and significant muscularisation

64
Q

What does O2 act as in systemic vessels?

A

Vasoconstrictor

65
Q

What does O2 act as in pulmonary vessels?

A

Vasodilator

66
Q

What does CO2 act as in systemic vessels?

A

Vasodilator

67
Q

What does CO2 act as in pulmonary vessels?

A

Vasoconstrictor

68
Q

Name another common vasodilator

A

Nitric oxide (NO)

69
Q

What is hypersensitivity?

A

An undesirable reaction produced by the immune system.

70
Q

Describe a type 1 hypersensitivity reaction

A
  • Antigens interact with IgE bound to mast cells
  • Histamine is released
  • Leads to: capillary dilation, bronchonstriction, mucus secretion, itching etc
71
Q

If there is a type 1 hypersensitivity reaction all over the body, what is this known as?

A

Anaphalaxis

72
Q

What is the significance of Laplace’s Law?

A

Smaller alveoli = Greater pressure.

So air will move from smaller to larger alveoli, causing the smaller ones to collapse

73
Q

What is intrinsic tone of the airways regulated by?

A

Parasympathetic nervous system

74
Q

Describe the action of sympathetic nerves on airways

A
  • Noradrenaline binds to Beta-2 adrenergic receptors
  • Causes bronchodilation
  • These are G-protein coupled
75
Q

Describe the action of parasympathetic nerves on airways

A
  • Acetylcholine binds to muscarinic M3 receptors
  • Causes bronchoconstriction
  • These are G-protein coupled
76
Q

What are the 2 types of cholingeric receptors and what type of receptor complex do they form?

A
  • Nicotinic: lignad-gated

- Muscarinic: G-protein coupled

77
Q

What are the 2 types of adrenergic receptors and what type of receptor complex do they form?

A
  • Alpha: G-protein coupled

- Beta: G-protein coupled

78
Q

What is a shunt in terms of a V/Q mismatch?

A

When the alveoli are well perfused, but too poorly ventilated for gas exchange.

79
Q

What nerve supplies the parasympathetic outflow in the lung?

A

Vagus

80
Q

What nerve supplies the sympathetic outflow in the lung?

A

Sympathetic trunk

81
Q

Describe hypoxic pulmonary constriction

A

When small arterioles constrict in low O2 levels to divert blood to areas of high O2, to avoid a V/Q mismatch

82
Q

List the 3 ways in which CO2 is carried in blood

A
  • Bound to Hb
  • Dissolved in plasma
  • As HCO3-
83
Q

What does Pa mean?

A

arterial partial pressure

84
Q

What does PA mean?

A

Alveolar partial pressure

85
Q

What does PIO2 mean?

A

Partial pressure of inspired oxygen

86
Q

What is the alveolar gas equation?

A

PAO2 = PiO2 - (PaCO2/R)

R = Respiratory quotient

87
Q

Outline the process of acute inflammation and summarise its action

A
  • Pathogen/tissue injury
  • Vasodilation - exudate plasma (including antibodies)
  • Biochemical cascade activated
  • Migration of neutrophils
  • Immediate onset, short lived, is resolved
88
Q

Outline the process of chronic inflammation and summarise its action

A
  • Persistent acute inflammation/ non-degradable pathogen
  • Mononucleate cells migrate
  • Delayed onset, lasts months/years, results in fibrosis/necrosis etc
89
Q

Describe neutrophil function

A
1 - Receptors
2 - Activation
3 - Adhesion (by integrins)
4 - Migration
5 - Phagocytosis
6 - Kill bacteria (ROS/elastase etc)
90
Q

What does necrosis result in?

A

Inflammation

91
Q

What does apoptosis result in?

A

Phagocytosis

92
Q

List 4 non-immune hot defence mechanisms

A

1 - Epithelial barriers
2 - Mucus
3 - Mucociliary escalator
4 - Coughing

93
Q

What is the mucociliary escalator?

A

Cilia beat in directional waves to move mucus up the airways

94
Q

Outline the process of coughing

A
  • Lots of air inspired
  • Epiglottis and vocal cords shut tightly to trap air in lungs
  • Diaphragm and internal intercostal muscles contract - cause increase in pressure and so tracheal narrowing
  • Epiglottis and vocal cords suddenly open wide.
  • Pressure difference and tracheal narrowing: air expired and high flow rate.
95
Q

What normally happens to airway epithelium after injury and why? What is it called when this goes wrong?

A
  • Repair due to their plasticity.

- When this goes wrong, leads to pulmonary diseases

96
Q

Describe the role of B lymphocytes in adaptive immunity

A
  • Pathogenic cell recognised as non-self
  • Antigen presentation
  • Clonal selection
  • Clonal expansion
  • Copies differentiate into:
    Memory B cells, plasma cells
97
Q

What is the role of plasma cells?

A

Produce specific antibodies

98
Q

Describe the role of T lymphocytes in adaptive immunity

A
  • Virus leaves non-self antigens on surface of cell it has invaded.
  • Clonal selection
  • Clonal expansion
  • Copies differentiate into:
    Cytotoxic cells, helper T cells
99
Q

What do helper T cells do?

A

Aid activation of cytotoxic cells and plasma cells by use of cytokines. Express CD4.

100
Q

Where do B cells mature and migrate to?

A

Mature in bone marrow, move to spleen and lymph nodes.

101
Q

Where do T cells mature?

A

Thymus

102
Q

What happens during antigen presentation?

A

Cell ingests pathogen and displays its antigens using MHC

103
Q

What are the 5 functions of adaptive immune response?

A
1 - Diversity - react to many pathogens
2 - Self-tolerance 
3 - Recognition of pathogens
4 - Effector functions - elimination of pathogens
5 - Immunological memory
104
Q

What is the significance of Boyle’s Law?

A

Relates to breathing mechanism - when volume of lungs/thorax increases during inspiration, pressure decreases.

105
Q

What is the significance of Dalton’s Law?

A

Air will always have the same relative concentrations regardless of whether it is atmospheric or in the lungs etc.

106
Q

What is the significance of Henry’s Law?

A

Implies that the amount of oxygen dissolving in the bloodstream (via capillaries) in proportional to the amount of oxygen in the air in alveoli.

107
Q

Define type 1 respiratory failure

A

Hypoxia with no hypercapnia

108
Q

Define type 2 respiratory failure

A

Both hypoxia and hypercapnia

109
Q

Define forced vital capacity (FVC)

A

The maximum amount of air that can be expired after maximal inspiration, usually in 6 seconds.

110
Q

How do you calculate FEV1%?

A

FEV1/FVC

111
Q

What does an FEV1% of less than 70% indicate?

A

Airways obstruction

112
Q

What are pattern recongnition receptors? What is their purpose?

A
  • Part of innate immune system
  • Recognise either PAMPs (pathogen-associated molecular patterns) or DAMPs (damage-associated molecular patterns)
  • Allow us to recognise pathogens never seen before
113
Q

Describe the Gells and Coombs classification of hypersensitivity

A

Type 1: Allergy - IgE mediated
Type 2: Cytotoxic - Ig bound to cell surface antigen
Type 3: Immune complex formed
Type 4: Delayed-response - mediated by T-cells

114
Q

What are affinity and efficacy?

A

Affinity - Ability of drug to bind to receptor

Efficacy - Ability to illicit a response after binding

115
Q

What is an antagonist?

A

Has affinity but no efficacy. Block agonists.

116
Q

What is an agonist?

A

Has affinity and efficacy, binds to receptor and can illicit a response.

117
Q

Why is it useful that increased pH and temperature shift the oxygen dissociation curve to the right?

A

Because more metabolically active tissues have a higher pH and temperature, and shifting the curve to the right means more oxygen is unloaded, which is needed by the tissue.

118
Q

What does a low FVC always indicates?

A

Airway restriction

119
Q

What is the rhythm generator?

A

Pacemaker cells which set the basal respiratory rate