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Respiratory Flashcards

1
Q

which centres are responsible for regulating breathing?

A

pontine

  • pneumotaxic centre
  • apnuestic centre

medullary

  • dorsal respiratory group
  • ventral respiratory group.
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2
Q

role of the apnuestic centre

A

acts on the DRG to adjust inspiration and increase inspiratory intensity

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3
Q

role of pneumotaxic centre
- what does increased innervation cause

A

causes time dependent inhibition of apneustic centre to allow expiration
- increased innervation => shallow ventilation and increased breathing rate

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4
Q

role of the dorsal respiratory group

A

inspiratory neurones
stimulate the diaphragm and external intercostal muscles

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5
Q

role of the ventral respiratory group

A

forced inspiration and expiration
stimulates the accessory muscles of breathing

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6
Q

where do the 5 main inputs to the respiratory control centres come from

A

chemoreceptors

  1. central chemoreceptors
  2. peripheral chemoreceptors

mechanoreceptors

  1. lung mechanoreceptors
  2. muscle proprioceptors
  3. voluntary control - cerburm
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7
Q

where are the central chemoreceptors found?

A

Located in the brain stem at the pontomedullary junction NOT within the DRG/VRG complex

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8
Q

what do central chemoreceptors respond to? and how?

A

[CO2]

  • increased levels of CO2 in CSF => increased H+ which lower the ph and increase action pds and thus breathe faster ventilation.
  • CO2 + H2O <=> H2CO3 <=> HCO3- + H+
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9
Q

where are peripheral chemoreceptors found

A
  • carotid bodies = in the bifurcation of the carotid arteries in CN9 afferents
  • aortic bodies = in the aortic arch of CN10 afferents
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10
Q

what do peripheral chemoreceptors respond to?

A

peripheral receptors detect hypoxia - low [O2]

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11
Q

what are the 3 types of pulmonary receptors

A
  1. Stretch receptors - AKA slow adapting stretch receptors
  2. J receptors
  3. Irritant receptors - AKA rapid adapting strech receptors
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12
Q

where are stretch receptors found?

A

in the smooth muscle of conducting airways

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13
Q

what is the function of stretch receptors?

A

they inhibit inspiration in response to the level of stretch in the airways, determined by lung volume

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14
Q

where are J-receptors found and what is their full name

A

found in the alveolar walls juxtapositioned to the pulmonary capillaries
- juxtapulmonary receptors.

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15
Q

what do J-receptors respond to and what response do they cause

A
  • irritants, pulmonary congestion
  • bronchoconstriction, rapid shallow breathing
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16
Q

where are irritant receptors found, what do they respond to and how do they act

A
  • found in the larger conducting airways’ epithelial cells
  • rapidly adapting
  • respond to rate of change of volume and irritants
  • cause bronchoconstriction and cough
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17
Q

what do irritant receptors respond to

A

respond to inhalation of any irritants and initiate a cough reflex and rapid exhalation.

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18
Q

what is the role of muscle proprioceptors?

A

they tell the brain where the intercostal muscles are at a moment in time relative to everything else, helping the body understand its pattern of breathing
- this helps calibrate breathing control

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19
Q

what types of muscle proprioceptors are involved in breathing?

A

joint, muscle and spindle fibres

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20
Q

which muscles are involved in inspiration - main and accessory

A

main= diaphragm and external intercostal muscles [ribs 2-12]
accessory =
- scalenes, lift ribs 1 and 2
- sternocleidomastoid, elevates the sternum
- pectoralis major - lifts ribs 3-5

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21
Q

which nerve innervates the diaphragm

A

the prenic nerve - C3-5
C3,4,5 keeps the diaphragm alive

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22
Q

Which muscles are involved in active expiration?

A

internal intercostals - depresses ribs 1-11
rectus abdominis - depresses the lower ribs and compresses the abdominal organs and diaphragm.

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23
Q

a. PaCO2 =
b. PACO2 =
c. PaO2 =
d. PAO2 =
e. PiO2 =
f. VA =
g. V’CO2 =

A

a. arterial CO2 pressure
b. alveolar CO2 pressure
c. arterial O2 pressure
d. Alveolar O2 pressure
e. pressure of inspired oxygen
f. alveolar ventilation
g. CO2 production

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24
Q

how many layers of pleura are there, what are they called and what is the role of the pleura

A

2
parietal - outer
visceral - inner
- pleura attaches the lung to the inner chest wall
- there is a potential space with small amount of fluid that allows the lungs to slide within the chest wall for expansion.

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25
Q

what makes up the conducting airways and what is its role

A

Nose, pharynx, larynx, trachea, bronchi, and bronchioles
- they conduct, clean, warm, and moisten the air.

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26
Q

where does alveolar ventilation occur

A

Terminal bronchioles => respiratory bronchioles => alveolar ducts => alveoli

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27
Q

what is anatomic dead space and roughly what volume is it

A

• Dead space = volume of air not contributing to ventilation
o Anatomic dead space ~150ml

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28
Q

what is perfusion of capillaries dependent on?

A

a) Pulmonary artery pressure
b) Pulmonary venous pressure
c) Alveolar pressure

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29
Q

what is pulmonary vasoconstriction and what causes it and what is its function

A

it is vasoconstriction of areas of the lung with low oxygen
caused by hypoxia
it is meant to match ventilation and perfusion by diverting blood away from poorly ventilated areas to maximise perfusion. [opposite to systemic circulation]

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30
Q

what is alveolar recruitment

A

recruiting more alveoli in times of high oxygen demand e.g. exercise

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31
Q

what are the main organs for acid-base balance control

A

lungs and kidneys

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32
Q

which enzyme plays a role in acid-base balance in the lungs and what does it convert

A

carbonic anhydrase
CO2 +H2O <=> H2CO3 <=>H+ + HCO3-
- carbonic anhydrase converts carbonic acid into water and CO2 in the lungs allowing the CO2 to be exhaled ->

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33
Q

which nerves are involved in breathing

A

phrenic nerve
intercostal nerves

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34
Q

what are the steps of inspiration?

A
  • the diaphragm and the external intercostal muscles contract
  • this increases the volume of the thoracic cavity and the lungs due to attachment to the chest via the pleura.
  • which lowers the pressure below that of the surrounding atmosphere
  • this draws air into the lungs down a pressure gradient
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35
Q

what are the steps of expiration

A
  • the muscles involved in inspiration relax (diaphragm and internal intercostal muscles)
  • this reduces the volume of the thoracic cavity and the lungs -> increased pressure, higher than the surrounding atmosphere
  • this forces air out of the lungs and into the atmosphere down the pressure gradient.
    this is a passive process.
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36
Q

which muscles are involved in active inspiration?

A

scalenes
pectoralis major
sternocleidomastoid
serratus anterior
Latissimus dorsi

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37
Q

which muscles are involved in forced expiration

A

internal intercostal muscles
abdominis rectus

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38
Q

what factor determines the extent of lung expansion and what influences this factor?

A
  • compliance = the lungs ability to stretch
    influenced by:
  • amount of elastic tissue present
  • surface tension in the alveoli - reduced by surfactant.
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39
Q

which organ controls acid-base levels via CO2 and which is by Bicarbonate. which of the 2 is faster?

A

CO2 = lungs
HCO3- = renal
lungs is faster

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40
Q

what is the Henderson Hasselbach eqn and what does it mean

A

pH = 6.1 + log( [HCO3-] / [0.03 * PCO2] )
• The HH eqn basically says there is a fixed component to the pH which cant be changed and the ratio between bicarb and the associated acid can be controlled.

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41
Q

what are the four main acid base disorders and how do they occur

A
  • Respiratory acidosis; increased PaCO2, decreased pH, mild increased HCO3-
  • Respiratory alkalosis; decreased PaCO2, increased pH, mild decreased HCO3-
  • Metabolic acidosis; reduced bicarbonate and decreased pH
  • Metabolic alkalosis; increased bicarbonate and increased pH
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42
Q

what is respiratory acidosis and how does it come about

A

a condition where the body cannot remove the CO2 produced by the body -> hypercapnia

  • increased CO2 causes increased carbonic acid which can be converted into H+ and bicarbonate –> reduced pH.
  • the renal system compensates for this by retaining and producing bicarb to maintain the log of the ratio at 1.3 and maintain the ph at 7.4.
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43
Q

what causes respiratory acidosis

A

respiratory depression / lack of respiratory drive
restriction of airways - COPD

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44
Q

what is respiratory alkalosis and how does it come about

A

an increased blood pH due to reduced CO2 levels and carbonic acid levels meaning less H+ ions are around to acidify the blood.
carbonic acid is converted to CO2

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45
Q

what causes respiratory alkalosis

A

hyperventilation
fever

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46
Q

what is Dalton’s Law

A

the sum of the partial pressures of gasses = total pressure (PT)
PT = P1 +P2 + P3

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47
Q

What is Boyles Law?

A

P1V1 = P2V2
- applied during inspiration - increased volume => decreased pressure

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48
Q

What is Laplace’s law?

A

P = 2T/R
the pressure needed to keep an alveoli open is directly proportional to the surface tension and inversely proportional to the radius.
- surface tension can be reduced via surfactant to reduce the pressure needed to keep alveoli open.
- thus numerous alveoli can open and expand during gas exchange providing the large surface area needed.

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49
Q

what is Henry’s Law

A

at higher pressures, insoluble gases are more likely to dissolve
e.g. nitrogen in joints while diving.

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50
Q

Poiseuille’s Law

A

Laminar flow or resistance in a tube is dependent on the radius of the vessel and the viscosity of the fluid

volume flow rate (F) = ( pi * pressure difference * radius4 [to the power of four] /
8 * viscosity * length.
F = pi *P * R4 / 8*N*L

resistance to flow (R) = 8*N*L / pi*R[4]

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51
Q

what is the alveolar gas eqn?

A

PAO2 = PiO2 - PaCO2 / R
R=respiratory quotient = 0.8 at sea level

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52
Q

how does CO2 travel in the body

A

dissolved in plasma
bound to Hb
as carbonic acid

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53
Q

what does a LEFT shift on an O2 dissociation curve indicate?

A

A shift to the left indicates increased hemoglobin affinity for oxygen and an increased reluctance to release oxygen

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54
Q

what does a RIGHT shift on an O2 dissociation curve indicate?

A

A shift of the curve to the right indicates decreased affinity of the haemoglobin for oxygen and hence an increased tendency to give up oxygen to the tissues.

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55
Q

What causes a left shift in the O2 dissociation curve?

A
  • decreased temperature
  • decreased H+ (increased pH)
  • decreased 2,3DPG - DPG stabilises the deoxygenated form of Hb and facilitates O2 release at tissues
  • carbon monoxide
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56
Q

what causes a right shift on an O2 dissociation curve

A

increased temperature
increased DPG
increased H+ ions (lower pH)

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57
Q

what are the 7 layers of gas exchange?

A
  1. Fluid lining alveolus
  2. Layer of epithelial cells – type I pneumocytes
  3. Basement membrane of type I cells
  4. Interstitial space
  5. Basement membrane
  6. Endothelia
  7. Erythrocyte
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58
Q

there are 8

What are the different lung volumes?

A
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59
Q

Define tidal volume

A

volume inhaled/exhaled in a normal breath, ~500ml

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60
Q

define inspiratory reserve volume

A
  • maximum air that can be inhaled minus the tidal volume ~3L.
    • The amount of air that can be forced in after the tidal volume
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61
Q

Define expiratory reserve volume

A
  • maximum air that can be forcibly exhaled, minus the tidal volume
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62
Q

Define residual volume

A

the volume of air remaining in the lungs after maximal exhalation, to prevent lung collapse ~ 1.2L

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63
Q

Define Vital capacity

A
  • The amount of air exhaled following maximal inspiration.
  • VC = TV+IRV+ERV.
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64
Q

Define inspiratory capacity

A

maximum inhalation following normal tidal exhalation.

  • IC = IRV + TV
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65
Q

Define functional residual capacity

A

The amount of air left in the lungs after a normal exhalation

  • ERV + RV
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66
Q

Define Total lung capacity

A

Maximum volume of air the lungs can hold after max inspiration

  • TLC = RV + VC
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67
Q

what are the four measures of lung function?

A
  1. Peak expiratory flow
  2. forced expiratory volume
  3. forced vital capacity
  4. DLCO - diffusion capacity of lung for carbon monoxide
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68
Q

Define FEV1 and FVC and their ratio

A
  • FEV1 – forced exp. Volume in 1 second. 80% of vital capacity in healthy person
  • FVC – forced vital capacity – max air expired under max force after max inspiration
  • FEV1 / FVC = 0.8 in healthy people.
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69
Q

Define PEF

A

Peak expiratory flow = the highest velocity of air reached during forced vital capacity

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70
Q

define DLCO

A

diffusion capacity of lungs for carbon monoxide.

  • measures the lungs efficiency of gas exchange
  • a known volume of carbon monoxide is inhaled → 10 second breath hold → exhaled CO is then measured
  • the value is lower for pts with COPD.
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71
Q

what chart is FEV and FVC obtained from?

A

time - flow chart

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72
Q

what type of chart is PEF obtained from

A

flow volume chart

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73
Q

what is airway obstruction and how does it affect FEV1/FVC ratio and the flow volume chart?.

A
  • airway obstruction reduces airflow especially on exhalation.
  • it significantly lowers the FEV1 and slightly lowers the FVC → a ratio less than 0.7
  • the bottom of the flow loop becomes scalloped
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74
Q

what is airway restriction, how does it affect the FEV1/FVC ratio and the flow chart

A
  • restriction is the reduced compliance - expansive capability
  • FVC is reduced due to poor lung expansion thus FEV1 is also reduced.
    • overall there is therefore, no overall change in the ratio = >0.7
  • flow volume loop becomes narrow and teardrop like
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75
Q

what are the main types of host defence

A
  1. intrinsic - always present and can be physical or chemical
  2. innate - induced by an infection e.g. interferon, cytokines, macrophages etc.
  3. adaptive - is tailored to a specific pathogen – T and B cells.
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76
Q

what are the main functions of respiratory epithelium

A
  1. moisten and protect the airways
  2. acts as a barrier to potential pathogens
    1. secrete molecules that act as a chemical barrier to bacteria
    2. endogenous commensal bacteria protect against pathogens
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77
Q

how does the respiratory epithelium vary throughout the airway

A
  • nasal cavity and superior pharynx: respiratory mucosa with goblet cells and cilia forming mucociliary escalator
  • inferior pharynx portion: stratified squamous epithelium for protection
  • larynx / lower respiratory conducting tract: respiratory mucosa with goblet cells and cilia forming mucociliary escalator
  • Fine bronchioles: squamous epithelia
  • alveoli: simple squamous epithelium
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78
Q

name 7 non-immune mechanism of defence in the lungs

A
  1. respiratory epithelia - mucociliary clearance
  2. production of antimicrobial molecules, antiproteinases and surfactants: all help with opsonisation
  3. commensal bacteria population
  4. coughing: in/voluntary clearance of irritants
  5. sneezing: involuntary reflex in response to nasal mucosa irritation or excess fluid in the airway
  6. multipotent basal cell population [functional plasticity]: can differentiate into resp. epithelia in case damage occurs
  7. surfactant production: oxygenises bacteria → phagocytosis.
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79
Q

what is the difference between innate and adaptive immunity

A

innate you are born with and adaptive you acquire

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80
Q

what are the 2 main effectors in innate immunity

A
  • specialist macrophages [kupffer cells, dendritic cells, alveolar macrophages]
  • neutrophils
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81
Q

what are the precursor of alveolar macrophages

A

monocytes

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82
Q

how prevalent are alveolar macrophges

A

make up ~ 93% of pulmonary macrophages

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83
Q

what are neutrophils

A

a type of WBC

84
Q

where are neutrophils made

A

in the bone marrow, making the myeloid cells.

85
Q

what is a key component of neutrophils that helps with their function

A
  • They contain granules:
    • PRIMARY – myeloperoxidase, elastase, cathepsins, defensins
    • SECONDARY – receptors, lysozyme, collagenase
86
Q

neutrophils are not involved in inflammation - T/F

A

False

  • neutrophils participate in the inflammatory response and protect against infection
  • They are present in blood at all times but are only activated when needed → generation of ROS
  • as the insult is removed and healing begins, the inflamm cells must be removed via
    • exudate
    • migration
    • apoptosis
87
Q

what are the 7 functions of neutrophils

A
  1. identification of pathogen
  2. activation
  3. adhesion
  4. chemotaxis / migration
  5. phagocytosis
  6. bacterial killing -
    1. achieved via enzymes and ROS generation by NADPH oxidase complex
  7. apoptosis
88
Q

which cells mediate adaptive immunity and by what mechanism?

A
  • B cells by humoral responses
  • T cells by cell-mediated responses
89
Q

what is an antigen

A
  • a molecule able to induce a specific immune response from the host.
    • Can be proteins, polysaccharides, lipids, DNA etc.
90
Q

what is an epitope

A

One antigen can have different epitopes – recognisable regions of the antigen

91
Q

what are the 4 main types of T-cells

A
  1. Cytotoxic T-cells
  2. T-helper cells
  3. T-regulatory cells
  4. Memory T- cells
92
Q

where are B and T cells made and where do they mature?

A
  • B cells:
  • made in the bone marrow
  • maturation begins in the bone marrow and ends in the spleen, lymph nodes
  • T cells
  • made in the bone marrow
  • Mature in the thymus
93
Q

what are 3 key functions of adaptive immunity?

A
  1. specificity and diversity
  2. self- tolerance - recognition of self-antigens and elimination of autoreactive clones
  3. memory via signature BCRs and TCRs.
94
Q

how do T and B cells recognise antigens?

A
  • B cells
  • B cell receptors recognise antigens in the native form AND when presented by antigen presenting cells.
  • T cells recognise antigens presented on MHCs on APCs
    • APCs include: dendritic cells, macrophages, B cells
95
Q

what is an antibody

A

a protein with a constant and a variable region

96
Q

describe cell-mediated immunity

A

t-cells can have CD4 or CD 8 expression

  • CD8
  • a cell that is infected presents the pathogen’s antigen on its surface via an MHC1 molecule
  • T-cells that fit the antigen, with CD8 expression, encounter and bind to MHC1 presenting cells
    • all nucleated cells have MHC1
  • this → activation of the T-cell → CD8 cytotoxic T-cell response.
  • CD4
  • an antigen presenting cell encounters a pathogen and presents the antigen on its surface via MHC2
  • the APC travels to the lymph node and presents to a matching T-helper cell with CD4 expression
  • this binding → activation and multiplication of the T-cells
  • T-helper cells and CD4 cytotoxic T-cells are produced
    • the helper cells
      • help B cells produce antibodies
      • form memory T-cells
      • form Regulatory T-cells to stop immun overreaction and help identify self-antigens
97
Q

Describe Humoral immunity

A
  1. the pathogen’s antigen binds to a matching BCR either in its native state or via and APC.
  2. the antigen is then taken up into the B cell by endocytosis and the antigen is presented on its surface via MHC2
  3. a follicular T-helper cell with a matching TCR binds to the antigen presented on MHC2 on the B-cell → activation of the follicular T-cell → production of helper factors
  4. helper factors activate the B-cell → plasma cell formation and memory B-cell formation.
98
Q

how are such variable BCRs and TCRs created

A
  • VDJ gene recombination
    • Variable, Diversity, Joining segments
  • this recombination process is very random → ⇡ diversity.
99
Q

what is somatic hypermutation and where does is occur?

A
  • after a matching BCR binds to an antigen it proliferates.
  • during proliferation loads of mutations occur in the binding regions of the BCR to increase affinity for the antigen → more efficient antibodies.
  • only occurs in B cells
100
Q

what is immune tolerance and how is it mediated?

A
  • immune tolerance is the bodies ability to not respond to the adaptive immunity system to avoid an overreaction.
  • T-reg cells are responsible for this by killing immune cells with receptors capable of binding to self-cells.
101
Q

how many hypersensitivity classes are there?

A

4

  1. Type 1: Allergy, anaphylaxis and atopy – IgE dependent acute response
  2. IgG binding to self antigens (autoimmune)
  3. immune complex diseases
  4. delayed type hypersensitivity reaction
102
Q

describe a type 1 hypersensitivity response

A
  • Type 1: Allergy, anaphylaxis and atopy – IgE dependent acute response
  • involved in conditions such as asthma, eczema and hay fever
  • IgE causes release of histamine from mast cells by activating FcεR1 receptor. → vasodilation and opening up of gap junctions
  • treated with antihistamines, steroids and avoiding triggers
    • effects seen immediately - within an hour
103
Q

describe a type 2 hypersensitivity response

A

IgG binding to self antigens (autoimmune)

  • cytotoxic
  • the immune system attack the body’s own cells
  • e.g.
    • effect seen in hours - days
104
Q

Describe a type 3 hypersensitivity response

A

Immune complex disease

  • A large scale immune response
  • complexes of IgG precipitate and can’t be cleared by macrophages
  • e.g. Farmers lung
    • effects seen within 7-10 days
105
Q

describe a type 4 hypersensitivity response

A

delayed hypersensitivity reaction

  • Type IV hypersensitivity is a T-cell-mediated hypersensitivity, meaning the inflammation and potential tissue damage is caused by either T helper cells (CD4+) or cytotoxic T cells (CD8+).
  • antibodies are not involved
  • e.g. tuberculosis
    • effects seen in day - weeks - months
106
Q

characteristics of IgE

A
  • involved in type 1 hypersensitivity reactions
  • seen in asthma, atopic dermatitis and hayfever
107
Q

characteristics of IgG

A
  • most abundant antibody/ immunoglobulin
  • acts as an opsonin - binds to the pathogen and signals phagocytes towards it for phagocytosis
108
Q

characteristics of IgM

A
  • IgM is the first antibody secreted by the adaptive immune system
  • it activates complement
  • doesnt require t-cell help
109
Q

characteristics of IgM

A
  • IgM is the first antibody secreted by the adaptive immune system
  • it activates complement
  • doesnt require t-cell help
110
Q

Characteristics of IgD

A
  • helps mature B cells leave the bone marrow
111
Q

characteristics of IgA

A
  • found on the mucosa surface
  • prevents pathogens from entering the body
112
Q

what does the pleura originate from

A

the mesoderm

113
Q

how many layers does the pleura have?

A

2

  • visceral on lung surface
  • parietal on thoracic wall
114
Q

what innervates the pleura?

A
  • Visceral pleura receives autonomic innervation
  • parietal pleura receives phrenic nerve innervation
    • this can sense pain and must be anaesthetised in surgery.
115
Q

which division of the nervous system control bronchodilation

A

sympathetic autonomic system

116
Q

which division of the nervous system control bronchoconstriction

A

parasympatheitc autonomic system.

117
Q

how do sympathetic and parasympathetic ganglia differ?

A
  • sympathetic ganglia sit near the spinal cord and have longer post-ganglionic nerves.
    • The sympathetic system uses ACh and NAd
    • no connection to cranial nerves
    • act on adrenergic and nicotinic recptors
      • parasympathetic ganglia sit near the effector organ and have shorter post-ganglionic nerves
    • only uses ACh
    • mostly come from the cranial nerves [10, 9,7,3]
    • act of muscarinic and nicotinic receptors
118
Q

what is respiratory failure

A
  • Fundamentally, it is a failure of gas exchange and an inability to maintain normal blood gases.
119
Q

causes of acute resp. failure

A

opiate overdose

trauma

pulmonary embolism

120
Q

causes of chronic respiratory failure

A

COPD

fibrosing lung disease

121
Q

what are the characteristics of type 1 resp. failure

A
  • low blood [O2] = hypoxemia
  • low or normal [CO2] = hypocapnia/normal
122
Q

what are the characteristics of type 2 resp. failure?

A
  • low blood [O2] = hypoxemia
  • high [CO2] = hypercapnia
123
Q

think broadly

causes of Type 1 resp. failure

A
  1. airway disorders
  2. congential
  3. infection
  4. vasculature problems
  5. neoplasm
124
Q

Causes of type 2 resp. failure

A
  1. airway disorders - COPD, asthma
  2. drugs
  3. neurological - loss of resp. drive
  4. metabolic
125
Q

T1RF treatment

A
  • Oxygen delivery – increasing the FiO2
  • Treat the primary cause of hypoxia e.g. abx for pneumonia
  • Assess airway patency
126
Q

T2RF treatment

A
  • Oxygen delivery – increasing the FiO2
    • must be careful delivering O2 as these pts rely on oxygen for resp. drive.
    • they switch from CO2 dependent resp. drive to hypoxic drive due to tolerance to chronic hypercapnia.
    • so too much oxygen will tell their brain they don’t need to breath.
  • Treat the primary cause of hypoxia e.g. abx for pneumonia
  • Assess airway patency
  • Assisted ventilation: non/invasive, used when:
    • Inadequate PaO2 despite increasing FiO2
    • Increasing PaCO2
    • Patient tiring
127
Q

what are the types of hypoxia

A
  • Hypoxic hypoxia – low arterial O2 tension in blood
  • Anaemic hypoxia – not enough Hb to carry O2
  • Stagnant hypoxia – blood flow to the tissue us so slow
  • Histotoxic hypoxia – toxic agent prevents cell from using O2 e.g. CO
128
Q

clinical features of hypercapnia

A
  • irritability
  • Headache
  • Warm skin
  • Bounding pulse
  • Confusion
  • Somnolence
  • Coma
129
Q

what is the mediastinum

A

The mediastinum is the central compartment of the thoracic cavity, located between the two pleural sacs.

It contains most of the thoracic organs, and acts as a passageway for structures traversing the thorax on their way into the abdomen.

130
Q

pec minor:

  • origin
  • insertion
  • innervation
  • action
A
  • originates at ribs 3,4,5
  • inserts at coracoid process of the scapula
  • innervated by the medial pectoral nerve
  • stabilising the scapula by drawing it forward and downwards to rest against the thoracic wall.
131
Q

Pec major

  • origin
  • insertion
  • innervation
  • action
A
  • originates at the clavicle and sternum - 2 heads
  • inserts onto the humerus
  • innervated by the lateral and medial pectoral nerves
  • Adducts and medially rotates the upper limb and draws the scapula forward and down.
132
Q

what is origin and insertion of muscles

A

The origin is the fixed point that doesn’t move during contraction, while the insertion does move

133
Q

serratus anterior

  • origin
  • insertion
  • action
A
  • originates from the first 8 ribs
  • inserts onto the costal surface of the scapula
  • rotating the scapula allowing the arm to rise more than 90degrees. Also holds the scapula to the ribcage.
134
Q

what are the articulations of the clavicle?

A
  • sternoclavicular joint
  • acromioclavicular joint
135
Q

how many ribs are there

  • how many are “true” ribs
  • how many are false ribs
  • how many have no attachment to the sternum
A

12 pairs of ribs in total

  • Ribs 1-7 attach independently to the sternum
  • Ribs 8 – 10 attach to the costal cartilages superior to them.
  • Ribs 11 and 12 do not have an anterior attachment and end in the abdominal musculature. Because of this, they are sometimes called ‘floating ribs’.
136
Q

how many intercostal muscles are there and how do they attach?

A

11 pairs

  • originate from inferior aspect rib and insert on superior aspect of rib below
  • the external intercostal muscle fibres run parallel to the external oblique muscle
  • the internal intercostal muscle fibres run parallel to the internal oblique muscle
137
Q

actions of internal and external intercostal muscles and their innervation

A
  • internal ones depress the lungs to reduce thoracic cavity volume and force expiration
  • external ones pull the ribcage upwards and outwards to increase the volume of the thoracic cavity and cause inspiration.
  • both innervated by spinal nerves T1-T11.
138
Q

how many lobes does each lung have and what are they called and what are their fissures called

A
  • right has 3 lobes and left has 2
  • right:
    • superior, middle and inferior lobe
    • oblique fissure and horizontal fissure
  • left
    • superior and inferior lobes
    • oblique fissure
139
Q

What are the surface markings of the following

  • Apex of the lung
  • Lower border of the lung
  • Lower border of the pleural cavity
  • Oblique and horizontal fissues
A
  • Apex of the lung
    • above the clavicle into the base of the neck
  • Lower border of the lung
    • 6th rib anteriorly, 8th rib laterally and 10th rib posteriorly
  • Lower border of the pleural cavity
    • 8th rib anteriorly, 10th rib laterally and 12th rib posteriorly
  • oblique
    • 4th rib posteriorly and 6th rib anteriorly
  • horizontal
    • 4th rib anteriorly
140
Q

describe the structure of the lower airways

A

trachea → left and right main bronchi → lobar bronchi → segmental bronchi → respiratory bronchioles → terminal bronchioles → acini - containing alveolar ducts and alveoli.

141
Q

what is the carina

A

A ridge at the base of the trachea that separates the openings of the right and left main bronchi

142
Q

what is the hilum and what does it contain

A

hilum = the passageway for the contents of the root of the lung

  • root of the lung consists of
    • a bronchus,
    • pulmonary artery,
    • two pulmonary veins,
    • bronchial vessels,
    • pulmonary plexus of nerves and lymphatic vessels.
143
Q

if a person inhales an object which lung is it more likely to enter and why

A

the right lung as the right bronchus is angled more vertically than the left, making it easier for an object to pass through.

144
Q

describe innervation of the lungs

A
  1. Parasympathetic innervation derived from vagus nerve.
  2. Sympathetic innervation derived from sympathetic trunks.
  3. Visceral afferent - conducts pain impulses to sensory ganglion.
145
Q

what is sensory and motor nerve supply to the diaphragm

A

the phrenic nerve

146
Q

where is the anterior triangle and what are its borders

A

on the neck, its borders are:

  • the mandible
  • sternocleidomastoid
  • midline of the neck
147
Q

what is the carotid sheath

A

a fibrous connective tissue surrounding the vascular components of the neck:

  • carotid artery
  • vagus nerves
  • internal jugular vein
148
Q

what are the strap muscles and how are they innervated and what is their function?

A
  • 4 strap muscles - infrahyoid muscles TOSS
    • thyrohyoid
    • omohyoid
    • sternohyoid
    • sternothyroid
  • all but thyrohyoid innervated by ansa cervicalis
  • They are responsible for depressing the hyoid during swallowing.
149
Q

how is the thyroid gland innervated?

A

The thyroid gland is innervated by branches derived from the sympathetic trunk.

These nerves do not control the secretory function of the gland – the release of thyroid hormones is regulated by the pituitary gland.

150
Q

label the thyroidand describe anatomical location

A

wrapped around the cricoid cartilage and the superior rings of the trachea.

151
Q

describe the thyroid gland’s arterial supply and where they arise from

A
  • Superior thyroid artery – arises as the first branch of the external carotid artery
  • Inferior thyroid artery – arises from the thyrocervical trunk (a branch of the subclavian artery).
152
Q

describe the thyroid gland’s venous supply and where they drain into

A

Venous drainage is carried by the superior, middle, and inferior thyroid veins, which form a venous plexus around the thyroid gland.

The superior and middle veins drain into the internal jugular vein and

The inferior empties into the brachiocephalic vein.

153
Q

Why is the blood supply to the thyroid so rich?

A

The thyroid gland secretes hormones directly into the circulation thus it is highly vascularised.

154
Q

what is the only complete cartilage ring around the airway?

A

the cricoid cartilage

155
Q

which structures may be compressed by an enlarged thyroid

A

trachea and oesophagus

156
Q

where are the parathyroid glands located and how many are there and what is their function

A
  1. parathyroid glands are usually located on the posterior aspect of the thyroid gland.
  2. 4 in total: 2 superior and 2 inferior
  3. They are responsible for the production of parathyroid hormone (PTH), which acts to increase the level of serum calcium.
157
Q

name the parts of the pharynx

A
  1. nasopharynx
  2. oropharynx
  3. laryngopharynx
    1.
158
Q

name the parts of the pharynx

A
  1. nasopharynx
  2. oropharynx
  3. laryngopharynx
159
Q

what are the openings of the pharynx

A

superiorly opens up to the oral and nasal cavities

inferiorly opens up to the larynx and the oesophagus

160
Q

name the 3 pharyngeal constrictor muscles and describe their anatomy and their function

A
  1. superior, middle and inferior pharyngeal constrictors
  2. They are stacked like glasses, which form an incomplete muscular circle as they attach anteriorly to structures in the neck.
  • The circular muscles contract sequentially from superior to inferior to constrict the lumen and propel the bolus of food inferiorly into the oesophagus.
161
Q

what are the origin and insertion of the middle pharyngeal constrictor?

A
  • Originates from the stylohyoid ligament and the horns of the hyoid bone.
  • Inserts posteriorly into the pharyngeal raphe.
162
Q

what are the origin and insertion of the superior pharyngeal constrictor?

A
  • Originates from the pterygomandibular ligament, alveolar process of mandible and medial pterygoid plate and pterygoid hamulus of the sphenoid bone.
    • Inserts posteriorly into to the pharyngeal tubercle of the occiput and the median pharyngeal raphe.
163
Q

what are the origin and insertion of the inferior pharyngeal constrictor?

A

cricoid and thyroid cartilages

164
Q

where are each of the pharyngeal constrictor muscles located

A
  • superior is in the oropharynx
  • middle and inferior are in the laryngopharynx.
165
Q

which muscles are involved in swallowing?

A
  • the 3 pharyngeal constrictor muscles - superior, middle and inferior contract in succession to push the food bolus down.
  • the strap muscles - depress the hyoid bone
  • muscles of the larynx: aryepiglottic and thyroepiglottic muscles pull the epiglottis to prevent food passing to the trachea and lungs
166
Q

how are the muscles of the pharynx innervated

A

via the vagus and glossopharyngeal nerves - CN 9 and 10

167
Q

where and when does lung development begin?

A
  • lung buds develop from the resp. diverticulum, which is an outbranch of the foregut.
  • this occurs at week 4-5.
168
Q

what is oesophageal atresia

A

failure of the trachea and oesophagus to separate

169
Q

what are the 4 main stages of lung maturation and their weeks

A
  1. embryonic phase - 0-5 weeks: lung bud formation as the resp. diverticulum
  2. pseudoglandular phase - 5-17 weeks: development of the conducting airways
  3. cannalicular phase - 16-25 weeks: capillaries, vasculature and alveoli form
    1. termnial sac - 16-26 weeks: type 1 and 2 cells and alveolar sacs develop
  4. alveolarisation - 25 weeks → birth and up till age 5
170
Q

when does surfactant start to be produced

A

week 34

171
Q

what is the purpose of surfactant?

A

allows equal aeration of the alveoli by reducing surface tension, allowing the alveoli to remain open.

172
Q

which cell allows the lungs to be filled with fluid and how

A

Type 2 pneumocytes, containing NKCC and apical Cl- channels

173
Q

how is pulmonary circulation bypassed in a foetus

A
  1. foramen ovale - shunts blood from right to left atria
  2. ductus arteriosus - shunts blood from the beginning of the pulmonary artery to the aorta
174
Q

what happens if foramen ovale doesnt shut properly after birth

A

it causes persistent hypertension and hypoxia due to mixing of oxygenated and deoxygenated blood

175
Q

at birth what happens to the pressures of the aorta and pulmonary artery

A
  • pressure in the aorta rises
  • pressure in the pulmonary artery drops
176
Q

key features of foetal circulation

A

1,2,3

  • 1 umbilical vein - carries blood away the placenta, to foetus
  • 2 umbilical arteries - carries blood to the placenta
  • 3 shunts
    1. ductus venosus
    2. foramen ovale
    3. ductus arteriosus
      1. these shunts ensure that oxygenated blood from the placenta passes round the foetal body and that the lungs are bypassed
      2. shunts are able to work because the pulmonary pressure is high due to being fluid filled and the alveoli are shut
177
Q

what are the steps leading to the first breath?

A
  1. Fluid squeezed out of lungs by the birth process
  2. Adrenaline stress → increases surfactant release
  3. Air inhaled due to greater negative pressure
  4. Oxygen → vasodilation of pulmonary arteries
    1. pulmonary circulation pressure decreases encouraging blood to flow through the lungs
  5. As a result the foramen ovale shuts and the ductus arteriosus constricts as this pathway is more favourable due to less resistance.
    1. systemic resistance has also now risen after clamping
    2. Ductus arteriosus constricts due to reduction in PGs [caused by oxygenation]
  6. Umbilical vein and arteries and ductus venosus constrict as the umbilical cord is clamped.
    1. this raises the systemic circulation pressure helping to shut the shunts
178
Q

describe foetal circulation

A
  1. umbilical vein carries oxygenated blood from the placenta towards the liver. A branch bypasses the liver via the ductus venosus which joins onto the inferior vena cava
  2. oxygenated blood enters the right atria and is shunted through to the left atria via the foramen ovale and then round the body via the aorta.
  3. some O2 blood goes through the right ventricle and passes into the pulmonary trunk towards the lungs, and is passed through the ductus arteriosus into the aorta.
    1. steps 2 and 3 mean the lungs are bypassed
  4. the blood travels down the aorta → common iliac arteries.
  5. the umbilical arteries carry deoxy blood from the internal iliac arteries.
179
Q

what is the main risk premature neonates face and why?

A
  • respiratory distress syndrome
  • lack of type 2 pneumocyte development meaning insufficient amount of surfactant to keep the alveoli open.
    • also underdeveloped acini.
180
Q

what part of the airway faces the largest resistance

A

the trachea and primary bronchi

this is because the smaller airways run in parallel to each other reducing the total resistance to airflow, otherwise, it would be the smaller airways due to their smaller radius.

181
Q

trache structure and function

A
  • starts at the larynx and ends at the carina [C6 -T5]
  • Pseudostratified ciliated columnar epithelia with interspersed goblet cells – mucociliary clearance
    *
182
Q

where does the conducting airway end

A

terminal bronchioles

183
Q

what are pores of Kohn

A

pores connecting adjacent alveoli that allow movement of macrophages and help to equalise pressure between adjacent alveoli. this helps the lungs to inflate easily and evenly during inspiration.

184
Q

how many cell types in an alveoli and what are their function

A
  1. Type 1 pneumocytes: primarily for gas exchange and make up 90% of alveolar surface
  2. Type 2 pneumocytes: produce surfactant and make up ∼ 5-10% of alveolar surface
185
Q

how thick is the alveolar membrane and why

A

1micron thick

to allow efficient gas exchange by minimising the distance between air and RBC

186
Q

what;s this

A

pseudostratified columnar ciliated epithelial cells with interspersed goblet cells.

187
Q

what are the nostrils lined with

A
  1. the opening of the nostrils is lined by keratinising stratified squamous epithelium
  2. further back it changes to non-keratinising
  3. further back still, the nose is then lined with respiratory epithelium.
188
Q

the nose is poorly vascularised T/F

A

False

the connective tissue beneath the resp. epithelium has a rich network of blood vessels

189
Q

what is olfactory epithelia

A
  • pseudo stratified columnar epithelia - NOTE:
    • no goblet cells.
    • non motile cilia (stereo cilia)
    • basal epithelial cells - in contact with basal membrane
190
Q

what’s respiratory epithelia

A

pseudostratified columnar ciliated epithelial cells with interspersed goblet cells.

191
Q

how do you tell the difference between olfactory and respiratory epithelium?

A

the connective tissue beneath

  • respiratory epithelia with have seromucus glands that produce catarrh
  • olfactory epithelia serous glands of bowman which secrete fluid that washes the surface.
    • also richly innervated
192
Q

nasopharynx lining and function

A
  • resp. epithelia
  • conducts gas, humidifies and warms the air and olfaction.
193
Q

laarynx composition, lining and function

A
  • hyaline cartilage
  • inner aspect is lined with respiratory epithelium, with the exception of the vocal chords
  • involved in voice production and stays open against -ve pressure of inspiration
194
Q

vocal cord lining

A

They are lined with thin stratified squamous epithelium

195
Q

what is the vasculature of the vocal cords like

A
  • they have blood vessels BUT no lymphatics.
  • therefore, a cancer in this location will not spread.
196
Q

trachea composition, lining and function

A
  • hyaline cartilage C-shaped rings [except cricoid]
  • resp. epithelia
  • conducts air to the lungs
197
Q

how do you differentiat bronchioles from bronchi and trachea

A
  • The absence of cartilage
  • The simplification of resp. epithelium as it changes to ciliated columnar epithelium BUT is still referred to as resp. epithelium
  • fewer goblet cells which are replaced with Clara cells, which are mostly found in terminal bronchioles.
    • clara cell function unclear but involved with surfactants
198
Q

does the resp. epithelium change as you move from trachea → alveoli? if so how?

A

Yes

  • resp. epithelium simplifies from pseudo-stratified columnar ciliated with goblet cells → cuboidal ciliated epithelia
  • smooth muscle only no cartilage in the bronchioles and downwards.
199
Q

how do type 1 and 2 pneumocytes differ?

A
  • type 1:
    • squamous epithelial cells - are flat and as thin as possible
    • they have v. few organelles as they aim to be as thin as possible.
  • type 2
    • larger cells in the walls of the alveoli
    • rounded cells with central round nucleus, cytoplasm rich, mitochondria, SER and RER and spherical bodies
200
Q

what are alveolar macrophages derived from, where are they found and what is their function?

A
  • derived from monocytes
  • found in the interstitial connective tissues of the alveoli and also in the lumen of the alveoli.
  • phagocytose, pathogens and foreign particles
201
Q

how many layers are there in the blood air barrier?

A

3 - type 1 pneumocyte, basement membrane and vascular endothelial cell

4 if you include surfactant

202
Q

what does alveolar interstitium contain

A

blood vessels and lymphatics

collagen

elastin

macrophages

203
Q

describe the lining of the pleura

A

flattened squamous epithelial cells (mesothelial cells) which rest on loose fibrocollagenous connective tissue which has an inner layer of elastic tissue

204
Q

what is the function of the soft palate

A
  • to control the orifice between the nasal and oral parts of the pharynx
  • Elevation prevents reflux of food and liquid into the nasopharynx during swallowing
205
Q

What is the purpose of coughing?

A

To move material from the vocal cords to the pharynx

206
Q

are type 1 pneumocytes joined together?

A

yes

by tight junctions

207
Q

The normal oesophagus is lined by what type of epithelium

A

stratified squamous non-keratinising

my phase 1 (11 decks)

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