respiratory important Flashcards
inspiration
intercostal muscles = contract
diaphragm = contracts
volume = increases
pressure = decreases
chest wall moves away from lung surface and parietal pleura moves away from visceral slightly
pressure enough to overcome elastic recoil, lungs expand - air forced in
what is the innervation of the diaphragm
phrenic nerve C3,4,,5
expiration
intercostal muscles = relaxes
diaphragm = relaxes
volume = decreases
pressure = increases
conducting airways
No alveoli and no exchange with blood Trachea Main Bronchus(Right and Left) Lobar Bronchus Segmental Bronchus Terminal Bronchiole
respiratory airways
Contains alveoli and gas exchange with blood
Respiratory Bronchiole
Alveolar Duct
Alveolar Sac
what type of epithelium is respiratory epithelium
Ciliated pseudostratified columnar epithelium
type 1 pneumocytes
95% of alveolar area, thin barrier for diffusion, connected by tight junctions.
type 2 pneumocytes
60% of total number of cells, secrete
Surfactant and decreases surface tension
alveolar macrophages
Immune cells
Derived from monocytes
Ingest bacteria and particles
what are the layers of gas exchange
- Fluid lining alveoli
- Layer of epithelial cells (type I pneumocytes)
- Basement membrane of ^ cells
- Interstitial space between alveoli epithelium and capillary endothelial cells
- Basement membrane of capillary endothelium
- Capillary endothelial cells
- Red blood cell
describe the binding of oxygen to haem
Oxygen bindsreversibly tohaem, so eachhaemoglobinmolecule can carry up to fouroxygenmolecules. Haemoglobinis an allosteric protein; thebindingofoxygento onehaemgroup increases theoxygenaffinity within the remaininghaemgroups
what shifts the oxygen dissociation curve left?
decreased temperature
decreased 2,3-DPG
decreased H+
CO
what shifts the oxygen dissociation curve right
(reduced affinity)
increased temperature
increased 2,3-DPG
increased H+
why is there V/Q mismatch in healthy people
natural inequality of 5mmHg due to gravitational effects
increased filling of blood vessels at the bottom of the lung
examples of V/Q mismatch
- There may be ventilated alveoli but no blood supply at all (known as dead space or wasted ventilation) due to a blood clot for example
- There may be adequate blood flow through the areas of the lung but there is no ventilation (this is termed shunt) due to collapsed alveoli
what are 2 local homeostatic responses to V/Q mismatch?
Hypoxic pulmonary constriction
- vasoconstriction to divert blood away from the poorly ventilated area
Local bronchoconstriction
- diverts airflow away to areas of the lung with better perfusion
inspiratory reserve volume (IRV)
amount of air in excess tidal inspiration that can be inhaled with maximum volume
expiratory reserve volume (ERV)
amount of air in excess tidal expiration that can be exhaled with maximum effort
residual volume (RV)
amount of air remaining in the lungs after maximum expiration, keeps alveoli inflated between breaths and mixes with fresh air on next inspiration
vital capacity (VC)
amount of air that can be exhaled with maximum effort after maximum inspiration
functional residual capacity (FRC)
amount of air remaining in the lungs after a normal tidal expiration
inspiration capacity (IC)
maximum amount of air that can be inhaled after a normal tidal expiration
total lung capacity (TLC)
maximum amount of air the lungs can contain
tidal volume (TV)
amount of air inhaled or exhaled in one breath
FEV1
Forced expiratory volume in the first second. The volume of air that is forced out in one second after taking a deep breath.
PEF
peak expiratory flow
what does a flow-volume curve show
flow as the volume inside the lungs decreases
what does a volume-time curve show
FEV over time
FEV6 should be equal to FVC
airways obstruction
blockage of airways
FVC normal (>80% of predicted value)
FEV1/FVC ratio is less than 0.7
E.g COPD, asthma, Cystic fibrosis
airways restriction
decreased ability to expand
FVC reduced (<80% of predicted value)
FEV1/FVC ratio is normal (>0.7)
E.g Pulmonary fibrosis, sarcoidosis
definition of Hypoxia
deficiency of O2 at tissue level (low PO2)
what are the 4 types of Hypoxia
- Hypoxaemia (hypoxic hypoxia) – most common
- Anaemia or CO hypoxia
- Ischaemia hypoxia
- Histotoxic hypoxia
causes of hypoxaemia - hypoventilation
resulting in increased arterial partial CO2 pressure
failure to ventilate the alveoli adequately
caused by: muscular weakness, obesity & loss of respiratory drive
causes of hypoxaemia - diffusion impairment
Results from the thickening of the alveolar membranes or a decrease in their surface area - causes the blood partial O2 pressure and alveolar partial O2 pressure to fail to equilibrate
causes of hypoxaemia - shunting
- An anatomical abnormality of the cardiovascular system that causes mixed venous blood to bypass ventilated alveoli in passing from the right side of the heart to the left side e.g. ventricular septal defect (VSD) - Eisenmenger’ Syndrome
- An intrapulmonary defect in which mixed venous blood perfuses unventilated alveoli
causes of hypoxaemia - V/Q mismatch
most common (occurs in COPD)
- Arterial partial CO2 pressure may be normal or increased, depending on how much ventilation is reflexively stimulated
- Can be caused by; a pulmonary embolus (blockage of an artery in the lung), asthma, pneumonia & pulmonary oedema
definition of hypercapnia
increased arterial partial CO2 pressure
caused by hypoventilation
what is the main drive to breath
hypercapnia (high CO2)
Boyles Law
P1V1=P2V2
Daltons law
PT = P1 + P2 + P3 +…
Henrys law
C = k P
Poiseuille’s law
R = 8nL/pi r ^4
It states that the flow (Q) of fluid is related to a number of factors: the viscosity (n) of the fluid, the pressure gradient across the tubing (P), and the length (L) and diameter(r) of the tubing.
alveolar gas equation
PA02 = PiO2 - PaCO2/R
Laplace law
P = 2T/r
where is CO2 predominantly controlled
respiration in lungs
where is HCO3- predominantly controlled?
kidneys
Henderson-Hasselbalch equation
pH = pKa + log [conjugate base]/[acid]
examples of respiratory acidosis
COPD
asthma
severe obesity
hypoventilation
examples of respiratory alkalosis
hyperventilation
examples of metabolic acidosis
hyperkalaemia
diabetic ketoacidosis
renal failure
examples of metabolic alkalosis
diarrhoea
vomiting
what cell types are involved in innate immunity
monocytes/macrophages, mast cells, dendritic cells, NK cells
what cell types are involved in adaptive immunity
B cells, T cells
what are the 5 classes of antibodies
IgG, IgA, IgM, IgE, IgD
features of innate (non-specific) defence
front line provides barrier to antigen present from birth slow response no-memory integrates with adaptive response
features of adaptive (specific) defence
specific to antigen learnt behaviour memory to specific antigen quicker response requires lymphocytes diversity requires somatic mutation
what are the 2 medullary systems
DRG
VRG
Dorsal respiratory group
DRG
Rapidly fire during inspiration
Input to spinal nerves that control diaphragm and inspiratory intercostals
ventral respiratory group (VRG)
Respiratory rhythm generator is located in Pre-Botzinger Complex of neurons
Sets the respiratory basal rate
Neurons fire during both inspiration and expiration
Have input to muscles of inspiration
Lower VRG also contains expiratory neurons
Input to muscles of expiration
what are the 2 pontine systems
Apneustic centre
Pneumotaxic centre
Apneustic centre
Area of lower pons
Major source of input to medullary inspiratory neurons
fine tunes medullary inspiratory neuron output and helps to continue activating inspiratory neurons to inhibit expiration
Pneumotaxic centre
Area of upper pons
Modulates activity of apneustic centre and smooths transition from inspiration to expiration
Switches off inspiratory neurons to prevent hyperinflation thus allowing expiration
what are pulmonary stretch receptors and what are the 2 types
mechanoreceptors
types: Slowly adapting stretch receptors (SASR)
Rapidly adapting stretch receptors (RASR)
slowly adapting stretch receptors (SASR)
In smooth muscle layer of airways in lungs
Stimulated by large lung inflation
Send afferent impulses to brain and inhibit medullary inspiratory neurons in DRG
Rapidly adapting stretch receptors (RASR)
In-between epithelial cells of airways
Stimulated by lung distension and irritants
Stimulation causes bronchoconstriction and an activity burst
what are the 2 types of chemoreceptors
Peripheral
central
peripheral chemoreceptors
Aortic bodies (arch of the aorta) and carotid bodies (high in the neck at bifurcation of common carotid arteries)
Stimulated by a decrease in arterial PO2 and an increase in arterial H+ concentration. Not sensitive to small reductions of the arterial partial O2 pressure
Provide excitatory input to medullary inspiratory neurons to increase the rate of respiration
central chemoreceptors
In medulla
Provide excitatory synaptic input to medullary inspiratory neurons
Very small increases in the arterial partial CO2 pressure causes a marked reflex increase in ventilation
Stimulated by an increase in the H+ concentration in the CSF which is represented by an increase in Co2 levels
respiratory drive - control by PO2
Decrease in PO2 will stimulate peripheral chemoreceptors
Send impulses to medullary inspiratory neurons and cause an increase in ventilation rate
respiratory drive - control by CO2
Increase in PCO2 will cause an increase in the concentration of H+ in the blood
As CO2 + H2O -> H+ + HCO3-
Stimulates peripheral chemoreceptors and medullary inspiratory neurons
Increase in CO2 in brain CSF
H+ stimulates central chemoreceptors
Ventilation increased to remove excess CO2
sympathetic airway tone
bronchodilation
Neurotransmitter: Noradrenaline acts on adrenal glands which secrete adrenaline
receptor: B2 (beta-adrenergic)
effect: indirect
parasympathetic airway tone
bronchoconstriction
neurotransmitter: Acetylcholine
receptor: M3 (muscarinic)
effect: direct
what does the upper respiratory tract consist of
nose > larynx
what are the functions of the upper respiratory tract
1) filter, warm, humidify, inspired air (turbinates!)
2) voice production (larynx)
3) quality of voice (sinuses and larynx affect this)
how many turbinates are there
3: superior, middle, inferior
what are the 4 regions of airflow
sphenoethmoidal recess, superior meatus, middle meatus, inferior meatus
what are the 4 pairs of paranasal sinuses
frontal, maxillary, ethmoid, and sphenoid
what are the 3 areas of the pharynx
base pf the skull to C6
nasopharynx
oropharynx
laryngopharynx
what are the 9 cartilages of the Larynx and which are elastic and hyaline
Single: epiglottis, cricoid, thyroid
Paired: cuneiform, corniculate, arytenoid
Elastic= epiglottis Hyaline= thyroid, cricoid, arytenoid
what does the superior laryngeal nerve innervate
internal= all sensation to laryngopharynx
external= motor to cricothyroid
what does the recurrent laryngeal nerve innervate
motor to all laryngeal muscles except cricothyroid
what are the borders of the anterior triangle
Superiorly– inferior border of the mandible (jawbone)
Laterally– anterior border of the sternocleidomastoid
Medially– sagittal line down the midline of the neck
what does the lower respiratory tract consist of?
vocal cords > alveoli
what is in the conducting zone
trachea > terminal bronchioles
what is in the respiratory zone
respiratory bronchioles > alveoli
components of the respiratory tree
Trachea R & L main bronchi R & L lobar bronchi Segmental branches Terminal bronchioles Respiratory bronchiole Alveolar duct Alveolar sac Alveoli
describe the lung blood supply
1) deoxygenated pulmonary arteries &
2) oxygenated bronchial artery (from thoracic aorta)
innervation of the lungs
vagus
venous drainage of the lungs
1) bronchial veins (drain deoxygenated to azygous) &
2) four pulmonary veins (drain oxygenated blood into LA)
inferior lung borders
ribs 6,8,10
inferior pleural borders
ribs 8,10,12
features of the right lung
3 lobes, 2 fissures
features of the left lung
2 lobes, 1 fissure
where is the apex of the lung
3cm above medial 1/3 clavicle
position of the hilum of the lung
costal cartilage 2,3,4
positions of structures in hilum of lung
Right: PA anterior to bronchus
Left: PA most superior
Both: bronchus= posterior & PV anterior and inferior
what structures pass through the diaphragm and at what levels
IVC= T8
Oesophagus=T10
Aorta= T12
what 3 structures are in the carotid sheath
- carotid
- internal jugular
- vagus
minute volume =
5L/min
what kind of pressure causes air to move into lungs
negative intra-alveolar pressure
what is transpulmonary pressure (Ptp)
difference in pressure between inside and outside of lung (alveolar pressure - intrapleural pressure)
alveolar pressure (Palv)
air pressure in pulmonary alveoli
intrapleural pressure (Pip)
pressure in pleural space- ‘intrathoracic pressure’
compliance
change in lung volume caused by given change in Ptp
greater the lung compliance, more readily the lungs expand
what is compliance affected by
stretchability of elastic lung tissue
surface tension of alveoli
ventilation
flow of air into and out of the alveoli
perfusion
flow of blood to alveolar capillaries
dead space
150ml UA + 25ml ALV = 175ml
CO2 elimination equation
PACO2 = k V’CO2 / V’A
hypersensitivity
diseases in which immune responses to environmental antigens cause inflammation and damage to the body itself
Gell and Coombes Classification
Type 1 – IgE, allergy, hay fever, acute anaphylaxis > histamine > reaction
Type 2 – IgM/IgG, transfusion reactions, autoimmune diseases
Type 3 – IgG = circulatory immune complexes, farmers/pigeon fanciers lung
Type 4 – T cell-mediated Delayed Type Hypersensitivity, TB, sarcoidosis
type 1 respiratory failure
low oxygen pO2 < 8kPa
normal pCO2 < 6kPa
type1 = 1 change (only O2 is low)
ARDS
type 2 respiratory failure
low oxygen pO2 < 8kPa high pCO2 > 6kPa type2 = 2 changes (low O2 + high CO2) hypoxia with hypercapnia COPD
foetal circulation features
Lungs filled with fluid
one umbilical vein- oxygenated blood from placenta
two umbilical arteries- deoxyg blood to placenta
three shunts:
ductus venosus (hepatic system)
foramen ovale (betw RA & LA)
ductus arteriosus (PA to desc aorta)
first breath
Fluid squeezed out & inc surfactant Air inhaled O2 vasodilates PAs > lungs perfused Pressure in systemic circulation inc > shunts in liver & DA to close Umbilical arteries and shunts constrict
foetal to adult features
UV > ligamentum teres UA > medial umbilical ligaments DV > ligamentum venosum DA > ligamentum arteriosum FO > fossa ovalis
