Physiology Flashcards
define internal respiration
intracellular mechanism involving oxygen and carbon dioxide between body tissues and the blood
define external expiration
external exchange of oxygen and carbon dioxide between external environment and cells of the body
define the 4 steps of external respiration
ventilation
gas exchange between alveoli and blood
gas transport
gas exchange between blood and tissues
describe the process of ventilation
mechanical process of moving air between atmosphere and lungs (both in and out)
air flows down a pressure gradient from ___ to ___ pressure?
high, low
during inspiration is intra-alveolar pressure lower or higher than atmospheric pressure?
lower
define Boyles law
as the volume of a gas increases, the pressure exerted by the gas decreases.
what two factors link the lungs to the thorax
intrapleural fluid cohesiveness and negative intrapleural pressure
what are the three pressures involved in ventilation
atmospheric, intra-alveolar, intrapleural
are inspiration and expiration active or passive processes
inspiration is active relying on muscle contraction whereas expiration is passive
what nerves supply the diaphragm
phrenic nerve which is via C3, 4, 5
what is a pneumothorax
air within the pleural space
what can cause a pneumothorax
trauma, iatrogenic, spontaneous
symptoms of pneumothorax
shortness of breath and chest pain
physical signs of pneumothorax
hyper-resonant percussion sounds and decreased or absent breath sounds
what gives the lungs their elastic behaviour
elastic connective tissue and alveolar surface tension
what creates the alveolar surface tension
attraction between water molecules at air liquid interface
what reduces surface tension in the lungs
pulmonary surfactant
what is surfactant made up of
lipids and proteins
two forces that keep the lungs open
transmural pressure gradient and surfactant
two forces promoting collapse of the lungs
elasticity of lung connective tissue and alveolar surface tension
what are the main inspiratory muscles
diaphragm and external intercostals
what cells secrete surfactant
type II alveolar cells
parasympathetic nerve fibres promote
bronchoconstriction
sympathetic nerve fibres promote
bronchodilatation
what is peak flow rate
a test to measure someones maximum speed of expiration
what is emphysema
air within the alveoli
results in them becoming enlarged and damaged
lung are kept open by
surfactant
transmural pressure gradient
lungs can be closed by
alveolar surface tension
connective tissue in lungs
smaller alveoli are more likely to collapse true/false
true
two main muscles used for inspiration
diaphragm
external intercostals
two muscles used for active expiration
abdominals
external intercostals
what is tidal volume
volume of air entering or leaving the lungs in one breath
inspiratory reserve volume is
extra volume that can be inspired above the tidal volume
expiratory reserve volume is
extra volume of air that can be expired above the tidal volume
residual volume is
volume of air remaining in lungs after expiration
total lung volume is
vital capacity + residual volume
vital capacity is
max volume of air that can be expired after normal inspiration
total lung volume can be measured by spirometry true/false
false because residual volume cannot be measured with spirometry
what is spirometry
a test used to measure dynamic lung volumes and assess lung function
what is FVC
forced vital capacity
maximum volume of air that can be forcefully expelled from the lungs following maximum inspiration
what is FEV1
forced expiratory volume in 1 second
maximum volume of air that can be expired in the first second of an FVC determination
FEV1/FVC ratio is ___ in normal people
> 70%
obstructive diseases affects __ example is __
the airway
example asthma and COPD
restrictive disease affects __ example is __
the lungs
example is sarcoidosis
in an obstructive disease, FEV1 is ___ FVC is ___ and ratio is ___
FEV1 - reduced
FVC - normal
ratio - reduced
in a restrictive disease FEV1 is ___ FVC is ___ and ratio is ___
FEV1 - reduced
FVC - reduced
ratio - normal
alveolar ventilation is less than pulmonary ventilation true/false
true
why is alveolar ventilation less than pulmonary ventilation
due to alveolar dead space
what 4 factors affect the rate of gas exchange
partial pressure of CO2 and O2
diffusion co-efficient of CO2 and O2
surface area of alveolar membrane
thickness of alveolar membrane
define partial pressure
total pressure a gas would exert if it occupied the total volume of the mixture
adult haemoglobin is made up of ___
this is the same/different as foetal haemoglobin
2 alpha and 2 beta subunits
different to foetal haemoglobin
name three things oxygen delivery to tissues is impaired by
respiratory disease
anaemia
heart failure
saturation of oxygen increases as partial pressure of oxygen __
increases
what is the Bohr effect
shift in the standard oxygen curve to the right, due to release of oxygen at tissues
increased by pCO2, increased [H+] and 2,3 - biphosphoglycerate
name three ways carbon dioxide is transported in the blood
bicarbonate (60%)
carbamino compounds (30%)
solution (10%)
CO2 is more/less soluble than O2
more, this is why its transported mainly as bicarbonate
describe the Haldane effects
removing O2 from Hb increases affinity for Hb to pick up CO2
specifically where is the respiratory rhythm generator in the medulla
pre-botzinger complex
during inspiration, pre-botzinger complex activates which neurones to initiate contraction of inspiratory muscles?
dorsal group neurones
what steps occur during active expiration
increased firing of dorsal neurones - excites ventral neurones which excites intercostals and abdominal muscles - forceful expiration
where is the pneumotaxic centre and what does it do to inspiration
located in pons
terminates inspiration allowing passive expiration
in normal breathing ventral neurones are excited true/false
false
only in forceful expiration
what does the apneustic centre do to inspiration
prolongs inspiration
what are the chemoreceptors responsible for
sensing value of gas tensions
where are peripheral chemoreceptors located
aortic and carotid bodies
where are the central chemoreceptors located
near the medulla
hypoxia at high altitudes is caused by
decreased partial pressure of inspired oxygen
hyperventilation
adaptation for high altitude hypoxia are
increased RBCs
increased capillary numbers
increase 2, 3-biphosphoglycerate so oxygen moves through tissues more easily
what factors shift the oxygen dissociation curve to the right
CADET CO2 Acid 2,3-Diphosphoglycerate Exercise Temperature
respiratory alkalosis can be caused by
hyperventilation increased intracranial pressure PE pregnancy altitude
respiratory acidosis can be caused by
COPD, life threatening asthma, pneumonia, choking, opiates overdose
metabolic acidosis can be caused by
diabetic ketoacidosis, impaired H+ excretion
metabolic alkalosis can be caused by
potassium, deficiency, extreme vomiting, alkali indigestion
