RESPIRATORY Flashcards
FUNCTIONS OF RESPIRATORY CENTRE (6)
- Gas exchange
- Regular blood pH
- Smell
- Filter warm and moisten air
- Produce sound
- Excretes water and heat
Name conducting zone vs respiratory zone
Conducting zone
* nose, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
Respiratory zone (external respiration or gas exchange occurs)
* respiratory bronchioles. Alveolar ducts, alveolar sacs, alveoli
Describe the pharynx + functions
- skeletal muscles with mucous membranes
- comprised of naso/oro/laryngopharynx
- part of conducting airways
Functions - passage for food and air
- resonating chamber for speech sounds
- houses the tonsils
describe larynx structure and position
- Short tube of cartilage
- Lined by mucous membrane
- Connects pharynx to trachea
function of thyroid cartilage
forms anterior wall of the larynx
epiglottis, made from what, does what
- Elastic cartilage
- Partial section is free to move up and down with swallowing to protect larynx
- Food diverts down into oesophagus
Cricoid cartilage, made from what, does what
- Ring of hyaline cartilage
- Forms inferior wall of larynx
Trachea structure and function
- Passageway for air anterior to oesophagus
- Divides into left and right bronchi
- Lined with mucous membrane (cilia and goblet cells)
- Supported by cartilage
Describe bronchioles structure
progressively become smaller
cartilage decreases and then dissapears
smooth muscle cells are no longer present past the bronchioles
decrease of cilia
decrease of goblet cells = decrease mucous
parietal vs visceral pleura
- Parietal pleura- outer layer, attached to wall of thoracic cavity and diaphragm
- Visceral pleura- inner payer, attached to the lungs
lobes of lungs
right - 3 lobes
left 2 lobes
how much fluid in intrapleural space
18mls
alveoli structure and function
lined with epithelium
covered with surfactant
respiratory pattern medulla vs pons
Medulla
* Controls rhythm
* Both inspiratory and expiratory areas
Apneustic
* Area in lower pons
* Increases time of inhalation
Pneumotaxic
* Area in upper pons
* Help turn off inspiration to…decrease time of inhalation, increase respiratory rate
What stimulates our medulla for respiratory drive
Cortical influences
* Impulses from hypothalamus and limbic system stimulate respiratory centre
Chemoreceptor regulation
* Located in medulla
* Responds to H+ and PCO2 levels in CSF
this is a negative feedback system
Pulmonary ventilation, describe inhalation and exhalations relationship to atmospheric pressure
Inhalation occurs when pressure in lungs is LESS than the atmospheric pressure
Exhalation occurs when the pressure in the lungs is GREATER than the atmospheric pressure
Muscles of ventilation, inspiratory vs expiratory
Quite unforced inhalation
* Diaphragm and external intercostals
* Diaphragm = decreased pressure so air can flow in
Quiet exhalation is a passive process
* Begins when diaphragm and intercostals relax
* Due to elastic recoil of chest wall and lungs
* Volume decreases which forces air out
Ventilation pressure changes
At rest, inhalation, exhalation
comparing atmospheric pressure and alveolar pressure
At rest
* Atmospheric pressure = 760mmhg
* Alveolar pressure = 760mmhg
Inhalation
* Atmospheric pressure = 760mmhg
* Alveolar pressure = 756 mmhg
Exhalation
* Atmospheric pressure = 760mmhg
* Alveolar pressure = 762mmhg
Boyles Law define and relate to ventilation
relationship between pressure and volume
decrease volume = increase pressure and vice versa
* This happens when the muscles of inhalation cause the chest and lungs to expand on the command of the medulla oblongata (intrapulmonary pressure then falls to 758mmHg)
Daltons Law define and relate to gas exchange
The total pressure exerted by a mixture of gases is the sum of the pressures exerted by each gas in the mixture
* The partial pressure is proportional to the percentage of that gas in the mixture
* This is important in determining the movement of oxygen and co2 between the atmosphere and the alveoli, alveoli and blood and blood and cells.
* Each gas operates independently and diffuses from a higher PP to an area of lower PP
Henrys Law
The amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid when the temperature is kept constant.
Increased temp = decreased solubility
O2 and nitrogen solubility is less than CO2 meaning very little can enter circulation at normal pressures
% of gases inspired at atmospheric pressure
- Nitrogen = 78.6%
- Oxygen = 20.0%
- Carbon dioxide =0.04%
- Water vapour = 0.46%
External respiration vs internal respiration brief description
aka pulmonary gas exchange
- Diffusion of O2 from air in alveoli to blood in pulmonary capillaries
- Diffusion of CO2 from pulm caps back to alveoli and then exhaled
internal = systemic gas exchange
= exchange of O2 and CO2 between systemic capillaries and tissues
Tidal volume vs minute volume
TV= volume of one breath
MV= rr x tidal volume
% of VT that participates in gas exchange vs what remains in conducting airways
70% for gas exchange at bronchioles and alveoli
30% remains in conducting airways
IRV vs ERV vs RV
IRV- forced inhalation/deliberate deep breath, how much can we breath under forced inspiration
ERV- how much can we breath out under forced expiration
RV - air that remains in the lungs following expiration (ie the amount that is in the conducting airways/anatomical deadspace)
Average RV for males and females
- 1200mls males
- 1100mls females
IC vs FRC vs VC vs TLC
IC = VT+IRV
FRC= RV+ERV
VC= IRV+VT+ERV
TLC= VC + RV
hypoxia vs hypoxemia
Hypoxemia = low oxygen levels in your blood
hypoxia = low oxygen levels in your tissues.
Hypoxemia can lead to hypoxia and they often both appear together, but not always.
Oxygen transport
- 1.5% dissolved in plasma
- 98.5% bound to Hb in RBC
- When oxygen is bound it cannot participate in gas exchange it must be dissolved
L shift OHDC
Incressed affinity
decreased temp
decrease PCO2
decrease 2-3 DBG
increased Ph
R shift OHDC
Decreased affinity
increased temp
increased PCO2
increased 2-3DPG
decresased ph
CO2 transport
- Dissolved (7% in plasma)
- Bound to amino acids 23%
- (mostly to Hb)
- Bicarbonate ions (transported in blood approx. 70%)
normal V/Q ratio
Normal V/Q = 0.4 (4L O2/5L blood)
decreased V = shunting
provide examples
what is occurring in lungs
asthma, COPD, APO
ventilation has gone down but perfusion is normal
- Body compensates and will vasoconstrict pulmonary circulation causing increased pressure = pulmonary hypertension = right sided heart failure eventually
- You may not be able to get your SPO2 to normal levels and you need to accept a lower limit
- Treat the respiratory issue to improve
- Here our V/Q ratio is decreasing
decreased P = deadspace
this is a phsyiological issues as opposed to anatomical
there is an obstruction in pulmonary circulation
Reduction in PAO2 and SPO2
Need to fix the perfusion to fix the oxygenation
here our ratio is increasing
compare obstructive lung vs restrictive lung and their respective volumes
Obstructive lung
the overall size has increased so we see an increase in ERV AND RV (not helpful, we need an increase in IRV and TV)
increased compliance but decreased recoil
asthma and COPD- able to get the air in, unable to get it out
Restrictive Lung
smaller lung volumes
decreased compliance but increased recoil
pneumonia, fibrosis, ARDS
SPO2 % to PaO2 correlation
97%- 95mmhg
92%- 60mmhg
89%- 50mmhg
75% - 40mmhg
40%- 27mmhg
Normal wave form capnography phases
1 baseline
2 start of exhlation
3 exhalation (movement of air through conducting airways)
end of 3 is end tidal co2 value
4 inspiration
rounded capnography waveform
osephageal in nature
will decrease to nothing
increasing in size capno waveform
hypoventilation
rosc pt with increased perfusion
hypermetabolic state
increase in temp (producing more co2)
shark fin capno
bronchospastic, occlusion of circuit
decreasing in size capno
hyperventilation, decreasing perfusion, decrease metabolic state, PE
reversible causes 5 H’s and 4 T’s
- Hypoxia
- Hypovolemia (low etco2)
- Hypothermia (low)
- Hyperkalaemia
- H+ (acidosis, high etco2)
T’s - TpT (low etco2)
- Tamponade (decrease perfusion)
- Toxins (metabolic state)
- Thrombosis
compare asthma vs COPD
asthma
reactive
bronchodilator +corticosteroid response
mast cells, eosinophils and macrophages
all airways involved
COPD
no reactivity
poor broncho and corticosteriod response
neutrophil and macrophage response ++
peripheral airways
mucous secretion +++
