Respiratory System Flashcards
Functions
Warming, humidification and filtering the air
Smell (olfaction)
Protection and defence
Speech (phonation)
Pulmonary ventilation
Maintains blood pH
Endocrine
Gas exchange
Upper respiratory tract (URT)
From head to neck
URTI - common cold, sinusitis, tonsillitis, laryngitis
Nose
Enters nares (nostrils) to nasal cavity - connnected to several paranasal sinus cavities, lined with mucosal membrane (mucosa) - ciliated columnar epithelial cells
Veins warms air
Glands produce mucus
Mucus - moistens air, traps pathogens, lysozymes
Cilia - move mucus toward back of throat
Pharynx
Back of nasal cavity, down back if mouth and past the entrance to the larynx
Passageway
Warms and humidifies air
Hearing - protects middle ear. Naropharynx - auditory tubes connect middle ear
Protection - lymphoid tissue
Speech - resonance
Larynx
Voice box
Epiglottis - protects lungs by closing
Thyroid cartilage - vocal cords are attached here
Warms and humidifies air
Lower respiratory tract (LRT)
In the thorax
LRTI - bronchitis, bronchiolitis, chest infection, pneumonia
Trachea
Windpipe
C-shaped cartilage - supports and keeps airways open
Lines by columnar ciliated epithelium
Goblet cells
Mucocillary escalator
Warms and humidifies air
Lungs
Cones shaped
Right - 3 lobes
Left - 2 lobes, accommodate the heart in cardiac notch
Alveoli, connective tissue, nerve and capillaries sitting in an elastic matrix of connective tissue
Thoracic cavity
Entrance and exit at the hilum
Pleura and pleural cavity
Sac of serous membrane
Serous - secrets serum; pleural fluid - creates surface tension, lubricates
Visceral pleural
Bronchi and bronchioles
Trachea -> two bronchi
Bronchi -> five or six lobar and segmental bronchi -> bronchioles; spirals of smooth muscle ANS control
Bronchoconstriction
Terminal bronchioles - alveolar ducts and sacs at end
Walls get thinner
Alveoli
Single layer of squamous epithelium
Loos, elastic connective tissue - macrophages, fibroblasts, nerves, BV, lymph vessels
Respiratory membrane - fused wall of alveoli and capillary
Type II pneumocyte (septal) - surfactant, decrease surface tension, prevents collapsing
Divisions in the respiratory system
Structure - URT, division at bottom of larynx and LRT
Function - conducting zone; passage of air and dead space, 150ml. Division at bronchioles. Respiratory zone; gaseous exchange, alveoli
Tracheostomy
Hole into trachea through neck
Treat airway obstruction
Breath via mouth and nose
Speech through speaking valve
Normal sounds
Temporary
Laryngectomy
Removal of the larynx and redirection of trachea
Treat cancer of larynx
Breathes through stoma
Speech not normal
Permanent and irreversible
Breathing musculature
Intercostal muscles - EIM; relaxed and forces inhalation. IIM; forced exhalation
Diaphragm - contraction; increase volume of thorax, drops and flattens. Relaxation; decrease volume of thorax, rises and domed
Pulmonary ventilation
Breathing
Regular and mainly automatic process
Refresh air in alveoli
Rest - inhalation; two seconds, exhalation; three seconds, pause
Boyles law
As volume decreases pressure increases
As volume increases pressure decreases
Pressure is inversely proportional to volume
Air flows down the pressure gradient
Relaxed inhalation
- Diaphragm and EIM contract = rib cage rise
- Thoracic cavity volume increase
- Lung volume increase
- Intrapulmonary pressure decreases
- Air flows into lungs down pressure gradient
Relaxed exhalation
- Diaphragm and EIM relax, ribcage descends
- Thoracic cavity volume decreases
- Lung volume decreases
- Intrapulmonary pressure increases
- Air flows out down the pressure gradient
Ease of breathing - elasticity
Shrink
Lungs ability to return to normal shape after inspiration due to connective tissue
Loss of connective tissue results in disease and forced expiration
Ease of breathing - compliance
Stretch
The effort required to inflate the alveoli
Reduces when surfactant is insufficient
Ease of breathing - airway resistance
More resistance means more effort to inhale and exhale
Airway obstruction - physical e.g. cystic fibrosis, or physiological, e.g. oedema
Forced inhalation - restrictive disorders
Helps lift the ribs and diaphragm more
Volume increases and pressure decreases more
Neck muscles - sternocleidomastoid & scalenes
Chest muscles - pectoralis major & minor
Spinal muscles - erector spinae
Forced exhalation - obstructive disorders
Helps lower ribs more
Volume decreases and pressure increases more
Intercostal muscles - internal intercostal muscles
Abdominal muscles - transverse abdominals & rectus abdominals
Back muscles - latissimus dorsi
Tidal volume (TV)
Amount of air inhaled or exhales with each breath under resting conditions
Adult male average - 500ml
Adult female average - 500ml
Inspiratory reserve volume (IRV)
Amount of air that can be forcefully inhaled after a normal TV inspiration
Adult male average - 3100ml
Adult female average - 1900ml
Expiratory reserve volume (ERV)
Amount of air that can be forcefully exhaled after a normal TV expiration
Adult male average - 1200ml
Adult female average - 700ml
Residual volume (RV)
Amount of air remaining in the lungs after a forced expiration
Adult male average - 1200ml
Adult female average - 1100ml
Dalton’s law
The total pressure is the sum of the partial pressures of each gas in the mix
P total = PN2 + PO2 + PCO2
Only replenish 15% volume every five seconds for respiration
Changes in respiratory rate
PO2 and CO2 changes in arterial blood - measured by receptors
ANS causes increase rate and depth of respiration if PP move too far out of normal range
Gaseous exchange in alveoli
Atrial blood - low O2 high CO2
After - high O2 and low CO2
Diffuse down gradient O2 into capillaries from alveoli
Venous blood - high O2 and low CO2
Gaseous exchange in tissues
Atrial blood - high O2 and low CO2
Tissue cells - low O2 and high CO2
Diffuse down gradient O2 into tissue cells from capillaries
Venous blood - lobe O2 and high CO2
Factors affecting movement of O2 and CO2
Ventilation (V) - air that reaches alveoli
Perfusion (Q) - blood surrounding alveoli in capillaries
V/Q coupling
How well they are matched
How efficient and adequate the system is
Ideally 1:1 but more like 0.8
Local autoregulation - blood vessels
Poor ventilation - lower alveolar PO2, BV constrict, redirect to better areas
Good ventilation - higher alveolar PO2, BV dilate to accept more blood, more efficient
Local autoregulation - bronchioles
Good ventilation - lower alveolar PCO2, constrict to redirect airflow to areas of poor ventilation
Poor ventilation - higher alveolar PCO2, dilate to accept more air
Transport of gases in blood
Bohr effect
Rise on PCO2
Increase in H+ ions and lower pH
Release of O2 from Hb
Helps use venous reserve of O2
Bohr effect in tissues
Higher PCO2 in respiring tissues
More H+ ions = low pH
H+ = release of O2 from Hb
Haldane effect - property of haemoglobin
Oxygenation of blood in lungs displaces CO2 which is bound to Hb
Hb carries more CO2 in deoxygenated blood
Oxygen
1.5% dissolve in plasma
98.5% attaches to Hb to form oxyhaemoglobin - unstable, easily dissociate especially in areas of low O2 levels, low pH or increased temperatures
Carbon dioxide
7% dissolves in plasma
70% as bicarbonate ion (HCO3) - negative, role in buffering blood pH
23% attached to Hb to form carbaminohaemoglobin
Respiratory failure
Failure to maintain adequate gas exchange
Characterised by abnormalities of arterial blood gas tension (ABG)
Normal values; pH: 7.35-7.45, PaCO2: 4-6kPa, PaO2: 10-13kPa, HCO3-: 22-26mmols/L
Type 1 respiratory failure (T1RF)
Hypoxia - oxygen movement impaired, PaO2 is <8kPa. 8-10kPa means impairment. >8 means failure
Normal or low CO2 concentration
Caused by a V/Q mismatch
T1RF causes
V/Q mismatch
Lack of oxygen
Unwell
Chest infection
Pneumonia
Type 2 respiratory failure (T2RF)
Hypoxia - impaired oxygen movement, PaO2 is <8kPa. 8-10kPa means impaired. >8kPa means failure
Hypercapnia - high carbon dioxide levels, PaCO2 >6kPa
Caused by ventilation failure - not enough air being breathed out
T2RF causes
Spinal cord injuries
Muscles don’t work
MND - muscles don’t work
Brain injuries
Collateral ventilation
Alveoli are interdependent and connected
Keeps them open
Utilise a blocked alveoli by air going through different pathways so gas exchange can still occur
Once air is biting the mucus blocking the affected alveoli it can be removed
Forced vital capacity (FVC)
The largest amount of air that you can forcefully exhale after deep inhalation
Maintain ventilation
Limited in neuromuscular disorders and spinal cord injuries
Forced expiratory volume in one second (FEV1)
How much air you can form from your lungs in one second
Spirometers lung function test (LFT) - obstructive
Reduced FEV1 but can reach the FVC
Peak flow
Simple measurement of how quickly you can blow air out of your lungs
Peak cough flow - coughing into the same device, <160ml cough augmentation is required
Obstructive conditions - characterised
Reduction in airflow
Difficulty exhaling
Shortness of breath
Hyperinflation
Obstructive conditions - chronic obstructive pulmonary disease (COPD)
No cure but can be treated
Chronic bronchitis - productive cough, lots of mucus
Emphysema - breathlessness, normally T1RF, damage to the alveoli so they become larger; trapped air
Obstructive conditions - asthma
Inflammatory disease
Mast cells, eosinophils, T lymphocytes, neutrophils and epithelial cells are present
Wheezing, breathlessness, chest tightness and cough
Obstructive conditions - bronchiectasis
Chronic cough, sputum and breathlessness
Caused by airways being damaged or widened by infection or another condition
Cilia stick together as there is excess mucus
Restrictive conditions - characterised and disorders
Reduction in lung volume
Difficulty inhaling
Limitations in compliance and elasticity of lung tissue
Disorders - interstitial lung disease, scoliosis, neuromuscular disease, obesity, spinal cord injuries
Breathlessness
Multi-factorial sensory contribute to the sensation
Mismatch between sensory input and motor effect to achieve an adequate breath
Sense of effort to breathe
Spirometer lung function test (LFT) - restrictive
Reduced FEV1 and cannot reach FVC
