Respiratory Flashcards
What are the functions of the nose? (4)
Warming of inspired air
Humidification
Filteration
Defence
What divides the nasal cavity into meatuses?
Conchae
What are the functions of the paranasal sinuses? (2)
Warm & humidify air
Reduce the weight of the skull
What are the 4 paranasal sinuses?
Frontal
Maxillary
Ethmoidal
Sphenoid
What innervates the frontal sinus?
Ophthalmic branch of CNV
Where does the maxillary sinus open into?
Middle meatus via hiatus semilunaris
What does the sphenoid sinus drain into?
Sphenoethmoidal recess
What do the pharyngeal constrictors do?
Contract sequentially to move food bolus down CNX
What do the inner longitudinal muscles do?
Contract to shorten & widen pharynx
What is the sensory innervation to the pharynx?
Naso - CNV2
Oro - CNIX
Laryngo - CNX
What are the true vocal cords lined by?
Stratified squamous non-keratinising epithelium
What are the 9 laryngeal cartilages?
Single:
epiglottis
thyroid
cricoid
Double:
cuneiform
coniculate
arytenoid
What is the larynx innervated by?
CNX (everything’s bloody innervated by this)
What does the carotid sheaf contain?
Common carotid artery
Internal jugular vein
Vagus nerve
At what level is the thyroid gland?
C5-T1
At what level is the carina?
Level of sternal angle
What are the borders of the anterior triangle of the neck?
Superior - inferior border of mandible
Inferior -medial border of sternocleidomastoid
Medial - immaginare line down middle of neck
What is the mucociliary elevator?
Combination of sweeping movements by the cilia & mucus to trap inhaled particles & move them out of the airways to be swallowed & destroyed
What is the sensory innervation of the trachea?
Recurrent laryngeal nerve
Which main bronchus is shorter, wider & more vertical?
Right
Where are the Clara cells & what do they produce?
Bronchioles
Surfactant lipoprotein - prevents bronchioles from collapsing upon expiration
What are the 3 cell types found in alveoli?
Type I pneumocytes
Type II pneumocytes
Alveolar macrophages
What cells produce surfactant?
Type II pneumocytes
What does surfactant do?
Helps overcome the initial part of inhaling by reducing surface tension
What are the 3 main openings in the diaphragm?
Oesophageal hiatus (oesophagus, CNX) Aortic hiatus (aorta, thoracic duct, azygous vein) Caval opening (IVC)
What does the phrenic nerve innervate?
3Ps (sensory) Pericardium Pleura Peritoneum & diaphragm (motor) C345 keeps the diaphragm alive!
What do the azygous & hemiazygous veins drain?
Posterior walls of thorax & abdomen
Where does the azygous vein recieve blood from?
Ascending lumbar veins & right subcostal veins
What are the true ribs?
1-7
Attached directly to sternum
What are the false ribs?
8-10
Connected to the 7th rib by cartilage
What are the floating ribs?
11-12
Not attached anteriorly
In which direction do the external intercostal muscles run?
Inferioanteriorly
What is the action of the internal intercostal muscles?
Depress ribcage
What is the action of the pectoralis major?
Flexion, adduction, rotates the humerus (medially)
What is the innervation of the pectoralis major?
Medial & lateral pectoral nerves
What is the main action of serratus anterior?
To rotate the scapula, raising the arm
What is the innervation of the serratus anterior
Long thoracic nerve
What do the subcostal muscles do?
The same as internal intercostals (depress ribcage)
What muscle is continuous with the transverses abdominis?
Transversus thoracis
What are the 2 parts of the lung pleura?
Visceral (inner)
Parietal (outer)
How many lobes does each lung have?
L - 2
R - 3
What are the fissures of the lung?
Oblique
Horizontal
What is at the level of the sternal angle?
2nd rib
Describe the process of inspiration
- Motor neurone of phrenic nerve causes diaphragm to contract & flatten
- This increases the thoracic volume
- The chest wall moves away from the lung surface, which moves the parietal pleura away from the visceral pleura slightly
- Intrapleural pressure decreases, and transpulmonary pressure increases
- Pressure strong enough to overcome elastic recoil > lungs expand
- Volume of lungs increases > pressure decreases (Boyle’s law)
- When the pressure decreases below the atmospheric pressure, air is forced in
When do the neutrons in the dorsal respiratory group in the medullary respiratory centre fire?
During inspiration
What controls the basal rate of respiration?
The respiratory rhythm generator in the VRG of the medullary respiratory centre
What does the apneurstic centre do? (lower pons)
Fine tunes medullary inspiratory neuron output & helps terminate inspiration by inhibiting these neurons
What does the pneumotaxic centre do? (upper pons)
Smooths transition from inspiration to expiration
Where are the slowly adapting stretch receptors found, what are they stimulated by & what do they do?
Smooth muscle layer of airways
Stimulated by large lung inflation
Send afferent impulses to brain & inhibit medullary inspiratory neutrons in DRG
Where are the rapidly adapting stretch receptors found, what are they stimulated by & what do they do?
In between epithelial cells of airways
Stimulated by lung distension
Bronchoconstriction & an activity burst
What will a decrease in PO2 do?
Stimulate peripheral chemoreceptors
Impulses to medullary inspiratory neurons
Increase in ventilation rate
Give the dissociation equation involving CO2 & H2O
CO2 + H2O H2CO3 H+ + HCO3-
What are J receptors stimulated by?
Lie in capillaries/interstitium of lung
Stimulated by increase in lung interstitial pressure, caused by collection of fluid in interstitium
What are the effects of the stimulation of J receptors?
Rapid breathing
Dry cough
Sensation of pressure in chest
Dyspnoea
Where is the apex of the lung? (surface anatomy)
2 finger widths (patient’s fingers) above the clavicle
Lower margin of lungs are at what levels? (surface anatomy)
6, 8, 10
Where is the oblique fissure? (surface anatomy)
Along 6th rib
Where is the horizontal fissure? (surface anatomy)
Along 4th rib (only R)
What does a lower V/Q ratio mean?
Decreased ventilation in the area
Decrease in O2 content of arterial blood
Results in vasoconstriction of blood vessels to that area
What does a higher V/Q ratio mean?
Decreased perfusion in the area
Decrease in CO2 content of alveolar air
Results in bronchoconstriction of airways to that area
What are the 3 layers of the gas exchange pathway in the lungs?
Thin alveolar epithelial cells (usually type I pneumocytes)
Basement membrane
Capillary epithelium
What is the equation for percentage haemoglobin saturation?
O2 bound to Hb / maximum capacity of Hb to bind to O2
x100
What is the oxygen-haemoglobin dissociation curve?
As PaO2 increases, SaO2 increases (saturation)
An increase in PCO2, H+, temperature & DPG will do what to the dissociation curve?
Shift it to the right
At any given PO2, increasing one of these factors will decrease haemoglobin saturation (more PO2 is needed for the same saturation)
What will happen to the affinity of haemoglobin to O2 when a tissue’s metabolic activity increases?
It will decrease, delivering more O2 to the tissue
What is Dalton’s law?
The total pressure of a mixture of gases is equal to the sum of each of the gases as if it were present alone
What is Boyle’s law?
The volume of a container & the pressure within the container are inversely related
What is Henry’s law?
The amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above that liquid
Solubility is directly proportional to partial pressure
What is the alveolar gas equation?
PAO2 = PiO2 - PaO2/R
PAO2 - alveolar oxygen
PiO2 - inspired oxygen
PaO2 - arterial oxygen
R - respiratory quotient
What is Laplace’s law?
The pressure within an alveolus is directly proportional to the surface tension & inversely proportional to the radius
What is the CO2 + H2O reaction catalysed by?
Carbonic anhydrase enzyme
only present in erythrocytes
What is the chloride shift?
HCO3- moves out of erythrocytes via a transporter that exchanges them for a Cl-
Describe CO2 transport in the lungs
PCO2 is higher in the blood than in the alveolar space
CO2 diffuses into alveoli
Moves position of equilibrium to left
H+ + HCO3- combine to form H2CO3, which dissociates into CO2 + H2O
More CO2 can now diffuse out into alveoli
What does haemoglobin act as a buffer for?
H+ ions
What is the Henderson-Hasselbalch equation?
pH = pK + log( [A-] / [HA] )
What is hypoxia?
Deficiency of O2 at tissue levels
What are the causes of hypoxia?
Hypoxemia (reduced arterial PO2)
Anaemia
Ischaemic hypoxia (blood flow too low)
Histotoxic hypoxia (cell unable to utilise because of a toxic agent)
What is hypercapnia?
Increase in PCO2 in arterial blood
What are the causes of hypercapnia?
Hypoventilation
Lung disease
Inhaling too much CO2
Define respiratory failure
A condition in which there is insufficient gas exchange to maintain arterial O2 & CO2 levels
What is Type I respiratory failure?
Hypoxia but not hypercapnia
PaO2 low, PaCO2 normal
What is Type I respiratory failure caused by?
Low atmospheric pressure V/Q mismatch Avelolar hypoventilation Shunt in heart Asthma Pneumonia
What is Type II respiratory failure?
Hypoxia & hypercapnia
Low PaO2, high PaCO2
What is Type II respiratory failure caused by?
Increased airways resistance (asthma, COPD)
Reduced breathing effort (brainstem lesions, obesity)
Decreased lung area
Neuromuscular conditions
Head injuries affecting respiratory centres in the brain
Define tidal volume (500ml)
Volume of air moved in & out of lungs during quiet breathing
Define inspiratory reserve volume (3000ml)
Volume of air that can be inspired in addition to inspiration of tidal volume
Define residual volume (1000ml)
Volume of air that cannot be expired from lungs
Define vital capacity (5000ml)
Total volume of air that can be moved in & out of the lungs
Define functional residual capacity (2500ml)
Volume of air that remains in lungs during quiet breathing
Define FEV1
Forced expiratory volume in 1 second of expiration
What is the difference between a blockage of the upper & lower airways?
Upper - choking
Lower - obstructive lung disease
What are the differences between pulmonary and systemic circulation?
Pulmonary - thin vessel walls, minor muscularisation, lower pressure
Systemic - thicker walls, significant muscularisation
What are the 4 key changes in the ageing lung?
Chest wall compliance decreases
Respiratory muscle strength decreases
Elastic recoil decreases
Gas exchange becomes impaired
What are the 2 types of immunity?
Innate (requires no previous exposure)
Adaptive (requires previous exposure, immunological response)
What are the 3 main antibodies/immunoglobulins in an immune response?
IgM - produced at beginning of infection
IgG - highly specific
IgE - allergic response
What are the 4 types of hypersensitivity?
Gell & Coombs classification of inflammatory diseases
Type I - allergic, IgE
Type II - cytotoxic, IgG (attacks body’s own cells)
Type III - complexes, IgG (complexes on joints causing local inflammation)
Type IV - delayed, T-cell mediated
Where is histamine released from and what does it cause?
Mast cells in a Type I reaction
Causes inflammation, vasodilation, mucous secretion & smooth muscle contraction
What is the intrinsic tone of the airways controlled by?
Parasympathetic NS
ACh acts on cholinergic receptors on smooth muscle & causes them to contract
What type of muscarinic cholinergic receptor is found in the smooth muscle of the airways?
M3
What does adrenaline do to the airways?
Causes bronco dilation by acting on B2 adrenergic receptors in the airways
What are the steps of coughing?
- air inspired
- epiglottis closes, vocal cords shut
- abdominal & intercostal muscles contract forcefully
- intrathoracic pressure increases, narrowing trachea
- epiglottis & vocal cords open widely
- air expired
What do alveolar macrophages arise from?
Monocytes (WBCs) that circle in the blood
What are the 6 main functions of a neutrophil in an innate immune mechanism?
- identification of threat
- activation
- adhesion to the thread
- migration/chemotaxis
- phagocytosis
- bacterial killing
What is the role of B-lymphocytes?
Produce & release immunoglobulins
Becomes a plasma cell when activated
Antibodies bind to antigens & help in phagocytosis
What is the role of T-lymphocytes?
Secrete cytokines
What is respiratory epithelium?
Pseudostratified columnar ciliated interspersed with mucus secreting goblet cells
Which structures are lined by respiratory epithelium?
Nose Olfactory epithelium Oropharynx Larynx Trachea
What are the true vocal cords lined by?
Stratified squamous non-keratinizing epithelium
What are the bronchioles lined by?
Simple cuboidal epithelium
What are the alveoli lined by?
Simple squamous epithelium
What are the 7 layers of gas exchange?
1) alveolar epithelium
2) tissue interstitiel
3) capillary endothelium
4) plasma layer
5) red blood cell membrane
6) rbc cytoplasm
7) Hb binding forces
