Week 4 Flashcards
• List the functions of the upper respiratory tract.
○ Filter station to stop microorganisms and debris from reaching lungs-cleaning
○ Conduction of air
○ Humidifies air
Warm air
• Describe and illustrate the main anatomical structures of the upper respiratory tract.
○ Nasopharynx-from choanae to soft palate
§ Opening pharyngotympanic tube-eustachian tube
§ Pharyngeal tonsil=adenoid if enlarged
○ Oropharynx-between palate and superior border epiglottis
§ Palatine tonsil
§ Palatopharyngeal arch
○ Laryngopharynx (hypopharynx)-connects oropharynx and esophagus
Posterior to larynx until inferior border
• List the functions of the lower respiratory tract.
Respiration=ventilation-mechanical muscles, bones and cartilage used to get air into lungs + gas exchange of CO2, N2 and O2 from blood to lung and vice versa
• Describe and illustrate the main anatomical structures of the lower respiratory tract.
- Trachea-10 to 12cm from larynx (lower border cricoid cartilege to carina=T4
- Bronchi-2 mian bronchi branching off the carina
- Aorta passes left bronchus to descend posteriorly
- Azygos vein passes right bronchus
- Pulmonary arteries and veins on top and anteriori of main bronchi
- Right bronchus is shorter and wider and more straight left bronchus narrower more oblique
- Right lung has 3 lobes
- Left lung has 2 lobes
- Segmental bronchi for specficic regions
- 1 segment supplied by 1 airway and 1 larger airway and vein-they may be removed, lobes and lungs without affecting other untouched parts○ Alveoli-compoenents of alveolar wall
○ Alvoeolar epithelial cells-2 types
§ Type 1-cover alveoli mostyl-really thin for diffusion
§ Type 2 produce srufactance
○ 150-300 million in 1 adult SA-140 m2
Largest SA in body that is exposed to oither environment-skin=1.5-2m2
TRACHEA• Define the histological features of the lower airways (trachea to alveoli).
- Trachea
○ Mucosal layer
® Loose CT of lamina propria close to lumen
® Glands-seromucous glands (some serous some mucus)
® Macrophages, lymphocytes and plasma cells-deal with invasion of toxins or pathogens that can cross epithelium
® Elastic fibres form CT-cannot be distinguished from collagen fibres
® Smooth muscle(deeper part of mucosa or part of submucosa)-trachealis muscle joins posterior ends of C shaped hyalin catirlege rings
® Mucosal venules-wide diameter vessels with thin or attenuated walls
§ Sub mucosa
□ Dense fibrous CT
□ Hyaline cartilage-16 on rings to keep airways open for inflow and outflow of air
□ Large veins
□ Seromucous gland may be here-depends on distance from overlying respiratory epithelium
§ Adventitia
□ Outermost CT-wall merges into surorunding CT to anchor tube in place
□ Around cartilage CT perichondrium
□ Arteriole and venule may be here
BRONCHI AND BRONCHIOLES • Define the histological features of the lower airways (trachea to alveoli).
- Bronchi
○ More respiratory epithelim
○ Neuroendirne cells-kulchitsky cells
○ Smooth muscle
§ Mainly secrete catecholamines (fight or flight hormones) adranaline and also secrete, serotonin, calcitonin, bombesin- Bronchioles
○ Anything narrower than 1mm
○ Cilliated simple columnar epithelium
○ Surrouned by smooth muscle-bronchoconstrict, bronchodilate
○ Respiratory broncholes end in alveolar sacs and ducts
- Bronchioles
ALVEOLI • Define the histological features of the lower airways (trachea to alveoli).
- Alveoli
○ Air sacs in lungs at end of alveolar ducts
○ Adjacent alveoli-interalveolar septae
○ Alveolar walls lined by simple squamous epithelium
○ Septae has:
§ Very little smooth muscle
§ Abundant elastic fibre
§ Extensive capillary network
§ Alveolar epithelium
□ Type 1 alveolar cell/septal cell/pneumocyte
® Squamous for exhange
® Thin cytoplasm minimse distance for efficient gas exchange
□ Type 2 alvoelar cell
® Cuboidal cell
® More organelles for function to secrete surfactant onto alveoli-secretory granules (lamellar bodies) contain phospholipis, neutral lipids and proteins
◊ Secretions decrease alveolr surface tension
◊ Discourages surfaces from collapsing or sticiking with elastic recoil
◊ Don’t get water droplets forming
◊ Clear foreing materials
◊ Modulate alveolar immune response
® Located at septal juntions
® 5% air surface
□ Alveolar macrohpage (dust cell)
® Not part of epithelium, sits on top in alveolus
® Start off as monocytes in blood and differentiale to be macrophages
® Migrate into alveoli and back to septae
® Scavenge alveolar surface to remove perticular matter
® Remove escaped RBCs from septal CT
® Once role is over
◊ pass up bronchial tree via mucosillary escalator
◊ Remain in situ in septal CT
Moved to pulmonary lymph node
• Discuss the processes and structures involved in air modification.
l Air Modification
○ During inspiration the passage of air through nose achieves 3 things:
§ Warm by extensive surfaces of nasal septum and conchae
§ Humidification to almost full saturation
§ Filtraction achieved by turbulent airflow and entrapment by mucus coating airways
○ During expiration 2 related functions identifiec
§ Expired gas passing over cooling upper airways mucosa lead to return of some of its heat
§ Water can be reclaimed by condensation process
If someone is no longer airway breathing some functions may be lost
• Describe the mechanisms of ventilation.
- Ventilation
○ Anatomy
§ Muscles-diaghpagm, intercostal muscles
§ Bones and joints-ribs sternum vetrebral column (increase volume of thoracic cavity, has to have capacity to enlarge)
§ Membranes-pleura-parietal (outside) and visceral (inner)
§ Extracellular structures-elastic fibres
○ Control via nerves
§ Afferent-towards CNS-sensors and processors in BV lung and brainstem
§ Efferent phrenic nerves and intercortal nerves-tells diaphragm to contract or relax- Conduction of air
○ Upper airways (larynx and above) plus lower airways (larynx to respiratoy bronchiole) until respiratory zone of gas exchange
○ Air has to be modified in its way to lungs
§ Humidifaction-to add water vapour for efficient gas exchange
§ Warm it up-effieicnt gas exchange higher temp
§ Cleaned-no debris or pathogens interfering via immune response and mucocilliary escalatory
○ Upper airways-anotomical dead space-no gas exchange happens-150mL of normal breathing-tidal volume-TV per breath 500mL
○ Physiological dead space-anatomical dead space+ alveolar dead space (alaveoli that are not perfused with blood) - Gas exchange
○ Respiratory bronchioles and alveoli
○ Each bubble-invidiual alveoli
More capillaries more efficient gas exchange
- Conduction of air
• Outline the functional features and the role of pleura.
- Pleaura
○ 2 layers connected at lung hilum
○ Visceral pleura on top of lungs
○ Parietal pleaura inside ribcage and bordrring mediastinum
○ Is innervated by noireceptive fibres
○ Connected at lung hilum (pulmonary ligament)
Between layers is pleural fluid which contains low amount of immune cells and works as lubricant and adhesive
• List the structures and functions of the accessory respiratory muscles.
§ Muscles-diaghpagm, intercostal muscles
§ Bones and joints-ribs sternum vetrebral column (increase volume of thoracic cavity, has to have capacity to enlarge)
○ Ribs depend on contraction of intercostal muscle to enlarge lung ○ Pump handle-enlarge anterioly ○ bucket-enlarge laterally Diaphragm-deep in ribs pushes to where nipples are at expiration
• Describe the structural features of the blood-air barrier.
○ Components of Blood Brain Barrier § Alveolar 1 epithelial cell § Basmement membrane § Endothelial cell § Plasma § Erthyrcyte membrane □ Air travels from inner wall of alveolar epithelial cells then basement membrane then endothelial cell then plasma then erythrocyte membrane so O2 enters erythrocyte
• Outline the process of gas exchange.
- Air has to be humidified-because if not every expiration would remove water from the body
○ CO2 diffuses from blood into alveoli which adds additional 40mmHg=PO2 100mmHg
○ In alveoli, inspiration and expiration has the same amount of gases
○ Deoxygenated blood has a partial pressure of 40 for O2 and after it has to take O2 it has a partial pressure of 100- Partial pressure of O2 and CO2 in body resting
○ Trachea
§ PO2-149mmHg
□ Alveoli
® PAO2-100mmHg
® PACO2=40mmHg
□ Alveolar capillaries
□ Entering alveoli before gas exchange
® PAO2-40MMHg (relatively low as blood just returned from systemic circulation and has lost much O2)
® PACO2-45mmHg (relatively high as blood returning from systemic circulation has picked up CO2)
- Partial pressure of O2 and CO2 in body resting
§ Fick’s law-higher the concentration difference and the shorter the distance the better
§ Bigger area more gas diffused, hgiher pressure diff more gas diffused, bigger thickness less gas diffused
• Define the process of oxygen and carbon dioxide transport, (external respiration and gas exchange).
○ O2 transported either dissolved low amount or bound to the haemoglobin-cooperative binding
○ O2 shows cooperative binding
○ CO2 transported in blood either dissolved or converted to bicarbonate or bound to proteins in erythrocytes
○ N2 rapidly dissolves in blood in high amount
○ Unloading O2 in capillaries of the body outside the lung facilitates the loading of CO2-high concentration of CO2 diffuses into blood and uptake of CO2 facilitates release of O2 into tissue=Haldane effect
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- CO2 diffuses to interstitial fluid between cells converts to H2CO3 and ionises then H+ bind to plasma proteins slowly or can do this fast with carbonic anhydrase
H+ on haemoglobin is generated by CO2 makes it easier for O2 to be released as bicarbonate - charge is taken away then Cl with - charge is taken up via chloride shift to balance charge
• Describe the control mechanisms regulating respiration.
- Control of respiration
○ Input via peripheral and central chemoreceptors-processing-modulating of ventilation-voluntary control for speech
○ Gas exchange cannot be controlled but ventilation may be for speech
○ Peripheral chemoreceptors measure things in blood communicate info to nerves that go to CNS CNX and CN9 communicate to brain stem where central and peripheral chemoreceptors deliver info to central pattern generator-breathing patterns change with actions drugs-go to spinal chord and muscles of respiratory to affect ventilation
