Flashcards in Respiratory System Deck (76):
Upper Respiratory Tract (URT)
- Nose & nasal cavity - paranasal sinus
URT: Nose and Nasal Cavity functions
- What does it provide?
- What does it do to the incoming air?
- What does sinuses increase? And serve as?
- Provide an airway for ventilation
- Filters and cleans the incoming air
- Moistens and warms the incoming air
- Sinuses increase mucosal surface area, and also serve as resonating chambers for speech
- Sense of smell - houses olfactory receptors
URT: Nose and Nasal Cavity functions
Nasal cavity features (8)
- Divided by what? - What is this made up of?
- What is posterior?
- What is on the roof?
- What is on the floor?
- What is on the lateral walls?
- What is the purpose of the structures?
- Divided in midline by nasal septum - hyaline cartilage (anterior) & bone (posterior)
- Posterior nasal aperture (nares) open into nasal pharynx
- Roof: ethmoid and sphenoid bones
- Floor: hard (anterior) and soft (posterior) palates
- On the lateral walls, there are three, mucosa-covered projections, the superior, middle, and inferior turbinates (conchae)
-These curved structures swirl the inspired air, so that heavier particles are deflected onto the mucosa
-The turbulence assist to clean the incoming air
What are the three mucosa-covered projections on the lateral walls?
- Superior turbinate
- Middle turbinate
- Inferior turbinate
URT: paranasal sinuses features (4)
- What is the group of sinuses (cavities) that surround the nose?
- What is the function of sinuses
- What do the sinuses allow
- What can mucous from the sinuses do>
- A group of sinuses (cavities) surround the nose - the frontal, sphenoid, ethmoid and maxillary sinuses
- Sinuses lighten the skull and help warm and moisten the incoming air
- Sinuses also allow sound resonance
- Mucous from the sinuses can block the drainage, and lead to a 'sinus headache'
URT: Pharynx (throat) features
- What type of tube is the pharynx?
- What does the pharynx connect?
- What regions the pharynx divided into?
Muscular tube (funnel-shaped) connects the;
- Nasal cavity to the oral cavity (mouth)
- Larynx and the esophagus
Divided into three regions
- The NASOPHARYNX, the OROPHARYNX and the LARYNGOPHARYNX
- Nasopharynx (above the soft palate) serves only as an air passage
URT: Nasopharynx features (5)
- Nasopharynx extends from?
- During swallowing, what happens?
- What drains into the nasopharynx?
- What happens when pharyngeal is infected?
- Posterior to nasal cavity
- Extends from the posterior nares to the soft palate
- During swallowing, the soft palate and the uvula swings posteriorly and superiorly, covering the nasopharynx, thus the nasal cavity
- The auditory tubes drain from the middle ear into the nasopharynx
- The posterior wall of the pharynx contains lymphoid tissue (pharyngeal tonsils or adenoids) - Infected pharyngeal can enlarge and restrict air flow = "adenoidal' voice
URT: Oropharynx features (6)
- Location of oropharynx?
- What passes through the oropharynx?
- What tissue does the oropharynx contain?
- Which one is commonly infected in children?
Posterior to the oral cavity and extending from the soft palate to the epiglottis
- Both food and air pass through the oropharynx
- Contains lymphoid tissue (palatine & lingual tonsils) - the palatine tonsils are commonly infected in children
- Epithelium changes in this region
- Stratified, squamous epithelium
- To prevent the throat from friction and chemical trauma during food ingestion
URT: laryngopharynx features (3)
- Location of the laryngopharynx?
- Extends to?
- During swallowing?
- The laryngopharynx is the region inferior the epiglottis
- Extends to the level where the respiratory and digestive tract diverge
- During swallowing, food has the 'right of way' over air and breathing is paused
URT: Larynx Features (4)
- What production?
- What does the larynx provide?
- Extends from?
- What protects and maintains an open airway?
- What does the larynx divert
- Sound/voice production
- Provides a patent airway - conducts air & protects the airway from collapse
- Extends from the region of the hyoid bone to level of the esophagus
- Nine cartilages protect and maintain an open airway
- Diverts air and food in proper directions (epiglottis)
URT feature (2)
- What type of epithelium?
- What is the region called where only air?
- Regions where air and food pass = stratified (layered) squamous (flattened) epithelium
- Regions where air only = respiratory (mucosa)
URT: Epithelium ('cells') features
- What is the vestibule lined with?
- What is the purpose of hairs?
- Vestibule, lined with skin that contains sebacous and sweat glands, and hair follicles (=protection)
- The hairs (vibrissae) filter coarse particles (dust, lint, pollen, ash etc) from the inhaled air
URT: Epithelium features (2)
- Location of the olfactory mucosa?
- what does it contain?
- What is the epithelium of the respiratory mucosa?
- Openings at the roof of the nasal cavity and contains sensory (smell) receptors (CN1)
- Pseudostratified, ciliated, columnar epithelium (containing goblet cells)
URT: Warming the incoming air feature (3)
- What warms the incoming air?
- What happens if the inspired air temperature drops?
- Where do nose bleeds originate from?
- Underneath the respiratory epithelium lies a bed of thin-walled veins, which warm the incoming air
- If the inspired air temperature drop, the vascular plexus responds by dilating and becoming filled with more blood, thus intensifying the heat transfer
- Nose bleeds originate from these thin-walled veins, which are close to the surface
URT: Runny nose features (2)
- What does the movement of cilia create?
- Why does your nose dribble (runny nose)?
- The movement of the cilia creates a slow moving current of mucus towards the pharynx, so that the contaminated mucus is swallowed and hydrolysed (digested) by stomach acid
- On a cold day the cilia in your nose 'cool down' and stop 'beating' - hence your nose dribbles = aka 'runny nose'
Regions of the lower respiratory tract (LRT)
LRT: Trachea to alveoli functions
- What does it conduct?
- What does this process complete?
- Where does gas exchange occur?
- Conducts air to/from site of gas exchange
- Completes the cleaning, warming and humidification of inhaled air
- Gas exchange occurs at the alveolus (Pl. alveoli)
LRT: Trachea functions
- What does the trachea maintain?
- What does cilia form? why?
- Maintain patent (open) airway for conduction of air
- cleans, warms and humidifies inhaled air
- Cilia form the mucociliary escalator to remove debris to the pharynx, and redirect to the stomach
LRT: Trachea features (4)
- Trachea location?
- Where does the trachea extend?
- What epithelium is the trachea lined with?
- What shaped cartilages?
What muscle is posterior?
- Trachea is anterior to esophagus
- Rigid tube from larynx to primary bronchus
- Lined with respiratory mucosa (epithelium)
- "C" shaped cartilages
- Trachealis muscle posteriorly
LRT: Brochial Tree arrangement
Trachea → 1* bronchi → 2* (lobar) bronchi → 3* (segmental) bronchi (>1mm) → Bronchioles (<1mm) → branching, branching.... → Terminal bronchioles (0.05mm)
LRT: Primary bronchi
- Located outside lungs
LRT: Intrapulmonary bronchi features (3)
- 2* to each lobe
- 3* to each lobule (segment)
LRT: Lung structure (5)
- Where is the lung situated?
- What region of the lung is apex?
- What region of the lung is base?
- Costal surface location?
- Hilum location?
- Right and left lungs are situated within two pleural cavities
- The 'apex' is superior region of a lung: near the clavicle
- The 'base' of a lung is inferior; sits on diaphram
- The costal surface - outer surface; against ribs
- The hilum - medial; structures enter/ exit
LRT: Right & Left lung
- Amount of lobes and fissures
- 2 lobes
- 1 fissure
- 3 lobes
- 2 fissures
LRT: Blood-gas barrier features
- The lungs have a LARGE surface area for gas exchange
LRT: Respiratory zone structure (2)
- What are the alveoli located in?
- Describe the walls of the alveoli
- Alveolar sacs are like bunches of grapes, containing many alveoli; the site of gas exchange
- The walls of the alveoli are very thin, a single layer of flattened epithelial cells with a thin basement membrane (aka the basal lamina)
LRT: Alveolus structure (3)
- What covers alveolus surface?
- What are the lung epithelial cells?
- what type of epithelial cells are they?
- What reduces surface tension of the alveolar fluid?
- Dense capillary network covering the surface
- 'Pneumocytes' (lung epithelial cells)
- Type 1 pneumocytes (squamous; epithelial cells)
- Type 2 pneumocytes (cuboidal; surfactant-secreting cells)
- Type 2 cells scattered amongst the type 1 cells
- Surfactant is a complex lipoprotein (phospholipid) that reduces the surface tension of the alveolar fluid
LRT: respiratory zone function (3)
- What is the external surface of the alveoli covered with?
- What forms the respiratory membrane (blood-air barrier)?
- The external surfaces of the alveoli are covered with a fine network of pulmonary capillaries
- The alveolar and capillary cell walls, and their joined basement membrane, form the respiratory membrane (aka the blood-air barrier)
LRT: epithelium structure
- What type of epithelium?
- What glands are underneath the epithelium?
- What do these glands secrete?
- What does respiratory epithelial cells secrete?
- Respiratory mucosa (pseudo stratified, ciliated columnar epithelium, containing goblet cells) is present in most of the LRT
- Underneath the epithelium are mucous and serous glands (seromucous)
- Mucous cells secrete mucus, and serous cells secrete a watery fluid (seromucous) containing mucous & enzymes
- Respiratory epithelial cells secrete defensins, antibacterial/antifungal prions
RT: Epithelial & Structural changes
- What occurs to epithelial cells as height changes?
- What happens to the cartilage support as the bronchi decrease in diameter?
- What is not found in the bronchioles or alveoli?
- What removes any inhaled debris that reaches the bronchioles or alveoli?
- Epithelial cells decrease in height
- Cartilage support decreases as the bronchi decrease in diameter
- No cilia, or mucous-secreting cells are found in the bronchioles or alveoli
- Macrophages remove any inhaled debris that reaches the bronchioles or alveoli
- P1V1 = P2V2
- Mechanisms of pulmonary ventilation
Body cavities (volume) structure
- Mediastinum → Pleural cavity → pericardial cavity → diaphragm → abdominal cavity → pelvic cavity
Thoracic cavity - boundaries
- Superior → clavicle → costosternal articulation → sternum (manubrium → body → xiphoid process) → lateral (intercostal ms/ribs) → costal cartilage → diaphragm ← inferior
What are the anterior thoracic joints?
Sternum to ribs
- Synovial (most) - Cartilaginous joints
What are the posterior thoracic joints?
What are the muscles of respiration?
- Accessory muscles
Muscles of the respiration - Diaphragm (1*) features (4)
- Location of diaphragm?
- What type of muscle?
- What innervates the diaphragm?
- When does it contract?
- Lower boundary of thoracic cavity, ie the thoracic floor
- Skeletal muscles
- Phrenic nerve (C3-C5) innervation
- Contracts during inspiration
Muscles of the respiration - Intercostals (2*) features (2)
- External intercostal location?
- Direction of muscle fibres?
- When are these muscles used?
- Internal intercostal location?
- Direction of muscle fibres?
- Superficial to internal intercostals
- Direction of muscle fibres inferior and medial (downward & forward)
- Deep to the external intercostals
- Direction of muscle fibres inferior and lateral (downward & backward)
- Forced expiration
Muscles of the respiration - Accessory features (2)
- When are they used?
- What muscles are they?
- Used during forced inspiration or expiration
- Muscles attached to clavicle or ribs, eg abdominal muscles
Thoracic cavity movement - pleura structure
- What lines the body cavities? what does it secrete?
- What covers the lungs?
- What covers the thoracic wall & mediastinum
- Serous membranes line body cavities and secrete serous fluid
- Visceral pleura - covers lung
- Parietal pleura - lines thoracic wall, mediastinum
- What does pleural fluid (serous) allow?
- Pleural fluid (serous) allows low-friction and adhesion
Thoracic cavity movement - Inspiration
- Requires alveoli pressure to be?
- Throracic size (volume)?
- Alveolar pressure?
- Vertical dimension thoracic cavity
- Requires alveolar pressure lower than atmospheric P
- Contract respiratory muscles
- Thoracic size (volume) increase
- Alveoli pressure decreases
- Diaphragm & external intercostal concentrically contract
- flattens inferiorly
- Vertical dimension thoracic cavity increases, therefore volume of thoracic cavity increase
Thoracic cavity - Expiration
- What type of process is expiration?
- Requires alveolar pressure to be?
- Relaxation of?
- Thorax size (volume)?
- Alveoli pressure?
- Mostly a passive process
- Cartilage and elastin tissue for recoil
- less energy used
- Requires alveolar pressure higher than atmospheric pressure
- Relaxation of respiratory muscle
- Thorax size (volume) then decreases
- Diaphragm moves upwards
- Alveoli pressure increases
More expiration needed?
- Forced expiration
- Internal intercostals
- Abdominal muscles
- Thorax size (volume) decrease
- Exchange of O2 & CO2 b/w what?
- External exchange?
- Transport of what?
- Internal exchange?
- Overall regulation of what?
- What does it do to air we breathe?
- Exchange of 02 and CO2 between the tissues and the environment
- External - Exchange of 02 and C02 between the atmosphere and blood flowing through the lungs
- Transport of gases by the blood
- Internal - gas exchange between capillaries and tissues
- Overall regulation of respiratory function
- Filters, warms and humidifies the air we breathe
What is the respiration steps
1) Ventilation (BULK FLOW)
- Process of moving air into and out of the lungs
- Supply O2 to and remove CO2 from the alveoli
2) Gas exchange (DIFFUSION)
- Exchange of O2 and CO2 across alveolar membrane (air to blood ie into body)
3) Gas transport (BULK FLOW)
- Deliver O2 from lungs to tissues and transports CO2 produced by metabolism to lungs (cardiorespiratory)
4) Gas exchange (DIFFUSION)
- Exchange of O2 and CO2 between capillaries and the cells
5) Cellular respiration (METABOLISM)
- Cells us O2 and produce CO2
- Partial pressure = fraction of individual gas x total gas P
Lung and chest wall separated by intra-pleural space features
- Lung has tendency to?
- Chest wall tends to?
- Lung has tendency to recoil inwards
- Chest wall tends to expand outward
- They pull away from each other
Inspiration series of events
1) Contraction of diaphragm + relaxation of expiratory muscles + contraction of chest-elevating muscles
2) Increase in vertical diameter of thorax + increase in anteroposterior and transverse dimensions of thorax
3) Decrease in intrapleural pressure + cohesion of visceral and parietal pleurae + compliance of thorax and lungs
4) Expansion of lung
5) Decrease in alveolar pressure
6) Establish pressure gradient
Expiration series of events
1) Relaxation of inspiratory muscles + Contraction of expiratory muscles
2) Decrease in size of thorax + Elastic recoil of lung tissue
3) Increase in intrapleural pressure
4) decrease in size of lungs
5) Increase in alveolar pressure
6) Pressure gradient from alveoli to atmospher
Airway resistance equation (Poiseulles Law)
R = 8nl/πr4
n = viscosity
l = length
r = radius
what is work of breathing?
Ventilation → pressure gradient → Airflow
Pulmonary function tests (spirometry): How much?
- 500ml (VT or TV). Volume of air moved in & out during normal quiet breath
Inspiratory reserve volume
- 3L (IRV). Extra volume that can be inspired with maximal inhalation - external intercostal muscles
Expiratory reserve volume
- 1.5L (ERV). Extra volume that can be exhaled with maximal effort - internal intercostal and abdominal muscles
- 1.2L (RV). Volume remaining in lung after maximal exhalation
What are the lung capacities
- 5L. Maximal breath into maximal out-volume of air you can shift in/outs
Total lung capacity
- 6L. Total volume in lungs when maximally full =VC+RV
- Tidal volume + IRV
Functional residual capacity
- 2.5L. Volume at end of normal breath out (equilibrium point for thorax/lungs)
What can spirometry identify?
- Increase resistance to airflow
- Chronic obstructive lung disease
chronic bronchitis and emphysema
- Decrease lung volume (reduced lung capacity)
- Reduced lung compliance (eg fibrosis): chest-wall
- Abnormalities: respiratory muscle disease
Pulmonary (mouth) ventilation (VE) equation
VE = frequency x VT
What is dead space?
- Some of the inhaled air never gets to the alveoli so cannot gas exchange - Known as DEAD SPACE (VD) - about 150ml
What is alveolar ventilation (VA)?
- Measures the flow of fresh gases into and out of alveoli
- VA = frequency x (VT-VD)
- Low VA = hypoventilation
- Extra VA = Hyperventilation
What is Ficks law of Diffusion? (explains gas exchange through the membranes
F = AD x (P1-P2)/T
- F = flux (amount flowing)
- A = surface area
- T = thickness
- D = diffusion constant
- P1-P2 = pressure difference
Features of Alveolar partial pressure of O2 (PAO2) - 100mmhg
1) PIO2 of inspired air
2) Alveolar ventilation VA
3) Oxygen consumption VO2
- The atmospheric PO2 is usually constant, so it is the balance between oxygen consumption and alveolar ventilation that is most important
Features of alveolar partial pressure CO2 (PCO2) - constant at 40 mmhg
PACO2 depends on:
1) PICO2 of inspired air
2) Alveolar ventilation VA
3) Carbon dioxide production VCO2
- Alveolar PCO2 is usually determined only by the balance between carbon dioxide production and alveolar ventilation, because atmospheric PCO2 is neglible
Typical Partial pressure (assume PB is 760)
- PO2 = 159
- PIO2 = 149
- PAO2 = 100
- PaO2 = 100
- PvO2 = 40
- PACO2 = 40
- PaCO2 = 40
- PvCO2 = 46
How is O2 transported
- O2 is carried in the blood in two forms:
1) Dissolved O2
2) Combined with haemoglobin
Dissolved O2 features
- For each mmHg PO2 can dissolve 0.3ml of O2 per 100 ml of blood
- Dissolved O2 = very ineffective for O2 transport
O2 combined with haemoglobin features
- O2 form an easily reversible combination with HB to give oxyhaemoglobin
- O2 + Hb equilibrium HbO2
- Binding depends on PO2 - dissociation curve - saturation
02 saturation features
- Arterial blood: PaO2 = 100mmHg → (SaO2) is ~97%
- Venous blood PvO2 = 40mmHg → (SvO2) is ~75%
What are the advantages of the sigmoidal shape of the curve?
1) Upper flat part of the curve
- small effect on the % saturation and therefore the amount of O2 carried by arterial blood
2) Steep part of curve at lower PO2
- Helps with loading of Hb in lungs AND unloading of O2 to the tissues
- Small changes in PO2 results in changes in amount of O2 bound to haemoglobin
- O2 content of arterial blood (ml O2/litre blood) = 200
- O2 content of venous blood (ml O2?litre blood) = 150
Arterial - Venous 02 difference
- a-v difference (200-150) + 50ml O2/Litre blood
Carbon dioxide Transport
CO2 is transported in 3 forms
1) dissolved in plasma - 20 times more soluble than 02 (10%)
2) As bicarbonate (70%)
3) Combined with proteins as carbamino compounds (20%)
Three basic elements (control of breathing)
1) Central control: brainstem
- sets pattern/rhythm of breathing
- Co-ordinates sensors & effectors to maintain respiratory homeostasis
2) Sensors: central/peripheral
- Gather chemical/physical info
- The respiratory centre receives a variety of neural & chemical inputs from central & peripheral receptors
3) Effectors: respiratory muscles
- Adjust ventilation
Respiratory control centre features
- Brainstem respiratory centre: neurons located in pons & medulla control rythemic nature of inspiration & expiration
- Medulla rsp. centre: DRG is inspiration & VRG is mainly expiration
- Cortex: can override/modify brainstem → voluntary control/ emotion (eg holding breath)
Features of the Central chemoreceptors (located medulla - brainstem)
- Most important for controlling breathing
- Sensitive to the PCO2 (but not PO2)
- CO2 diffuses out of the cerebral capillaries
- Changes pH of the ECF/CSF
- Central chemoreceptors respond to pH change
Features of peripheral chemoreceptors (located in the carotid & aortic bodies)
- Respond to decreased arterial PO2 (limited response to PO2 changes)
- Rapidly responding
Ventilatory response to CO2 steps
- What is the most important stimulus to ventilation?
- what is it tightly controlled at?
- Where does most of the stimulus come from?
- What does limiting breath holding increase?
- What is the ventilatory response to PCO2 decreased by?
1) PaCO2 is the most important stimulus to ventilation (tightly controlled +/- 3mmHg)
2) Most of the stimulus comes from the central chemoreceptor - peripheral chemoreceptors also contribute to an extent
3) limits breath holding - increase PaCO2 creates powerful drive to breathe
4) The ventilatory response to PCO2 is decreased by: sleep, Increased age, genetic factors, training & drugs
Ventilatory response to hypoxia (Low PO2)
- What is involved?
- What do you need PO2 to be less than to get a stimulation of ventilation by hypoxia?
- How do you get an increase response to hypoxia?
- When does hypoxic control become important?
- In long-term what is hypoxemia caused by?
1) only the peripheral chemoreceptor are involved
2) Theres negligible control during normal conditions - need PO2 less than 60mmHg to get stimulation of ventilation by hypoxia
3) Get increase response if hypercapnic (extra CO2)
4) Hypoxic control becomes important at high altitude, in long-term hypoxemia caused by chronic lung diease