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Flashcards in Respiratory System Deck (63):
1

Upper Respiratory Tract (URT)

- Nose & nasal cavity - paranasal sinus
- Pharynx
- Larynx

2

URT: Nose and Nasal Cavity functions

- Provide an airway for ventilation
- Filters and cleans the incoming air
- Moistens and warms the incoming air
- Sinuses increase mucosal surface are, and also serve as resonating chambers for speech
- Sense of smell - houses olfactory receptors

3

URT: Nose and Nasal Cavity functions
Nasal cavity features (8)

- 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

4

Lateral wall features (3)

- Superior
- Middle
- Inferior

5

URT: paranasal sinuses features (4)

- 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'

6

URT: Pharynx (throat) features (2)

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

7

URT: Nasopharynx features (5)

- 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

8

URT: Oropharynx features (6)

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

9

URT: laryngopharynx features (3)

- 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

10

URT: Larynx Features (4)

- 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)

11

URT feature (2)

- Regions where air and food pass = stratified (layered) squamous (flattened) epithelium
- Regions where air only = respiratory (mucosa)

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URT: Epithelium ('cells') features
- Nose

- 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

13

URT: Epithelium features (2)

Olfactory mucosa
- Openings at the roof of the nasal cavity and contains sensory (smell) receptors (CN1)
Respiratory mucosa
- Pseudostratified, ciliated, columnar epithelium (containing goblet cells)

14

URT: Warming the incoming air feature (3)

- 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

15

URT: Runny nose features (2)

- 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'

16

Regions of the lower respiratory tract (LRT)

- Trachea
- Bronchi
- Bronchioles
- Alveoli

17

LRT: Trachea to alveoli functions

- 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)

18

LRT: Trachea functions

- 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

19

LRT: Trachea features (4)

- Trachea is anterior to esophagus
- Rigid tube from larynx to primary bronchus
- Lined with respiratory mucosa (epithelium)
- "C" shaped cartilages
- Trachealis muscle posteriorly

20

LRT: Brochial Tree arrangement

Trachea → 1* bronchi → 2* (lobar) bronchi → 3* (segmental) bronchi (>1mm) → Bronchioles (<1mm) → branching, branching.... → Terminal bronchioles (0.05mm)

21

LRT: Primary bronchi features (2)

- Located outside lungs
- Right & left 1* bronchi - 'bronchus' (singular)

22

LRT: Intrapulmonary bronchi features (3)

- 2* to each lobe
- 3* to each lobule (segment)
- Bronchioles

23

LRT: Lung structure (5)

- 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

24

LRT: Right & Left lung
- Amount of lobes and fissures

Left lung
- 2 lobes
- 1 fissure
Right lung
- 3 lobes
- 2 fissures

25

LRT: Blood-gas barrier features (4)

- The lungs have a LARGE surface area for gas exchange

26

LRT: Respiratory zone structure (2)

- 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 thincbasement membrane (aka the basal lamina)

27

LRT: Alveolus structure (3)

- 'Pocket like'; open at one side
- 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

28

LRT: respiratory zone function (3)

- 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)
- Gas exchange occurs at this surface via simple diffusion

29

LRT: epithelium structure

- 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

30

RT: Epithelial & Structural changes

- 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

31

Boyles law

- P1V1 = P2V2
- Mechanisms of pulmonary ventilation
- Inspiration
- Expiration

32

Body cavities (volume) structure

- Mediastinum → Pleural cavity → pericardial cavity → diaphragm → abdominal cavity → pelvic cavity

33

Thoracic cavity - boundaries

- Superior → clavicle → costosternal articulation → sternum (manubrium → body → xiphoid process) → lateral (intercostal ms/ribs) → costal cartilage → diaphragm ← inferior

34

What are the anterior thoracic joints?

Sternum to ribs
Hyaline cartilage
- Sternocostal
- Synovial (most) - Cartilaginous joints
- Costochondral
- Cartilaginous
- Interchondral
- Synovial

35

What are the posterior thoracic joints?

- Costotransverse
- Costovertebral

36

What are the thoracic cavity contents?

- Right & Left lung
- Vertebra
- Primary bronchus
- Pulmonary artery
- Pulmonary vein
- Visceral & parietal pleura
- Intrapleural space
- Strernum
- Pulmonary trunk
- Heart

37

What are the muscles of respiration?

- Diaphragm
- Intercostals
- Accessory muscles

38

Muscles of the respiration - Diaphragm (1*) features (4)

- Lower boundary of thoracic cavity, ie the thoracic floor
- Skeletal muscles
- Phrenic nerve (C3-C5) innervation
- Contracts during inspiration

39

Muscles of the respiration - Intercostals (2*) features (2)

External intercostals
- Superficial to internal intercostals - Inspiration
- Direction of muscle fibres inferior and medial (downward & forward)
Internal intercostals
- Deep to the external intercostals - Forced expiration
- Direction of muscle fibres inferior and lateral (downward & backward)

40

Muscles of the respiration - Accessory features (2)

- Used during forced inspiration or expiration
- Muscles attached to clavicle or ribs, eg abdominal muscles

41

Thoracic cavity movement - pleura structure

- Serous membranes line body cavities and secrete serous fluid
- Visceral pleura - covers lung
- Parietal pleura - lines thoracic wall, mediastinum

42

Thoracic cavity movement - pleura - function

- Pleural fluid (serous) allows low-friction and adhesion

43

Thoracic cavity movement - Inspiration

- Requires alveoli pressure lower than atmospheric P
- Contract respiratory muscles
- Thoracic size (volume) increase
- Alveolar pressure decreases
- Diaphragm & external intercostal concentrically contract
- flattens inferiorly
- Vertical dimension thoracic cavity increases, therefore volume of thoracic cavity increase

44

Thoracic cavity - Expiration

- 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

45

More expiration needed?

- Forced expiration
- Internal intercostals
- Abdominal muscles
- Thorax size (volume) decrease

46

Respiration function

- 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

47

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

48

Daltons Law

- Partial pressure = fraction of individual gas x total gas P

49

Lung and chest wall separated by intra-pleural space features

- Lung has tendency to recoil inwards
- Chest wall tends to expand outward
- They pull away from each other

50

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
7) inspiration

51

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
7) Expiration

52

Airway resistance equation (Poiseulles Law)

R = 8nl/πr4
n = viscosity
l = length
r = radius

53

what is work of breathing?

Ventilation → pressure gradient → Airflow

54

Pulmonary function tests (spirometry): How much?

Tidal volume
- 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
Residual volume
- 1.2L (RV). Volume remaining in lung after maximal exhalation

55

What are the lung capacities

Vital capacity
- 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
Inspiratory capacity
- Tidal volume + IRV
Functional residual capacity
- 2.5L. Volume at end of normal breath out (equilibrium point for thorax/lungs)

56

What can spirometry identify?

Obstructive
- Increase resistance to airflow
- Asthma
- Chronic obstructive lung disease
chronic bronchitis and emphysema
Restrictive
- Decrease lung volume (reduced lung capacity)
- Reduced lung compliance (eg fibrosis): chest-wall
- Abnormalities: respiratory muscle disease

57

Pulmonary (mouth) ventilation (VE) equation

VE = frequency x VT

58

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

59

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

60

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

61

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

62

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

63

Typical Partial pressure (assume PB is 760)

O2
- PO2 = 159
- PIO2 = 149
- PAO2 = 100
- PaO2 = 100
- PvO2 = 40
CO2
- PACO2 = 40
- PaCO2 = 40
- PvCO2 = 46