Introduction to the respiratory system Flashcards
1
Q
What is the main function of the respiratory system?
A
- Delivery of 02 to the lungs for gas exchange and removal of CO2 produced by tissues out of the lungs
- I.e. external respiration
2
Q
What is external respiration?
A
- exchange of gases between atmospheric air and blood
3
Q
The respiratory system also has other important functions what are these?
A
- Acid-base balance (lungs and kidneys work together
- Immunity
- Thermoregulation (dog panting)
- site of metabolism/activation
- vocalisation/communication
4
Q
What does the upper respiratory tract (URT) consist of?
A
- nasal cavity (plus paranasal sinuses)
- pharynx
- larynx
- Trachea
5
Q
What does the lower respiratory tract (LRT) consist of?
A
- trachea
- bronchi and bronchioles
- alveolar ducts and alveoli
6
Q
In the URT where does the air enter?
A
- air enters via nose (and sometimes the mouth in some species)
7
Q
What determines whether mouth breathing is possible?
A
- anatomy of soft palate and larynx
8
Q
In the URT what are the left and right nasal cavities divided by?
A
- nasal septum
9
Q
What is found in the nasal cavities and what is it lined by?
A
- conchae AKA turbinates (scrolls of bone lined by mucosa)
- meatuses (openings/canals)
10
Q
What are the nasal cavities mostly lined by?
A
- respiratory epithelium = pseudostratified columnar epithelium
11
Q
Where is the pharynx found?
A
- at the region of cross-over between respiratory and alimentary tracts
12
Q
In the URT what is the purpose of the epiglottis?
A
- protects airway during swallowing
- flaps shut and prevents food going down the trachea
13
Q
What is the role of the conchae?
A
- filters air such as particulates
- ensures air comes into contact with olfactory surfaces
- humidifies air coming in
- degree of scrolls in species variable
14
Q
You can find paranasal sinuses within the skull - what are they?
A
- Diverticular of nasal cavity = blind ending spaces
15
Q
What animals have well developed paranasal sinuses?
A
- ox
- horse
16
Q
What are the function of the paranasal sinuses?
A
- thermal and mechanical protection (can warm up air as it enters or cool it down and prevents mechanical forces being transmitted directly to the brains)
- lightens head
17
Q
Why can paranasal sinuses cause clinical issues?
A
- narrow openings (blockage/access)
- lined by thin poorly vascularised respiratory epithelium (slow healing)
- roots of teeth (dental complications)
- frontal sinus extends into horns (in cattle)
18
Q
What are the roles of the pharynx in respiration?
A
- the common cavity through which air and ingesta pass
- connects oral cavity to oesophagus and nasal cavity to larynx
- pathway through pharynx depends on epiglottis and soft palate
19
Q
What is the dorsal border to the phalangeal area?
A
- base of the skull and C1-C2
20
Q
What is the ventral border of the phalangeal region?
A
- larynx and mandible
21
Q
What is the lateral border of the phalangeal region?
A
- pterygoid muscles and suspensory part of hyoid apparatus
22
Q
What is the rostral border of the phalangeal region?
A
- soft palate separates rostral pharynx into dorsal and ventral (nasopharynx and oropharynx)
23
Q
What does cuffing or folds of soft tissue around the pharynx cause?
A
- nose breathers
24
Q
What connects the pharynx to trachea?
A
- musculocartilagenous organs
25
What type of epithelium is found near the pharynx (which is different to the respiratory epithelium elsewhere)?
- stratified squamous keratinised epithelium
26
What does the larynx function to do?
- protect trachea (aspiration of material into lower airway)
- vocalisation (vocal folds)
- pressure build up (glottis closure) e.g., coughing and defaecation
27
There are bilaterally symmetrical cartilages that form walls of larynx - Describe the rest of the structure?
- cartilages connect hyoid apparatus rostrally and trachea caudally
- synovial joints between cartilages (except epiglottis - elastic connections to flap)
- connected by muscles and ligaments - moveable
28
The larynx is innervated by branches of the Vagus - what are these?
- cranial laryngeal nerve - branches off near larynx
- caudal (recurrent) laryngeal nerve - goes down to base of heart and back up to larynx
29
What does the recurrent laryngeal supply?
- supplies all intrinsic muscles except circithyroideus
30
What causes paralysis in horses (roarers) of the RL nerve?
- usually left
- inability to abduct arytenoid cartilage
- vibrates (roars) and obstructs airflow
31
Where does the trachea extend from and to?
- Extends from larynx to bifurcation (into bronchi) at base of heart
32
There are C-shaped hyaline cartilages in the trachea described these:
- connect longitudinally by fibroelastic tissue to from a tube
- dorsally incomplete, bridged by tracheal muscle
33
Why are the C-shaped cartilages of the trachea dorsally incomplete?
- to allow food boluses to come down
34
The mucosal surface of the trachea is lined with what types of respiratory epithelium? and what does it also contain?
- lined by ciliated pseudostratified columnar
- interspersed with goblet cells (mucus)
35
What does the trachea divide into and then what does it do?
- the left and right mainstem bronchi
- enters the lungs
- (tracheal bronchus in ruminants and pigs)
36
The bronchi are histologically similar to trachea - what do are they lined with and interspersed with?
- lined by ciliated pseudostratified columnar epithelium
- interspersed with goblet cells
37
What ae the walls of the bronchi supported by and what can this do?
- supported by cartilage and smooth muscle
- this can change diameter (bronchodilation/constriction)
38
What do bronchi give way to?
- smaller conducting airways, bronchioles
39
Bronchioles are histologically distinct from bronchi - what are there features?
- lined by variably ciliated or non ciliated columnar epithelium
- walls are composed of smooth muscle
- lack cartilage and glands
- smaller size
- club cells
40
All airways up until bronchioles are conducting airways - what are these?
- no gas exchange happens here
- anatomic dead space
41
What are the respiratory airways?
- bronchioles to alveoli
- gas exchange happens here
42
What is the acinus?
- is the functional unit
- terminal bronchial and its distal structures
43
What can happen to acinus during surgery?
- they can get squashed when the animal is lead on its side
44
What do respiratory bronchioles look like?
- cuboidal epithelium (club cells) which produce secretions and source of new cells
- discontinuous wall opening into alveoli
45
Alveoli have 2 types of cells - what are these and what do they do?
- flattened squamous epithelium (type 1 pneumocytes) for gas exchange
- cuboidal cells (type 2 pneumocytes) secrete fluid (surfactant) which prevents alveolar collapse (atelectasis)
46
What do alveoli have that helps prevent collapse and what aids in efficient movement of air?
- share adjacent walls which helps prevent collapse
- gaps in septum (pores of kohn) connect alveoli for efficient movement of air
47
What are the components of the blood-gas interface?
- close contact, single cell layers
- surfactant
- alveolar epithelial cell (pneumocyte)
- epithelial basement membrane
- connective tissue around alveolus (don't want too much)
- capillary basement membrane
- capillary endothelial cell
- blood plasma
- red blood cell
48
What do the lungs consist of?
- parenchyma (functional tissue)
- interstitium
49
What does the parenchyma (functional tissue) in the lungs consist of?
- bronchioles
- alveolar ducts
- sacs
50
What does the interstitium of the lungs consist of?
- elastic and collagenous soft tissue
- nerves
- glands
- blood
- lymph vessels
51
What are the lungs covered by?
- covered by pleura
52
What is pleura?
- serous membranes enclosing potential space and small amount of fluid
53
What are the two types of pleura and what do they line?
- parietal pleura lines thoracic walls
- visceral pleura covers lungs
54
What is the hilus medially?
- site of entry for all structures entering the lungs
- not covered by pleura
- blood vessels, airways, nerves entering lung
55
What are lung lobes?
- divisions based on infolding of pleura and primary branches of the left and right principal bronchi
56
The left lung has two lobes what are these?
1. cranial (sometimes subdivided)
2. caudal
57
The right lung has up to four lobes - what are these?
1. cranial (subdivided in ruminants)
2. middle (except horses)
3. caudal
4. accessory
58
What left and right lobes do dogs, cats and pigs have in their lungs?
- left = cranial (cr, cau)
- right = cranial, middle, caudal, accessory
59
What left and right lobes do cows, sheep and goats have in their lungs?
- left = cranial and caudal
- right = cranial (cr, cau), middle, caudal, accessory
60
What left and right lobes do horses have in their lungs?
- left = cranial and caudal
- right = cranial, caudal and accessory
61
Where is visceral pleura attached to and what does it contain?
- visceral pleura is attached to surface of lung including fissures and contains abundant elastic fibres
62
Parietal pleura lines the wall of the thoracic cavity and can be divided into 3 parts - what are these?
- Costal pleura lines inside of thoracic wall (rib cage)
- diaphragmatic pleura lines the cranial surface of the diaphragm
- mediastinal pleura lines the mediastinum
63
What is the diaphragm?
- musculotendinous sheet separating thoracic and abdominal cavity in mammals
64
Describe the structure of the diaphragm:
- central tendon portion
- openings for passage of structures e.g., aorta, oesophagus, vena cava
65
What does the diaphragm do?
- derives volume change of thorax and therefore negative pressure for breathing
66
The parietal pleura continue from thoracic walls over what? - and what does the pleura do here?
- over thoracic surface of diaphragm
- pleura reflects back on itself due to convex shape of diaphragm
67
What can the mediastinum be affected by?
- diseases such as tumours
68
What is the mediastinum?
- compartment between left and right pleural sacs
69
The mediastinum contains most (non-lung) thoracic structures what are these?
- heart in pericardiac sac
- trachea and oesophagus that are within thorax
- thymus
- mediastinal LNs
- great vessels (crania vena cava, aorta etc.)
- nerves including vagosympathetic trunk
70
What does the mediastinum not contain?
- lungs
- caudal vena cava (contained in its own fold, plica venae cavae)
- right phrenic nerve
71
What is the tidal volume?
- breathing volume at rest
72
What is the inspiratory reserve volume?
- extra air you can take in
73
What is expiratory reserve volume?
- extra air you can breathe out
74
What is residual volume?
- air that is constantly in the lungs as it keeps lung tissue slightly inflated
75
What is vital capacity?
- the maximum volume that can be breathed in and out
76
What is pulmonary circulation in the lungs?
- non-oxygenated blood from RV to lungs to LA
- gas exchange
- large volume, low pressure
- pulmonary arteries follow bronchi, veins do not always
77
What is bronchial circulation?
- From aorta to supply bronchial tree and its tissues
- low volume, high pressure
- oxygenated blood from LV to lungs to RV (via azygous)
78
What can also happen between bronchial and pulmonary circulation in the lungs?
- oxygenated blood to LA via anastomoses between bronchial and pulmonary circulation
- small right-to-left shunt
79
What does anastomoses between bronchial and pulmonary circulation help with?
- helps preserve lung tissue if the pulmonary supply becomes compromised
80
Describe the process of anastomoses:
- vasodilation of bronchial arteries increases flow
- increased blood flow is able to by-pass the obstructed pulmonary artery
- angiogenesis = new bronchopulmonary arterial anastomoses
81
Where does hypoxic vasoconstriction occur?
- in the lung pulmonary circulation
82
What does hypoxic vasoconstriction do?
- reflex vascular smooth muscle contraction
- areas that receive little alveolar oxygen also get reduced flow from the pulmonary artery
83
What does matching of ventilation and perfusion do?
- maximises oxygen exchange
