Week 2 Respiratory Flashcards
1
Q
Define the nasopharynx. Name one significance
A
Region of the pharynx dorsal to the soft palate. Auditory tubes open into the nasopharynx (lateral wall)
2
Q
What is the significance of the soft palate?
A
Allows animal to breathe while chewing without aspiration of food. Also, stops food from entering the nasopharnynx as it raises during deglutition (swallowing).
3
Q
What is the normal position of the soft palate in most species?
A
Free edge rostral to epiglottis in most species
4
Q
Who has a long soft palate, what does this cause?
A
Horses and brachycephalic dogs- rests over or hangs down beneath epiglottis- horses unable to breathe through mouth- sometimes displaced over epiglottis during horses exercising
5
Q
What does the auditory tubes do?
A
Allow equilization of pressure between middle ear cavity and external environment
6
Q
When does the auditory tube close and open?
A
Normally closed but opens during swallowing
7
Q
What are guttural pouches?
A
Air filled diverticula of auditory tubes, thin-walled, lined with respiratory mucosa
8
Q
Where are the guttural pouches separated by?
A
Rectus capitis ventralis dorsally. Moulded over stylohyoid bone which divides each pouch incompletely into lateral and medial components.
9
Q
What nerves are guttural pouches associated with?
A
Facial (CN VII, 7), glossopharyngeal (CNIX 9), vagal (CNX), accessory (CNXI), and hypoglossal (CNXII)
10
Q
How do guttural pouches drain?
A
Via auditory tubes into nasopharynx
11
Q
What is the surgical approach through Viborg’s triangle?
A
Caudal border of mandible
Sternocephalicus tendon
Linguofacial vein
12
Q
What are the larynx’s walls formed by?
A
Laryngeal cartilage and muscle
13
Q
What is the larynx lined by?
A
Mucous membrane
14
Q
What is the larynx suspended from skull by?
A
Hyoid apparatus
15
Q
What is the function of the larynx?
A
Connection between pharynx and trachea, protection of respiratory tract (closure during swallowing), sensory innervation- coughing reflex, vocalization (vocal and vestibular folds)– phonation and articulation
16
Q
What are the unpaired laryngeal cartilages?
A
Epilgottis, thyroid, and cricoid
17
Q
What is the paired laryngeal cartilage?
A
Arytenoid
18
Q
What kind of cartilage makes up the arytenoid cartilage?
A
Part hyaline, part elastic
19
Q
At what joint and what is the movement of the arytenoids responsible for?
A
Cricoarytenoid joint responsible for the closure of the larynx
20
Q
Describe the cricoid cartilage
A
Forms ring, enlarged dorsally to form roof of larynx, caudal and partly medial to thryoid cartilage, hyaline cartilage
21
Q
Describe the epiglottis
A
Most rostral, elastic cartilage
22
Q
Describe thyroid cartilage
A
Largest, two lateral planes (walls of larynx) meet ventrally to form floor of larynx, most rostral part thickened (adam’s apple), hyaline cartilage
23
Q
What is the laryngeal vestibule?
A
Open rostral part of larynx
24
Q
What is the glottis?
A
lumen narrows at caudal limit of vestibule- comprised of arytenoid cartilages and vocal folds
25
What are the vocal folds?
comprised of m. vocalis and mucosal covering- runs from vocal process of arytenoid cartilage to floor of thyroid cartilage, position dependent on position of arytenoids, position controls diameter of glottis, air passing over vocal folds leads to phonation
26
What is the vestibular fold?
Parallel to vocal fold but more rostral
27
What is the laryngeal ventricle?
Pocket of mucosa between vestibular and vocal folds (particularly deep in horses)
28
What are the muscles that move the larynx?
Thyrohyoideus, sternothyroideus (draws larynx caudally), hyoepiglotticus (draws epiglottis ventrally)
29
What does the cricothyroideus do?
Moves cricoid cartilage (and arytenoid with it) dorsally thus tensing vocal folds
30
What does the cricoarytenoideus dorsalis do?
Abducts vocal folds
31
What does the cricoarytendoideus lateralis do?
Adducts vocal folds
32
What is the thyroarytenoideus composed of?
M. vocalis and m. ventricularis (occupy vocal and vestibular folds)
33
What innervates the laryngeal cavity?
Vagus nerve (branches of- CNX) sensory innervation to larynx and motor innervation to all intrinsic muscles of the larynx, cranial laryngeal nerve (motor to cricothyroideus/ sensory to mucosa cranial to vocal folds), caudal laryngeal nerve from recurrent laryngeal nerve (motor to all intrinsic muscles except cricothyroideus/ sensory to mucosa caudal to vocal folds/ damage to caudal laryngeal nerve has serious clinical implications
34
Where is the trachea located in the neck?
Ventrally
35
Where does the trachea bifurcate into two principal bronchi?
At the level of the 4th and 5th thoracic vertebrae
36
What species has complete rings on the trachea?
Birds
37
What kind of cartilage is in the trachea?
Hyaline
38
What muscle forms the roof of the trachea?
Trachealis (smooth muscle)
39
What are annular ligaments?
Connective tissue joining adjacent rings
40
What are carina?
Cartilaginous ridge at tracheal bifurcation
41
What is the sensory innervation in the trachea?
Mechanoreceptors sense foreign material or mucus to initiate cough reflex
42
What is the structure of bronchi?
Similar to trachea but with cartilaginous plates instead of rings
43
Go through the sequence of branching bronchi.
Principal bronchus--> lobar (secondary) bronchus-->segmental (tertiary) bronchus--> small bronchus--> bronchiole-->terminal bronchiole--> respiratory bronchiole--> alveolus--> alveolar duct--> alveolar sac
44
What is a bronchopulmonary segment?
A segmental bronchus and the lung tissue which it ventilates
45
What is a pulmonary acinus?
A respiratory bronchiole and the lung tissue which it ventilates- contains many alveoli arranged in walls of respiratory bronchioles, alveolar ducts and alveolar sacs
46
How does air move in the bronchial tree?
Bi-directionally
47
Where does the lower airways come from embryologically?
Develop as an outgrowth from embryonic foregut
48
Which side of neck is trachea palpable in birds?
Right side
49
Why is the syrinx?
Vocal organ of bird
50
Where is the syrinx located?
Birfurcation of trachea- partly in trachea, partly in bronchi
51
What is the pessulus?
Separates the bronchial openings- vertical wedge shaped cartilage- otherwise no cartilage in walls of birds bronchi
52
What is the role of tympanic membranes?
Produce sound by vibration
53
How many secondary bronchi are in fowls?
40-50
54
What are parabronchi or tertiary bronchi? How many are there?
Arise from secondary bronchi. 400-500. 1-2 mm diameter in fowl. Anastomose with each other- loops between secondary bronchi
55
What are air capillaries?
Form loops from walls of parabronchi through lung tissue back to parabronchi (where gas exchange occurs)
56
What are air sacs in birds?
Large thin-walled sacs connected by secondary bronchi to lungs and principal bronchi. Lie between organ (thoracic and abdominal viscera) no diaphragm.
57
Name the air sacs in birds? What are the two groups?
Cranial group- cervical, clavicular, cranial thoracic and cervicocephalic
Caudal group- caudal thoracic and abdominal
58
What is the role of air sacs in birds?
Act like bellows pushing air through lungs, caudal group supply fresh air into lungs, cranial group receive stale air from lungs and expel it through trachea-- allow unidirectional air flow
59
What happens in inspiration in birds?
Fresh air flows into lungs and caudal air sacs, stale air moves from lungs into cranial air sacs
60
What happens on expiration in birds?
air sacs are compressed--> fresh air pushed from caudal air sacs into lungs, and stale air expelled from cranial air sacs via trachea
61
What happens in both inspiration and expiration in birds?
Oxygen rich air enters lung during both inspiration and expiration
62
What type of epithelium is present in the nasal tract?
Pseudostratified columnar epithelium, goblet cells, basal cells (can differentiate into other epithelial cell types), ciliated cells (200-300 motile cilia), brush cells (thick microvilli, sensory receptors associated with trigeminal nerve), olfactory cells, sustentacular cells (support cells)
63
What types of glands are found in the respiratory mucosa of the nasal tract?
Nasal glands that are both serous and mucous secreting
64
What is the basic airway wall structure?
Epithelium, lamina propria, smooth muscle, cartilage, adventitia
65
As airways get smaller, how does tissue change?
Columnar to cuboidal epithelium, goblet cells become less, laminar propria decreases in thickness, smooth muscle prominent in bronchi, less in respiratory airways, absent in alveoli, C shaped cartilage rings in trachea become plates in smaller bronchi and absent in bronchioles, clara cells in bronchioles, mucous glands become less common and abesent in bronchioles
66
Bronchioles have no what? And what controls the calibre?
No glands and no cartilage. Smooth muscle control of airway calibre- elastic fibres as well
67
What are the defence mechanisms of the respiratory system?
Nasal hairs, cough and sneeze reflexes, lymphoid organs- tonsils and adenoids, epithelium (lumenal), mucociliary clearance (faster in larger airways due to faster beating of cilia), specialized small airway defence cells (clara cells), alveolar macrophages, remodelling of airway epithelium (increased collagen content- walls become thicker- allergen exposed)
68
How is columnar epithelium a defence mechanism?
Boundary to the outside world, interacts with immune cells, secretes cytokines and mediators on activation, allows dendritic cell processes to sample lumen particles
69
What is one airway defence mechanism that is stopped in Cystic Fibrosis?
Lack of mucociliary clearance
70
When MCC is impaired, such as in asthma, what kind of drugs can you use to increase MCC in diseased states?
Beta- 2 agonists
71
What is the role of clara cells? Describe them.
Protect bronchiolar epithelium. Dome shaped cells, nonciliated, secretory bronchiolar epithelial cells, function as stem cells for repair in the bronchioles ciliated or nonciliated bronchiolar cells, secrete Clara cell secretory protein (CCSP) and a solution like surfactant, secrete glycosaminoglycans, proteins such as lysozymes and conjugation of the secretory portion of IgA antibodies, clara cells engulf airborne toxins and break them down via their cytochrome P-450 enzymes
72
How does the sneezing reflex differ from the coughing reflex?
Source of irritation is in the nasal passages (vs. trachea and bronchi in coughing), APs are conducted along trigeminal nerve (CNV) to the medulla, where the reflex stimulus is processed and acted upon through efferent motor pathways, uvula and soft palate are depressed soair is directed throguh the nasal passages mostly, rapidly flowing air dislodges particular matter from the nasal passages and propels it a considerable distance from the nose
73
What are the steps in the sneeze reflex?
Irritant receptors in the nasal airways initiate protective reflex sneezing, deep inspiration, brief closure of the glottis, contraction of respiratory muscles, abrupt forced blast of air mainly through the nasal passages
74
What are the steps in the cough reflex?
Irritant receptors in the larynx and trachea (also in pharynx and bronchi) initiate protective cough reflex, deep inspiration, brief closure of glottis, contraction of respiratory muscles, abrupt forced blast of air directed through the mouth
75
What is one role of the thoracic cavity?
Mechanical source of ventilation
76
What does the pleura form within the thoracic cavity?
Forms mediastinum between two pleural cavities (two complete airtight cavities or sacs containing only a small amt of fluid)
77
What is the sternopericardial ligament?
Folds of pleura attaching heart to sternum
78
What is the plica venae cavae?
Fold of pleura suspending caudal vena cava
79
What is found in the mediastinum?
Mediastinum encloses the thymus, heart, trachea, oesophagus, major thoracic vessels, and nerves (cranial med., middle med. (contains heart), caudal med.)
Completeness and consistency vary between species- thick in ruminants- thin in horse and dog- can break down easily
80
What is the principal muscle of inspiration? What other muscles can be used during forced inspiration?
Diaphragm (thin sheet of muscle and tendon). External intercostals and scalenus muscles, e.g. during exercise (Expand the thorax by drawing ribs cranially and laterally)
81
How does expiration work? Forced expiration too?
Normal expiration is passive- utilizes the elastic recoil of lungs. Active expiration occurs when requirements for ventilation is elevated. Contraction of internal intercostal and abdominal muscles- reduces volume of thorax below equilibrium volume
82
Innervation of muscles of ventilation?
Diaphram innervated by phrenic nerve, which originates from spinal cord in 5th-7th cervical nerves, other muscles innervated by intercostal nerves
83
What is a coelom?
The area in the body of a bird- they have no diaphragm so not divided thorax and abdomen
84
What is alveolar pressure when muscles of ventilation are relaxed or fixed and glottis is open?
760 mm Hg
85
What is intrapleural (intrathoracic) pressure generally?
756 mm Hg. Subatmospheric pressure in pleural space. Creates a vaccum. Allows lungs to stay partially inflated when in a rested state.
86
What is the transmural pressure gradient?
Difference between alveolar and intrapleural pressure
87
What are the steps of inspiration?
Contraction of diaphragm--> expansion of thorax --> drop in pressure in the pleural cavity (754 mm Hg)--> expansion of lungs and drop in intra-alveolar pressure--> airflow down pressure gradient into lungs (until pressure equal to atmospheric)
88
What are the steps of expiration?
Relaxation of inspiratory muscles--> decrease in thoracic (and lung) volume--> increased intra-alveolar pressure (761 mm Hg in quiet expiration)--> airflow down pressure gradient out of lungs
89
What is the difference between forced and normal inspiration and expiration?
Use more muscles (or use muscles at all in expiration) and faster breather and emptying-- more complete emptying of lung as well
90
What is a pneumothorax?
Entry of air into pleural space due to trauma to lung or thoracic wall. Airflow into thorax results in loss of partial vacuum and lung collapse (atelectasis)-- important that mediastnum remains intact, so that second lung does not collapse
91
What is respiratory dead space?
The volume of airways that does not participate in gas exchange
92
What is anatomical dead space?
Not anatomically adapted for gas exchange. i.e. all airways from nose to terminal bronchioles i.e. conducting airways
93
What is physiological dead space?
Total volume of airways not participating in gas exchange Include anatomical dead space plus volume of any alveoli with inadequate circulation. Virtually identical to anatomical dead space in healthy animals.
94
What is tidal volume?
Volume of air breathed in or out in a single breath
95
What is pulmonary minute ventilation?
pulm. minute ventilation= tidal volume x resp. rate (breaths/min)
96
What is alveolar ventilation?
Alveolar ventilation= (tidal volume- dead space) x respiratory rate. The volume of air entering (or leaving) alveoli in one minute
97
More beneficial to increase pulmonary ventilation by increasing TV or respiratory rate?
More beneficial to increase pulmonary ventilation by increasing tidal volume than by increasing respiratory rate (because all additional air taken in is available for gas exchange). Due to the existence of dead space, not all air breathed in is available for gas exchange.
98
Example of tidal volume, resp. rate, dead space, pulm. minute ventilation, alveolar vent. in a human.
500 mL, 12 breaths/ min, 150 mL, 6,000 mL/min, 4,200 mL/min
