respiratory 2 Flashcards
1
Q
what is the normal position of the soft palate during breathing
A
1) free edge rostral to epiglottis in most species
2) soft palate very long in horses, hanging down beneath epiglottis ( ⇒ horses unable to breathe through mouth); sometimes displaced over epiglottis during exercise (causes partial obstruction)
3) brachycephalic dogs - long soft palate rests over epiglottis (⇒ problems with breathing) - excess soft tissues - in constant state of partial obstruction
2
Q
what occurs during deglutition
A
raised to stop food entering nasopharynx
3
Q
auditory tubes what also called, where located, what enter into, what surrounded by, function and when opened
A
formerly known as Eustachian tubes
• lead from middle ear cavity to open into lateral wall of nasopharynx (respiratory tract)
• partially surrounded by cartilaginous tube
• allow equalization of pressure between middle ear cavity and external environment
• entrance normally closed, but opens during swallowing
4
Q
what are the 3 parts of the ear and which is air filled
A
1) external
2) inner
3) middle - air filled
5
Q
guttural pouches what species found, what are they, what separated into and what lined with
A
- only in horses
- air-filled diverticula of auditory tubes - left and right pouches
- thin-walled, lined with respiratory mucosa
6
Q
guttural pouches where located, what do they sit on and what does it divide them into
A
- medial to mandible between skull and atlas (dorsally) and pharynx and proximal oesophagus (ventrally)
- moulded over stylohyoid bone, which divides each pouch incompletely into lateral and medial
7
Q
what is the guttural pouches associated with
A
facial (CNVII), glossopharyngeal (CNIX), vagal (CNX), accessory (CNXI), and hypoglossal (CNXII) nerves (motor innovation for the tongue); sympathetic trunk and internal carotid artery (major supply of blood to the brain), medial retropharyngeal lymph nodes
8
Q
guttural pouches what is the function, how drain and how to enter through surgery
A
function unknown, but possibly:
- buffering pressure changes around middle ear
- cooling of blood to brain (internal carotid a.)
• drain via auditory tubes into nasopharynx
• surgical approach through Viborg’s triangle:
- caudal border of mandible
- sternocephalicus tendon
- linguofacial vein
9
Q
larynx what is the wall formed by and what suspended by
A
- wall formed by the laryngeal cartilages and muscles
- suspended from skull by hyoid apparatus
10
Q
List the 6 hyoid bones, which are paired and which are fused in the horse
A
1) tympanohyoid cartilage - articulates with skull
2) stylohyoid bone - fused
3) epihyoid bone - fused
4) ceratohyoid bone
5) basihyoid bone - unpaired bone - connect the pairs of hyoid bones
6) thyrohyoid bone -
11
Q
what are the 3 main functions of the larynx and describe
A
1) connection between pharynx and trachea
2) protection of respiratory tract
- closure during swallowing (epiglottis, vocal folds)
- sensory innervation (⇒ coughing reflex)
3) vocalisation - vocal and vestibular folds - structures that cause vocalisation
- Two components:
○ phonation - production of sound
○ articulation - modification by structures of mouth and sinuses
12
Q
list the paired and unpaired laryngeal cartilages
A
• unpaired: - epiglottis - thyroid - cricoid • paired: - arytenoid
13
Q
arytenoid cartilages what position compared to thyroid cartilage, what are the two important structures that come off it, what type of cartilage and what is movement responsible for
A
- medial
- vocal process (vocal fold)
- muscular process (cricoarytenoideus dorsalis and cricoarytenoideus lateralis)
• part hyaline (more rigid cartilage), part elastic cartilage
• movement of arytenoids (at cricoarytenoid joint) responsible for closure of larynx
14
Q
circoid cartilage what does it form, where positioned compared to thyroid cartilage, what type of cartilage
A
- forms a ring and enlarged dorsally to form roof of larynx
- caudal and partially medial to thyroid cartilage
- hyaline cartilage
15
Q
epiglottis where positioned in larynx, what type of cartilage
A
- most rostral
- elastic cartilage (flexible)
16
Q
thyroid cartilage what made of and what form, what is special about it and what type of cartilage
A
- two lateral plated (wall of larynx) meet ventrally to form floor of larynx
- most rostral part thickened (adams apple) - also largest cartilage
- hyaline cartilage
17
Q
what are the 5 sturctures that make up the laryngeal cavity
A
1) laryngeal vestible
2) glottis
3) vocal fold
4) vestibular fold
5) laryngeal ventricle
18
Q
what is the laryngeal vestible, vestibular fold and laryngeal ventricle
A
- laryngeal vestibule - open rostral part of larynx
- vestibular fold - parallel to vocal fold, but more rostral
- laryngeal ventricle - pocket of mucosa between vestibular and vocal folds
- depth varies between species (particularly deep in horse)
19
Q
what is the glottis and what compromised of
A
where lumen narrows at caudal limit of vestibule
- comprised of arytenoid cartilages (dorsally) and vocal folds (ventrally)
20
Q
vocal fold what comprised of, where does it run ad function
A
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
21
Q
extrinsic laryngeal muscles where extend from and what are the two types and muscles within
A
• extend from components of larynx to other structures
• Pharyngeal constrictors:
- series of muscles forming walls and roof of pharynx
- most caudal pharyngeal constrictors attached to larynx
• Muscles that move larynx:
- thyrohyoideus
- sternothyroideus (draws larynx caudally)
- hyoepiglotticus (draws epiglottis ventrally)
22
Q
intrinsic laryngeal muscles name the 3 main ones and what they do
A
1) cricothyroideus - moves circoid cartilage dorsally - tense vocal folds
2) cricoarytenoideus dorsalis - moves artenoid cartilage pen vocal process - need to breath
3) thyroarytenoideus composed of m. vocalis and m. ventricularis - occupy vocal and vestibular folds
23
Q
what is the laryngeal innervation
A
- branches of vagus nerve (CNX) provide sensory innervation (coughing - protection)
1. cranial laryngeal nerve - branches off vagus nerve cranial to caudal nerve
2. caudal laryngeal nerve - from recurrent laryngeal nerve - branches from vagus in abdomen and goes up the neck before becoming the caudal etc
24
Q
what does the Cranial laryngeal nerve innovate
A
- motor to cricothyroideus (only one muscle)
* sensory to mucosa cranial to vocal folds
25
what does the Caudal laryngeal nerve innovate and what are complications with this nerve
• motor to all intrinsic muscles except cricothyroideus
• sensory to mucosa caudal to vocal folds
• damage to caudal laryngeal nerve has serious clinical implications
- Prone due to the tract of the nerve through the abdomen - partially common in horses
26
what is the larynx in birds supported by and function
• supported by cricoid and paired arytenoid cartilages (i.e. there is no epiglottis or other cartilages)
- not used for vocalisation
27
glottis in the bird what formed by, how closed and what is missing
- formed by arytenoids
- closed by reflex muscle actin during swallowing
- no vocal folds
28
carina
cartilage ridge at tracheal bifurcation (branching point)
29
trachea where bifurcates into what, what supported by, what muscle needed and where located
• bifurcates (branches) into two principal bronchi (left and right) at level of 4th-5th thoracic vertebrae
• supported by cartilage rings:
- incomplete dorsally in mammals (complete rings in birds)
- hyaline cartilage
• trachealis muscle: smooth (involuntary) muscle forming roof of trachea
- carnivores - outside, herbivores within the cartilage ring
30
bronchi structure, what type of bronchi
- similar structure to trachea but with cartilaginous plates instead of rings
1) principle bronchi - enters each lung - left and right
2) secondary bronchus split from primary etc
2) terminal bronchial - when no further branching
31
what is a bronchopulmonary segment
a segmental bronchus and the lung tissue which it ventilates
32
what is a pulmonary acinus
a respiratory bronchiole and the lung tissue which it ventilates:
- contains many alveoli (units of gas exchange), arranged in walls of respiratory bronchioles, alveolar ducts and alveolar sacs
33
ventilation in mammals what is the issue
structure of bronchial tree results in bi-directional movement of air through all airways
• at end of expiration, stale air remains in airways and alveoli
• on inspiration, fresh air mixes with stale air
- alveoli oxygen concentration always lower then air breathing in
34
development of the lower airways, what develop from and main structure involved
develop as outgrowth from embryonic foregut
- laryngotracheal groove:
○ forms in endoderm of floor of prospective oesophagus
○ lips of groove fold in and fuse ⇒ tube (= respiratory diverticulum):
35
steps in development of lungs from respiratory diverticulum
1) respiratory diverticulum continues to grow caudally into thoracic cavity and branches to form two lung buds
2) lung buds continue caudal growth giving rise to left and right principal bronchi
3) continued branching of bronchi to form smaller bronchi (embryonic day 25 in sheep - very early in embryonic development) and bronchioles
36
what are the 3 congenital defect in airway development
1) tracheo-oesophageal fistulas - failure of separation of caudal laryngotracheal groove from foregut - food enter respiratory tract
2) tracheal hypoplasia - abnormal narrowing of trachea
3) accessory lungs - extra lung bud usually abnormal site
37
trachea in birds, what supported by, is it palpable, where bifurcates
supported by complete (no dorsal gap (mammals)), overlapping cartilaginous rings
* palpable on right side of neck
* bifurcates dorsal to base of heart to form two principle bronchi
38
what is the syrinx, where located and what present
* vocal organ of bird
* located at bifurcation of trachea (partly in trachea, partly in bronchi)
* tracheal part: strong cartilages
39
bronchial openings in the bird what separated by, what does wall contain
- separated by vertical wedge-shaped cartilage - pessulus
- otherwise no cartilage in walls
- lateral and medial walls contain tympanic membranes:
○ produce sound by vibration of these membranes
40
bronchi how many secondary in fowl, what is the next branching how many of them and what can occur
secondary bronchi enter lung at regular intervals
- about 40-50 secondary bronchi in fowl
* parabronchi (tertiary bronchi):
- about 400-500 arise from each secondary bronchus
- 1-2 mm in diameter in fowl
anastomose with each other ⇒ loops between secondary bronchi
41
what are air capillaries and where located
- form loops from walls of parabronchi through lung tissue ⇒ back to parabronchi
where gas exchange occurs
42
what is the function of the air sacs and what connected to
- expansion of respiratory tract for air intake - used to push air through the lungs
- no gas exchange
- caudal group supply fresh air to lungs
- cranial group receive stale air from lungs and expel through trachea
- lighten body by extending into medullary cavities of pneumatic bones - lighten the bones:
- connected by secondary bronchi to lungs and principle bronchi
43
what is the function of the pneumatic bones in the bird
1) maximize size of respiratory system while minimizing weight - needed for flight
2) fracture can result in subcutaneous emphysema (air bubbles under skin)
44
what are the air sacs divided into and the names of them
1) cranial group
1. cervical
2. clavicular
3. cranial thoracic
4. cervicocephalic
2) caudal group
1. caudal thoracic
2. abdominal
45
list the cranial air sac groups are they paired or unpaired and where located
- Cervical: unpaired; within and adjacent to cervical and thoracic vertebrae
- Clavicular: unpaired, large; fills thoracic inlet and extends into sternum and humeri
- Cranial thoracic: paired; between sternal ribs, heart and liver
- Cervicocephalic: only some species (strong fliers); extends over head and along neck; communicates with infraorbital sinus - paranasal sinus in birds ⇒ direct communication with nasal cavity
46
list the caudal groups are they paired and unpaired and where located
- Caudal thoracic: paired; between body wall and abdominal viscera
- Abdominal: paired; caudodorsal abdominal cavity, extending into adjacent vertebral and pelvic bones
47
what occurs in inspiration and expiration in birds
* on inspiration, fresh air flows into lungs (pushes stale air out) and caudal air sacs, and stale air moves from lungs into cranial air sacs
* on expiration, air sacs are compressed (not the lung - no diaphragm) ⇒ fresh air pushed from caudal air sacs into lungs, and stale air expelled from cranial air sacs via trachea
48
why is bird ventilation more efficient than mammal ventilation and what maintains this
- airflow unidirectional - no mixing of fresh and stale air - concentration of oxygen is increased
- oxygen-rich air enters lungs during both inspiration and expiration
- - system has no valves, but unidirectional flow probably maintained due to anatomical orientation of secondary bronchial openings of cranial group of air sacs (bypassed by inspired air)
49
what type of epithelium is the nasal epithelium and what cell types are within
```
Pseudostratified columnar epithelium
Goblet cells
- wine glass mucus secreting cells
Basal cells
- Attached at base of epithelium
- Can differentiate into other epithelial cell types
Ciliated cells
- Each cell has 200-300 motile cilia
- Numerous microvilli
Brush cells
- Thick microvilli
- Sensory receptors associated with trigeminal nerve
```
50
olfactory cell what type of cell, structure and function
sensory cell
- Microvilli into lumen of the cell - bind odours changing polarity of the membrane - generation of AP in olfactory cell generates another AP down olfactory nerve
51
what cell types are present in olfactory epithelium and functions
1) bowmans glands - secrete serous solutions that wash away odours ready for the next odour
2) olfactory cells
3) sustenacular cell - metabolic and physcial support
4) basal cell - stem like cell
52
7 changes that occur on cellular and tissue level as airways get smaller
1) Columnar to cuboidal epithelium
2) Goblet cells become less
3) Lamina propria decreases in thickness
4) Smooth muscle prominent in bronchi, less in respiratory airways, absent in alveoli
5) C shaped cartilage rings in trachea become plates in small in smaller bronchi, absent in bronchioles
6) Clara cells evident in bronchioles
7) Mucous glands become less common, absent in bronchioles
53
structures present in the trachea in dog and ox and horse
Dog
Cartilage in trachea - almost complete ring - C shape
- Dorsal side gap with smooth muscle to bring airways together
- Tachialaris muscle sits in outside of ring
- Important in coughing and sneezing
Ox and Horse - the tachialiaris muscle sits on the inside of the ring
54
structures within bronchi how differ from trachea
1) Glands - mucus secreting glands
2) Lamina propria - blood vessels Conducting airways
3) Goblet cells within epithelium
4) Columnar epithelium
- Is shorter than the trachea
- Become more cuboidal
- Still have cilia
5) Smooth muscle
- Exists as a spiral doesn't completely go the full way around
6) Cartilage is present but more smaller plates
55
what is the function of the smooth muscle in airways
regulates calibre of the airways
56
what are the structures in the bronchioles and how different from bronchi
- No glands - lamina propria is very small - if produce mucus will block the airways
○ impede the flow of air
- No cartilage
- Smooth muscle control of airway calibre - can almost completely close
- Clara cells present
- elastic fibres - elastic recoil - keeps airway open in expiration
57
respiratory bronchioles structures and functions
Little bit of gas exchange is occurring due to the thin walls
Very flat cuboidal epithelium
Lamina propria doesn't exist, no blood vessels, gets all blood supply from capillaries from the heart
Small amount of smooth muscle
58
List the 7 defence mechanism of the respiratory system
1) Nasal hairs
2) *Cough & sneeze reflexes
3) Lymphoid organs - tonsils & adenoids - well enhanced immune system
4) *Epithelium (lumenal)
5) *Mucociliary clearance
6) *Specialised small airway defence cells (Clara cells)
7) Alveolar macrophages
59
what are the 4 functions of the columnar epithelium of the respiratory tract
* boundary to outside world
* interacts with immune cells
* secretes cytokines and mediators on activation - extension of the immune system
* allows dendritic cell processes to sample lumen particles
60
what is the mechanism of mucociliary clearance and what increases it
Glands secrete mucus, is very sticky and sit ontop of the cilia layer
Cilla - pericilia layer - serous layer is secreted allowing the cilia to beat (one direction) and moves the mucus up towards the trachea and out through the mouth
- increased with beta-2 agonists
61
what occurs with mucociliary clearance in cystic fibrosis
No longer get serious layer as ion channel deficiency so cilia get stuck in mucus and cannot clear
Problems with bacterial infections
62
what are clara cells and their function
- dome shaped cells
- nonciliated, secretory bronchiolar epithelial cells
- function as stem cells for repair in the bronchioles ciliated or nonciliated bronchiolar cells.
- secrete Club cell secretory protein (CCSP) and a solution similar to the component of the lung surfactant.
○ secrtete glycosaminoglycans, proteins such as lysozymes, and conjugation of the secretory portion of IgA antibodies
- Club cells engulf airborne toxins and break them down via their cytochrome P-450 enzymes
63
what are the 5 steps in the sneezing reflex
1. Irritant receptors in the nasal airways initiate protective reflex sneezing
2. Deep inspiration - build-up of pressure
3. Brief closure of the glottis
4. Contraction of respiratory muscles
5. Abrupt forced blast of air directed mainly through the nasal passages (Sneeze)
64
what are the 5 steps in the coughing reflex
1. Irritant receptors in the larynx and trachea (also pharynx & bronchi) initiate a protective cough reflex
- Up through the vagus nerve and glossopharyngeal nerve - cough centre in the brain
2. Deep inspiration
3. Brief closure of the glottis
4. Contraction of respiratory muscles
5. Abrupt forced blast of air directed through the mouth (cough)
65
what is bounds the thoracic cavity
- ribcage and intercostal muscles
- sternum
- thoracic vertebrae
- diaphragm
- thoracic inlet (opening bounded by 1st ribs, 1st sternebra and 1st thoracic vertebra)
66
what is the pleura called in the lungs, and what are the two types and the tw cavitites
1) pulmonary or visceral pleura - covers surface of all organs and vessels
2) parietal pleura - lines inner walls of thoracic cavity - 1. costal 2. diaphragmatic 3. mediastinal
67
define the following: sternopericardial ligament and plica venae cavae
- sternopericardial ligament: folds of pleura attaching heart to sternum
• plica venae cavae: fold of pleura suspending caudal vena cava
68
mediastinum what does it enclose, the divisions and how vary with species
```
• encloses thymus, heart, trachea, oesophagus, major thoracic vessels and nerves
• divisions:
- cranial mediastinum - cranial to heart
- middle mediastinum - containing heart
- caudal mediastinum - caudal to heart
•- thick in ruminants
- thin and incomplete in horse and dog
```
69
what is required for inspiration, when used and what made up of
- requires active muscular contraction
1) diaphragm - attachments - transverse process of first 2-3 lumbar vertebrae, internal thoracic cavity of abdomen, caudal end of sternum
2) external intercostal and scalenus muscles
- only used with forced inspiration and draws ribs cranially and laterally - expansion of thorax
70
what are the two types of expiration and what do they use
1) normal passive expiration - relaxation of the diaphragm - utilises elastic recoil of lungs
2) active expiration - when requirement for expiration elevated
- internal intercostal and abdominal muscles (put pressure on diaphragm)
71
what is the innervation for the muscle of ventilation
- diaphragm innervated by phrenic nerve, which originates from spinal cord in 5th- 7th cervical nerves
- If injury in thoracic or lumbar region, will still have innovation as other muscles innervated by intercostal nerves
72
mechanical source of ventilation in birds
- muscle in thoracic wall are active throughout inspiration and expiration
-- on inspiration, ribs are drawn forwards and outwards and sternum lowered
Air sacs expands resulting in increasing volume - the lungs don't expand
73
what is atmospheric and alveolar pressure and do they change
Atmospheric pressure: 760 mm Hg at sea level - lower when go higher altitude
Alveolar pressure: ~ 760 mm Hg when muscles of ventilation relaxed or fixed and glottis open
- transient changes: decreased during inspiration increased during expiration
- increased when muscles compress thorax against closed glottis
74
what is the intrapleural (intrathoracic) pressure and what pressure gradient is important in maintaining pressure
Intrapleural (intrathoracic) pressure: ~ 756 mm Hg
Transmural pressure gradient:
- difference between alveolar and intrapleural pressure
- Pleural cavity pressure is always lower - only a tiny different
75
list the 5 steps of inspiration
contraction of diaphragm
⇓
expansion of thorax
⇓
drop in pressure in pleural cavity (754 mm Hg) - maintain transmural pressure gradient
⇓
expansion of lungs and drop in intra-alveolar pressure
⇓
airflow down pressure gradient into lungs (until pressure equal to
atmospheric)
76
list the 4 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
77
what occurs in active inspiration and expiration
- contraction of accessory muscles of inspiration together with diaphragm ⇒ increase in thoracic volume above resting inspiratory volume ⇒ greater drop in intra-alveolar pressure and greater pressure gradient
- contraction of muscles of expiration together with relaxation of diaphragm ⇒ reduction in thoracic and lung volume below resting volume ⇒ greater increase in intra-alveolar pressure ⇒ greater pressure gradient ⇒ faster and more complete emptying of lung
78
pneumothorax what is it, what does it result in, and what species worse in
- 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 mediastinum remains intact to prevent second lung collapse - speices without complete mediastinum more severe problem
79
what is the more beneficial way to increase pulmonary ventilation
by increasing tidal volume than by increasing respiratory rate (because all additional air taken in is available for gas exchange)
- Mostly increase tidal volume (breath deeper) and respiratory rate
80
what is the mechanism of allergic airway disease (heaves, feline asthma)
Activates
Mast cells
Dendritic cells - into lumen of airway
Eosinophils
Increase stimulation of sensory nerves - go up the brain for sneeze and cough reflex
Can result in oedema - impairment of gas exchange
Airway smooth muscle - is stimulated to constrict which closes up the airway
81
what are the two main treatment options for feline asthma and what are the aims of the treatment
1) bronchodilators
2) anti-inflammatory - stop overreaction of the immune system
• Aims of treatment are to
- control inflammation,
- minimise bronchoconstriction,
- minimise long term damage
82
steps in contraction and relaxation of smooth muscle
Contraction
- stimulus→ Ca++ release → Myosin +P → thin filament/thick filament engagement → contraction (lattice collapse)
• Relaxation steps
- Withdrawal of stimulus→ Ca++ uptake SR → Myosin loses P → thin filament/thick filament disengagement → relaxation (lattice normal shape)
83
what are the 3 classes of bronchodilators and what is the main one
1) Beta-2 adrenoceptor agonists - main ones used
2) Phosphodiesterase inhibitors
3) Muscarinic receptor antagonists
84
describe the mechanism of the beta-2 adrenoreceptor agonist
Stimulate beta receptors
Activate Adenylyl cyclase
Production cAMP
Activated PKA to remove Ca2+ back in SR, mitochondria or to the outside of the cell therefore inactivation of MLCK - bronchodilation, also increase in mucociliary clearance
85
List some of the beta-2 adrenoreceptor agonist and thier actions
Albuterolol - short acting
Salmeterol - longer acting
Long chain is non-polar - move through membrane of cell allowing longer duration of affect
Isoprenaline - acts on Beta 1 and Beta 2 receptors
- Therefore can act on beta 1 receptor in the heart causing increase in HR - heart failure with overdosing
clenbuterol - works best with anti-inflammatory, banned in racehorses
86
mechanism of phosphodiesterase inhibitors, effects and unwanted side effects
- block phosphodiesterase mediated breakdown of cAMP, and therefore causes relaxation of airways - bronchodilation, not as effective as beta agonist
- increased heart rate and increase in cardiac output
unwanted side effects
- CNS stimulation - tremor, nervousness
- diuresis as a result of increased renal blood flow
- narrow therapeautic window - GI symtoms with increasing dose, nausea
87
give example of phosphodiesterase inhibitors and its effects on inflammatory and structural cells
theophylline
inflammatory cells
- decrease number of eosinophils, decrease cytokines from macrophages, mast cells
structural cells
- airway smooth muscle - bronchodilation, increase leak of endothelial cell
88
Muscarinic receptor antagonists give two examples and mechanism and what are the two times you want to use it
Glycopyrrolate (aerosol or I/M)
• Ipratroprium (competitive muscarinic acetylcholine receptor antagonist)
- Activate muscarinic receptor results in constriction - block this activation results in bronchodilation
1) chronic obstructive pulmonary disease
2) dominant constriction due to vagal nerve stimulation
89
what is the other name for anti-inflammatory, mechanism and how work better
corticosteriods
- increase amount of beta 2 receptors by binding to internal receptor which acts in nucleus and inhibits transcription of inflammatory genes
- high effect in allergic disease
- works better with beta-2 adrenoceptor agonist (synergistic)
90
deposition of inhaled drugs how given, at what size and why
- Drugs ideally given as an aerosol
- Droplet size 2.5 microns in order for the drug to go to small airways
○ If higher then more likely in larynx, pharynx and trachea,
○ If lower then more likely to move through into blood and systemic circulation
91
what are the 3 other drugs used in airway disease and their action
1) anti-inflammatory
2) antitussives (cough suppreseants)
3) mucolytics - increase mucus clearnace, change character of mucus
92
values for normal and at excercise respiratory rate and upper respiratory tract airflow in a horse
```
Normal respiratory rate at rest
- 8-16 breaths per minute
Respiratory rate as result of exercise
- 150 breaths per minute
Upper respiratory tract airflow
- 240 Litres/minute
Respiratory tract airflow rate in response to maximal exercise
- 4500 litres/minute
```
93
what is the technical term for roar, what does it involve and cause
laryngeal hemiplegia
- Paralysis of the left arytenoid (usually left)
- Permanent problem
Iodopathic
94
why do you have a inspiratory noise with laryngeal hemiplegia and not at rest, when else can it occur
Inspiratory noise
- At exercise, negative pressure during inspiration pulls the paralysed left arytenoid cartilage into the laryngeal lumen, causing reduced airflow and turbulence
Why not as rest
- Large pressure isn't generated at rest therefore do not get the cartilage being pulled into laryngeal lumen - no obstruction
Can also occur with floppy soft palate
95
what is the muscle that abducts arytenoid cartilage
Dorsal cricoartyenoidues
96
what structures are involves with the laryngeal tieback procedure
- The laryngeal ventricle was everted and excised and two sutures were placed between the cricoid and arytenoid cartilages on the left side
