Respritory system Flashcards
What structures can be found in the mediastinum? (6)
- Heart
- Phrenic nerve
- Cardiac nerves
- Vessels
- Oesophagus
- Trachea
Name the lobes in a dogs lung
- Left cranial lobe cranial and caudal part
- Right cranial lobe
- Right middle lobe
- Left and right caudal lobes
- Accessory lobe
Where in the body can the thoracic duct be found?
In the mediastinum
What two membranes make up the pleura?
- parietal pleura split into mediastinal and costal
- Visceral pleura
Describe the process of inspiration (6)
- External intercostal muscles contract
- ribs expand
- Volume in the lungs increase
- diaphragm contracts and flattens further increasing volume
- pressure decreases
- air I forced into the lungs
Describe the process of expiration (6)
- Internal intercostal muscles contracts
- ribs are moved in
- volume in lungs decreases
- diaphragm relaxes and expands further decreasing the volume
- pressure increases
- air leaves the lungs
What nerve innervates the diaphragm?
Phrenic nerve
What hiatuses are present in the diaphragm and what runs through them?
- Aortic hiatus - aorta
- Oesophageal hiatus - oesophagus
- Caval formamen - vena cava
Where does the diaphragm attach?
- cranial ventral border of L4 and the body of L3
- oblique attachment to 13th-8th rib
- xiphoid cartilage
How would you oscillate the lung fields?
Lungs don’t extend past the last rib so start in the last rib space and move cranially and listen most sides
How would you place a thoracic catheter and check its in the right place?
Insert the tube in the 10th intercostal space and tunnel subcutaneously to the 8th intercostal space. push through the intercostal muscles into the pleural cavity. radiograph to check position
How are the lungs able to move with the ribs even though they are not connected to them?
Changes in thoracic volume are translated to changes in lung volume via the pleura
Why does the cross sectional area of the right and left bronchi always increase that of the trachea?
Because resistance must not increases
What is the structure of bronchial smooth muscle?
Spiral bands of muscle that criss cross right and left around the bronchi and bronchioles
What is the importance of the bronchial muscles?
They regulate diameter an length to balance anatomical dead space against resistance to air flow
What is the importance of surfactant?
increases lung compliance by reducing surface tension
How is ventilation regulated?
A stimulus is detected and signals are sent to the brain to stimulate the muscles of ventilation less or more
What is tidal volume?
The normal amount of air displaced when inhaling and exhaling
What is minute ventilation and how is it calculated?
The volume of air inspired or expired per minute, tidal volume X frequency
What are the effects of ventilation perfusion mismatching?
It impairs gas exchange and could cause hypoxia or hypercapnia
How is perfusion effected by posture?
When a dog stands, half of the lung volume is above the pulmonary trunk, so perfusion in this area will be lower as blood must be pumped against gravity
What mechanisms can limit ventilation?
- Resistance to flow in airways
- Lung compliance
- Alveolar surface tension
- Where about the lungs is positioned
What is lung compliance?
The ability of the lung to stretch
What is expiratory reserve volume?
Amount of air that can be exhaled after a normal expiration
What is inspiratory reserve volume?
The amount of air that can be further inhaled after a normal inhalation
What is residual volume?
The air still left in the lungs after a forced exhalation
What is vital capacity and how is it calculated?
The maximum amount of air that can be moved into or out of the lungs in a single respiratory cycle, ERV + IRV + TV
What is inspiratory capacity and how is it calculated?
Total volume of air that can be inhaled, TV + IRV
What is functional residual capacity and how is it calculated?
Volume of air remaining after a normal expiration, ERV + RV
What is alveolar ventilation
The amount of gas that reaches the alveoli in a normal breath
what is dead space?
The volume of breath that doesn’t take part in gas exchange
What is minute ventilation?
Volume of gas inhaled and exhaled in a minute
What is respiratory rate?
breaths per minute
What is the forced expiratory rate?
How much air can be forced out of the lungs per second
What is total lung capacity and how is it calculated?
The total volume of air the lungs can accommodate, RV + IRV + TV + ERV
Which lung volumes may change during exercise? (6)
- Tidal volume
- IRV
- ERV
- FRC
- Respiration rate
- Minute ventilation
What medical conditions may involve ventilation perfusion mismatching? (4)
- Asthma
- Pneumonia
- Pulmonary edema
- Airway obstruction
Describe the neurological control of ventilation? (5)
- peripheral chemoreceptors in carotid and aortic bodies detect changes in PO2,PCO2,H+,K+
- information sent from carotid body via Cn IX
- information sent from aortic body via Cn X
- Central chemoreceptors in medullary surface detect PCO2 changes
- information sent via phrenic nerve to alter muscles of ventilation
What are the four metabolic functions of the lungs and which cells are responsible for this function?
-Angiotensin I-II conversion
-Breakdown of norepinephrine
-Breakdown of bradykinins
-degredation of prostaglandin
Neuroendocrine cells and enzymes
What are the main nerve supplies to the horn? (3)
- Cornual
- Corneal branch of infratrochlear
- Cutaneous branches from 1st and second cervical vertebrae
What are the main blood supplies to the horn? (3)
- Maxillary artery
- Cornual artery
- Superficial temporal artery
Which sinus is connected to the horn? and which compartment of this sinus is the horn connected to in cattle?
Frontal sinus, Caudal compartment of the frontal sinus
What is the clinical relevance of the horn being connected to a sinus?
When dehorning the sinus is exposed, leaving it open for infection
Why do you have to be careful dehorning goat kids?
The frontal sinus is very small and a small amount of heat can damage the brain
Within which sinus does the nasolacrimal duct run? What other structures can be found within this sinus?
Maxillary, teeth
Describe the sinus drainage of a horse (5)
- Dorsal conchal sinus and frontal sinus drain into frontomaxillary aperture
- Which drains into the caudamaxillary sinus which also provides the drainage for the sphenopalatine
- this drains into the nasomaxillay opening which receives input from the ventral conchal and rostral maxillary
- this drains into the middle meatus which receives input from the ethmoidal
- this drains into the sinus drainage angle
What is the role of the nasal structures? (7)
- Warm air
- Moisten air
- olfaction
- trap small particles with mucus
- trap large particles
- resist airflow
- heat exchange to cool arterial blood.
What structures protect the respiratory tract from infection?
- coughing and sneezing
- cilia
- mucous in trachea
- lymphoid tissue
- mucus in nasal tissue
How is fitness measured?
using Vo2max
What is VO2max?
The maximum capacity to transport and utilise oxygen during incremental exercise
How do you calculate vo2max?
maximum ml of oxygen consumed in a minute/body weight in grams
What defence mechanisms are present in the respiratory system? (5)
- commensals
- nose hairs
- mucus
- lymph tissue
- reflexes
What are the major lymph nodes of the head? (4)
- Mandibular
- Retropharyngeal
- tonsil
- parotif
What are the 2 main lymph nodes of the neck?
superficial and deep cervical
What are the 4 main lymph nodes of the thorax?
dorsal and ventral thoracic, mediastinal, bronchial
Explain the mechanisms of allergic bronchoconstriction (5)
- Antigen or allergen presence
- inflammation develops
- IGE binds to mast cells and basophils which release granules
- inflammatory mediates like histamine cause smooth muscle contraction
- bronchoconstriction and coughing occurs
What types of cells are present in the respiratory system to act as defence? (4)
- Cilia
- Goblet cells
- Antibodies in mucosa
- lymphocytes
Define cyanosis
Blue skin and/or mucus membranes due to poor circulation or inadequate oxygenation of blood
State some causes of cyanosis (4)
- pneumonia
- hypoventilation
- Brachycephalic airway problems
- heart abnormalities
Define hypoxia
a reduced amount of oxygen in the tissues
State some of the causes of hypoxia (5)
- Reduced ability of blood to get to tissues
- Reduced ability to carry oxygen in the blood
- reduced intake of oxygen
- reduced diffusion of oxygen from the lungs into blood
- Reduced ability of oxygen to leave haemoglobin
How can hypoxia be diagnosed? (4)
- Blood gas analyser
- Cyanosis
- Pule oximetry
- lactate levels
What are the physiological compensation effects of hypoxia?
- Decreased arterial pO2
- Increased activity on peripheral chemoreceptors
- Increased activity of respiratory centre
- increased ventilation
How can hypoxia and hypercapnia be managed? (2)
- ventilate
- manage the underlying disease
Why shouldn’t you give respiratory stimulants to a hypoxic or hypercapnic animal?
increase heart rate will increase oxygen demand to the heart making the situation worse
Define hypercapnia
increase amount of arterial carbon dioxide
What are the 2 main causes of hypercapnia?
- Decreased amount of gas exchange
- increased carbon dioxide production from respiring tissues
What are the physiological compensation mechanisms for hypercapnia? (5)
- increased arterial CO2
- increased pCO2 and so H+ in extracellular fluid in brain
- Increased activity of central chemoreceptors
- increased activity of respiratory centre
- hyperventilation
What is the cascade for oxygen diffusion? (4)
- mitochondria
- even flow
- reduced PO2
- Increased pCO2
What is the driving force for the reaction between oxygen and haemoglobin?
The oxygen tension in the pulmonary capillaries
What does ficks law of diffusion say?
the rate of transfer of a gas through a tissue sheet is proportional to the tissue area and the difference in partial pressure between the two sides, and indirectly proportional to the tissue thickness
What three factors affect perfusion in the lungs?
- PO2
- Alveolar ventilation
- O2 utilisation
Which factors govern diffusion at the tissues? (3)
- carboxyhaemoglobin
- methaemoglobinemia
- abnormal Hb molecules
What does the oxygen haemoglobin curve plot?
Oxygen saturation on the Y axis and partial pressure of oxygen on the X
What shape is the oxygen haemoglobin dissociation curve and why is it this shape?
Sigmoid shape due to cooperative binding of oxygen
How does bronchoconstriction occur? (5)
- increased stimulation of parasympathetic nerves
- M3 receptors activated
- decrease in cellular CAMP
- increase mucus secretion and bronchial smooth muscle contraction
- M1 receptors activated which increase mucus secretion
How does bronchodilation occur? (4)
- increased sympathetic stimulation
- Activation of B2 adrenoreceptors
- increase in cellular CAMP
- dilation of the airways
What methods can be used for inhaled drug delivery? (4)
- jet nebulisers
- spacer devices
- metered dose inhalers
- ultrasonic nebulisers
What are the three metabolic functions of the lungs?
- conversion of angiotensin I to II
- degredation of prostaglandins
- breakdown of norepinephrine
Where can the peripheral chemoreceptors be found and by which nerve are they innervated?
Aortic arch - vagus and carotid bodies - glossopharyngeal
Where can the peripheral baroreceptors be found and by which nerve are they innervated?
Aortic arch - vagus and carotid sinus - glossopharyngeal
How can lower and upper airway disease be distinguished?
Upper usually shows nasal and/or ocular discharge and lower usually shows dyspnea
Describe how a cough occurs (3)
- receptors in the mucus membranes detect a stimulus
- they cause a maximal inspiration and a forced exhalation against a closed glottis
- bronchial smooth muscle also contracts
What is bronchoconstriction?
A narrowing of the airways which restricts breathing
does bronchodilation affect compliance?
No
What are some of the ventilation issues during anaesthesia? (3)
- causes relaxation of pharyngeal muscles so swallowing
- causes relaxation of the tongue which can obstruct
- affects respiratory centres
What are the effects of recumbency on ventilation?
the weight of the lungs can reduce the amount of air that flows through them
What is a circuit factor?
A term used to describe the amount by which a tidal volume is multiplied in order to administer the correct amount of gas
Why is a circuit factor important?
It ensures the patient receives the right amount of gas
How would you calculate a fresh gas requirement with a T-piece? (3)
- estimate tidal volume
- calculate minute volume
- multiply answer by circuit factor
What is albuterol?
it is a beta-2 adrenergic agonist that causes bronchodilation
What 2 cat breeds are predisposition to asthma?
Siamese and himalayan breeds
How many joints does the rib make with the vertebrae and what are these joints?
2, one to the vertebrae body via the neck and one to the transverse process of the more caudal vertebrae via the tubercle
which direction do the fibres of the external intercostal muscles run?
caudoventrally
Where can the intercostal vein/artery/nerve be found in relation to the ribs?
Just caudal to each rib and parallel
What nerve supplies to diaphragm?
phrenic
What holes are present in the diaphragm?
- aoritc hiatus
- oesphageal hiatus
- cavel foramen
which part of the diaphragm is tendinous?
The inside
What is the function of the pleural cavity?
To establish adhesion, smooth movement, help the lung flow the movement of the diaphragm and thoracic wall
Where abouts in the skull does the hyoid apparatus join?
The temporal bone
Name the hyoid bones from dorsal to ventral (6)
Tympanohyoid Stylohyoid Epihyoid Ceratohyoid Basihyoid Thyrohyoid
What three intrinsic muscles are important in respiration and phonation?
- Cricoaryteniodeus lateralis
- cricoarytenoideus dorsalis
- cricothyroideus
What nerve supplies motor innervation to the cricothyroideus?
Cranial laryngeal from the vagus
What nerve innervates all the laryngeal muscles except the cricothyroideus?
recurrent laryngeal from vagus
What is the role of the cricoartenoideus lateralis?
To close the glottis
What is the role of the cricoaretenoideus dorsalis?
To widen the glottis
What mechanisms occur during swallowing?
- larynx moves rostral and dorsal
- epiglottis tilts back
- arytenoid cartilages move towards each other
What is the difference between where the larynx in found in horses ruminants and birds, and other species
found between the rami of the mandible in horses whereas its in the neck in other species
What joints are present between the laryngeal cartilages? and what types of joints are these?
-cricothyroid
-cricoarytenoid
synovial
What two important ligaments of the aretynoid cartilages are present, which is more medial?
- most medial, vocal fold
- vestibular fold
What structures pass through the guttural pouch? (5)
- Cn 7.9.10.11
- internal carotid artery
- internal maxillary artery
- pharyngeal lymph nodes
- stylohyoid
What connects the guttural pouch to the pharynx?
auditory tube
what is viborgs triangle and what structures make it up?
The cutaneous landmarks for the guttural pouch, tendon of the sternocephalicus, lunguofacial vein, caudal border of mandible
