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