Resp Physiology And Anatomy Flashcards
What doctrine governs pressure within the cranium?
Monroe-Kelly doctrine
This doctrine considers the skull as a closed box.
What happens to CSF when there is an increase in mass in the cranium?
Loss of CSF
Once a critical point is reached, ICP rises sharply.
What is the critical volume of CSF loss that leads to a rise in ICP?
100-120ml of CSF
Beyond this volume, no further compensation can occur.
What occurs when pressure in the cranium equates with MAP?
Neuronal death
Herniation will also accompany this process.
How does the CNS autoregulate its blood supply?
Vasoconstriction and dilatation of cerebral blood vessels
Extremes of blood pressure can exceed this capacity.
What metabolic factor causes vasodilation in head-injured patients?
Hypercapnia
Important for ventilating head-injured patients.
What is the primary fuel the brain metabolizes?
Glucose
Falling glucose levels impair consciousness.
Which part of the brain coordinates automatic control of respiration?
Medulla
It controls respiratory rate and depth.
What is the function of the medullary respiratory center?
Controls inspiratory and expiratory neurons
Depressed by opiates.
Where is the apneustic center located?
Lower pons
Stimulates and prolongs inhalation.
What is the role of the pneumotaxic center?
Inhibits inspiration
Fine-tunes the respiratory rate.
Which gas levels are most important in ventilation control?
pCO2 levels
O2 levels are less important.
Where are peripheral chemoreceptors located?
Bifurcation of carotid arteries and arch of the aorta
They respond to changes in pO2, H+, and pCO2.
What do central chemoreceptors respond to?
Increased H+ in brain interstitial fluid
They do not respond to O2 levels.
What do stretch receptors in the lungs respond to?
Lung stretching
Causes a reduced respiratory rate.
What is pleural pressure?
Pressure surrounding the lung within the pleural space
During quiet breathing, pleural pressure is negative.
What determines lung size?
Transpulmonary pressure
Difference between alveolar pressure and pleural pressure.
What are Type 1 pneumocytes?
Very thin squamous cells covering 97% of the alveolar surface
Critical for gas exchange.
What is the role of Type 2 pneumocytes?
Secrete surfactant
They can differentiate into Type 1 pneumocytes during lung damage.
What is surfactant primarily made of?
Phospholipids, carbohydrates, and proteins
The main component is dipalmitoyl phosphatidylcholine (DPPC).
What is the effect of surfactant on alveoli?
Reduces alveolar surface tension
Helps prevent alveoli from collapsing.
What is the definition of lung compliance?
Change in lung volume per unit change in airway pressure
It indicates the lung’s ability to stretch.
What can cause increased lung compliance?
Age, emphysema
Emphysema results from loss of alveolar walls.
What can cause decreased lung compliance?
Pulmonary edema, pulmonary fibrosis, pneumonectomy, kyphosis
These conditions restrict lung expansion.
Where does the trachea bifurcate?
Upper border of T5 vertebra
Extends from C6 vertebra to T5.
What supplies arterial blood to the trachea?
Inferior thyroid arteries
Venous supply is from the thyroid venous plexus.
What is the anterior relation of the trachea?
Isthmus of the thyroid gland, inferior thyroid veins, etc.
Includes the manubrium and remains of the thymus.
What structures are found laterally to the trachea in the neck?
Common carotid arteries, thyroid gland lobes
Also includes inferior thyroid arteries and recurrent laryngeal nerves.
What are the lateral relations of the trachea in the thorax?
Pleura and right vagus on the right; left recurrent nerve and aortic arch on the left
Includes left common carotid and subclavian arteries.
What is the superior root of the ansa cervicalis?
Branch of C1 anterolateral to carotid sheath
What is the inferior root of the ansa cervicalis derived from?
Derived from C2 and C3 roots, passes posterolateral to the internal jugular vein
Which muscles are innervated by the ansa cervicalis?
- Sternohyoid
- Sternothyroid
- Omohyoid
Where does the ansa cervicalis lie in relation to the carotid sheath?
Anterior to the carotid sheath
What is the incidence rate of cervical ribs?
0.2-0.4%
What symptoms do most cases of cervical ribs present with?
Neurological symptoms
What is a common anatomical feature of cervical ribs?
Anomalous fibrous band that often originates from C7
What clinical sign may indicate compression of the subclavian artery due to cervical ribs?
Absent radial pulse and positive Adson’s test
What is the traditional operative method for excision of cervical ribs?
Transaxillary approach
What are the general indications for chest drain insertion?
- Trauma
- Haemothorax drainage
- Pneumothorax or pleural effusion drainage
What is the preferred method for chest drain insertion?
Anatomical guidance
In which area should chest drains be placed?
Safe triangle
What borders define the safe triangle for chest drain insertion?
- Anterior edge latissimus dorsi
- Lateral border of pectoralis major
- A line superior to the horizontal level of the nipple
- Apex below the axilla
What is the triangle of auscultation bounded by?
- Above: trapezius
- Below: latissimus dorsi
- Laterally: vertebral border of the scapula
What structures perforate the diaphragm at level T8?
Inferior vena cava
What structures perforate the diaphragm at level T10?
Oesophagus, vagal trunk
What structures perforate the diaphragm at level T12?
- Aorta
- Thoracic duct
- Azygos vein
What is the approximate length of the external auditory meatus?
2.5 cm long
What are the three anatomically distinct regions of the ear?
- External ear
- Middle ear
- Internal ear
What is the function of the organ of Corti?
Sense organ of hearing
What is the innervation of the middle ear?
Glossopharyngeal nerve
What is the diameter of the tympanic membrane?
Approximately 1 cm
What forms the laryngeal skeleton?
A number of cartilaginous segments
What are the paired cartilages of the laryngeal skeleton?
- Arytenoid
- Corniculate
- Cuneiform
What are the single cartilages of the laryngeal skeleton?
- Thyroid
- Cricoid
- Epiglottic
What is the function of the vocal folds?
Control sound production
Which muscle abducts the vocal fold?
Posterior cricoarytenoid
What is the blood supply of the larynx?
Laryngeal arteries, branches of the superior and inferior thyroid arteries
What is the lymphatic drainage of the supraglottic part of the larynx?
Upper deep cervical nodes
What are the two lobes of the left lung divided by?
Oblique fissure
What is the apex of both lungs located above?
Approximately 4 cm superior to the sterno-costal joint of the first rib
What is the pleura’s relationship to the lung levels?
Runs two ribs lower than the corresponding lung level
Name the four paired paranasal air sinuses.
- Frontal sinuses
- Maxillary sinuses
- Ethmoid air cells
- Sphenoid sinuses
What is the carotid sinus?
Dilatation of the internal carotid artery containing baroreceptors
How many pharyngeal arches develop during embryonic growth?
Six
What is the muscular contribution of the first pharyngeal arch?
- Muscles of mastication
- Anterior belly of digastric
- Mylohyoid
- Tensor tympanic
- Tensor veli palatini
What is the skeletal contribution of the second pharyngeal arch?
- Stapes
- Styloid process
- Lesser horn and upper body of hyoid
What is the origin of the phrenic nerve?
C3, 4, 5
The phrenic nerve originates from cervical spinal roots C3, C4, and C5.
What does the phrenic nerve supply?
Diaphragm, sensation central diaphragm and pericardium
The phrenic nerve provides motor innervation to the diaphragm and sensory innervation to the central part of the diaphragm and the pericardium.
Where does the right phrenic nerve run in the superior mediastinum?
Anterior to right vagus and laterally to superior vena cava
The right phrenic nerve’s pathway is important for understanding its anatomical relationships.
What is the pathway of the right phrenic nerve as it enters the thorax?
Runs posterior to the subclavian vein and posterior to the internal thoracic artery
This pathway is crucial for surgical considerations and understanding potential complications.
What structures does the left phrenic nerve pass lateral to?
Left subclavian artery, aortic arch and left ventricle
The left phrenic nerve’s course is significant for cardiac and thoracic surgeries.
What are the two parts of the scalenus anterior muscle?
Anterior and posterior parts
The scalenus anterior muscle has two parts through which the subclavian artery passes.
What is the commonest incision utilized to access the heart and great vessels?
Median sternotomy
A median sternotomy is a standard approach in cardiac surgery.
What is the relationship of the left brachiocephalic vein during a sternotomy?
Important posterior relation at the superior aspect of the sternotomy incision
Awareness of this relationship is crucial to avoid vascular injury during surgery.
What does the suprascapular nerve innervate?
Supraspinatus and infraspinatus
These muscles are important for shoulder abduction and stabilization.
What is the transpyloric plane?
Level of the body of L1
The transpyloric plane is an important anatomical landmark in abdominal surgery.
Fill in the blank: The thoracic outlet is where the subclavian artery and vein and the _______ exit the thorax and enter the arm.
brachial plexus
The brachial plexus is critical for upper limb nerve supply.
True or False: The right phrenic nerve exits the diaphragm at T8.
True
The exit point at T8 is important for understanding its anatomical course.
What structures are associated with the transpyloric plane? (13)
- Pylorus of stomach
- Left kidney hilum
- Right hilum of kidney
- Fundus of gallbladder
- Neck of pancreas
- Duodenojejunal flexure
- Superior mesenteric artery
- Portal vein
- Left and right colic flexure
- Root of the transverse mesocolon
- 2nd part of the duodenum
- Upper part of conus medullaris
- Spleen
These structures are significant for understanding abdominal anatomy and surgery.
What is the mnemonic to remember the key structures of the transpyloric plane?
Larry’s Pancakes And Syrup Make Real Breakfasts Ridiculously Sweet, Damn Perfect And Delicious
This mnemonic helps to recall the 13 structures associated with the transpyloric plane.
What does the ‘L’ in the mnemonic represent?
L1 vertebral body
The L1 vertebral body is considered the backbone of the transpyloric plane.
What does the ‘P’ in the mnemonic stand for?
Pylorus
The pylorus is where the meal begins in the digestive process.
What is represented by the ‘A’ in the mnemonic?
Ampulla of Vater
The Ampulla of Vater is where bile and pancreatic juices mix.
What does ‘S’ refer to in the mnemonic?
Superior mesenteric artery
The superior mesenteric artery provides the main blood supply to the intestines.
What does the ‘M’ in the mnemonic indicate?
Midpoint between the suprasternal notch and pubic symphysis
This midpoint serves as a reference point for the transpyloric plane.
What does the ‘R’ in the mnemonic represent when mentioned for the first time?
Renal hila
The renal hila are associated with the kidneys, which control blood quality.
What does the ‘B’ stand for in the mnemonic?
Body of pancreas
The body of the pancreas is likened to the chef overseeing the kitchen.
What does the second ‘R’ in the mnemonic refer to?
Root of transverse mesocolon
This structure is compared to a tablecloth spread under the digestive organs.
What does ‘S’ refer to when it appears later in the mnemonic?
Spinal cord ends (conus medullaris)
The conus medullaris marks the end of the spinal cord.
What does ‘D’ denote in the mnemonic?
Duodenojejunal flexure
This is the location where the small intestine changes direction, likened to a pancake flip.
What does ‘P’ represent in the context of the mnemonic?
Portal vein formation
The portal vein is formed from the superior mesenteric vein (SMV) and splenic vein, supplying blood to the liver.
What does ‘A’ refer to when mentioned again in the mnemonic?
Apex of gallbladder
The apex of the gallbladder is likened to the syrup in this breakfast analogy.
What does the last ‘D’ in the mnemonic signify?
Deep inguinal ring
This structure is considered optional, representing dessert delivery in the analogy.
True or False: The spinal cord keeps the whole system upright and functioning according to the mnemonic.
True
The spinal cord is likened to a support system in the breakfast analogy.
