Chest wall - OCT?? Flashcards
Which nerves supply the intercostal muscles?
Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves).
The diaphragm is innervated by what?
phrenic nerve
Which part of the brain stem initiates breathing?
Medulla Oblongata
A “cut” above c3 will cause which important muscle to cease work? What impact will this have?
Diaphragm. You’ll cease breathing!
The Lumsden transections are strong evidence for what?
The origin of spirometry rhythm in the medulla oblongata
What are the names given to the respiratory neurones in the medulla?
There are two symetrical groups on either side:
DRG: Dorsal respiratory group
VRG: Ventral respiratory group
DRG neurones fire during ____.
Inspiration (initiation)
VRG neurones fire mainly during ___.
During expiration.
Distributed network models refers to which hypothesis?
The respiratory rhythm begins in networks of respiratory neurones - not in any particular place - arising from distributed networks of neurones.
Single oscillator models refer to which hypothesis?
The hypothesis that there ARE distinct groups of neurones, that do generate rhythm in a specific place.
Multiple oscillator models refer to which hypothesis?
The hypothesis that there are several groups of neurones, each responsible for different aspects/phases of respiration.
What are the 4 stages of the group pacemaker mechanism hypothesis?
1 Post burst hyperpolarisation - Synapses silent
2 Recover - Endogenous activity resumes
3 Recurrent excitation - Positive feedback
4 Burst - Synaptic excitation evokes intrinsic currents
pBC means what? What is its relevance?
pre-Botzinger complex
Single oscillator hypothesis is supported (to a degree) by experiments showing this area as a site for respiratory rhythm generation.
It also drives output in the roots of the hypoglossal nerve.
The corticospinal tracts control ____ respiration
Voluntary
The corticospinal tracts control ____ respiration
Voluntary. Voluntary control arises from the motor and premotor cortex and descends in the cord in the corticospinal tract.
The anterior spinal tracts control ___ respiration
Automatic
Nasal Receptors trigger which reflexes?
Sneeze, Diving Reflex (causes apnoea and bradycardia), coughing, aspiration reflex. Irritant receptors (vagus stim.)
Where are J receptors found and which reflexes are they involved in?
Prob. Alveolar walls, next to capillaries. Engorged capillaries and < interstitial fluid stimulates the Vagus nerve, causing Dyspnoea (SOB) e.g. in Left heart failure.
What happens to ventilation rate as Alveolar Pco2 rises?
Ventilation increases. An increase in Pco2 is STRONGLY correlated with an increase in ventilation.
What constantly adjusts (via chemoreceptors) to match changes in alveolar intake of oxygen and carbon dioxide, and keep the partial pressure(s) of oxyegn and carbon dioxide in the blood within normal limits?
Alveolar ventilation (VA)
What happens to ventilation below 60mmHg PO2?
A BIG and rapid increase in ventilation
A low partial pressure of oxygen stimulates what?
If the partial pressure of oxygen is lower than normal, there is increased sensitivity to raised PCo2. Below 60mmHG, PO2 becomes a very strong stimulus of ventilation.
Metabolic acidosis has what effect on ventilation?
It is a strong driver of ventilation - as pH increases, so does ventilation rate.
Where are the central chemoreceptors found?
Experiments suggest that these are in close proximity to the ventrolateral medulla - some in the medullary raphe, the retrotrapezoid nucleus, and glial cells.
Central chemoreceptors respond to what?
Arterial PcO2
pH
Which chemoreceptors respond to the partial pressure of oxygen?
Peripheral chemoreceptors.
What are the peripheral chemoreceptors?
These are located in the CAROTID and AORTIC bodies found at the bifurcation of the carotid, and is a separate structure from the artery. They respond rapidly to variations in oxygen (i.e hypoxia), carbon dioxide (hypercapnia), and low glucose (hypoglycemia). HYPOXIA and HYPERCAPNIA are the most heavily studied and understood conditions detected by the peripheral chemoreceptors. Afferent nerves carry signals to the brainstem, which responds accordingly (e.g. increasing ventilation).
What are the peripheral chemoreceptors?
These are located in the CAROTID and AORTIC bodies found at the bifurcation of the carotid, and is a separate structure from the artery. They respond rapidly to variations in oxygen (i.e hypoxia), carbon dioxide (hypercapnia - ESP. FAST RISE IN PCO2), and low glucose (hypoglycemia). HYPOXIA and HYPERCAPNIA are the most heavily studied and understood conditions detected by the peripheral chemoreceptors. Afferent nerves carry signals to the brainstem, which responds accordingly (e.g. increasing ventilation).
How do Glomus cells respond to low PO2?
Low PO2 causes depolarisation of the membrane, causing calcium influx, releasing neurotransmitter, which stimulates 9th nerve to signal to Medulla.
What are the key risk factors for sleep apnoea?
Male Overweight Diabetes Drinking before bed Previous/current smoker Sedative drugs
Side effects of Metformin?
Weight loss
Can cause kidney failure as a result of lactic acidosis.
Drowziness
Side effects of Amitriptyline?
Drowziness
Fits
Arrhythmias
Side effects of Pregablin?
Fluid retention/weight gain
Drowsiness
Side effects of Celecoxib?
Serious Stomach and intestinal ulcers.
What is the biggest indicator of obstructive sleep Apnoea?
Collar size
A better indicator than BMI (Body mass index)
BUT still large variation - requires clinical assessment.
If you have a patient that has told you they are tired, what important advice should you give?
DRIVING advice - State and RECORD this.
Large fluid effusion in the pericardium may show what on ECG?
Low voltage QRS complex
“Electrical alternans”
Large effusion of the pericardium looks like what on a Chest X-Ray?
A Spherical, “round”, large looking heart.
What are the differential diagnostic differences between acute CS, PE, and cardiac tamponade
PE - SOB, but sim. risk factors. Different sort of pain to CS. ECG will come back normal (usually).
Tamponade - May see Electrical alternans - Ultrasound to assess chambers and x-ray to assess potential fluid.
Acute coronary syndrome will also have raised Troponins - far greater than other two.
What is pulsus paradoxus?
The exaggeration of a normal response.
Tends to occur in patients with pericardial fluid.
Results in change in pulse during inspiration/expiration as a result of intra-thoracic/pericardial pressure changes.
Feeling brachial pulse - Feels strong, almost disappears on inspiration.
The visceral pericardium is also known as what?
The Epicardium
Which two layers make up the serous pericardium?
Visceral (inner) and Parietal (outer)
What is the name given to the pericardial layer surrounding the serous pericardium? What is it continuous with?
Fibrous perciardium
Continuous with adventitia of the great vessels
Anchored to diaphragm and posterior surface of the sternum
What does the fibrous pericardium do?
Anchors heart in place - limits how much the heart chambers can fill.
What is the Transverse pericardial sinus
A space between the two layers within the serous pericardium. It allows space for fingers to be placed under and around the great vessels (useful in surgery)
Tamponade is due to fluid between the ___ and ____ pericardium.
Visceral and parietal.
Pain in the heart is referred where?
T1-T4
Afferent fibres from Cardiac plexus enter the spinal tract at about T4. Somatic pain is felt as the brain isn’t used to “feeling” visceral pain.
Pain in the pericardium refers through which nerve?
Via Phrenic nerve, referring pain up to C3,4,5 (esp 4) causing pain to shoulder.
Describe the functions of the pericardium
- Stabilization of the heart within the thoracic cavity by virtue of its ligamentous attachments – limiting the heart’s motion.
- Protection of the heart from mechanical trauma and infection from adjoining structures.
- The pericardial fluid functions as a lubricant and decreases friction of cardiac surface during systole and diastole.
- Prevention of excessive dilation of heart especially during sudden rise in intra-cardiac volume (e.g. acute aortic or mitral regurgitation).
How much fluid does the pericardium normally contain?
15-50 ml fluid normally.
What are the aetiologies of Pericardial effusion?
- Inflammation from infection, immunologic process.
- Trauma causing bleeding in pericardial space.
- Noninfectious conditions such as:
a. Increase in pulmonary hydrostatic pressure e.g. congestive heart failure.
b. Increase in capillary permeability e.g. hypothyroidism
c. Decrease in plasma oncotic pressure e.g. cirrhosis. - Decreased drainage of pericardial fluid due to obstruction of thoracic duct as a result of malignancy or damage during surgery.
Viral pericardial effusion are usually ___ or ___.
Viral effusions are usually serous or serofibrinous
Malignant pericardial effusions are usually ____.
Malignant effusions are usually hemorrhagic.