ILA formatives Flashcards
What do central chemoreceptors in the ventral medulla respond to?
CSF pH
What cell provides cilia for mucocillary escalator?
Columnar epithelial cells
Equation for vital capacity
Tidal volume + Inspired reserve volume + Expired reserve volume
Arterial gas picture for type 1 respiratory failure
Low pO2
Normal/low pCO2
Where are the main peripheral chemoreceptors located?
Aortic arch and carotid arteries
What is the term used to describe a malignant tumour of the pleural membranes?
Mesothelioma
What can cause type 1 respiratory failure?
Conditions that affect oxygenation
- Low ambient oxygen (e.g. at high altitude)
- Ventilation-perfusion mismatch (e.g. pulmonary embolism)
- Alveolar hypoventilation due to reduced respiratory muscle activity, e.g. in acute neuromuscular disease (this form can also cause type 2 respiratory failure if severe)
- Diffusion problem ( e.g. in pneumonia)
- Shunt (oxygenated blood mixes with non-oxygenated blood from the venous system, e.g. right to left shunt)
What is the arterial blood gas picture for type 2 respiratory failure?
Low pO2
High pCO2
Normal/high HCO3
What factors cause bronchoconstriction?
Cold dry air
Parasympathetic stimulation
Histamine release
Beta-Blockers
If a peanut is inhaled, where in the airway is it most likely to become lodged?
Right main bronchus
Which nerve supplies motor function to the diaphragm?
Phrenic
Which changes in blood stimulate carotid chemoreceptors?
Oxygen, carbon dioxide and H+ ions
What can lead to type 2 respiratory failure?
Inadequate alveolar ventilation
- Increased airways resistance - COPD
- Reduced breathing effort (drug effects, brain stem lesion, extreme obesity)
- A decrease in the area of the lung available for gas exchange (chronic bronchitis)
- Neuromuscular problems
Which nerve are superior laryngeal and recurrent laryngeal branches of?
Vagus
In sickle cell, what does hypoxia cause the HbS to do?
Polymerise
What structure is a protein in multiple sub units?
Quaternary
How does hydroxyurea work in treating sickle cell?
Increases the synthesis of HbF (2 alpha 2 gamma chains, greater affinity for oxygen than HbA)
What causes sickle cell anaemia?
An autosomal recessive inherited condition substituting an amino acid in the beta globin chain
What causes the sickling in sickle cell?
Deoxygenated HbS polymerises and binds to the cell cytoskeleton which distorts the normal cell shape into the classic sickle shape
What is a disulphide bond?
A covalent bond between side chains of cysteine residues
What is a hydrogen bond?
A type of Vander Waals force. It is the strongest of them and is the interaction between dipoles, involving a hydrogen and an oxygen/nitrogen/fluorine
What is van der waals force?
A weak attractive interaction between two atoms due fluctuating electrical charges
What is hydrophobic force?
the attraction of hydrophobic protein side chains which form tightly packed cores on the interior of proteins which exclude water molecules
Which enzyme causes the double helix to unzip?
Helicase
In sickle cell, occlusion of what typically causes acute pain crisis?
Bone
- Early presentations can be pain in the hands and feet with severe pain in bones such as femur, humerus, ribs and pelvis occurring in older children
- These are due to vaso-occlusive events in the small vessels
- Repeated events in the bones can lead to chronic infarcts
Which enzyme unwinds supercoiled DNA?
Topoisomerase
What is renin and what is its function?
Renin is a proteolytic enzyme which activates angiotensinogen to produce angiotensin I
How is water distributed in a healthy 70kg man?
Intracellular 28L. Interstitial 11L. Intravascular 3L.
What is the principle site of renin production?
Juxtaglomerular cells
If the patient does have diabetes insipidus and is not producing any ADH which of the following is MOST LIKELY to show her blood and urine osmolality after 3 hours of water deprivation?
Blood 300/urine 100
- During the water deprivation test the body should detect an increased serum osmolality (300) and produce ADH in order to promote water retention.
- As she is unable to produce ADH she will produce dilute urine (low osmolality, 100) instead of concentrated urine.
What can low albumin cause?
A low albumin causes a decrease in oncotic pressure and water diffuses from the blood into the interstitial fluid
Seen in pitting oedema
What is insensible fluid loss and give an example?
Insensible fluid loss is loss that is not easily measured e.g. sweating, water lost from respiration, evaporation during abdominal surgery.
Where is ADH synthesised and stored?
Synthesised by the supraoptic and paraventricular nuclei of the hypothalamus.
Stored in the posterior pituitary gland
What is the role of aldosterone and where is it synthesised?
Steroid hormone released from the adrenal cortex in response to stimulation by angiotensin II
It promotes sodium reabsorption and potassium secretion in the distal tubules of the kidneys
What is severe pulmonary hypertension a cause of?
Right heart failure
- Right ventricle has to work harder to pump blood through the pulmonary artery
- RV unable to generate sufficient pressure and therefore starts to fail
What is pulmonary oedema in the presence of a normal central venous pressure a sign of?
Left heart failure
- Left sided heart failure causes an increase in pulmonary pressure leading to pulmonary oedema
- A raised central venous pressure is a reflection of right sided heart failure
Which nerve innervates the pericardium?
Phrenic
Describe the normal pathway of electrical conduction through the heart
SAN
Contraction of atria
AVN
Bundle of His
Purkinje fibres
Contraction of ventricles
What is the purpose of the Ductus Arteriosus in the foetal cardiovascular system?
allow blood to bypass the foetal lungs by shunting it from the Pulmonary Artery to the Aorta
What does shortness of breath, severe peripheral oedema and ascites after a heart attack indicates
Biventricular failure
If the end diastolic volume (EDV) in the average healthy person’s left ventricle is 120mls, what would you expect the end systolic volume (ESV) to be?
50mls because stroke volume of 70mls in the average person
Which artery most frequently supplies the Atrio Ventricular Node?
R coronary artery
- RCA supplies the area above including both SA & AV nodes
- LAD supplies most of the area below the AV conducting system, the His-Purkinje system
What does an increase in L ventricular end-diastolic pressure signify
L heart failure
- reduced contractility, reduction in stroke volume so end diastolic volume and end diastolic pressure will be increased
Equation for cardiac output
heart rate x stroke volume
What does an increase in L atrial end-systolic pressure signify?
Mitral valve stenosis
- Mitral stenosis causes an increased resistance to blood flow across the valve therefore a higher pressure is required to force blood from atrium to ventricle i.e. a higher left atrial end systolic pressure
What is secreted by Chief cells?
Pepsinogen