5) Flashcards
A 56 year old woman is referred to the Oncology department after developing a lump in the upper outer quadrant of her left breast. Mammography revealed a 1.8 cm tumor which on biopsy was shown to be a HER2-positive infiltrating ductal grade 3 carcinoma. HER2 gene mutations are implicated in up to 25% of breast cancers. Mutation of this gene enables which of the 6 hallmarks of cancer? Ability to invade and metastasise Angiogenesis Cell immortalisation Resistance to growth stop signals Self-sufficiency in growth signal
Self-sufficiency in growth signal CORRECT – It is believed that a fully evolved malignant neoplasm exhibits six hallmarks of cancer plus one enabling feature: (1) self-sufficiency in growth signals; (2) resistance to growth stop signals; (3) no limit on the number of times a cell can divide (cell immortalisation); (4) sustained ability to induce new blood vessels (angiogenesis); (5) resistance to apoptosis; (6) the ability to invade and produce metastases. Hallmarks 1 to 5 are primarily about increased growth and are therefore likely to be relevant to both benign and malignant neoplasms. Hallmark 6 is exclusively relevant to malignant neoplasms. Genetic instability is regarded as an enabling characteristic. Genetic instability refers to the accelerated mutation rates found in malignant neoplasms that occurs as a result of a mutation of a caretaker gene (a subtype of tumour suppressor gene). Self-sufficiency in growth signal is associated with mutations in the HER2 gene.
A 58 year old man with prostate cancer has developed a metastasis in one of his cervical vertebrae. The affected vertebra has a long spinous process which is not bifid. The transverse process is large, but the transverse foramina are small and only transmit the accessory vertebral veins. Which vertebra is affected in this man? C1 C2 C5 C7 C8
CORRECT – The C7 vertebra is also known as the vertebra prominens. It has the longest spinous process, which unlike the other cervical vertebrae, is not bifid. The transverse process is large but the foramen transversarium is small and only transmits the accessory vertebral veins.
A researcher designing a cross-sectional study to investigate coronary heart disease in adult e-cigarette users employs power analysis to determine the sample size for her study. What parameter would decrease as the number of people selected for this study increases? Bias Precision Prevalence of coronary heart disease Random error Systematic error
Correct. Random error or chance will decrease as sample size gets larger. Prevalence
A 12 year old boy falls from a climbing frame onto his outstretched right hand in the mid flexed position. As a result he has dislocated his right elbow posteriorly. The elbow is a synovial joint. From what tissue does this class of joint originate during embryological development? Periosteum Hyaline Cartilage Mesenchyme Endosteum Synovium
Mesenchyme CORRECT – In utero bones develop as rods of cartilage which become mineralised. A synovial joint is simply an interruption in the cartilage model of a bone. Starting during the sixth week, areas of mesenchyme within the growing limb buds begin to differentiate into the hyaline cartilage that will form models for each of the future bones. The synovial joints will form between the adjacent cartilage models, in an area called the joint interzone. Cells at the centre of this interzone region undergo apoptosis to form the joint cavity, while surrounding mesenchyme cells from the perichondrium will form the periosteum where they lie in contact with bone, and the articular capsule and supporting ligaments where they lie in contact with the developing joint. In the knee joint, some of the cartilage within the joint is preserved and develops into intra-articular ligaments: the anterior and posterior cruciate ligaments of the knee.
A 33 year old female motorcyclist is involved in a road traffic accident and sustains a compression fracture of one of her thoracic vertebral bodies. The affected vertebra has a pair of superior costal facets and a pair of inferior costal facets; however, the superior costal facets are whole facets and the inferior costal facets are demi facets. Which vertebra has been fractured in this patient? T1 T2 T6 T9 T12
T1 CORRECT – In addition to the superior and inferior articular facets that are present on all vertebrae, in the thoracic region there are superior and inferior costal facets located on the sides of each vertebral body. They consist of cartilage lined depressions which articulate with the heads of the ribs. In the majority of the vertebrae (T2-T8) these facets are demi-facets (literally ‘half facets’). The superior demi-facet articulates with the head of the adjacent rib, and the inferior demi-facet articulates with the head of the rib below i.e. the T3 vertebra articulates with ribs 3 and 4 (or the rib articulates with the vertebra of the same number and the vertebra above). However, the T1 vertebra is the first thoracic vertebra and is the only vertebra which articulates with the first rib. Therefore, its pair of superior costal facets are whole facets, which articulate with the first rib, whereas, as both the T1 and T2 vertebrae articulate with the second rib, the inferior costal facets of the T1 vertebra are demi-facets.
A first year dentistry student attends a Health centre clinic during freshers week to receive a Meningitis ACWY vaccine Which Neisseria virulence factor is part of the vaccine that protects against some, but not all serogroups of Neisseria meningitidis? Peptidoglycan Capsule Exotoxin Pili Porin
Capsule CORRECT – Neisseria meningitidis has a polysaccharide capsule that is an important virulence factor. It prevents phagocytosis and contributes to the host’s inflammatory response. The chemical composition of the capsule defines the organism’s serogroup. For some serogroups (ACWY), the capsule is antigenic and so is used as part of the vaccine. For the Serogroup B vaccine, the capsule does not trigger a good response and so a number of subcapsular antigens are used.
A newborn baby boy is severely short of breath. His lips, tongue and hands are blue (he is cyanosed). An echocardiogram shows he is suffering from the transposition of the great arteries of his heart. This is a congenital heart defect where the aorta is connected to the right ventricle and the pulmonary trunk is connected to the left ventricle. It is a medical emergency and is initially treated by keeping the ductus arteriosus open and then surgically switching the position of the vessels.
Where in the primitive heart tube do the endocardial cushions form during the septation of the outflow tract of the heart?
Aortic Roots
Bulbus Cordis
Truncus Arteriosus
Sinus Venosus
Primitive Atrium
Truncus Arteriosus
CORRECT – Endocardial cushions form within the truncus arteriosus. As the cushions grow towards each other they twist around each other, forming a spiral septum. This septum divides a single outflow tract into two, the pulmonary trunk and the aorta.
what type of hormone is thyroid hormone
amine hormone
Probability
is the risk of an event happening divided by the total number of people at risk of having that event.
In this scenario the risk (or probability) of selecting a Scottish person is 13/52 = 0.25 = 25%.
The numerator is the number of Scottish people and the denominator is the total number of possible people that could be selected.
Odds
The odds of something happening is the ratio of the probability that something will happen over the probability that it won’t.
The probability of selecting a Scottish person 0.25.
The probability of not selecting a Scottish person is 1 - 0.25. So the odds are 0.25/0.75 or 1:3 (or 0.33 or 1/3 pronounced 1 to 3 odds).
A researcher randomly selects 1 experimental subject from a population of 52 consisting of 13 Scottish, 13 English, 13 Irish and 13 Welsh people.
What are the probability and odds that the person selected will be Scottish?
13% probability, 1 to 3 odds
13% probability, 1 to 4 odds
25% probability, 1 to 3 odds
25% probability, 1 to 4 odds
25% probability, evens odds
25% probability, 1 to 3 odds
Correct.
Probability is the risk of an event happening divided by the total number of people at risk of having that event. In this scenario the risk (or probability) of selecting a Scottish person is 13/52 = 0.25 = 25%. The numerator is the number of Scottish people and the denominator is the total number of possible people that could be selected.
Odds The odds of something happening is the ratio of the probability that something will happen over the probability that it won’t. The probability of selecting a Scottish person 0.25. The probability of not selecting a Scottish person is 1 - 0.25. So the odds are 0.25/0.75 or 1:3 (or 0.33 or 1/3 pronounced 1 to 3 odds).
A haematologist is assessing a sample of blood in the lab. After centrifugation the sample is separated into 3 layers as shown below.
What blood components would be present in the middle fraction (M) of this sample?
Breakdown products of erythrocytes.
Emulsified fats and chylomicrons.
Lymph and proteins.
Precipitated blood sugars and proteins.
White blood cells and platelets.
An increase in ADP concentration in exercising skeletal muscle would promote glycolysis by increasing the activity of which enzyme?
Glycogen synthase
Fructose 1,6 bisphosphatase
Phosphofructokinase
PEPCK (phosphoenolpyruvate carboxykinase)
Glucose-6-phosphate dehydrogenase
Phosphofructokinase
CORRECT. Phosphofructokinase, the key regulator of glycolysis is stimulated by high AMP and inhibited by high ATP
A 38 year old man is taken to hospital after collapsing when running. The man is physically fit; however, it is a very hot day and the on-call junior doctor believes that the man may have collapsed due to hyperthermia. His body temperature is 38.1oC.
How does the cutaneous blood circulation react to an increase in core body temperature above the normal range?
The build-up of metabolites leads to the vasodilation of the Arteriovenous Anastomoses
Increased sympathetic stimulation leads to the vasodilation of the Arteriovenous Anastomoses
Decreased sympathetic stimulation leads to the vasodilation of the Arteriovenous Anastomoses
The build-up of metabolites leads to the vasoconstriction of the Arteriovenous Anastomoses
Increased parasympathetic stimulation leads to the vasodilation of the Arteriovenous Anastomoses
Decreased sympathetic stimulation leads to the vasodilation of the Arteriovenous Anastomoses
CORRECT – The sympathetic nervous system stimulation the vasoconstriction of arteriovenous anastomoses (AVAs) which are found in apical skin. When constricted, AVAs divert blood away from the skin, preventing heat loss. However, when the body temperature increases, the body will aim to lose heat to cool down. This means that the sympathetic drive to the AVAs will be decreased, allowing them to dilate, thereby allowing more blood to apical skin, aiding heat loss. It should be noted that AVAs are under sympathetic control and are not influenced by the actions of local metabolites.
A 23 year old woman is assessed for motor function after a road traffic accident.
Which muscle anchors and depresses the clavicle?
Coracobrachialis
Pectoralis Minor
Subscapularis
Pectoralis Major
Subclavius
Subclavius
CORRECT – The subclavius is small muscle, which is located directly underneath the clavicle, running horizontally. It affords some minor protection to the underlying neurovascular structures (e.g. in cases of clavicular fracture or other trauma). Subclavius originates from the junction of the 1st rib and its costal cartilage and inserts onto the inferior surface of the middle third of the clavicle. Subclavius anchors and depresses the clavicle and is innervated by the nerve to subclavius.
What ion channels are responsible for the slow pacemaker potential in cells of the sinoatrial node?
HCN Channels
L-Type Calcium Channels
Voltage Gated Chloride Channels
Voltage Gated Potassium Channels
Voltage Gated Sodium Channels
CORRECT – HCN channels are responsible for the ‘funny current’ present in the action potential of the cells of the sinoatrial and atrioventricular nodes. As a result of this current, the cells slowly depolarise until they reach the threshold required for the triggering of an action potential.
A 38 year old man falls whilst playing football and fractures his right humerus. On examination at the emergency department his right hand presents with a hyper-extension at the metacarpophalangeal joints and flexion at the proximal and distal interphalangeal joints of the 4th and 5th fingers.
Where is this man’s right humerus most likely to be fractured?
Lateral epicondyle
Medial epicondyle
Mid-shaft
Surgical neck
Supracondylar ridge
Medial epicondyle
CORRECT – Out of all of the options, a fracture of the medial epicondyle of the man’s humerus is the most likely to damage the man’s ulnar nerve. This is because the ulnar nerve passes just posteriorly to the medial epicondyle before entering the cubital tunnel at the elbow. An ulnar nerve injury at this level would lead to a loss of sensation palmar and dorsal surfaces of the ulnar (medial) one and a half fingers, and the ulnar aspect of the palm and dorsum of the hand. The patient will also experience paralysis of their 3rd and 4th lumbricals, interossei, hypothenar muscles and adductor pollicis, flexor carpi ulnaris and the ulnar half of flexor digitorum profundus. This paralysis will lead to the formation of a high ulnar claw, during which the metacarpophalangeal joints on the patient’s ulnar two fingers are hyperextended due to unopposed extension from extensor digitorum (as a result of the loss of the lumbricals). The proximal interphalangeal joints are flexed due to unopposed flexion from the long flexor muscle flexor digitorum superficialis. Note that the distal interphalangeal joints are not flexed as would be expected in a low ulnar nerve injury. This is because the ulnar half of flexor digitorum profundus is also paralysed, making the resulting ulnar claw less pronounced than what would be presented in a low ulnar nerve injury (this is the ulnar paradox). Extensor digitorum, cannot extend the proximal interphalangeal joints as its energy is dissipated in hyperextending the metacarpophalangeal joints. In a high ulnar nerve injury, the palmar cutaneous branch (supplying the palmer aspect of the ulnar side of the hand), the dorsal cutaneous branch (supplying the dorsal aspect of the ulnar side of the hand and ulnar two fingers until the distal interphalangeal joint) and the palmar digital branches (which supply the palmer aspect of the ulnar one and a half fingers and the dorsal aspect of these fingers from the distal interphalangeal joint distally) of the ulnar nerve are all damaged. This means that sensation of the ulnar side of the hand and the ulnar one and a half fingers is lost.
