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An A level Biology teacher shows her students a diagram to illustrate base pairing in DNA
Which two bases are illustrating this interaction in the diagram?
Adenine : Adenine
Adenine : Thymine
Cytosine : Cytosine
Guanine : Cytosine
Guanine : Guanine
Guanine : Cytosine
A 40 year old woman develops involuntary and irregular movements of her limbs, neck, head, and face (chorea) and is referred to a consultant neurologist by her GP. Further testing reveals that the woman has Huntington’s disease, an autosomal dominant inherited disease caused by mutation of the huntingtin gene.
What type of mutation results in this disease?
- Deletion of 3 nucleotides resulting in loss of phenylalanine at position 508 (ΔF508)
- Frameshit mutation (+1 insertion)
- Increased number of CAG repeats
- Missense mutation resulting in a Glu to Val substitution
- Nonsense mutation resulting in a premature stop codon at position 508
CORRECT – Huntington’s is a trinucleotide repeat disorder. Trinucleotide repeat disorders result from errors in DNA replication leading to increasing numbers of repeated sequences of three nucleotides. In general, the greater the number of trinucleotide repeats, the greater the chance of exhibiting symptoms and the worse the clinical manifestations.
A 26 year old butcher slips holding a knife and badly cuts his arm. The bleeding from the wound stops within 10 minutes due to the process of haemostasis
What sequence of events occurs during this physiological process?
A platelet plug forms, arteries contact, fibrin filaments accumulate and trap red blood cells.
- A platelet plug forms, fibrin filaments accumulate and trap red blood cells, arteries contract.
- Arteries contract, a platelet plug forms, fibrin filaments accumulate and trap red blood cells.
- Arteries contract, fibrin filaments accumulate and trap red blood cells, a platelet plug forms.
- Fibrin filaments accumulate and trap red blood cells, a platelet plug forms, arteries contract.
Arteries contract, a platelet plug forms, fibrin filaments accumulate and trap red blood cells.
CORRECT – This is the correct sequence of events in haemostasis. The severed artery contracts, not enough to stop the bleeding but enough to decrease the pressure downstream (contraction doesn’t occur in veins but the pressure in them is much lower). A primary haemostatic plug of activated platelets then forms at the hole in the vessel, sticking to the injured vessel and the connective tissue outside it. This is fragile but may control the bleeding and forms in seconds to minutes. The secondary haemostatic plug of fibrin filaments forms as fibrin filaments stabilise the friable platelet plug into a blood clot. This forms in approximately 30 minutes.
A 42 year old woman presents her GP with a 12-week history of pain in the right upper quadrant of her abdomen and a low-grade fever. On examination, the woman is Murphy’s sign positive. The GP believes that the woman may have chronic cholecystitis and organises a biopsy. A histological section from this the biopsy is shown below:
What type of cell is indicated by the green arrows?
Macrophage
CORRECT – The word ‘macrophage’ means ‘big eater’. Before macrophages enter the tissue spaces and whilst they are circulating in the blood, they are called monocytes. Once they enter the tissue spaces, they are called macrophages (or histiocytes). Monocytes are made in the bone marrow and circulate in the blood for about six days. They then enter the tissues and become dormant until activated by a local challenge. Macrophages appear to live for many months and can replicate (unlike neutrophils). The macrophage is a very versatile cell and it is the mastermind of chronic inflammation and the immune response. They arrive at the site of inflammation after the neutrophils and then take over from them. Macrophages have many functions. They include phagocytosis (although not always as effectively as neutrophils, they are better at destroying some difficult to kill bacteria such as Mycobacterium tuberculosis), secretion of numerous (in the order of 100) substances that summon and activate other cells, presenting antigens to the immune system and initiation of the immune response, stimulating angiogenesis (the formation of new blood vessels) which is important in wound healing, inducing fibrosis and inducing fever, acute phase reaction and cachexia.
hypertrophy
Hypertrophy refers to an increase in tissue or organ size due to an increase in cell size without an increase in cell numbers.
healing by primary intention
Healing by primary intention occurs in wounds with dermal edges that are close together (e.g a scalpel incision). It is usually faster than by secondary intention, and occurs in four stages:
-
Haemostasis – the action of platelets and cytokines forms a haematoma and causes vasoconstriction, limiting blood loss at the affected area
- The close proximity of the wound edges allows for ease of clot formation and prevents infection by forming a scab
- Inflammation – a cellular inflammatory response acts to remove any cell debris and pathogens present
- Proliferation – cytokines released by inflammatory cells drive the proliferation of the fibroblasts and the formation of granulation tissue
- Angiogenesis is promoted by the presence of growth mediators (e.g VEGF), allowing for further maturation of the granulation tissue; the production of collagen by fibroblasts allows for closure of the wound after around a week
- Remodelling – collagen fibres are deposited within the wound to provide strength in the region, with the fibroblasts subsequently undergoing apoptosis
Secondary Intention
Healing by secondary intention occurs when the sides of the wound are not opposed, therefore healing must occur from the bottom of the wound upwards.
A 40 year old woman develops involuntary and irregular movements of her limbs, neck, head, and face (chorea) and is referred to a consultant neurologist by her GP. Further testing reveals that the woman has Huntington’s disease, an autosomal dominant inherited disease caused by mutation of the huntingtin gene.
What type of mutation results in this disease?
- Deletion of 3 nucleotides resulting in loss of phenylalanine at position 508 (ΔF508)
- Frameshit mutation (+1 insertion)
- Increased number of CAG repeats
- Missense mutation resulting in a Glu to Val substitution
- Nonsense mutation resulting in a premature stop codon at position 508
Increased number of CAG repeats
CORRECT – Huntington’s is a trinucleotide repeat disorder. Trinucleotide repeat disorders result from errors in DNA replication leading to increasing numbers of repeated sequences of three nucleotides. In general, the greater the number of trinucleotide repeats, the greater the chance of exhibiting symptoms and the worse the clinical manifestati
Name the 2 daughter cells produced by meiosis 1 in oogenesis.
Answer
The secondary oocyte and the first polar body (both of which are haploid with 23 chromosomes and 46 chromatids)
As sperm cells mature they move through between across the ……………. from the ………… compartment towards the …………. compartment of the seminiferous tubule.
As sperm cells mature they move between the sertoli cells from the basal compartment towards the adluminal compartment of the seminiferous tubule.
Which type of reaction is depicted in the graph below?
endergonic or exergonic
endergonic
the paradox of REM sleep
- EEG activity is similar to that seen during arousal (beta waves), however the person is difficult to rouse due to strong inhibition of the thalamus
- Muscle tone in most of the body is lost due to descending inhibition of LMNs by glycinergic fibres arising from the reticular formation and running down the reticulospinal tracts
- To stop us acting out our dreams e.g. sleep walking
- Eye movements and some other cranial nerve functions are preserved (e.g. nocturnal bruxism)
- Autonomic effects are seen including penile erection and loss of thermoregulation (how people die if they sleep without adequate shelter)
as we get deeper into sleep the ……. become more deactivated
thalamus
- less sneosry info and motor info having to pass through the thalamus
exam of a 2 month year old boy reveals a bulging fontanelle and a downward gaze. Most likely diagnosis
congenital hydrocephalus
types of MRI
CSF is dark on T1-weighted imaging and bright on T2-weighted imaging.
T2 - white water (inc fat which is water rich)
wher ein the ventricular system is a ventriculoperitonel shunt inserted
lateral ventricles
describe how the ventricular septum forms
- msucular portion grows upwards from the floor of the ventricles
- membranous portion derive dfro the endocardial cushions and grows ndownwards to fuse with the muscular portion
a ventircular spetal defect causes a left to right shunt. Give 2 other causes of left to right shunt
- atrial septal defect
- patent ductus arteriosus
define secondary amenorrhea
Secondary amenorrhea is defined as the cessation of regular menses for three months or the cessation of irregular menses for six months.
- having had previous periods before
cause sof secondary amenorrhea
PCOS
Weight loss
Stress
what hormone can be measured to reliably demonstatre ovulation has occured
progestrogen
at ovulation, the CL is formed–> secretes progesterone in the luteal phase –> showing ovulation hasa occured
first tst in a women with secondary amenorrhea
pregnancy test
where is RA in the hand most commonly found
metacarpophalangeal joint
signs of RA on x-ray
narrowing of joint space
juxta articular bony erosions
soft tissue swelling
deformity
signs of OA on X-raY
joint space loss, osteophyte formation, cyst formation and subchondral sclerosi
2 autoantibodies associated with RA
Rheumatoid Factor and anticitrullinated protein antibodies (ACPAs)
extra-articular features of RA
pulmonary fibrosis,
vasculitis,
skin ulceration,
lymphadenopathy,
peripheral neuropathy, splenomegaly,
episcleritis or
pericarditis.
blood supply to the nose
sphenopalatine and kkieselbach plexus
symptoms of sinusitis
Runny nose.
Stuffy nose.
Facial pain or pressure.
Headache.
Mucus dripping down the throat (post-nasal drip)
Sore throat.
Cough.
Bad breath
rare complication of sinusitis
venous sinus thrombosis
mechanism of action of apixiban
inhibits factor Xa- DOAC
stages of ehaling
Healing by primary intention occurs in wounds with dermal edges that are close together (e.g a scalpel incision). It is usually faster than by secondary intention, and occurs in four stages:
Haemostasis – the action of platelets and cytokines forms a haematoma and causes vasoconstriction, limiting blood loss at the affected area
The close proximity of the wound edges allows for ease of clot formation and prevents infection by forming a scab
Inflammation – a cellular inflammatory response acts to remove any cell debris and pathogens present
Proliferation – cytokines released by inflammatory cells drive the proliferation of the fibroblasts and the formation of granulation tissue
Angiogenesis is promoted by the presence of growth mediators (e.g VEGF), allowing for further maturation of the granulation tissue; the production of collagen by fibroblasts allows for closure of the wound after around a week
Remodelling – collagen fibres are deposited within the wound to provide strength in the region, with the fibroblasts subsequently undergoing apoptosis
state 4 cardiovascular compensatory mechanisms mediated by the symapthetic nervous system in hypovolaemic shock
vasoconstriction
venoconstriction
increased stroke volume
increased heart rate
under what circumstances is lactate produced
anaerobic respiration
how is alctate produced
lactate dehydrogenase converts pyruvate to lactate
how is lactate utilise dby the body
why does a pt with ischameic heart disease get itnense muscle cramps following vigorous exercise
reduced cardiac output (CO= SVxHR)
therefore oxygenated blood delivered less efficiently to respiring muscles
lactate builds up –> cramps
name 2 molecules that can cause metabolic acidosis
lactate
ketones
ATP
most likely causative organism of an exacerbation of COPD
Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae.
a 68 yea rold pt started smoking aged 26 and stopped 2 years ago. In the interim, she smoked an average of 40 cigs a day. Pack year?
40/20 x 40= 80 pack year
type 1 vs type 2 respiratory failure
type 1= low oxygen <8, normal CO2
Type 2= low oxygen, high CO2
3 steps GP should take regarding subsequent management of COPD after exacerbation
pulmonary rehab
rescue pack of antibiotics and steroids
flu vaccinations
method of investigating vaginal discharge
high vaginal swab
endocervical swab
2 risk factors for cotnracting a sexually transmitted infection
young age of first intercourse
multiple partners
alcohol and drug abuse
the sciatic nerve typically exits the pelvis via the greater sciatic forament infeiror tow hich muscle
piriformis
name the artery that accompanises the sciatic nerve at this point
superior gluteal artery
name given to degeneration of enrve caused by injury
wallerian
borders of the posteiror triangle
Anterior – posterior border of the sternocleidomastoid.
Posterior – anterior border of the trapezius muscle.
Inferior – middle 1/3 of the clavicle.
Which term is used to describe the cycle by which the lactate produced in skeletal muscle is converted back to glucose in the liver?
TCA cycle
Urea cycle
Cori cycle
Alanine cycle
cori cycle
A 58 year old man presents to his GP with a 2 month history of central crushing chest pain on exercise which is relieved on rest. The GP records an ECG (shown below).
What is the patient’s heart rate?
90 beats per minute
CORRECT – The rhythm is an irregular non-sinus rhythm (i.e the RR intervals are irregular). Therefore, the only way to calculate the heart rate it to count the number of R peaks that occurs within 30 large squares (6 seconds) and multiply it by 10. In this case 9 R peaks occur within 30 large squares, so 9 x 10 = 90 beats per minute.
skin terms
A 27 year old woman is diagnosed with Neurocardiogenic Syncope (NCS), a condition resulting from disturbances to the function of the autonomic nervous system.
What are the properties of the pre- and postganglionic neurones in the sympathetic branch of this division of the nervous system?
dermatomal map of the whole body
where is dopamine released from
4 different pathways
mesolimbic (think schizophrenia)
mesocortical
nigrostriatal (think parkinsons)
tubuloinfundibular
giant cells
touton- fat necrosis
langhans- TB
foreign body
larynx anatomy
- Thyroid (2 lamina – superior and inferior horn)
- When one lamina meets the other lamina = laryngeal prominences – Adams apple
- Cricoid cartilage -below thyroid
- inferior horn of thyroid cartilage articulates with the cricoid cartilage- synovial joint
- thicker at the back than front (signet ring)
- Retinoid cartilage- sits on the cricoid cartilage
- Epiglottis- attached by its stalk to the inner surface of the thyroid cartilage
laryngeal inlet made up of the
aryepiglottic folds and epiglottis
cricothryoid
- Intrinsic muscle
- Found on the outside of the cartilages
- external branch of superior laryngeal nerve
- will increase tension of vocal cords- important for reaching higher pitches
torsades de pointes
polymorphic ventricular tachycardia characterized by a gradual change in amplitude and twisting of the QRS complexes around an isoelectric line on the electrocardiogram.
Hydrocele (adult)
imbalance of fluid production and resorption between tunica albuginea and tunica vaginalis
Examination
- Testis not palpable separately
- Can get above
- Transilluminates
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breast cancer prognosis
