Block 31

Question 1

cystic mass at the lower spine that is covered with skin and sometimes tuft of hair.

Answer 1

Meningocele and meningomyocele.

• meningocele consists of spinal meninges that protrude through the vertebral arch defects.
• meningomyocele has portions of the spinal cord or cauda equina within the protrouding meningeal sac.
• neural tube defect is defined as failure of closure of neuropore by 4 weeks.
• anterior neural tube defects is assoicated with anencephaly
• posterior is associated with spina bifida occulta, meningocele and meningomycoele

Question 2

Hep E general features

Answer 2

Unenveloped
SsRNA
Fecal oral route
Causes fulminant hepatitis in pregnancy

Question 3

Edematous and erythmatous plaque with mild central pallor is indicative of

Answer 3

Wheal, allergic reaction
Peripheral arythema is flare
(Wheal and flare reaction)

Question 4

Status epilepticus

Answer 4

Single seziures that lasts >5 min or the occurance of multiple discrete seziures with incomplete recovery of consciousness between episodes.

• common causes include structural brain injury, infection , metabolic abnormalities and medication non compliance in individual with known epilepsy.
• IV lorazepam, potentiates the effect of inhibitory GABA in CNS. Its the first drug of choice in treatment of status epelipticus
• IV phenytoin is long acting sodium channel blocker that is administred concurrently to prevent recurrence of seziures.

Question 5

Mechansim of common antisezures drugs

Answer 5

1. Blocks Na channels: phenytoin, carbamazepine
2. Blocks Na and increases GABA: valproic acid
3. Increases GABA(a) action: benzodiazepine, and phenobarbital
4. modulate GABA and glutamate release: levetiracetam.
5. Blocks thalamic T type Ca channels : ethusoximide.

Question 6

Alpha 2 adrenergic stimulation leads to

Answer 6

1. Sympathetic outflow
2. Decrease insulin release
3. Decrease lipolysis
4. Platelet aggregation
5. Decrease aqueous humor production

Question 7

Epithelial cells covered with gram variable rods on mount microscopy

Answer 7

Clue cell - bacterial vaginosis.

Question 8

P, auriginosa and C,diphteriae toxins

Answer 8

Both exotoxin A and diphteria toxins. Although they are structually different, they both ribosylate and inactivate EF-2, halting human cell protein synthesis and causing cell death.

Question 9

Diastolic heart failure

Answer 9

Is a common cause of acute demopensated HF. Its characterized by normal LVEF and end diastolic volume in the setting of increased LV filling pressures.

• diastolic dysfunction can be due to conditions that decrease LV compliance, such as impaired myocardial relaxation or increased intrinsic ventricular wall stiffness (eg, amyloid deposition).
• this patient most likely has long standing hypertension leading LV wall hypertrophy, which can impair myocardial relaxation and increase intrinsic wall stiffness.
• LV diastolic pressure id determined by the blood volume in the LV cavity and compliance of the LV. Conditions that reduced ventricular compliance lead to increased LV end diastolic pressure (LVEDP) at the same LVED volumes.
• this causes an upward shift in the pressure volume curve (point a->b).
• as diastolic dysfunction worsens, LVEDP continues to rise as the heart attempts to maintain a near-normal stroke volume and cardiac output.
• decompensation occurs when the increased LVEDP, causes pulmonary edema and dyspnea.

Question 10

Periodic acid schiff reaction

Answer 10

Is used in histochemical staining because the periodic acid oxididezes carbon-carbon bonds, forming aldehydes that produce a brilliant magenta color upon reacting with fuchsin sulfurous acid.

• as a result, the PAS stain is particularly effective at highlighting polysaccharide of the fungal cell wall, mucosubstances secreted by epithelia and basement membrane.
• the glycoprotein that present in the cell walls of the gram positive actinomyceete trophyrma whippelii appears magneta with PAS and diastase resistance, which makes this stain an excellent choice when microoscipically evaluating small bowel mucosa for whipple disease.

Question 11

Clasp knife spasticity

Answer 11

Charactrized by initial resistance to passive extension followd by a sudden release of resistance.

• this form is seen in UMN lesions and results from lack of upper motor neuron inhibition on the spinal strech reflex arc.
• UMN can affect any part of the pyramidal motor system including corticospinal cord, medulla, pons and midbrain, the internal capsule and precentral gyrus.
• patients with internal capsule stroke commonly have pure motor weakness affecting contolateral, arm , leg and lower face.

Question 12

Latissimus dorsi

Answer 12

Large thoracolubar muscle that contribute to forecful movement of the humerus. It originates in a broad area spanning from the iliac crest and lumber fascia to the spinous processes of T7-T12 and lower ribs.
-its innervated by thoracodorsal nerve and involved in internal rotation of the arm

Question 13

Check what true pelvis means

Answer 13

True pelvis

Question 14

Long term Kidney changes in case of BPH

Answer 14

Parenchymal pressure atrophy, this is due to retention and retrograde flow to the kidney.
-increased BPH —> urinary retention —> bladder wall hypertrophy —> ureters, renal pelvis and calyces dilates and deform —> hydronephrosis —> renal parynchema atrophy and scarred

Question 15

Suprachiasmatic nucleus is involved in

Answer 15

Circadian rhythm regulation and pineal gland function.

Question 16

Jet lag syndrome

Answer 16

• associated with long flight that cross severl time zones, symptoms include insomnia, daytime drowsiness and decrease work performance
• GI symptoms and malaise also common
• caused by dyssynchrony between body circadian rhythms and envirnomental rhythm.

Question 17

Nocardiosis

Answer 17

-gram positive rod, partially acid fast and aerobic
-its endemic in soil from disease from inhalation or traumatic inovulation into skin
-immunocompromised or elderly patients
-clinically presents with
1. Pneumonia - similar to TB
2. CNS- brain abscess
3 cutaneous involvement
Treated with :
- trimethoprim-sulfamethoxazole.
-surgical drainage of abscess.

Question 18

tetanospasmin mechanism

Answer 18

• neurotoxin, spores are commonly found in soil and may contaminate injured tissue, classically puncture wounds from soil contaminated objects.
• the low oxygen tension and high availabilty of nutrients in puncture wound provides a localized anaerobic envirnoment for the germination of spores, growth of vegetative cells and production of toxin within bacterial cells.
• toxin gain access to motor neuron axon —> retrograde transport to spinal cord and medulla. (Organ remains at the local wound site, its the toxin that does).

Question 19

Psoriasis complication

Answer 19

Psoriatic arthritis
Nail changes : yellow brown discoloration, pitting ,thickening or crumbling
Inflammatory disorder of the eye : conjunctivitis, blepharitis or uveitis.

Question 20

Prenicious anemia leads to

Answer 20

1. Decreased IF —> low B12 —> megaloblastosis
2. Decreased secretion of hydrochloric acid causes elevated intraluminal PH that leads to increase of gastric secretion by gastic G cells.

Question 21

Ramleteon

Answer 21

Melatonin agonist, is one of the few medication with demonstrated safety and efficacy in older adults.
-it binds with high affinity to melatonin receptors in suprachiasmatic nucleus, it has few side effects and no dosage adjusment is necessary in geriatric patients.

Question 22

Syphillis - treatment

Answer 22

• penicillins work by covalently binding and inhibiting transpeptidase. This enzyme catalyze the final cross linking step in peptidoglycan cell wall formation. The joining of amino acid in the third position of a peptidoglycan molecule to the terminal D-alanine D-alanine of another peptidoglycan molecule.
• the structual similarity of penicillins to D-alanine D-alanine facilitate in their binding to transpeptidase.
• when transpeptidase is inhibitied, cell wall synthesis ceases and cell wall degradation by bacterial autolysins proceeds unchecked.

Question 23

Rifampin side effects and mechanism of action

Answer 23

• they commonly cause harmless red orange discoloration of body fluids (urine,sweat ,saliva, and tears).
• they inhibit DNA dependent RNA polymerase, thereby preventing transcription and leading to a deficiency of proteins necessary for mycobacterial growth.
• sructual alteration of this DNA dependent RNA polymerase leads to bacterial resistnace.

Question 24

Isoniazid mechanism of action

Answer 24

Inhibits mycolic synthesis. Resistance of mycobacterium to it is by decreasing bacterial catalase peroxidase activity.

Question 25

Peripheral displacment of the nuclei in anterior horn with dispersion of nissl substance to the periphery of the cells is found in

Answer 25

Axonal reaction, this is usualy due to trauma. - wallerian degeneration occurs in the segment of the axon that has lost connection with the cell body. It represents the degeneration of axon and myelin distal to a point of injury. - axonal reaction is the change seen in neuronal body after axon is severed, the cell body shows signs of cellular edema, it becomes swollen and rounded with the nucleus displaced to the periphery. - axonal reaction becomes visible after 24-48 hours after injury . Maximal changes in the neuronal body occur approximately 12 days after the injury. This changes reflect increased synthesis of protein by the cells in order to regenerate the severed axon.

Question 26

Side effects of dihydropyridines

Answer 26

Peripheral edema and dizziness or lightheadedness

Question 27

Familial erythrocytosis

Answer 27

- due to ß globin mutation resulting in reduced binding of 2,3 BPG. - normally, the binding of 2,3 BPG reduces the affinity of oxygen to hemoglobin allowing more oxygen to diffuse into the peripheral tissues. - the hemoglobin 2,3 BPG binding pocket contain positively charged amino acids( histidine and lysine) that attracts the negatively charged phosphate groups in 2,3 BPG. Mutation the decrease the positive charge of the binding site decrease 2,3 BPG, and increase hemoglobin oxygen affinity.

Question 28

Cephalic phase in gastric acid secretion

Answer 28

The stimulation by cholinergic, vagal mechanisms

Question 29

Peptide YY

Answer 29

- the ileum and colon release peptide YY which binds receptors on the endocrine histamin containing cells (ECLs). Such binding counteracts the cephalic and gastric phases of acid secretion by inhibiting gastrin stimulated histamine relesae from ECLs. - they act to down regulate gastrin relesae

Question 30

What substance have the fastest rate of metabolism in the glycolytic pathway.

Answer 30

Fructose 1 phosphate. - fructose is the only one wjose metabolites bypass phosphofructokinase. - metabolism of fructose in the liver begins with phosphorylation by fruckokinase to fructose 1-phosphate. - aldolase B can use both fructose 1,6 bisphosphate and F1P as substrates. It converts F1P into DHAP and glyceroaldehyde. - DHAP is then converted to glyceraldehyde 3 phosphate which —> glycolysis.

Question 31

Pitryasis versicolor

Answer 31

Charactrized by hperpigmented -hypopigmented or erythmatous macules or patches on the upper body. - its caused by malasezzia species yeas. - infection os confined to stratum corneum - common on hot humid climates. - diagnosis os made via KOH preperation of skin scrapings - it forms spres and hypahae witth characterestic sphagetti and meatballs appearance on light microscopy - its treated with topical antifungal agents or selenium containing shampoo.

Question 32

Bohr effect

Answer 32

In peripheral tissues the release of O2 from hemoglobin is enhanced by increased pCO2 and resultant decrease in PH. This effect occurs due to the histidine side chains found on the alpha and beta hemoglobin subunits. -as the tissue release CO2 the majority is converted by carbonic anhydrase to bicarbonate and H+. While bicarbonate is shifted out of the cell in exchange for chloride ions found on plasma, the hydrogen ions remain within the erythrocytes. -these hydrogen ions are buffered by histidine on hemoglobin and in the process help stabilize the deoxygenated form of hemoglobin and decrease its affinity for oxygen.

Question 33

Haldane effect

Answer 33

When deoxygenated blood enters the alveolar capillaries of the lung the rise in pO2 increases the binding of O2 to hemoglobin and causes the release of H+ and CO2 from hemoglobin. -as bicarbonate shifted back into erythrocytes in exchangefor chloride, the carbonic anhydrase converts H+ and HCO3 to CO2 and H2O, then CO2 is excreted.

Question 34

HER2 overexpression in breast cancer indicates

Answer 34

-its associated with poorly differentiated rapidly growing tumor.

Question 35

Neonatla vitamin K deficiency

Answer 35

Presentation: intracranial, GI , cutaneous and umbilical and surgical site bleeding Prevention is by IM vitamin K at birth

Question 36

Presence of anaerobes in lung suggests

Answer 36

- lung abscess - lung abscess may be caused by : 1. Oropharyngeal aspiration : risk factors include loss of consciousness and dysphagia such as alcoholism, drug overdose, seizures disorder , prolonged anesthesia and severe neurological disease. 2. Bacterial pneumonia : immunsuppression, old age, and underlying chronic lung disease. 3. Septeciemia of infective endocarditis

Question 37

Lung abscess with prior penetrating trauma

Answer 37

The etiology is more likely to be due to s.aureus or streptococci

Question 38

Signet cells

Answer 38

Found in diffuse type gastric adenocarcinoma -they consist of cells that doesnt form glands -cells often contain abundant mucin droplets that push the nucleus to one side and lead to apperance of signet ring. -

Question 39

Intestinal type gastric adenocarcinoma

Answer 39

Closely resembles colon cancer showing well formed glands that consist of cuboidal or coulmnar cells. -they tend to grow as nodular, polypoid and well demarcated masses that rapidly expand within the gastric lumen, these lesions often ulcerate/bleed and must be differentiated from peptic gastric ulcers by biopsy

Question 40

Subarachnoid hemorrhage complication

Answer 40

If pts survives initial hemorrhage a number of complication may occur: - more than half of the patients develops secondary arterial vasospasm - secondary vasospasm leads to cerebral ischemia - presents as new onset confusion and/or focal neuological deficit 4-12 days after the initial insult. - mechanism of vasospasm is related to impaired brain autoregulation.

Question 41

Intestinal atresia

Answer 41

-the more distal the atresia the more its likely to present with abdominal distension rather than billous emesis. 1. Dudenal : due to failure of recanalization at 8-10 weeks of gestation, present with emesis and double bubble sign on xray Its associated with downsyndrome 2. Jujenum/ileum: due to vascular injury present with billous emesis and abdominal distenstion (specific pattern is known as apple peel or christmas tree deformity) and associated with gastrochisis. 3. Colonic: uknown cause, present with constipation and abdominal distension, (hirschprung disease).

Question 42

Langrhans cells

Answer 42

Dendretic cells of the skin with a horseshoe shaped arrangement of multiple nuclei dervied from the monocytic cell line.

Question 43

merkel cells

Answer 43

Neuroendocrine cells of the basal layer of the epidermis that are felt to play a role in proprioception of touch.

Question 44

Osteoclast differentiation and role of estrogen

Answer 44

- the 2 most important factors in osteoclast differentiation include macrophage colony factor (m-CSF) and RANK-L, which stimulate the development of mature multinucleated osteoclasts. The interaction of RANK-L with RANK is blocked by osteoproteogrin which act as decoy receptor. - estorgen maintain bone mass by inducing the production of osteoprotegrin by osteoblasts and stromal cells. It also acts to decrease expression of RANK on osteoclast precursor. (Thus loss of E2-> increased osteoclast activity due to loss of Osteoprotegrin)

Question 45

Alpha receptor stimulation

Answer 45

When alpha agonist bind to receptor on vascular smooth muscle —> activates phospholipase C —> IP3 and DAG —> DAG stimulate protein kinase C and IP3 stimulate calcium release which in turn further stimulate protein kinase C.

Question 46

Weber and rinne test interpretation

Answer 46

Rinne: -normal and sensoneurual hearing loss leads to air conductance (AC) > than bone conductance (BC) -conductive hearing loss : BC>AC in affected ear and AC>Bc in unaffected ear. WEBER test: -normal : midline hearing -sensoneural: lateralizes to unaffected ear -conductive : laterlizes to affected ear.

Question 47

Polythyline glycol

Answer 47

Osmotic laxative commonly used to treat constipation in elderly - they are nonabsorbable or poorly absorbable substances that attracts water into the intestinal lumen, thus distending intestinal wall and increasing peristalisis.

Question 48

Hardy weinberg analysis

Answer 48

``` P= normal allele Q= mutant allele ``` Allele frequency = P+q Phenotypic frequency= P(2تربيع)+ 2pq + q(2 تربيع) Calculating mutant allele frequency from disease prevalance= √q(2 تربيع)= q

Question 49

Ether effect on virus

Answer 49

Ether and other organic solvents can inactivate the enveloped viruses —> loss of viral infectivity.

Question 50

Physical findings in mitral stenosis patients

Answer 50

- Loud first heart sound, - an early diastolic “high frequency” opening snap after the second heart sound (the more severe the MS the closer it is after S2) - low pitched diastolic rumble

Question 51

The importance in adding conjugate to hemophilus infleunza serotype b

Answer 51

Due to the fact that it elicts T-cell dependent immune response

Question 52

Pericarditis usually follows

Answer 52

- MI,ARF, uremia | - viral infection may occasionaly cause fibrinous exudate to accumulate in pericardial space

Question 53

Serpentine cords in myobacterium are important for

Answer 53

- its important for virulance - tHe growth of thick, ropelike cords of mycobacterial organisms in a twisted serpentine pattern in consistent with the presence of cord factor. - cord factor is mycoside, meaning its composed of 2 mycolic acid molecules bound to disaccharide treholase. - the presence of cord factor correlates with virulence, mycobacteria that doesnt posses cord factor arent able to cause disease.

Question 54

Iron absorption

Answer 54

- it usually occur in duodenum and proximal jejunum. - after gastrectomy, billroth II usually involves roux en y which bypasses the proximal jejunum and the duodenum thus leading to iron deficiency, thus iron should be supplemented.

Question 55

Post gastrectomy syndrome

Answer 55

-deficiency in B12, iron , vitamin D and calcium