NBDE 1998 Anatomy and Biochemistry

Antidiuretic hormone is PRODUCED by cells that reside in which of the following structures, cells or areas?A) Pars intermedia
B) Acidophils of the pars distalis
C) Pars nervosa
D) Supraoptic nucleus of the hypothalamus
E) Basophils of the pars distalis

The pyramids contain
A) upper and lower motor neuron fibers.
B) pain fibers.
C) lower motor neuron fibers only.
D) sensor fibers.
E) upper motor neuron fibers only.

Which of the following anterior primary rami form the medial cordof the brachial plexus?
A) C-4 and C-5
B) C-5, C-6, and C-7
C) C-6 and C-7
D) C-8 and T-1
E) T-2 and T-3

Preganglionic sympathetic fibers to the head have their cell bodies in the
A) gray rami communicantes of the thoracic region.
B) paravertebral ganglia.
C) superior cervical ganglia.
D) cervicothoracic ganglia.
E) intermediolateral horns of the thoracic spinal cord.

In the photomicrograph below of a ground section of a tooth viewed by transmitted light, some dentinal tubules appear black because they

A) contain deeply stained odontoblastic processes.
B) are filled with minerals.
C) have become filled with air during sectioning.
D) are filled with bacteria.
E) are filled with blood.

Fiber tracts passing from the thalamus to the cortex are found in which of the following?
A) Anterior commissure
B) Medial lemniscus
C) Lateral lemniscus
D) Corpus callosum
E) Internal capsule

Which of the following is the MOST numerous cell type in the normal dental pulp?
A) Adipocyte
B) Odontoblast
C) Macrophage
D) Mast cell
E) Fibroblast

Which of the following represents the MOST vascular portion of the articular disc of the temporomandibular joint?
A) Intermediate thin zone (band)
B) Anterior thick zone (band)
C) Posterior thick zone (band)
D) Bilaminar zone

Which of the following organs is the NEAREST to the right kidney?
A) Duodenum
B) Stomach
C) Spleen
D) Colon
E) Pancreas

The prochordal plate consists of
A) the cardiogenic mesoderm and the neurectoderm.
B) endoderm of the roof of the yolk sac and embryonic ectoderm
C) the cloacal membrane and the overlying amnion.
.D) embryonic endoderm, mesoderm, and ectoderm.
E) a circular area anterior to the notochord in which the endoderm is fused to the embryonic mesoderm.

Which group of fibers of the periodontal ligament offer the MOSTresistance to movement of the tooth in an apical direction?
A) Alveolar crest
B) Oblique
C) Horizontal
D) Apical
E) Interradicular

On a comparative basis, bone and cellular cementum are similar in that both
A) are difficult to resorb, heal well, and contain cement lines.
B) are deposited throughout life, acquire blood vessels during aging, and contain similar collagenous fibers.
C) contain cells in lacunae with canaliculi that extend primarily toward the nutritional source.
D) contain concentric patterns, have Volkmann's canals, and can be cancellous.

The core of a microvillus consists of which of the following?
A) Vimentin filaments
B) 9 triplets of microtubules
C) 9 + 2 arrangement of microtubules
D) Microfilaments
E) Intermediate filaments

The blood-testis barrier is maintained by
A) spermatogonia.
B) Leydig cells.
C) myoepithelial cells.
D) spermatocytes.
E) Sertoli cells.

Oxyphil cells are present in which of the following?
A) Neurohypophysis
B) Fundic stomach
C) Thymus
D) Spleen
E) Parathyroid gland

Which of the following is the nerve that supplies the mimetic muscles?
A) Vagus
B) Facial
C) Hypoglossal
D) Trigeminal
E) Spinal accessory

Which of the following is the posterior limit of the vestibular side of the cheek?
A) Pterygomandibular raphe
B) Retromolar pad
C) Sphenomandibular ligament
D) Sulcus terminalis
E) Stylomandibular ligament

Para-keratinized oral mucosa is often found on which of the following?
A) Oral surface of the soft palate
B) Attached gingiva
C) Ventral surface of the tongue
D) Skin surface of the lips
E) Floor of the mouth

Which of the following represents a popular theory for the force that is considered to be the MOST responsible for active tooth eruption?
A) Cells and fibers in the developing PDL pull the tooth toward the oral cavity.
B) Dentin formation in the root pushes the tooth into the oral cavity.
C) Crestal bone formation pulls the tooth.
D) Vascular pressure within the pulp pushes the tooth intraorally.
E) Apical fundal bone formation pushes the tooth.

Which of the following ligaments helps resist posterior movement of the mandibular condyles?A) Temporomandibular
B) Anterior cruciate
C) Sphenomandibular
D) Stylomandibular
E) Pterygomandibular raphe

Which of the following structures runs directly adjacent to, and parallel with, the median nerve in the arm?A) Brachial artery
B) Ulnar artery
C) Radial artery
D) Medial brachial cutaneous nerve
E) Cephalic vein

Structure of Thymus

Which of the following represents the normal substrate of thrombin?
A) Thrombospondin
B) Fibrin
C) Prothrombin
D) Fibrinogen
E) Thromboplastin

Epinephrine causes an elevation in cAMP levels in muscle cells which in turn activate
A) ATPase.
B) glycogen synthetase.
C) glycogen phosphorylase.
D) adenyl cyclase.
E) glycogen phosphorylase phosphatase.

Which of the following noncollagenous protein components BESTcharacterizes dentin matrix?
A) Laminin
B) Vimentin
C) Phosphophoryn
D) Fibronectin
E) Osteonectin

Intravenous injections of KCl solution would increase the secretion of which of the following?
A) Aldosterone
B) Insulin
C) Cortisol
D) Parathyroid hormone
E) Calcitonin

The movement of Ca++ across a membrane is characterized by which of the following?
A) In many cell membranes involves a Ca++–Na+countertransport system
B) Maintains Ca++ concentration very much higher in the cell than in the extracellular fluid
C) An example of a cotransport system
D) A facilitated diffusion

Which of the following is necessary for de novo synthesis of cholesterol?
A) NADP+
B) FADH2
C) NADH
D) NA+
E) NADPH

The enzyme catalyzing the rate-controlling step in the de novosynthesis of fatty acids is regulated allosterically by the positive modulator

A) cyclic AMP.
B) ATP.
C) oxaloacetate
.D) citrate.
E) NADPH.

Which of the following controls the excitability of the muscle spindle?
A) Gamma efferent system
B) Length of the extrafusal fibers
C) Alpha efferent discharge
D) Load on the muscle

Under strict anaerobic conditions, the catabolism of one glucose molecule would yield a net of
A) 2 ATP and 2 lactic acid molecules.
B) 2 ATP and 2 pyruvic acid molecules.
C) 4 ATP and 2 lactic acid molecules.
D) 4 ATP and 2 pyruvic acid molecules.

Which of the following represents a polyunsaturated fatty acid that is commonly found in animal cell membranes?

A) Linoleic
B) Stearic
C) Lactic
D) Sialic
E) Oleic

GABA increases the permeability of postsynaptic membranes to which of the following ions?
A) Chloride
B) Potassium
C) Magnesium
D) Calcium
E) Sodium

Formation of Microfilaments

Which of the following sweeteners is non-nutritive as well as non-cariogenic?
A) Maltose
B) D-fructose
C) Galactose
D) Saccharin
E) Sorbitol

If the pH becomes lower than the isoelectric point of a protein, then how will the protein respond in an electrophoretic system? It will
A) migrate to the positive pole
.B) separate into its different monomeric forms.
C) remain stationary and unchanged.
D) migrate to the negative pole.
E) become denatured.

Sodium fluoride inhibits glycolysis by affecting which of the following?
A) Amylase
B) Enolase
C) Phosphorylase
D) Phosphatase

Insulin INCREASES the activity of which of the following?
A) Fructose 1-6 diphosphatase
B) Enolase
C) Glucose-6-phosphatase
D) Phosphorylase a
E) Phosphofructokinase

When arterial pressure increases, pressoreceptors discharge and
A) increase cardiac rate and strength of contraction.
B) inhibit tonic activity of sympathetic nerves and excite parasympathetic nerves.
C) excite sympathetic nerves and inhibit parasympathetic nerves.
D) cause vasoconstriction throughout the peripheral circulatory system.

The level of nonprotein nitrogen in the blood is due principally to the level of which of the following?A) Arginine
B) Creatine
C) Uric acid
D) Ammonia
E) Urea

After prolonged acidosis, which of the following represents the nitrogenous product that is excreted in high amounts in the urine?
A) Uric acid
B) Creatinine
C) Ammonia
D) Urea
E) Aspartic acid

Which of the following are the immediate effects of calcitonin on serum levels of calcium and phosphate?A) Serum calcium decreases, Serum phosphate has no change
B) Serum calcium has no change, Serum phosphate increases
C) Serum calcium increases, Serum phosphate increases
D) Serum calcium decreases, Serum phosphate decreases
E) Serum calcium increases, Serum phosphate decreases

Most endogenous cholesterol in the liver is usually converted into which of the following?
A) Cholic acid
B) Glucose
C) Oxaloacetate
D) Steroids
E) Ketone bodies

The ability to concentrate urine varies among animal species. The maximum urine concentration that can be produced by an animal isMOST closely related to which of the following?
A) Diameter of the distal tubule
B) Glomerular filtration rate
C) Length of the loop of Henle
D) Total number of nephrons
E) Renal blood flow

In relative insulin insufficiency, acetyl CoA is usually channeled into
A) fatty-acid synthesis.
B) ketone-body formation.
C) gluconeogenesis.
D) the Krebs cycle.
E) cholesterol synthesis.