Basic Sciences Flashcards
Pituitary microadenomas are smaller than_____ mm in diameter.
10
What is Sutherland’s classification for nerve injury?
- 1st degree Reversible conduction block.
- 2nd degree Wallerian degeneration occurs but endoneurium stays intact and recovery is usually complete.
- 3rd degree Endoneurium is destroyed but perineurium stays intact and recovery is incomplete.
- 4th degree All is destroyed except for the epineurium; recovery is poor.
- 5th degree Complete nerve transection; untreated recovery is not expected.
When during the day does growth hormone production peak?
2-3 hours into sleep (stage III or IV).
How long does it take for Wallerian degeneration to occur after complete nerve transaction?
3 days
What is the half-life ofT4?
7 days.
Which part of the pituitary gland is derived from Rathke’s pouch?
Anterior pituitary.
In patients treated for thyroid cancer, posttherapy thyroglobulin levels are less useful in the presence of elevated’—_.
Antithyroglobulin antibodies.
What structures facilitate passage of CSF into the dural venous sinuses?
Arachnoid villi.
Which of these result in Wallerian degeneration?
Axonotmesis and neurotmesis.
What hormone is produced by the parafollicular C cells of the thyroid?
Calcitonin.
What are the three primary ways a cell reacts to a hormonal signal?
Changing its metabolite or protein; generating an electric current; contracting.
What produces CSF?
Choroid plexus.
The parasympathetic nervous system originates in the segntents of the spinal cord while the sympathetic nervous system originates in the segntents of the spinal cord.
Craniosacral; thoracolumbar.
Secretion of ADH from the posterior pituitary gland results in decreased or increased urine volume?
Decreased.
Secretion of TSH from the anterior pituitary gland results in increased or decreased colloid production in the thyroid gland?
Decreased.
What hormone receptors are present in juvenile nasopharyngeal angiomas?
Dihydrotestosterone and testosterone.
What time of day does cortisol production peak?
Early morning.
How many cervical spinal nerves are there?
Eight.
Which thyroid blood test correlates best with the metabolic state of the patient?
Free thyroxine index (FT41).
When is clock-dependent alerting most active?
In the afternoon.
What effect does PTH have on urine phosphorus?
Increases urine phosphorus excretion.
Which hormone normally regulates protein synthesis and breakdown?
Insulin.
What is “clock-dependent alerting”?
Internal signal from the biological clock that opposes the tendency to fall asleep.
What are the two major classes of hormone receptors?
Membrane receptors, binding peptides and catecholamines, and nuclear receptors, binding small molecules that can diffuse across a cell membrane.
What are the three types of nerve injury?
Neuropraxia, axonotmesis, and neurotmesis.
Which of these has a more rapid rate ofWallerian degeneration?
Neurotmesis.
Steroid hormones and thyroid hormones use which type of receptor?
Nuclear.
What will happen to reverse T3 and T3 levels during fasting, systemic illness, and acute psychiatric illness?
Reverse T3 levels will increase and T3 levels will decrease.
What happens to PTH levels as people age?
Rise.
What is the most common cause of diabetes insipidus?
so% of cases are idiopathic.
What is the major inhibiting hormone to growth hormone?
Somatostatin.
What effect do exercise and stress have on growth hormone secretion?
Stimulate secretion.
Where in the brain is the “biological clock”?
Suprachiasmatic nuclei.
What is the major inhibiting hormone ofTSH?
T3.
Which of these sends motor and sensory fibers to the posterior and superior scalp as the greater occipital nerve?
The second cervical nerve.
The thyroid hormones are stored as , the main component of colloid.
Thyroglobulin.
The FT41is the product of total T4 level and what?
Thyroid hormone binding ratio (THBR).
Most of the circulating thyroid hormone is bound by.
Thyroxine-binding globulin.
Motor impulses are carried by the root of the spinal cord and sensory impulses are carried by the root of the spinal cord.
Ventral; dorsal.
What substance is unique to CSF, perilymph, and vitreous humor?
NAME?
What is a Type I error?
A false-positive result.
A prospective cohort study where exposure to the risk factor and subsequent health outcomes are observed after the beginning of the study is also known as what?
A longitudinal study.
Observational studies where the subjects are sampled based on presence or absence of disease and then their prior exposure status is determined are known as what?
Case-control studies.
Observational studies where the investigator determines the exposure status of the subjects and then follows them for subsequent outcomes are known as what?
Cohort studies.
What happens to the required sample size if the variability of the outcome diminishes?
Decreases.
How is the required sample size affected if one decreases the acceptable type I error?
Increases.
What are the advantages of case-control studies over cohort studies?
Less expensive and time-consuming and easier for studying rare diseases.
Tests with high sensitivity are useful to rule in or rule out disease?
Rule out.
What are the three primary forms of bias?
Selection bias, information bias, and confounding.
What is external validity?
The extent to which the results of a study are applicable to other populations.
What is the beta level of a test?
The likelihood of obtaining a type II error (false-negative).
1 - beta= _____
The statistical power (likelihood of detecting a true difference between the groups).
In autosomal recessive disorders, what is the risk of a child receiving a mutant gene from both parents and having the recessive trait?
25%.
What is the risk of the sibilings of affected persons being carriers?
67%.
What does 47, XY+21mean?
A male with three copies of chromosome 21.
What is genetic anticipation?
A phenomenon seen in disorders caused by unstable trinucleotide repeats where the age of onset of the disorder is younger and the phenotype becomes more severe with each succeeding generation.
How could a person with an autosomal dominant disease have no affected family members?
Due to a new mutation in the gene or nonpenetrance, where the gene lacks a phenotypic effect in a known carrier.
Autosomal recessive conditions are frequently associated with. defects whereas autsosomal dominant conditions are frequently associated with defects.
Enzyme; protein structure.
True/False: All complete autosomal monosomies are lethal early in development.
False; sex chromosome monosomy, such as Turner syndrome (45,X), can be viable.
What is an association?
Malformations occurring together more frequently than would be expected from chance alone.
What is the term for cell division in gametes?
Meiosis.
In which type of genetic defect can the father not pass a mutation to any offspring?
Mitochondrial defects.
What is a sequence?
Multiple defects arising from a single structural anomaly where the order of maldevelopment is understood.
What is a syndrome?
Pattern of multiple anomalies pathogenetically related.
Which type of inheritance pattern has a recurrence risk that varies with the number of affected family members?
Polygenic inheritance.
A classic example of genetic imprinting is seen with microdeletions of the region 15q11to 15q13. A microdeletion of the paternal chromosome 15 causes and microdeletion of the maternal chromosome 15 causes.
Prader-Willi syndrome; Angelman syndrome.
What syndrome is caused by a microdeletion in chromosome 17 and is associated with mental retardation, broad feet and hands, peripheral neuropathy, hearing loss and recurrent otitis media, disturbed sleep patterns, and inserting foreign objects into bodily orifices?
Smith-Magenis syndrome.
What is mosaicism?
The presence of two or more different chromosome constitutions in different cells in the same individual (i.e., may have some cells with 46 chromosomes and some with
Hurler-Scheie syndrome is caused by which gene mutations with which inheritance pattern?
This syndrome is inherited in an autosomal recessive pattern with the phenotype a product of two different mutations of the IDUA gene (compound heterozygotes.)
What are the most common numerical chromosome abnormalities in humans?
Trisomies.
What is a microdeletion syndrome?
Variable phenotypic pattern resulting from duplication or deletion of a small segment of linked chromosome material/genes that are functionally unrelated.
What is the concentration of immunoglobulins in the perilymph compared to the serum?
1/1000th.
What is the mechanism of type IV or delayed-type hypersensitivity immune reactions?
An overenthusiastic T-cell response to an environmental antigen where macrophages damage adjacent tissues.
What type ofT-cell receptor do Class II MHC antigens have?
CD4
Do helper T cells (TH) work with Class I or Class II MHC antigens?
Class II
Which type ofT cells remove the body’s own cells that have undergone change from a virus or malignancyin response to an antigen?
Cytotoxic or “killer” T cells.
In which area of the inner ear are immunologically active structures most commonly found?
Endolymphatic sac.
True/false: The light chain determines the class of the immunoglobulin.
False; the heavy chain determines the class.
Which immunoglobulin plays an important role in the prevention of parasitic infections?
IgE.
What is the mechanism of type II immune reactions?
IgG and IgM antibodies form against the self.
What is the mechanism of type III immune reactions?
IgG and IgM complexes deposit in the basement membranes of blood vessels, resulting in outflow of plasma into the tissues, activation of complement, and influx of neutrophils.
What is the only immunoglobulin that can cross the placenta?
IgG.
What is the predominant immunoglobulin in the perilymph?
IgG.
Which cells can serve as antigen-presenting cells?
Monocytes, macrophages, dentritic cells, Langerhans cells and B cells.
Which immunologic cells display CD2, CD16, and CD56 markers and kill some types of tumor cells without depending on prior immunization?
Natural killer cells.
Which subtype of TH cells requires IL-1 to proliferate in response to an antigen?
TH2 cells.
Which subtype off TH cells upregulate allergic inflammation?
TH2 cells.
What role does substance P play in the allergic response?
Through VIP, it causes vasodilation of the blood vessels in the nose, and through acetylcholine, it causes mucus secretion.
True/False: Class I MHC antigens appear on the surface of all nucleated cells in the body and have CDS as their T-cell receptor.
True.
Inhalant allergy and anaphylaxis are examples of which type of Coombs and Gell hypersensitivity reaction?
Type I, mediated by IgE.
Myasthenia gravis is an example of which type of Coombs and Gel hypersensitivity reaction?
Type II
Rheumatoid arthritis is an example of which type of Coombs and Gel hypersensitivity reaction?
Type III
Coombs and Gell described 4 types of hypersensitivity reactions of the immune system; which of these is mediated primarily by T cells and macrophages?
Type IV
How do lymphocytes responding to antigenic stimulation in the inner ear enter from the systemic circulation?
Via the spiral modiolar vein.
What percent of the population is colonized in the nasopharynx with Streptococcal pneumoniae?
40%.
How long does it take most acid-fast bacilli to grow?
7-10 days.
Which are the four primary features of”competent” bacteria?
Can self-aggregate, easily form protoplasts, are prone to autolysis, and have increased H+ and Na+ content that leads to increased glycolysis and ATP reserves.
The ability of bacteria to take up extracellular DNA from their environment is known as what?
Competence.
Which infectious organisms are eukaryotics?
Fungi and protozoa.
What are the five stages of biofilm development?
Initial attachment, irreversible attachment, maturation I, maturation II, and dispersion.
How does a virus replicate?
Only through infecting a cell.
Which cell type contains peptidoglycan in its cell wall?
Prokaryotes.
Are bacteria eukaryotic or prokaryotic?
Prokaryotic.
A single blood culture containing which contamination?
Staphylococcus epidermis, Staphylococcus hominis, Bacillis spp., Corneybacterium diptheriae (and other diptheroids).
Which bacterial infection accounts for more deaths than any other vaccine-preventable bacterial disease?
Streptococcal pneumoniae.
What are some ways to distinguish between true infection and contamination or colonzation?
The presence of large numbers of epithelial cells suggests contamination and the growth of normal skin flora suggests colonization.
Darkfield examination is necessary for detection of which organism?
Treponema pallidum.
What chromosome is P53 located on?
17p.
What is the basic structure of DNA?
A right-handed double helical structure composed of two antiparallel strands of unbranched polymeric deoxyribonucleotides (adenine, cytosine, guanine, and thymine) linked by phosphodiester bonds.
Which deoxyribonucleotides always pair together?
Adenine with thymine and cytosine with guanine.
What is the most common genetic alteration found in human cancers?
An acquired mutation in P53, a tumor-suppressor gene.
What is senescence?
An irreversible arrest in G1 of the cell cycle.
Cellular apoptosis is goverened by which group of protienases?
Capsases.
What is the role of cyclin Dt in head and neck cancer?
Cyclin D1 is a kinase that leads to phosphorylation of the RB protein (inactivating it) and has been shown to be amplified in up to 1/3 of head and neck cancers.
Cellular proliferation is goverened by which group of enzymes?
Cyclin-dependent kinases (CDKs).
True/False: TGF-fl stimulates cell proliferation.
False; it inhibits it.
What are the four phases of a cell’s cycle?
G1 (1st gap phase before DNA synthesis), S (DNA synthesis), G2 (gap before mitosis), and M (mitosis).
Extracellular signals primarily impact which phases of the cell cycle?
G1 and G2.
What is the prognostic significance of EGFR expression?
High levels of EGFR expression are correlated with poor prognosis and resistance to radiation therapy.
What is the role of retinoblastoma tumor-suppressor protein (pRB) in cell proliferation?
In its hypophosphorylated state, it inhibits entry from G1 into the S phase of the cell cycle; loss of pRB enables cancer cells to enter a mitotic cycle without the normal input from external signals.
What is the role of p53?
In the presence of cellular injury and DNA damage, P53 is upregulated, arresting the cell cycle at the Gl/S checkpoint.
What happens when epidermal growth factor receptor (EGFR) is bound by EGF or TGF-a?
Intracellular tyrosine kinase is activated, leading to inhibition of apoptosis and activation of cell proliferation and angiogenesis.
What is the role of HPV in head and neck cancer?
More than so% of tumors in the oropharynx harbor oncogenic HPV. Those associated with E6 and E7 proteins have better outcomes than HPV-negative tumors. HPV binds to pRB and inactivates it.
What are the two primary classes of cancer genes?
Oncogenes and tumor suppressor genes.
What group of intracellular proteins does TGF-fl stimulate to inihibit cell proliferation?
SMAD proteins.
What are the products of platelet degranulation?
TGF-P and platelet-derived growth factor (PDGF).
What is the role ofEGFR and TGF-a in head and neck cancers?
They are overexpressed in So-go% of squamous cell carcinomas of the head and neck.
What is the role of the MHC (major histocompatability complex) in the development of head and neck cancer?
Tumor cells can escape early detection by the patient’s immune system via decreased expression of class I MHC antigens.
What is the Warburg effect?
Tumor cells use the tumor M2-PK enzyme to consume glucose at an accelerated rate; tumor cells predominately produce energy by a high rate of anaerobic glycolysis followed by lactic acid fermentation in the cytosol, even in the presence of oxygen.
What enzyme is responsible for the Warburg effect in tumor cells?
Tumor M2-PK, a form of the pyruvate kinase enzyme.
What is the role of cyclooxygenase (COX-1 and COX-2) in head and neck cancer?
Upregulation of cyclooxygenase has been shown to increase prostaglandins, decrease apoptosis, and increase angiogenesis via vascular endothelial growth factor in head and neck tumors.
What is the appropriate ratio of the long and short axes for elliptical incisions
0.167361111111111
What is the ratio of Type I to Type II collagen in the skin
0.334027777777778
How much time does it take for a surgical wound to fully heal
2 years.
What is the absorption rate of chromic catgut sutures
20 days.
When is the wound tensile strength of irradiated tissues equivalent to that of non-irradiated tissues
3 weeks after RT.
What is the tensile strength of a wound after 4 weeks
30% of normal.
What is the maximum tensile strength of a surgical scar
80% of normal uninjured tissue.
What is the wound bursting strength
A direct measure of the force required to separate a healing, linear incision.
What complication will occur if the above ratio is not met
A dog-ear deformity.
What is the major event during the proliferative phase
Accelerated production of collagen.
When is return of sensation after skin grafting considered maximal
After 2 years.
When does the production of collagen peak during wound healing
Day 7 after wound closure (continues at this pace for 2 - 3 weeks).
What are 4 ways to correct hypertrophic or wide scars
Excision/undermining, Z-plasty or W-plasty, geometric broken line closure, and dermabrasion.
T/F: Scar maturation occurs more rapidly in children than in adults
False.
T/F: Large doses of vitamin E enhance wound healing
False.
T/F: TGF-fi stimulates endothelial cell proliferation
False. It inhibits it.
Poor wound healing after RT is primarily due to injury to which cell
Fibroblasts.
When does tensile strength correlate with total collagen content during wound healing
For about the first 3 weeks of wound healing.
Which amino acid is a key fuel for rapidly dividing cells
Glutamine.
What can the surgeon do to prevent wound complications after salvage surgery
Handle tissues carefully; leave fascia and underlying muscle attached to subcutaneous tissue; fill all potential dead space; drain wounds; close incision without tension; leave sutures in for a prolonged length of time but remove before RT begins.
What are the 3 phases of healing for skin grafts
Imbibition, inosculation and neovascularization.
What is the best level for undermining skin flaps
In the subdermal layer.
What are the 3 stages of normal surgical wound healing
Inflammation (d l-3), proliferation (d3-week 4), maturation (week 4 - 2 years).
Which stage is most sensitive to the effects of chemoradiation
Inflammatory stage.
Which hormone normally regulates protein synthesis and breakdown
Insulin.
What is the function of epidermal growth factor (EGF)
It stimulates DNA synthesis and cell division in a variety of cells, including fibroblasts, keratinocytes and endothelial cells.
What is the main difference between a keloid and a hypertrophic scar
Keloids extend beyond the boundary of the original tissue injury; hypertrophic scars do not.
What serum albumin level is associated with malnutrition
Less than 3 g/dl.
What is the tensile strength of a wound during the inflammatory stage
Less than 5% of normal.
Deficiency of which white blood cell is most likely to compromise wound healing
Macrophages.
Under what conditions is epithelial migration and replication most facilitated
Moist wound surfaces under gas-permeable dressings.
What are the first inflammatory cells to enter the wound space
Neutrophils.
When should scar revision take place
Not for at least I year after injury.
Which suture materials incite the greatest inflammatory response
Plain catgut and chromic catgut.
What suture material loses its strength within 7 days
Plain catgut.
What process allows survival of skin grafts in the first 48 hours
Plasmatic imbibition.
What is the most important factor in minimizing hyperpigmentation of skin grafts
Protection from UV light for a full year postoperatively.
What are the main events of the maturation stage
Reduction in the number of fibroblasts and macrophages, increase in collagen content, gradual increase in tensile wound strength.
What lines are perpendicular to the line of force of the underlying muscle
Relaxed skin tension lines.
What is the single best measure of nutritional status
Serum albumin level.
What effect does radiation therapy (RT) have on the wound bursting strength
Significantly decreases it… after 18 Gy, it is 52% of normal.
What are the products of platelet degranulation
TGF-13 and platelet derived growth factor (PDGF).
What is meant by inosculation with regard to skin grafts
The process by which vascular buds from the recipient bed make contact with capillaries within the graft.
What are the differences between thin and thick split thickness skin grafts
Thin grafts take better, but thick grafts have better color match, less contraction, and are more resistant to trauma.
Which serum proteins can be used to assess short-term nutritional status
Transferrin (half-life of 8 to 9 days), prealbumin (half-life of 2 days) and retinal-binding globulin (half-life of 12 hours).
T /F: Epithelialization produces a watertight seal within 48 hours.
True.
T/F: Epithelialization is more rapid under moist conditions than dry conditions
True.
T/F: Exogenous use of TGF-Jl appears to improve healing in tissues injured by RT
True.
T /F: Split-thickness skin grafts (STSG) contract more than full-thickness skin grafts (FTSG).
True.
The dermis primarily contains what type(s) of collagen
Type I (80%) and Type III ( 15%).
What is the predominant type of collagen in scar tissue
Type I.
Which type of collagen is a crucial component of the basement membrane
Type IV.
How long can skin grafts be stored when banked in saline-soaked gauze sponges at 4° Celsius
Up to 21 days.
When does irreversible ischemia of peripheral nerves occur
Within 8 hours of warm ischemia.
