Practice Problems Quiz 6

Question 1

1. Klinefelter’s syndrome is a relatively rare genetic disorder characterized by 47XXY karyotype. Individuals typically develop as males, with low fertility and a specific phenotype (see image). Consider the following case report: “During the third pregnancy of R.M., who had previously given birth to a normal son and daughter, a routine prenatal diagnosis was performed at 16 wk of gestation because of her advanced maternal age of 331⁄2 yr. A 47,XXY karyotype diagnostic for Klinefelter syndrome was found in all of the 16 investigated fetal amniocytes derived from two independent cell-culture flasks. At birth, however, the newborn presented with a female, not male, phenotype, with normal female external genitalia, and with bilateral clubbed feet. Karyotype analysis from peripheral blood lymphocytes of the newborn girl, B.M., con- firmed the cytogenetic result obtained during pregnancy: 47,XXY, with no indication of mosaicism (15 metaphases analyzed). Additionally, the karyotypes of both parents were investigated. In the father, a normal 46,XY male karyotype was found, whereas cytogenetic analysis of 13 metaphases from peripheral lymphocytes of the mother, R.M., unexpectedly revealed the same 47,XXY karyotype as her daughter B.M. Again, no evidence for mosaicism was found, and the sex chromosomes and autosomes were of apparently normal structure.” Discuss ways in which a 47XXY individual could have a fertile female phenotype, and speculate whether these individuals are likely to have any male phenotypic elements (prostate, testes, etc.).

Answer 1

http://www.ncbi.nlm.nih.gov/pubmed/11173857. The report states “The mother carries a structurally altered Y chromosome [in which] Yp material, including SRY, has been replaced by terminal Xp sequences. The fertility of the XXY mother can be attributed to the presence of the additional X chromosome that is missing in XY gonadal dysgenesis females. To our knowledge, this is the first human XXY female described who is fertile.” In this situation, it is unlikely that any male phenotypic components persist, since the gonads developed as female, and therefore did not produce testosterone.

Question 2

2. National Organization for Rare Disorders (NORD) includes a listing for a Wnt4-related condition, described below : “…a rare genetic disorder that affects females. It is characterized by the absence or underdevelopment of the uterus and sometimes absence or underdevelopment of the vagina. Affected females also experience abnormally high levels of androgens (hyperandrogenism), which are male sex hormones. Androgens promote and control the development of male sex characteristics and, consequently, affected females may have certain symptoms such as a male pattern of hair growth (hirsutism). Females with WNT4 develop normal secondary sexual characteristics during puberty (e.g., breast development and pubic hair), but do not have a menstrual cycle (primary amenorrhea). The failure to begin the menstrual cycle may be the initial clinical sign of this disorder. This disorder can cause significant psychological challenges and counseling is recommended. In some cases, affected individuals may have kidney (renal) abnormalities such as absence of one kidney (unilateral kidney agenesis). This condition may cause affected individuals to have an increased susceptibility to urinary tract infections and/or kidney stones (renal calculi).” Discuss 1) why this disorder is only seen in females, 2) what the likely source of high levels of androgens might be and 3) whether the condition is likely to be due to a loss of function of Wnt4, reduced function, or misexpression of the Wnt4 gene

Answer 2

Discussion: Wnt4 plays important roles in formation of the gonads, kidneys, lungs and other structures. SERKAL syndrome (female sex reversal and dysgenesis of kidneys, adrenals, and lungs) is a lethal human syndrome associated with complete loss (or severe deficiency) of Wnt4: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2253972/ In this condition, 46XX individuals develop as phenotypic males, but typically die due to the other abnormalities listed. In contrast, the condition described by NORD is likely to be due to incomplete loss of Wnt4 function, resulting in the gonads developing at least partially along a male pattern and producing low levels of testosterone. Interestingly, this condition is likely to occur in both males and females, but due to relatively normal male development in XY patients with reduced Wnt4, male patients are likely to be diagnosed as having a kidney disorder of unknown etiology, with the association with Wnt4 function being undetected.

Question 3

3. Cases of 5-alpha-reductase deficiency have been intensively studied for decades to investigate the contributions of testosterone exposure and societal gender roles in gender identity at puberty. Most studies confirm that in cases where the testes were not removed (i.e. testosterone exposure was normal in prenatal and postnatal life), most patients undergo a shift from a female to a male gender identity at puberty (see for example: http://www.ncbi.nlm.nih.gov/pubmed/431680). In cases where the testes were removed at birth due to genital ambiguity, and patients were raised female, results are much more variable (see, for example, this study reporting 60% of patients raised as female elect to switch gender to male; http://www.ncbi.nlm.nih.gov/pubmed/23044880). Review the roles of testosterone and dihydrotestosterone in male reproductive development and discuss the factors that should be considered in management of 46XY infants presenting with 5-alpha-reductase deficiency.

Answer 3

Discussion: 5-α reductase deficiency causes an intersex condition (pseudovaginal perineoscrotal hypospadias). It was first discovered in indigenous cultures of Papua, New Guinea, where children were born with feminine genitalia in the absence of endogenous DHT during pregnancy, but with the surge of testosterone during adolescence, changed to males at puberty. Because of this change at puberty, the condition is also sometimes called “guevedoche.” There is a range of external appearance that has been described of external genitalia at birth, with varying degrees of virilization. Currently, individuals with ambiguous genitalia at birth are routinely tested for DHT deficiency. Factors contributing to management are complex, and include the extent of the genital anomaly, likely functional state of the gonads and other reproductive anatomy and (most controversially) the will of the parents. In addition, early surgical management tends to have better outcomes, but is undertaken without the informed consent of the patent.

Question 4

A pathologist has received a biopsy or uterus taken from late in the menstrual cycle, several days before menstrual bleeding begins in the next cycle. Fortunately for the patient, the biopsy is totally normal. What is the histological appearance of the uterus in this sample? Myometrium is thick; endometrium consists of a thin lamina basalis and virtually no lamina functionalis Myometrium is thick; endometrium consists of a thin lamina basalis and thick lamina functionalis with narrow, straight tubular glands Correct Answer Myometrium is thick; endometrium consists of a thin lamina basalis and thick lamina functionalis with distended, coiled sacculated glands Myometrium is thin; endometrium consists of a thin lamina basalis and virtually no lamina functionalis Myometrium is thin; endometrium consists of a thin lamina basalis and thick lamina functionalis with narrow, straight tubular glands Myometrium is thin; endometrium consists of a thin lamina basalis and thick lamina functionalis with distended, coiled sacculated glands

Answer 4

Myometrium is thick; endometrium consists of a thin lamina basalis and thick lamina functionalis with distended, coiled sacculated glands: The biopsy was taken during the secretory phase of the menstrual cycle. During this phase, the functionalis is much thicker and the tubular glands are coiled and full of secretory product.

Question 5

Answer 5

A

The biopsy was taken during the menstrual phase of the menstrual cycle. At the end of this phase, much of the functionalis layer of the endometrium has been sloughed off.

Question 6

The primary spermatocyte is one of the most frequently seen cells of the seminiferous
tubule epithelium. Which of the following is the best explanation for the prevalence of this cell type?

The primary spermatocytes are in an extended stage of meiosis.

The primary spermatocytes are most intimately associated with the Sertoli cells and thereby receive increased metabolic support.

The primary spermatocytes divide very rapidly and are thus more numerous.

The mitotic division of spermatogonia provides a constant source of primary spermatocytes.

The primary spermatocytes are the largest cells of the tubules

Answer 6

The primary spermatocytes are in an extended stage of meiosis.

These cells remain in meiosis I for approximately 3 weeks.

Question 7

The initiation of the secretory phase of the uterus coincides with the:

Recruitment of primordial follicles

Establishment of the zona pellucida

Establishment of the corpus luteum

Peak of LH secretion

Constriction of the coiled (spiral) arteries

Answer 7

Establishment of the corpus luteum

Once ovulation has occurred the corpus luteum forms and becomes a temporary endocrine organ secreting progesterone. The progesterone stimulates the epithelial cells of the uterine glands to become coiled, and secret and accumulate glycogen.

Question 8

Which of the following hormones causes secretion of glycogen by epithelium of the female reproductive tract?

LH

Estrogen

FSH

Progesterone

Answer 8

Progesterone

Progesterone secreted from the corpus luteum stimulates the epithelial cells of the uterine glands to become coiled and secret and accumulate glycogen.

Question 9

The blood-testis barrier is formed by:

Tight junctions between endothelial cells in testicular capillaries

Tight junctions between spermatogonial cells

Tight junctions between Sertoli cells

Gap junctions between developing spermatocytes

Extracellular matrix laid down by Leydig cells

Answer 9

Tight junctions between Sertoli cells

This barrier is the tightest blood-tissue barrier in mammals and is part of a system to prevent autoimmune attacks against spermatogenic cells, which are formed after the immune system is mature.

Question 10

The mature follicle is converted into the corpus luteum:

When the zona pellucida is formed

When human chorionic gonadotropin is present in the blood

When the basement membrane is penetrated by blood vessels

Answer 10

When the basement membrane is penetrated by blood vessels

After ovulation, the granulose and thecal layers collapse and fold in, the capillaries are disrupted and invade the granulose layer.

Question 11

Sloughing of the lamina functionalis of the endometrium is the direct result of:

Increased blood levels of estrogen

Constriction of the spiral (coiled) arteries

Decreased blood levels of FSH

Constriction of the straight arteries

Answer 11

Constriction of the spiral (coiled) arteries

When fertilization does not occur, the drop in progesterone produces spasms of muscle contraction in the spiral (coiled) arteries, interrupting blood flow. This also causes the release of prostaglandins, causing constriction. As a result of hypoxia, cytokines are releases that trigger release of proteins that degrade the basement membranes.

Question 12

Sperm become mature and mobile in the:

Seminiferous tubules

Epididymis

Seminal vesicle

Ampulla of ductus deferens

Prostate

Answer 12

Epididymis

Fluids within the epididymis contain decapacitation factors that block the acrosome reaction in the sperm until it is within the female reproductive tract. Sperm are not fully mature until they pass through the epididymis.

Question 13

The monthly ovarian cycle in the human female is characterized by a recruitment of several primordial follicles to return to the meiotic cell cycle. However, only one of these follicles is usually ovulated, the remainder become atretic. What is the most likely explanation for this process?

The dominant follicle secretes progesterone, which inhibits the further development of other follicles

The dominant follicle establishes an increased sensitivity to FSH

The ovarian stroma can provide metabolic support for only one Graafian follicle

Most of the recruited follicles contain oocytes that have accumulated mutations and become unviable

Granulosa cells of the dominant follicle establish tight junctions, which increase metabolite concentration of the antral fluid

Answer 13

The dominant follicle establishes an increased sensitivity to FSH

Although there are likely complex hormonal balances that control selection, it is clear that FSH prompts follicular growth and development. The dominant follicle likely expresses more FSH receptor, which causes it to be more responsive to the effects of FSH.

Question 14

The proliferative phase of the uterine cycle is primarily maintained by which of the following hormones?

Estrogen

Progesterone

LH

FSH

Answer 14

Estrogen

The proliferative phase is often called the “estrogenic” phase. These estrogens are secreted by the thecal cells of developing follicles. Progesterone, while present, is more important for the secretory phase.

Question 15

What secretory product is characteristic, or diagnostic, of the prostate gland?

Acid phosphatase

Ascorbic acid

Fructose

Sialoproteins

Testosterone

Answer 15

Acid phosphatase

The prostrate produces acid phosphatase. This marker used to be used to test for prostate cancer and can be used to detect the presence of semen.

Question 16

The epithelial lining of the uterus is most similar to that of the:

Vagina

Cervix

Vas deferens

Ovary

Oviduct

Answer 16

Oviduct

Both the oviduct and the uterus have simple columnar epithelium with interspersed ciliated cells.

Question 17

Spermatogonia give rise to primary spermatocytes by what form of cell division?

mitosis

meiosis

mitosis followed by meiosis

no cell division is involved

Answer 17

Mitosis

Spermatogonia first undergo clonal divisions that leave the cells as a syncytium, then undergo a final mitotic division to produce two cells (either spermatogonia or spermatocytes committed to meiosis).

Question 18

Answer 18

E,F

The oocyte completes its first meiotic division right before ovulation (F).

Question 19

Leydig cells of the interstitial testicular space are responsible for the production of testosterone. These cells are inactive in adolescent males, and are absent in females. What accounts for the presence of testosterone in prepubescent boys and in females?

Conversion of estrogen to testosterone in the hypothalamus

De novo synthesis of testosterone in responsive tissues

Low level secretion of testosterone by the adrenal cortex

Conversion of corticosteroid to testosterone in responsive tissues

Absorption of ingested testosterone in the duodenum

Answer 19

Aderenal cortex

The adrenal cortex produces low levels of testosterone. At puberty, Leydig cells are stimulated to produce testosterone by LH, which is in turn triggered by GnRH (gonadotropin releasing hormone) from the hypothalamus.

Question 20

During spermiogenesis, which of the following cells is the first that will contain either an X or Y chromosome, but NOT BOTH, in its prophase nucleus?

Spermatogonial cell

Primary spermatocyte

Secondary spermatocyte

Early spermatid

Motile spermatozoon

Answer 20

Secondary spermatocyte

The secondary spermatocyte has undergone Meiosis I but not Meiosis II. Therefore, it is haploid with 23 chromosomes (22 + X or 22+ Y). Each consists of 2 chromatids so they are still 2N. The primary spermatocyte is diploid, has 44 +XY chromosomes and is 4N.

Question 21

Smooth muscle contractions involved in sperm ejaculation occur in which organ of the male reproductive system?

Epididymis

Ductus deferens

Seminal vesicle

Prostate gland

Bulbourethral glands

Answer 21

The ductus deferens has a very thick muscularis which when stimulated produce strong peristaltic contractions that move sperm along the duct from the epididymis.

Question 22

What are the stem cells of the germ cell population of the seminiferous epithelium?

Primary spermatocytes

Secondary spermatocytes

Spermatids

Spermatogonia

Answer 22

Spermatogonia divide by mitosis to produce stem cells, transient amplifying cells and spermatocytes committed to meiosis.

Question 23

Answer 23

E

Question 24

Answer 24

F

Question 25

Answer 25

B

Question 26

4. Ovulation is caused by a spike in LH and FSH release. What causes this spike to occur?

A. Decreased GnRH from the hypothalamus

B. Decreased ovarian estrogen release

C. Decreased ovarian progesterone release

D. Elevated ovarian estrogen release

E. Elevated ovarian progesterone release

Answer 26

D. Elevated ovarian estrogen release

Question 27

5. The corpus luteum prevents a second ovulatory event within one menstrual cycle primarily by secreting:

A. estrogen & progesterone

B. follicle-stimulating hormone and progesterone

C. follicle-stimulating hormone and luteinizing hormone

D. Luteinizing hormone and progesterone

Answer 27

A. estrogen & progesterone

Question 28

6. During the luteal phase of the ovarian cycle a woman’s basal body temperature increases by ~0.4°C. The action of which hormone, that is normally only high during the luteal phase, is most likely responsible for this temperature increase?

A. Estrogen

B. Follicle-stimulating hormone

C. Human chorionic gonadotropin

D. Leptin

E. Luteinizing hormone

F. Oxytocin

G. Progesterone

Answer 28

G. Progesterone

Question 29

7. During the early follicular phase of the ovarian cycle, what is most likely occurring in the uterus?

A. Increase in the number, length and complexity of the spiral arteries

B. Shedding of the functional layer of the endometrium

C. Thickening of the functional layer of the endometrium

D. Transcriptional induction of the progesterone receptor within the endometrium

Answer 29

B. Shedding of the functional layer of the endometrium

Question 30

8. If implantation of a zygote occurs in the endometrium, production of what hormone by the blastocyst prevents the atrophy of the corpus luteum?

A. Chorionic gonadotropin

B. Estrogen

C. Follicle-stimulating hormone

D. Luteinizing hormone

E. Progesterone

Answer 30

A. Chorionic gonadotropin

Question 31

9. One of the key functions of progesterone during pregnancy is to prevent uterine contractions (“quiet the myometrium”). The mechanism of action of progesterone most likely includes:

A. Activating adenylate cyclase to produce increased cAMP and active protein kinase A.

B. Allosterically activating a cell surface tyrosine kinase receptor and promoting a MAP kinase-signaling cascade

C. Binding to a nuclear hormone receptor to directly alter gene expression

Answer 31

C. Binding to a nuclear hormone receptor to directly alter gene expression

Question 32

10. Elevated blood levels of which hormone are most likely to be diagnostic of menopause?

A. Estrogen

B. Follicle-stimulating hormone

C. Human chorionic gonadotropin

D. Leptin

E. Luteinizing hormone

F. Oxytocin

G. Progesterone

Answer 32

B. Follicle-stimulating hormone

Question 33

A. Obesity

B. Ovarian cancer

C. Polycystic ovarian disease

D. Pregnancy

E. Premature menopause

F. Primary amenorrhea

Answer 33

D. Pregnancy

Question 34

12. Birth control pills function to inhibit follicular development and ovulation. The hormones in the pill reduce the cyclic pulses of gonadotropin-releasing hormone (GnRH) and inhibit the release of the gonadotropins. Therefore, birth control pills most likely contain small amounts of:

A. Estrogen and progesterone

B. Follicle-stimulating hormone

C. Human chorionic gonadotropin

D. Leptin

E. Luteinizing hormone

F. Oxytocin

Answer 34

A. Estrogen and progesterone

Question 35

13. On average, obese girls have earlier menarche than girls of normal body weight. One likely reason is that hypothalamic signaling of an adipose-derived hormone is important in establishing the rhythmic pulses of GnRH. This adipose-derived hormone is most likely:

A. Estrogen

B. Follicle-stimulating hormone

C. Human chorionic gonadotropin

D. Leptin

E. Luteinizing hormone

F. Oxytocin

G. Progesterone

Answer 35

D. Leptin

Question 36

Answer 36

A. Clitoris, B. Urethra, C. Vagina, D. Anus, E. Bulb of the vestibule, F. Greater vestibular gland, G. Perineal membrane on deep perineal pouch, H. Ischiocavernosus muscle, I. Bulbospongiosus muscle, J. Superficial transverse perineal muscle, K. Levator ani muscle, L. Gluteus maximus muscle

Question 37

Answer 37

Question 38

Question 39

Question 40

Question 41

Question 42

Endometriosis is a condition where endometrial tissue flourishes outised the uterine how does it get there?

Answer 42

Via the uterine tube and external os of the tube.

Question 43

Surgury to remove the cervix….what artery besides the vaginal and uterine arteries should be clamped

Answer 43

The ovarian

Question 44

Left Ovarian vein thrombosis extends into what?

Answer 44

Renal vein

Question 45

Mass at 8 oclock of vestuble of supine patient, tender and warm to touch, red and slightly raised inguinal lymph node is enlarged

Answer 45

Greater vestibular gland abscess

Question 46

For a nerve block of the pudendal nerve coursing around the sacrospinous ligament what area is blocked by anesthetic

Answer 46

S2-S4 cutaneous field

Question 47

Answer 47

Question 48

Explain the path of rhythmic contraction of the bulbospoongiosus muscle

Answer 48

Question 49

Explain the innervation and path of contraction of the ductus deferens

Answer 49

Question 50

Explain the innervatio of stimulation of the penis

Answer 50

Question 51

Explain the innervatio and method of erection

Answer 51

Question 52

Histological examination of 50 infertile men from Zambia revealed parasitic infection of the seminal vesicles by Schistosoma haematobium with histological inactivity of this gland. Identify the most likely component of semen that would be in low yield as a result of this infection.

A.Fructose

B.Mucus

C.PSA

D.Sperm

E.Testosterone

Answer 52

A. Fructose

Question 53

Upon palpation of a 57-year-old patient’s prostate gland (via digital rectal exam), the examiner documents her findings as, “the prostate is smooth, without nodularity or bogginess, size seems enlarged”. Identify a symptom the patient could describe that would most likely confirm diagnosis of benign prostatic hypertrophy/hyperplasia (BPH).

A.Difficulty voiding bladder

B.Erectile dysfunction

C.Infertility

D.Loss of cremasteric reflex

E.Paresthesia of the penis

Answer 53

A.

Question 54

During sexual arousal, a nerve releases nitric oxide (NO), which dilates deep penile arteries. Blood fills the erectile tissue of the penis resulting in an erection. Identify the nerve most likely responsible for releasing NO.

A.Genitofemoral

B.Ilioinguinal

C.Pelvic splanchnic

D.Pudendal

E.Sacral splanchnic

Answer 54

C. Pelvic Splanchnic

Question 55

A 59-year-old man undergoes a prostatectomy. The plexus of nerves surrounding the prostate were damaged during the procedure. Identify potential difficulties the patient may experience as a result of this nerve damage.

. Ability to achieve an erection

B. Contraction of detrusor muscle

C. External anal sphincter contraction

D. Penile sensation

Answer 55

A. Ability to achieve an erection

Question 56

A 42-year-old man has a vasectomy. The physician explains to him that 3-4 months after the procedure, when he has an orgasm during sexual intercourse, most likely he:

A.No longer will produce an ejaculate

B.May or may-not have an ejaculate depending on stimulation

C.Will still produce an ejaculate

Answer 56

Will Still produce an ejaculate (just no sperm in it since the chord to the testes is gone)

Question 57

A 32-year-old man with carcinoma of the testis undergoes exploratory surgery to biopsy lymph nodes.

Which of the following lymph nodes is most likely sampled to determine if the cancer has metastasized via the lymphatic system?

A.External iliac

B.Femoral

C.Internal iliac

D.Paraaortic

E.Superficial inguinal

Answer 57

Paraaortic

Question 58

Answer 58

Question 59

Identify the muscle the helps to move the testis to regulate optimal temperature for sperm production.

Answer 59

A.Cremaster

Question 60

A 24-year-old man presents to the ED with nausea, vomiting, low-grade fever, and crampy abdominal pain that has gotten progressively worse over the past 12 hours. He is otherwise healthy except for a 6-month history of a previously non-painful, reducible bulge in his right groin that worsened with lifting. The physician diagnoses a strangulated indirect hernia with resulting bowel obstruction and necrosis.

ID the most likely cause for his hernia?

A.Congenital defect in diaphragmatic membrane

B.Enlarged external inguinal ring

C.Enlarged femoral ring

D.Patent processus vaginalis

E.Weak abdominal wall musculature

Answer 60

A.Patent processus vaginalis

Take home message:

Indirect inguinal hernias:

• are the result of a congenital defect of the processus vaginalis.
• provide a potential space through the deep inguinal ring for abdominal contents to herniate. Potential complications of any hernia include strangulation and infarction of bowel, as has occurred in this case.

Question 61

Answer 61

0.3

Question 62

Answer 62

2

Question 63

Answer 63

3/9

Question 64

Answer 64

2

Question 65

Answer 65

2/10

Question 66

Answer 66

3

Question 67

Answer 67

3/12

In recessive carrier by carrier mating, meiotic events from both parents have a chance of recombination. Therefore, there are 12 meiotic events in this pedigree. From left to right, child 1, 3 and 4 show signs up recombination.

Question 68

Answer 68

5

Question 69

Answer 69

6

Question 70

Answer 70

1/9

Question 71

A monoclonal antibody developed in a mouse specifically binds to cells found adjacent to central arteries in the human spleen. These cells are arranged symmetrically around such arteries. What is another area that you would expect to be rich in cells also able to bind this antibody?

The capsule of the spleen

The cortex of a lymph node, just below the capsule

The deeper cortex of a lymph node, near the medulla

The medulla of a lymph node

The red pulp of the spleen

Answer 71

The deeper cortex of a lymph node, near the medulla

The PALS in the spleen is staffed primarily by T cells; it’s a thymus dependent zone. Another such T cell area is the cortex of lymph nodes near the medulla, B cells staff the area near the capsule.

Question 72

The interaction between an NK cell and the MHC molecules of a normal cell serves to:

Initiate apoptosis in NK cell

Initiate killing reactions by the NK cell

Keep the NK cell inactive

Show the NK cell host cell antigens

Stimulate mitosis in the NK cell

Answer 72

Keep the NK cell inactive

NK cells have a receptor for MHC that serves to keep the NK cells inactive. Low levels of MHC on a cell reduce this inactivating signal, making it more likely that the NK cell will kill such a host cell, especially if it is displaying stress induced proteins on its surface.

Question 73

Generally speaking, after the first time that a naïve T cell’s antigen receptors bind its complementary antigen it will either: 1. begin dividing, or else 2. die or become inert. What is the principal factor that determines this choice?

The age of the T cell

The nature of the antigen

The nature of the host MHC

The presence of additional interactions at the time of antigen binding

The presence of homing receptors on the T cell

Answer 73

The presence of additional interactions at the time of antigen binding

The stop/go signal is determined by additional interactions, such as co-stimulatory molecules and cytokines.

Question 74

For which cell of the immune system does its eventual effector function involve the secretion of its antigen receptor?

B cell

CTL (CD8 T cell)

Eosinophil

PMN

Th (CD4 T cell)

Treg

Answer 74

B cell

The effector function produced by activation of a B cell is secretion of Ig molecules, derived from the same gene that codes for the cell’s antigen receptor. The transcript from the gene is differentially spliced, removing the membrane anchor sequence and allowing the protein to be secreted via the default pathway.

Question 75

Occasionally, reticulocytes are produced containing small chromatin fragments due to incomplete extrusion of the nucleus from the orthochromatophilic erythroblast. These dense lumps (called Howell-Jolly bodies) will impede the flexibility of the resulting RBC’s and such cells could plug up capillaries. This situation is corrected by:

Destruction of the RBCs by macrophages as the RBC’s reenter splenic sinuses from splenic cords.

Destruction of the RBCs by NK cells due to binding of anti-DNA antibodies

Digestion of the fragments by DNase in the cytoplasm of RBC’s

Removal of the nuclear fragment by macrophages as the RBC’s reenter splenic sinuses from splenic cords

Answer 75

Removal of the nuclear fragment by macrophages as the RBC’s reenter splenic sinuses from splenic cords

Inclusions present in red cells are removed by pitting in the spleen, as the cells re-enter the circulation from the splenic cords.

Question 76

What is the state of genes coding for antigen receptors in innate vs. adaptive immune system cells in a fertilized human egg?

Genes for acquired receptors are ready for transcription, innate receptor genes must be rearranged

Genes for both innate and acquired receptors are ready for transcription

Genes for both innate and acquired receptors must be rearranged

Genes for innate receptors are ready for transcription, acquired receptor genes must be rearranged

Answer 76

Genes for innate receptors are ready for transcription, acquired receptor genes must be rearranged

Functional innate antigen receptors are present in germ line DNA, adaptive receptor genes must be rearranged during the development of these cells.

Question 77

The initial response of the acquired immune system to a new pathogen is slow, on the order of a week or two. The reason for the delay is the acquired system’s requirement for:

Chemotaxis

Clonal selection

Cytokine signaling

Diapedesis

Recirculation

Answer 77

Clonal selection

Initial responses of the acquired immune system require clonal selection, which takes time to identify cells with useful receptors, expand clones of these cells by mitosis, and generate effector cells.

Question 78

What kind of immune system cell would be missing from a person who, beginning at birth, was kept free of all contact with antigens?

Basophils

B cells

Eosinophils

Macrophages

Memory cells

PMNs

T cells

Answer 78

Memory cells require antigen exposure to initiate clonal selection and expansion of a pool of cells, from which memory cells are then produced

Question 79

Typically, what are the first immune system cells recruited in large numbers to the site of a bacterial infection in connective tissue?

B cells

Basophils

CTLs (Tc cells, CD8 T cells)

Eosinophils

Macrophages

PMNs

Treg cells

Th cells

Answer 79

PMNs

PMNs are usually the first cells recruited to the site of a bacterial infection in large numbers, often by chemokines released from resident macrophages.

Question 80

What process eliminates pre-T cells that contain TCRs capable of binding to self-antigens?

Clonal selection

Immunological memory

Immunological surveillance

Negative selection

Positive selection

Answer 80

Negative selection removes self-reactive cells, positive selection ensures the TCR can recognize MHC.

Question 81

If exposure to a protein antigen eventually leads to a humoral antibody response, it is most likely that both B cells and Th cells were activated by antigen exposure. The B cells likely first saw the intact protein, or large pieces of it, presented on the surface of a follicular dendritic cell. How did the Th cells see the protein?

As large protein fragments presented by an APC on MHC class I

As large protein fragments presented by an APC on MHC class II

As peptides presented by an APC on MHC class I

As peptides presented by an APC on MHC class II

As an unprocessed protein directly on the pathogen

Exactly as the B cells did

Answer 81

As peptides presented by an APC on MHC class II

The TCR of Th cells sees antigen presented on another cell’s MHC class II molecule and only professional APCs express class II. In the case of a Th cell involved in helping a B cell in a cognate pair, the Th cell is seeing the peptide on the MCH class II protein of the partner B cell.

Question 82

A lymph node near an infected area is often swollen and tender to touch, while a lymph node swollen by the growth of a lymphoma is not painful. The lack of pain in the latter case is due to the relative absence of…

Connective tissue

Cytokines

Lymph

Rapid cell division

Sensory nerves

Answer 82

Cytokines

The lack of pain in nodes swollen by cancer is due to the lack of cytokines, which are not required for tumor cell growth.

Question 83

A patient presents with a swollen, non-tender axillary lymph node. Biopsy samples are prepared for histological analysis. A mass of uniform small cells is observed. Further testing reveals that these cells express surface IgM molecules, which are identical on every cell, and excess antibody proteins are detected in the patient’s blood. This tumor most likely arose from a(n):

Uncommitted lymphoid stem cell.

Activated B-cell

Activated T-cell

Plasma cell

Answer 83

Plasma cell

Tumors from the B cell lineage often maintain the activity of the originating cell, in this case, antibody production. Plasma cell tumors often, but not always, secrete antibody proteins.

Question 84

Answer 84

D

Dendritic antigen presenting cells in lymph nodes are able to activate both nave CD4 (Th) and CD8 (Tc) lymphocytes, so they must express both MHC class I and II. They are also able to express a co-stimulatory molecule, B7, to provide the “second handshake” necessary to activate nave T lymphocytes.

Question 85

Hepatitis C is a liver disease caused by infection with the hepatitis C virus (HCV). Some infections are asymptomatic and quickly cleared by the immune system. In other cases the infection can become chronic and after many years the fibrosis caused by the infection leads to cirrhosis. Rates of liver failure and liver cancer are high in such cases. In chronic cases the cells required to mount a cell-mediated attack on HCV-infected cells are present in the liver, but fail to perform properly, allowing the infection to persist. The presence of what immune system cells would most likely explain this failure?

B cells

Basophils

CTLs (Tc cells, CD8 T cells)

Eosinophils

Macrophages

PMNs

Treg cells

Th cells

Answer 85

Treg cells

Treg cells are able to suppress the effector activity of other T cells, so they are the most likely candidate on the list below. They are, in fact, found in the liver of patients with chronic hepatitis C infections and are thought to contribute to the failure to clear the infection by suppressing the activity of Tc and Th cells. Treg cells are thought to provide useful activities, such as suppressing potential autoimmune reactions, but it appears they can reduce useful activities in some cases, such as this.

Question 86

A researcher is studying a line of mice that has an inactivating mutation in the FOXN1 gene. Mice homozygous for this mutation are hairless and they are therefore called nude mice. The lack of FOXN1 in these nude mice also interferes with the development of the thymus. The thymus is entirely missing or very underdeveloped in newborn nude mice. The researcher determines that the levels of immunoglobulins in the mice are very low. A deficit in the numbers of what cells is most likely responsible for the reduction in immunoglobulins?

B cells

Follicular dendritic cells

Tc cells (CD8 T cells)

Th cells (CD4 T cells)

Treg cells

Answer 86

Th cells (CD4 T cells)

Th cells are required to supply cytokines and co-stimulatory interactions (second handshakes) for the development of B cells and eventual antibody production.

Question 87

The researcher studying the nude mice in the preceding question determines that much of the antibody present in serum is IgM. What activity is most likely missing and what is normally responsible for providing the activity?

Antigen receptor gene rearrangement, stem cells

Clonal deletion, epithelial reticular cells

Clonal anergy, Treg cells

Clonal selection, dendritic cells

Induction of isotype switching, Th (CD4) cells

Answer 87

Induction of isotype switching, Th (CD4) cells

Th cells are required for isotype switching.

Question 88

Answer 88

Question 89

Answer 89

Question 90

Answer 90

Question 91

Answer 91

Question 92

Answer 92

Question 93

Answer 93

Question 94

Question 95

Answer 95

Question 96

Answer 96

Question 97

Omohyoid syndrome results when there is damage to the inferior belly of the omohyoid muscle due to sustained and excessive extension or flexion of the cervical spine. Symptoms include pain in the supraclavicular region and when swallowing. Treatment includes an injection of NSAIDS (see arrow). For this injection, several fascial planes need to be pierced. Identify the fascial planes most likely pierced by the needle on route to the omohyoid muscle.

Answer 97

1. Superficial cervical fascia
2. Investing fascia
3. Pretracheal fascia

Question 98

Answer 98

Question 99

Answer 99

D – Anything with C3,C4, or C5!

Question 100

Answer 100

Question 101

Answer 101

Question 102

A 36-year-old woman undergoes a needle biopsy for a thyroid tumor. She reports difficulty breathing and the mass moves up and down with swallowing. Identify the fascial layers most likely pierced by the needle while taking the biopsy.

Answer 102

1. Superficial cervical fascia
2. Investing fascia
3. Pretracheal fascia

Question 103

The anterior pituitary gland produces and secretes thyroid stimulating hormone (TSH). TSH enters the hypophyseal circulatory system and eventually flows into the internal jugular vein (IJV) and targets thyroid follicles.

Trace a molecule of TSH from the pituitary to the thyroid follicles.

Answer 103

Question 104

One aspect of the physical exam is measuring the jugular venous pressure (JVP). The JVP appears as a pulse in the neck by the right internal jugular vein. Therefore, the JVP is caused by the venous system, not the arterial. There are no valves in the superior vena cava (SVC), brachiocephalic trunk or right internal jugular vein (IJV).

Hypothesize what would most likely cause the two pulsations in the right IJV as seen in a JVP? Where would you see the JV pulse in the root of the neck?

Answer 104