New_Head(1, ' The Male External Genitalia Are the Penis and Scrotum, pp. 85–91'); New_Question('Considerably greater research has been dedicated to the neural control of the male sex organs than to the female sex organs because ', 4, 3, 'of the traditional culture of male dominance', 'men disproportionately control research dollars', 'of the social emphasis on male sexuality', 'the female reproductive system is better understood', '.') New_Question('The male external genitalia include the ', 4, 1, 'penis and scrotum', 'penis and testicles', 'penis, scrotum, and testicles', 'penis, scrotum, and pubic hair', '.') New_Question('The penis is developmentally homologous with the ', 4, 3, 'pubic symphysis', 'vagina', 'clitoris', 'vestibule', ' and is made up of three parts: the head or ', 0, 'glans', ', the ', 0, 'shaft', ', and (at least for some men) the prepuce or ', 0, 'foreskin', '. Erection is accomplished by the expansion of the two corpora ', 0, 'cavernosa', ' and the corpus ', 0, 'spongiosum', '; this latter structure also makes up most of the structure of the ', 0, 'glans', '. The tough connective tissue capsule surrounding the corpus ', 0, 'cavernosa', ', which serves to limits its expansion is the ', 4, 3, 'suspensory ligament', 'bulbourethral gland', 'tunica albuginea', 'crura', '.') New_Question('The root of the penis attaches to the pubic symphysis via a ', 0, 'suspensory ligament', '. At the root, the corpora cavernosa divide into the two ', 0, 'crura', '. The base of the penis has the same muscles associated with it as does a woman’s ', 0, 'clitoris', '—namely the ', 0, 'ischiocavernosus', ' and bulbospongiosus muscles which are involved in erection and ', 0, 'ejaculation', '. The bulbospongiosus furthermore is associated with the ', 0, 'external anal', ' sphincter.') New_Question('Circumcision removes the ', 3, 2, 'fascia', 'prepuce', 'corona', ' from the penis. This surgery can be completed at any age, however it is commonly performed ', 2, 1, 'in infancy', 'in adulthood', '. Worldwide about ', 4, 1, 'one-fourth', 'one-half', 'three-fourths', 'two-thirds', ' of men are circumcised. The medical benefits associated with circumcision include a reduction in ', 0, 'urinary tract', ' infections in infancy and a reduction in risk for acquiring certain sexually transmitted infections such as ', 0, 'AIDS', ' and HPV. This in turn reduces the risk of ', 0, 'penis_penile', ' cancer and ', 0, 'cervical', ' cancer in female sex partners.') New_Question('In the United States about ', 4, 3, 'one-half', 'one-quarter', 'one-third', 'three-quarters', ' of all male infants are circumcised. This number seems to be ', 3, 2, 'increasing', 'decreasing', 'stable', '.') New_Question('The textbook cites five probable health benefits of male circumcision: (1) a reduction in infancy ', 0, 'urinary tract', ' infections; (2) a reduced risk of ', 0, 'penile_penis', ' cancer; (3) reduction in the occurrence of ', 0, 'smegma', '—cheesy substance that can accumulate under the foreskin; (4) reduced transmission of sexually transmitted disease; and (5) a reduced risk of ', 0, 'cervical', ' cancer in the female partners of circumcised men, secondary to a reduced rate of infection with ', 0, 'human papillomavirus_HPV', '.') New_Question('The main risks associated with circumcision include hemorrhage and ', 0, 'infection', ' although damage to the ', 4, 3, 'scrotum', 'testicles', 'penis', 'shaft', ' has occasionally been reported. It has not been substantiated that penile ', 0, 'sensitivity_sensation', ' is reduced by circumcision. Some activist groups such as NOCIRC ', 2, 1, 'oppose', 'encourage', ' the procedure in children as it is performed ', 2, 2, 'with', 'without', ' informed ', 0, 'consent', '.') New_Question('', 0, 'Subincision', ' is the surgical slitting of the underside of the penis to expose the urethra. It is ritually practiced among Australian aborigines and in some other cultures. ', 0, 'Superincision', ' is the slitting of the top surface of the ', 4, 4, 'glans', 'penis', 'shaft', 'foreskin', '; this is practiced in some Polynesian and Filipino cultures.') New_Question('The urethra of the penis traverses the corpus ', 0, 'spongiosum', ', terminating in the opening known as the urethral ', 0, 'meatus', '. The tunica albuginea ', 2, 2, 'does', 'does not', ' surround the corpus ', 0, 'spongiosum', '.') New_Question('The rim of the glans is called the ', 0, 'corona', '. The ', 0, 'frenulum', ' runs between the glans and the shaft and is located on the underside of the penis. Although stimulation anywhere on the penis can be sexually arousing, the ', 0, 'corona', ' and the ', 0, 'frenulum', ' are usually considered to be the most erotically sensitive regions of the penis.') New_Question('The average flaccid human penis measures about ', 4, 2, '6', '9', '13', '15', ' centimeters in length; when erect, the average length is about ', 4, 3, '6', '9', '13', '15', ' centimeters. Functional erect length increases this to about ', 3, 2, '14', '16', '18', ' centimeters. Not that length when erect really matters very much—despite rather prevalent concerns about size, the vagina is so elastic that “one size fits all” and a smaller penis may be advantageous for anal and ', 0, 'oral', ' sex.') New_Question('A surgery in which the ', 0, 'suspensory ligament', ' is severed can make the penis longer when ', 3, 1, 'flaccid', 'erect', 'either flaccid or erect', ' and its girth can be increased with implants of ', 0, 'fat', ' although this does not generally improve the sex lives of the patients.') New_Question('Some of the side effects of penis piercing include: scarring, damage to the ', 0, 'erectile tissue', ', nerve damage, interference with ', 0, 'urination', ', and serious infections such as ', 0, 'hepatitis', ' and HIV.') New_Question('Aside from erectile dysfunction and sexually transmitted infections, the penis is affected by only a few medical problems:
  1. Balanitis—inflammation of the ', 4, 2, 'shaft', 'glans', 'frenulum', 'fascia', '
  2. ', 0, 'Phimosis', ' is the inability to retract the foreskin far enough to expose the ', 0, 'glans', ', but only becomes a problem if ', 0, 'urine_urinary', ' flow is affected.
  3. Paraphimosis—the entrapment of a retracted ', 0, 'prepuce_foreskin', ' behind the corona
  4. Peyronie’s disease is an unnatural curvature of the erect penis caused by scar formation in the capsule of the ', 0, 'corpora cavernosa', '.
  5. Cancer of the penis is ', 2, 2, 'common', 'rare', '. Risk of developing penile cancer is increased if a man is infected with certain types of ', 0, 'human papillomavirus_HPV', '. Early intervention usually results in minor surgery to the penis; however, more advanced cases may require a(n) ', 4, 3, 'vasectomy', 'circumcision', 'penile amputation', 'penile implant', '.
') New_Question('The major function of the scrotum appears to be the regulation of the ', 0, 'temperature', ' of the testicles, which is accomplished by ', 0, 'sweat', ' from the skin of the scrotum and by contraction and relaxation of the ', 0, 'dartos', ' muscle, which causes the scrotal skin to thicken and become ', 0, 'wrinkled', '.') New_Head(1, ' The Testes Produce Sperm and Sex Hormones, pp. 91–99'); New_Question('The term “', 3, 1, 'testes', 'gonads', 'cremaster', '” is used to refer to the egg-shaped organs that produce male gametes and secrete ', 0, 'sex', ' hormones.') New_Question('The ', 2, 1, 'left', 'right', ' testicle usually hangs lower than the ', 2, 2, 'left', 'right', ' and one is usually larger than the other. Research has shown that men with a larger right testicle score well on ', 2, 1, 'masculine', 'feminine', ' cognitive tests, while men with a larger left testicle score well on ', 2, 2, 'masculine', 'feminine', ' cognitive tests.') New_Question('The ', 0, 'spermatic cord', ' is a bundle of structures that connects the testis with organ systems within the abdominal cavity. Contained within the ', 0, 'spermatic cord', ' is the vas ', 0, 'deferens', '. This structure runs through a 4-cm (1.5 inch) long tube (called the ', 0, 'inguinal canal', '), that passes through the abdominal wall in the groin region.') New_Question('The ', 0, 'cremaster', ' muscle surrounds the spermatic cord and also forms a sling around the testicles. The ', 0, 'cremaster', ' contracts in response to cold.') New_Question('The testes are generally maintained at ', 4, 3, '1–2', '2–3', '4–7', '8–10', '°C ', 4, 4, 'warmer than ambient temperature', 'cooler than ambient temperature', 'warmer than core body temperature', 'cooler than core body temperature', '. If the testes are maintained at a ', 2, 1, 'warmer', 'cooler', ' temperature, ', 4, 1, 'sperm count', 'hormone production', 'fetal development', 'secondary sexual development', ' is adversely affected.') New_Question('The testis is made up of fine tubes called ', 0, 'seminiferous tubules', ' where sperm are produced. This process is called ', 0, 'spermatogenesis', '. Production of sperm ', 4, 3, 'occurs only during fetal development', 'is complete by the time of puberty', 'commences at puberty', 'occurs throughout life', '. Like ova, sperm ', 4, 4, 'are produced through mitosis and are haploid', 'are produced through meiosis and are diploid', 'are produced through mitosis and are diploid', 'are produced through meiosis and are haploid', '. Sperm develop from ', 0, 'stem', ' cells while embedded within ', 4, 1, 'Sertoli', 'granulosa', 'Leydig', 'thecal', ' cells over a period of a little more than ', 4, 4, '10', '25', '45', '60', ' days. The sperm collect in a network called the ', 0, 'rete', ' testis before passing into the epididymis and vas ', 0, 'deferens', '.') New_Question('The average male produces approximately ', 4, 3, '50', '100', '150', '200', ' million sperm per day.') New_Question('Sertoli cells assist in spermatogenesis and synthesize ', 2, 1, 'peptide', 'steroid', ' hormones. The spaces between the ', 0, 'seminiferous', ' tubules are occupied by Leydig cells (also known as ', 0, 'interstitial', ' cells). These cells secrete ', 2, 2, 'peptide', 'steroid', ' hormones such as testosterone and some ', 0, 'peptide', ' hormones.') New_Question('The testicles can be affected by a number of medical conditions; however, testicular cancer is probably the most serious. It strikes approximately ', 4, 1, '7400', '4700', '3700', '7300', ' men annually in the United States and about ', 4, 3, '200', '300', '400', '700', ' of these men die from the disease. Men at increased risk for testicular cancer are encouraged to practice ', 4, 3, 'safe sex', 'masturbation', 'testicular self-examination', 'sexual abstinence', '. Other forms of noncancerous conditions affecting the testicles include:
  1. ', 0, 'Orchitis', '—inflammation of the testicle
  2. ', 0, 'Epididymitis', '—inflammation of the epididymis
  3. Varicoceles can impair ', 4, 2, 'sexual performance', 'fertility', 'erections', 'semen volume', ' if not surgically corrected.
  4. Hydrocele is a collection of ', 4, 3, 'pus', 'blood', 'fluid', 'sperm', ' in the space surrounding a testicle.
  5. Testicular torsion is the rather painful ', 4, 2, 'compression', 'twisting', 'injury', 'failed piercing', ' of a testicle and requires immediate medical attention.
') New_Question('Disorders of the prostate may be detected by ', 0, 'digital rectal_rectal', ' examination. A common condition affecting this region is prostatitis which is any ', 0, 'inflammation', ' of the prostate. The simplest form of prostatitis is ', 0, 'acute infectious', ' prostatitis—pain upon urination or ejaculation—and which may be diagnosed from cultures of ', 0, 'prostatic fluid_fluid', ' expressed during rectal exam, or from urine, etc. It usually results from infection of the prostate with microorganisms from a preexisting ', 0, 'urinary tract_urethral_urinary_bladder', ' infection and is treated with ', 0, 'antibiotics', '.') New_Question('In chronic prostatitis, the cause is often not evident and it may persist for ', 3, 3, 'days', 'weeks', 'years', '. It does not necessarily respond to ', 0, 'antibiotics', ' and many men diagnosed with this condition show ', 2, 2, 'significant', 'no', ' evidence of prostate gland inflammation. The term ', 0, 'chronic pelvic pain', ' syndrome has been proposed as an alternative.') New_Question('Benign prostatic hypertrophy or ', 0, 'enlarged prostate', ' is experienced by more than ', 4, 4, '5', '15', '35', '50', '% of men in their sixties and about ', 4, 4, '35', '50', '75', '90', '% of men in their seventies. Typical symptoms involve difficulty with ', 0, 'urination', '. The prostate is covered by a tight ', 0, 'capsule_membrane', ' so when it swells, it constricts the ', 0, 'urethra', ' that it surrounds.') New_Question('Benign prostatic hypertrophy may be treated with the anti-testosterone drug ', 0, 'finasteride', ' (Proscar) or other drug therapy; however, in cases in which the prostatitis does not respond to drug treatment, ', 0, 'surgery', ' may be required. This is often performed via the ', 0, 'urethra', ' and can damage the ', 0, 'urethral sphincter', ' at the base of the bladder. Various problems with sex may result, particularly ', 0, 'retrograde', ' ejaculation into the bladder and reduced ', 0, 'orgasm_orgasmic', ' intensity.') New_Question('There are about ', 4, 4, '200,000', '20,000', '2000', '220,000', ' new cases of prostate cancer diagnosed in the United States each year and ', 4, 3, '1 in 2', '1 in 3', '1 in 6', '1 in 15', ' men will be diagnosed with it at some point. The disease claims about ', 4, 3, '13,000', '17,000', '27,000', '30,000', ' thousand lives per year. The average age at diagnosis is ', 4, 3, '50', '60', '70', '80', ' and African-American men are ', 2, 2, 'less', 'more', ' likely than white men to develop it.') New_Question('The initial symptoms of prostate cancer generally involve problems with ', 0, 'urination', ', and the man may notice some ', 0, 'blood', ' in his semen or urine and some pain. Clinical investigations include ', 0, 'digital', ' rectal examination and blood tests for elevated ', 0, 'prostate-specific antigen', ' (PSA).') New_Question('One approach to dealing with prostate cancer called “', 0, 'watchful waiting', '” involves doing nothing but monitoring the progress of the disease. ', 0, 'Radical prostatectomy', ' is a complete surgical excision of the prostate gland and nearby lymph nodes. If hormonal treatments are used, the man usually will experience ', 3, 3, 'erectile dysfunction', 'lowered libido', 'erectile dysfunction and lowered libido', '.') New_Question('The vas deferens receives the secretions of the seminal vesicles in the vicinity of the prostate gland at which point it becomes the ', 0, 'ejaculatory duct', '. The main reservoir of mature sperm is the ', 4, 3, 'prostate', 'seminal vesicle', 'vas deferens', 'acrosome', '.') New_Question('Most of the volume of semen is contributed by the ', 4, 3, 'prostate gland', 'bulbourethral glands', 'seminal vesicles', 'testes', '. The other major contributor to semen is the ', 4, 1, 'prostate gland', 'bulbourethral glands', 'seminal vesicles', 'testes', '. In addition to making a contribution to the overall composition of semen, the secretions of the ', 4, 2, 'prostate gland', 'bulbourethral glands', 'seminal vesicles', 'testes', ' sometimes form a pre-ejaculatory emission or “pre-cum” that ', 3, 3, 'does', 'does not', 'sometimes does', ' contain sperm.') New_Question('An average ejaculation releases ', 4, 2, '1–2', '2–5', '5–10', '15–20', ' milliliters of semen each of which contains ', 4, 1, '50–150 million', '500–700 million', '50–150 billion', '500–700 billion', ' sperm. Each spermatozoon consists of: (1) a head carrying the DNA payload and capped by an ', 0, 'acrosome', ' that contains various receptors and enzymes involved in fertilization; (2) the “midpiece” full of energy-producing ', 0, 'mitochondria', '; and (3) the tail, or ', 0, 'flagellum', ', which propels the sperm forward. The sperm make up about ', 4, 1, '1', '10', '50', '90', '% of the volume of semen.') New_Question('The part of semen other than sperm is called the seminal ', 0, 'plasma', ' and is made up of the sugar ', 4, 4, 'glucose', 'sucrose', 'lactose', 'fructose', ', which provides energy to the sperm; buffers that keep the semen ', 4, 3, 'somewhat acidic', 'at neutral pH', 'somewhat alkaline', 'bacteria-free', '; and ', 0, 'fibrinogen', ' which, when broken down, yields the coagulant ', 0, 'fibrin', '. Citric acid prevents premature ', 0, 'coagulation', ' and ', 0, 'ascorbic_citric', ' acid prevents oxidization of sperm due to air contact. The prostate contributes a variety of ', 0, 'enzymes', ' that catalyze the coagulation and liquefaction of semen as well as contributing to sperm’s metabolism. Last, the semen may contain a high concentration of ', 0, 'viruses_virus particles', ' in HIV- or hepatitis-infected men.') New_Head(1, ' The Nervous System Orchestrates Sexual Arousal, pp. 99–107'); New_Question('The basic unit of the nervous function is the nerve cell or ', 0, 'neuron', ', which in the generic case receives information via the ', 0, 'dendrites', ' and then transmits it in the form of electrical impulses called ', 0, 'action potentials', ' along the nerve fiber or ', 0, 'axon', '.') New_Question('At the ', 0, 'synapse', ' the action potential triggers the release of ', 0, 'neurotransmitter_neurotransmitters', ' into the tiny space between the two cells called the ', 0, 'synaptic cleft', '.') New_Question('At the gross anatomical level, the central nervous system (CNS) consists of the brain plus the ', 0, 'spinal cord', '. The spinal cord is functionally divided into segments—closest to the skull are eight ', 4, 4, 'lumbar', 'thoracic', 'sacral', 'cervical', ' segments, followed in order by 12 ', 4, 2, 'lumbar', 'thoracic', 'sacral', 'cervical', ' segments, five ', 4, 1, 'lumbar', 'thoracic', 'sacral', 'cervical', ' segments, and five ', 4, 3, 'lumbar', 'thoracic', 'sacral', 'cervical', ' segments.') New_Question('', 0, 'Gray', ' matter is made up of cell bodies, dendrites, synapses, and supporting cells, whereas ', 0, 'white matter', ' is entirely made up of axons. ') New_Question('The symmetrical cerebral ', 0, 'hemispheres', ' consist of several lobes of cerebral cortex, the underlying white matter, and deeper structures called basal ', 0, 'ganglia', '. The cerebral hemispheres are connected by the corpus ', 0, 'callosum', '. In the approximate center of the brain is the ', 5, 5, 'cerebellum', 'hypothalamus', 'pons', 'medulla', 'thalamus', ', directly below which is the hypothalamus, a major participant in sexual function. Spanning between this latter structure and the ', 5, 3, 'cerebellum', 'hypothalamus', 'pons', 'medulla', 'thalamus', ' is the midbrain; about at this level we also find the paired hemispheres of the ', 5, 1, 'cerebellum', 'hypothalamus', 'pons', 'medulla', 'thalamus', '. The most rearward (or caudal) part of the brain is the medulla, which becomes the ', 0, 'spinal cord', ' after exiting the skull.') New_Question('The peripheral nervous system is made up of “', 0, 'efferent', '” nerve fibers that carry information to the body from the CNS and “', 0, 'afferent', '” fibers that carry sensory information from the body to the CNS. Sensory neurons lack ', 0, 'dendrites', ' and synapse in the dorsal root ', 0, 'ganglia', ' immediately before entering the spinal cord.') New_Question('The ', 4, 2, 'automatic', 'autonomic', 'autotactic', 'autosomal', ' nervous system coordinates the functioning of ', 4, 2, 'striate', 'smooth', 'sexual', 'voluntary', ' muscle and glands through two divisions—the sympathetic and ', 0, 'parasympathetic', ' nervous systems—which often act in ', 4, 4, 'synchrony', 'sequence', 'parallel', 'opposition', '.') New_Question('Although the brain can promote or inhibit a(n) ', 3, 1, 'erection', 'ejaculation', 'orgasm', ' in men and women, it is not essential. Patients who have sustained ', 0, 'spinal', ' injuries that interrupt communication between the ', 0, 'brain', ' and the genitals are often still capable of responding to ', 0, 'genital', ' stimulation with an ', 0, 'erection', '.') New_Question('The nervous system is intimately involved in the erection of the penis or clitoris subsequent to tactile stimulation. This output requires five components to complete a ', 0, 'reflex_reflexive', ' loop from the ', 0, 'genitals', ' to the spinal cord and back to the ', 0, 'genitals', ':
  1. Detection of the stimulus
  2. Transmission of ', 0, 'sensory_sensation_stimulus_stimulation', ' information to the spinal cord via ', 0, 'afferent', ' fibers
  3. Processing within the ', 0, 'CNS_spinal cord_central nervous system', '
  4. Transmission of ', 0, 'command_motor_vasomotor_response_output', ' information to the penis/clitoris system via ', 0, 'efferent', ' fibers
  5. Production of a response (activation of vascular elements)
') New_Question('The unique sensory nerve endings of the penis and clitoris—the ', 0, 'genital end-bulbs_genital end bulbs', '—are concentrated in the ', 0, 'glans', ' of the penis or clitoris although they are also found elsewhere. These structures are believed to be specialized in detection of the ', 4, 1, 'tactile', 'olfactory', 'thermal', 'friction', ' stimulus associated with sexual activity. ') New_Question('The penis and clitoris are not the only ', 0, 'erogenous', ' zones on the body. Many parts including the genital skin, the anus, and the ', 0, 'nipples', ' are erotically sensitive in both sexes. It is currently unknown, however, if these regions contain specialized ', 0, 'genital_sexual', ' receptors.') New_Question('Nerve fibers arising from the penis or clitoris travel in the ', 4, 4, 'perineal', 'pelvic', 'penile', 'pudendal', ' nerves toward the ', 4, 2, 'cervical', 'sacral', 'lumbar', 'thoracic', ' spinal cord. These inputs synapse with interneurons which then synapse on preganglionic ', 4, 1, 'parasympathetic', 'afferent', 'sympathetic', 'sensory', ' neurons. The axons of these cells exit the spinal cord and form the ', 4, 2, 'perineal', 'pelvic', 'penile', 'pudendal', ' nerves, synapsing on ganglia near the bladder. Postganglionic ', 4, 1, 'parasympathetic', 'afferent', 'sympathetic', 'sensory', ' neurons then innervate the ', 0, 'erectile', ' tissue of the penis or clitoris. Fibers of the ', 4, 3, 'parasympathetic', 'afferent', 'sympathetic', 'sensory', ' system work in opposition to this input to modulate erectile function. The neurons of this system are situated in the thoracic and ', 0, 'lumbar', ' segments and after passing out of the cord travel to the ', 4, 3, 'parasympathetic', 'afferent', 'sympathetic', 'sensory', ' ganglia and synapse with postganglionic neurons on their way back to the ', 0, 'erectile', ' tissue of the penis and clitoris.') New_Question('The penis becomes erect when blood flows into the hollow collapsible spaces (', 0, 'sinusoids', ') of the corpora ', 0, 'cavernosa', ' and spongiosum and is inhibited from exiting at the same rate. When flaccid, the activity of ', 4, 1, 'sympathetic', 'parasympathetic', 'sensory', 'cervical', ' neurons predominates, releasing the neurotransmitter ', 4, 3, 'acetylcholine', 'nitric oxide', 'norepinephrine', 'vasoactive intestinal polypeptide', ' which causes the ', 2, 2, 'relaxation', 'contraction', ' of the arterioles and ', 0, 'trabeculae', ' (walls of connective tissue that form spaces within the spongy erectile tissue).') New_Question('In an erection, there is decreased activity of ', 4, 1, 'sympathetic', 'parasympathetic', 'sensory', 'cervical', ' nerve fibers and increased activity of ', 4, 2, 'sympathetic', 'parasympathetic ', 'sensory', 'cervical', ' fibers. The parasympathetic fibers release neurotransmitters including a gas called ', 4, 4, 'nitrous oxide', 'carbon monoxide', 'nitrogen dioxide', 'nitric oxide', '. This induces the arterioles and trabeculae to ', 4, 3, 'break down', 'contract', 'relax', 'form', ' which increases blood flow into the sinusoids of the erectile tissue. As this tissue expands it compresses ', 4, 1, 'veins', 'arterioles', 'trabeculae', 'nerve fibers', ', reducing blood outflow. The rigidity of the erect penis is attributable to the tough covering of the ', 0, 'corpora cavernosa_corpus cavernosum', '.') New_Question('With complete erection, no more blood can enter the penis and blood flow ceases. The pooled blood gradually loses its ', 0, 'oxygen', ' and becomes a purplish color. This color change can be observed in the ', 2, 2, 'shaft', 'glans', '. Because of the deoxygenation of the blood in the ', 0, 'sinusoids', ', an erection that won’t go down—a condition called ', 0, 'priapism', '—will cause damage to the erectile tissue if it is prolonged for more than a few ', 3, 2, 'mintues', 'hours', 'days', '.') New_Question('The two striated or ', 0, 'voluntary', ' muscles associated with the root of the penis, the ', 0, 'ischiocavernosus', ' and the ', 0, 'bulbospongiosus', ', participate in a reflex loop that causes the penis to jump up and engorge in response to ', 0, 'tactile_touch_stroking_pressure', ' stimulation. The sensory ', 4, 3, 'efferent', 'effervescent', 'afferent', 'inferent', ' fibers enter the circuit via the ', 0, 'pudendal', ' nerves and connect with interneurons that synapse on the motor neurons of ', 0, 'Onuf’s', ' nucleus, which is substantially smaller in women and is thus said to exhibit sexual ', 0, 'dimorphism', '. Impulses are carried by the axons of these motor neurons again via the ', 0, 'pudendal', ' nerves to the genitalia, where some innervate the two ', 0, 'striated_voluntary', ' muscles.') New_Question('The ', 0, 'hypothalamus', ' is directly involved in regulation of sexual excitation. Descending pathways from this structure to regions in the brainstem such as the ', 0, 'pons_medulla', ' and ', 0, 'medulla_pons', ' control spinal sympathetic and ', 0, 'parasympathetic', ' neurons by increasing or decreasing their levels.') New_Question('Erections frequently occur during ', 4, 4, 'slow-wave sleep', 'stage 1 sleep', 'alpha sleep', 'REM sleep', ' in ', 3, 3, 'men', 'women', 'men and women', ' and in men can result in ', 0, 'wet dreams_nocturnal orgasms', '. One mechanism that promotes these erections is a decrease in the ongoing signal from the locus ', 0, 'coeruleus', ', a nucleus that is located in the ', 0, 'pons_brainstem', '. This shifts the “penis control” balance in favor of the ', 2, 1, 'parasympathetic', 'sympathetic', ' system and an erection results.') New_Head(1, ' Ejaculation Requires Coordination of Muscles and Glands, pp. 107–110'); New_Question('Research has shown it is ', 3, 3, 'easy', 'difficult', 'impossible', ' to differentiate men’s and women’s descriptions of their orgasms.') New_Question('As ', 0, 'orgasm', ' approaches, the ', 2, 2, 'parasympathetic', 'sympathetic', ' nervous system causes a(n) ', 2, 1, 'increase', 'decrease', ' in heart rate, blood pressure, and rate of breathing. Increased contraction of the ischiocavernosus and ', 0, 'bulbospongiosus', ' muscles causes further swelling of the penis, especially the ', 0, 'glans', ' The ', 0, 'cremaster', ' muscle draws the testicles upward, and the ', 2, 1, 'dartos', 'cremaster', ' muscle causes the scrotal skin to become thicker and ', 0, 'wrinkled', '. ') New_Question('The first event in ejaculation is the expulsion of the various fractions of semen into the ', 4, 4, 'anterior', 'muscular', 'vesicular', 'posterior', ' urethra, a process called ', 0, 'emission', '. This is accompanied by a sensation ', 4, 2, 'of needing to urinate', 'that ejaculation is inevitable', 'of needing to slow down', 'of fullness', '.') New_Question('The first component to be loaded is the ', 3, 3, 'sperm', 'secretion of the seminal vesicles', 'prostate secretions', ', followed by the ', 3, 1, 'sperm', 'secretion of the seminal vesicles', 'prostatic secretion', ', and lastly the ', 3, 2, 'sperm', 'secretion of the seminal vesicles', 'prostatic secretion', '. Loading in this order prevents premature ', 4, 2, 'ejaculation', 'coagulation', 'liquefaction', 'micturition', '.') New_Question('Ejaculation is caused by a series of powerful muscular contractions of smooth muscle in the walls of the ', 0, 'urethra', ' as well as through the ischiocavernosus and ', 0, 'bulbospongiosum', ' muscles, and other muscles of the ', 2, 1, 'pelvic floor', 'penis', '. These contractions occur at a rate of ', 4, 1, 'one', 'two', 'three', 'four', ' per second in response to a burst of activity in the ', 0, 'sacral', ' motor neurons.') New_Question('The urethral ', 0, 'sphincter', ' constricts with greater force at ejaculation to prevent semen from following backwards into the ', 3, 3, 'seminal vesicles', 'prostate', 'bladder', '. If the man ejaculates within the vagina, the semen can reach to the cervix; it ', 2, 1, 'does not', 'can', ' reach the ', 0, 'cervical canal', '.') New_Question('It is an oversimplification to call ejaculation simply a “spinal reflex” for two reasons. First, the majority of quadriplegic men (about ', 0, '60', '%) never ejaculate, suggesting that activation by the brain is required in most men. Second, it has been shown that brain stimulation, notably in the ', 0, 'paraventricular', ' nucleus of the hypothalamus, can cause erection and ejaculation to occur in rats.') New_Head(1, ' Nudity Is Culturally Regulated, pp. 110–111'); New_Question('Research has shown that heterosexual ', 3, 2, 'women', 'men', 'men and women', ' find the sight of a woman’s ', 4, 2, 'breasts', 'vulva', 'vagina', 'nipples', ' sexually arousing. For this reason, throughout history and across ', 0, 'cultures', ', woman have generally covered this part of their body.') New_Question('The nineteenth century was a period characterized by remarkable sexual modesty. When bathing at the beach, for example, men wore garments that were so all-covering it inhibited their ability to ', 4, 3, 'run', 'walk', 'swim', 'tan', '. This was part of a general belief that sexual arousal was dangerous to ', 0, 'health', ', morals, and social order. Current society is far more liberal and sex-', 2, 1, 'positive', 'neutral', '; however, social rules determine where and when a person can be naked.')