Biology Ch.4 Biol360
Cal State Fullerton
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Date Created: 03/28/16
CHAPTER 4 Book notes SEX CHROMOSOMES: and genes are the primary arbiters of sex. Every individual possesses a pair of sex chromosomes in the nucleus of every cell in his or her body. One of these chromosomes is inherited from the persons mother, via her OVUM, and is always a large X CHROMOSOMES The other is inherited from the person’s father, via his SPERM, and is either an X CHROMOSOME or a much smaller Y CHROMOSOME An embryo that posses TWO Xs develop a FEMALE An embryo with ONE X and ONE Y develops a MALE The father’s genetic contribution to the embryo determines the sex. The SPERM determines SEX o In 1990, a sex determining gene called SRY located ON THE Y CHROMOSOME, was identified as the switch, (sex determining region of the Y chromosome) that causes the embryo to develop as a male Many more genes linked together in complex networks are required for the formation of the gonads- the ovaries in the females or the testicles in males. At about 6 weeks after conception, early in the development of the gonads, two pairs of ducts run from the gonads to the outside of the embryonic body at the future site of the external genitalia. One pair, the MULLERIAN DUCTS, are the precursors of the FEMALE REPRODUCTIVE TRACT The other pair, the WOLFFIAN DUCTS, are the precursors of the male reproductive tract Embryos of both sexes begin with a pair of BOTH kinds of ducts o thus, MALE development involves ELIMINATING the MULLERIAN DUCTS and PROMOTING the development of the WOLFFIAN DUCTS, o MALE embryos eliminate the MULLERIAN ducts by means of ANTI-MULLIERIAN HORMONE (AMH) a hormone secreted by the testicles that prevent the development of the female reproductive tract o This hormone, secreted by the developing testicles, diffuses the nearby MULLERIAN DIUCTS and causes them to degenerate. o Beginning at about 3 months AFTER CONCEPTION, the testicles secrete testosterone. This hormone diffuses down the WOLFFIAN DUCTS, o triggering each one to develop into an EPIDIDYMIS, VAS DEFERENS, and SEMINAL VESICLE. o Testosterone also promotes development of the prostate gland, although this gland is not derived from the WOLFFIAN ducts. while FEMALE development involves ELIMINATING the WOLFFIAN DUCTS and PROMOTING the DEVELOPMENT of the MULLERIAN DUCTS In FEMALE embryos, the ABSENCE of testosterone causes the WOLFFIAN ducts to degenerate. The absence of AMH allows the MULLERIAN DUCTS to persist and to develop in to the OVIDUCTS, UTERUS, and the deeper part of the vagina. Although the development of the female reproductive tract is the “DEFAULT” pathway, in the sense that it goes forward in the absence of hormonal instructions to the contrary, It is an active process that is guided by many genes in the developing tract The external genitalia of both females and males develop from the same early tissues. About 4 weeks POSTCONCEPTION the embryo’s anogenital region consists of a slit known as the CLOACA o CLOACA: the common exit of the gastrointestinal and urogenital systems; in humans it is present only in embryonic life. o The CLOACA is closed by a membrane o It is flanked by two URETHRAL FOLDS [folds of ectodermal tissue in the embryo that give rise to the labia minora (in females) or the shaft of the penis (in males)], o And to the side of each urethral fold is a raised region names the GENITAL SWELLING. (regions of the genitalia in the embryo that give rise to the labia majora (in females) or the shaft of the penis (in males) o At the FRONT of the CLOACA is a small midline protuberance called the GENITAL TUBERCLE (a midline swelling in front of the cloaca, which gives rise to the glans of the clitoris, in females, or penis, in males) o By 2 weeks later, the urethral folds have fused with each other near their prosterior (rear) end The portion behind the fusion point is called the ANAL FOLD, (THE POSTERIOR PORITON OF THE URETHRAL FOLD WHICH GIVES RISE TO THE ANUS) eventually becomes the anus. The REGION of the FUSION itself becomes the PERINIUM (even in adults the line of fusion is visible as a midline ridge or scar, which can be seen most easily with help of a hand mirror) During the fetal period, the region in front of the fusion point, which includes the opening of the UROGENITAL SINUS, gives rise to the external genital structures in both sexes. (THE COMMON OPENING OF THE URINARY AND GENITAL SYSTEMS IN THE EMBRYO) o As with the internal reproductive tracts, the FEMALE external genitalia develop by default, in the absence of hormonal or other external signals. o The genital swelling develop into the LABIA MAJORA o The urethral folds develop in to the LABIA MINORA, the outer one-third or so of the vagina o And the CRURA (deep erectile structures) of the Clitoris. o The genital tubercle develops into the glan of the clitoris. Remnants of the cloacal membrane persists as the hymen o The VAGINA therefore develops from TWO DIFFERENT SETS OF TISSUES. o THE OUTER portion of the vagina, which develops from the URETHRAL FOLDS , is more muscular and more richly innervated than the inner portion, which develops from the Mullerian ducts In the MALE fetuses, the presence of circulating testosterone, secreted by the testicles, is required for the normal development of genitalia . The urethral folds fuse at The midline, forming the shaft of the penis and enclosing the urethra. If this midline fusion is incomplete, a condition called HYPOSPADIAS results, in which the urethra opens on the underside of the penis or behind the penis. The GENITAL SWELLINGS also fuse at the midline, forming the SCROTUM. The genital tubercle expands to form the glans of the penis. The prostate gland- and probably the homologous PARAURETHRAL GLANDS in females. – develops from tissue beneath the urethral folds o The same embryonic structures that become the LABIA MAJORA in females becomes the SCROTUM in MALES. o The structures that become the LABIA MINORA in females become the SHAFT of the penis in males. o The structure that becomes the GLANS of the CLITORIS becomes the GLANS of the PENIS in males FEMALE DEVLEOPMENT isn’t driven by secretion of estrogens from fetal ovaries in the same way that male development is activated by testosterone from fetal tissues because FETUSES OF BOTH SEXES are exposed to ESTROGENS coming from the mother’s body/ o Thus, estrogens would not be an effective signal for guiding fetal development in one sex only. In fetuses of both sexes, the gonads (ovaries and testicles) begin their development in an area near the KIDNEYS and later move downward. By about 10 weeks POSTCONCEPTION they are positioned near the top of the pelvis. In FEMALES, the OVARIES remain in the position for the remainder of fetal life, but after birth they gradually descend in the pelvis and end up on either side of the uterus o In MALES , the testicle move even greater distances. At 6 TO 7 MONTHS POSTCONCEPTION they descend into the pelvis, and shortly before birth they move down into the SCROTUM As each TESTICLE enters the scrotum, it draws various structures with it, including the vas deferens, blood vessels, and nerves,- which make up the SPERMATIC CORD. The connection between the pelvic cavity and the testicles is usually sealed off after the testicles descend. In 2% to 5% of full term newborn boys, one or both testicles have not yet arrived in the scrotum. The tardy testicle will arrive within a few weeks after birth, but if they are still no-shows when the boy reaches 3 months, the condition is considered abnormal and is called CRYPTORCHIDISM o CRYPTORCHIDISM- failure of one or both testicles to descend into the scrotum by 3 months of postnatal age. C is associated with lowered fertility and with an increased risk of testicular cancer after PUBERTY o Usually the missing testicle have been help up somewhere Along the path of their fetal descent- most commonly in the groin o Undescended testicles an often be SURGICALLY moved into the scrotum; the procedure is best done before 2 years of age. Correction of CRYPTORCHIDISM improves the prospects for fertility but does not eliminate the increased risk of cancer. o Once they are in the scrotum, the testicles can be monitored by regular self examination, thus increasing the likelihood that developing cancer would be detected at an early age Most prenatal sex development occurs during weeks 8 through 24 of fetal life, when testosterone levels are high in male fetuses. A second surge of testosterone production (to adult levels) occurs in boys from the first 6 months of postnatal life : Further maturation of the male genitals occurs during the half year period After that, sex hormone levels remain low in both sexes until PUBERTY, the transition to sexual maturity o At the onset of puberty, both testicles and ovaries begin secreting sex hormones at levels sufficient to initiate reproductive maturity, o and the bodies and brains of girls and boys begin to transform into those of women and men THE BRAIN also differentiates sexually Early hormonal influences do produce some sex differences in brain structure, function, and chemistry o Men’s brains are about 10% larger, on average, than those of women this overall size difference is proportioned to the overall difference in body size between the sexes, however probably has not great functional significance o The two cerebral hemispheres are about the same size in women, but in men the RIGHT HEMISPHERE is usually slightly larger than the left o Certain regions within the cerebral cortex are also larger in one sex or the other o It is possible that some of these size differences underlie the differences in cognitive skills between women and men o A brain structure called the AMYGDALA is involved in the encoding of emotionally laden experiences into memory in both sexes. o MEN use the RIGHT AMYGDALA for this task o WOMEN use the LEFT AMYGDALA o Men’s brains produce SERATONIN- a NEUROTRANSMITTER involved in the regulation of mood – at a rate 52% higher than women’s brains o In the case of another neurotransmitter, DOPAMINE, it’s the other way around o Such differences could offer a partial explanation for differences in the prevalence of certain mental disorders in the two sexes: o DEPRESSION, for example is twice as common in women, whereas alcoholism is twice as common in men o The difference in CIRCULATING ANDROGENS levels in the two sexes ( higher levels in males than in females) is the main driver of SEXUAL DIFFERNTIATION in the BRAIN, as the rest of the body o SEX DIFFERENCES in the size of a brain structure might not result from early developmental processes alone. o However, Dutch researchers reported that when young adult transsexuals were treated with hormones of the other sex as part of their sex reassignment process, the overall size of the brain changed o MALE TO FEMALE =brain became smaller o FEMALE TO MALE= BRAIN BECAME LARGER o Which means a person’ DEVIATIONS from stereotypical female or male development, pediatricians call DISORDERS OF SEXUAL DEVELOPMENT (Medical conditions producing anomalous sexual differentiation or intersexuality ) o CHROMOSOMAL anomalies affect growth and fertility o Standard set of chromosomes are XX (FEMALE) and XY (MALE) o Other combinations are possible. They can arise during cell division in the production of the ova or sperm, or during the first cell division after fertilization o Embryos with abnormal numbers of sex chromosomes are very common, but the great majority die early in development . among those that survive, these are the most common anomalies KLINEFELTER SYNDROME (XXY, XXXY) about 1 in 1000 live born babies posses one or more extra X chromosomes. These individuals are male because they possess a Y chromosome with its SRY gene, which masculinizes their bodies. In adulthood, they may have some breast development and feminine body contours, however with sparse body and facial hair They are generally taller than average They have a low sperm count and are usually infertile TURNER SYNDROME (XO) about 1 in 4000 live born children has one X chromosome and no Y chromosome They are girls, since they lack the Y Chromosome and its SRY gene ‘these girls tend to be short, with a characteristic broad chest and neck. They lack normal ovaries, and without medical assistance they do not enter puberty and are infertile. They may suffer from some cognitive deficits but they are not intellectually disabled. Women with TURNER SYNDROME have excelled in a variety of careers o XYY SYNDROME about 1 in 1500 babies possesses one X CHROMOSOME and TWO Y CHROMOSOMES. o They are male, but they have genital anomalies and low fertility o They also tend to have low intelligence. o Perhaps for this reason, they are overrepresented among convicted criminals, but most XYY men are behaviorally normal TRIPLE X SYNDROME (XXX) about 1 in 2000 newborns possesses three X chromosomes These babies are girls They develop mild cognitive deficits and their fertility is low. But many XXX females go undiagnosed THESE CHROMOSOMAL ANOMALIES CANNOT BE CORRECTED Hormonal and other medical treatment such as counseling , can often help a great deal. Some of these individuals can become parents with the help of reproductive technologies DISORDERS OF SEX DEVELOPMENT cause the gonads or the genitals to end up in a state that is intermediate between the sexes or has some features of both. Persons affected by such conditions may be refereed to as INTERSEXED (a person whose biological sex is ambiguous or intermediate between male and female ) o GONADAL INTERSEXUALITY – rare condition, which is also called “TRUE HERMAPHRODITISM” the person possess both ovarian and testicular tissue- either on different sides of the body or in gonads that contain mixtures of the two tissues o Cause is not known, but chromosomal anomalies may be to blame. o The appearance of external genitalia varies, but most persons with this condition look like women and identify as such o They are usually infertile ANDROGEN INSENSITIVITY SYNDROME (AIS) this is a genetic condition in XY individuals in which ANDROGEN RECEPTORS ARE DEFECTIVE or absent. AIS embryos develop as female because the body fails to respond to the testosterone secreted by the testicles People with AIS lack the reproductive tract of either sex; they possess a shallow, blind ending vagina. And they are infertile Persons with complete AIS look like and identify as women, but people with partial ANDROGEN insensitivity have a more variable appearance and self identification o CONGENTIAL ADRENAL HYPERPLASIA (CAH) is a genetic condition, the fetus’s ADRENAL GLANDS secrete abnormally large amounts of ANDROGENS during the latter part of fetal life o In XX fetuses, the condition causes a partial masculinization of the genitals m o The clitoris is often enlarged for example,and the labia may be partially fused with the midline o Most of these children are raised as girls but some children with very marked masculinization are raised as boys for many children with ambiguous genitalia, the cause is not known, whatever the cause, however the treatment of these children raises a host of difficult ethical questions. Should the genitalia be surgically altered? It is up to the child when they grow up and can decide The secrecy and denial that often surrounds these cases is harmful to children’s psychological development and self- acceptance, according to the testimony of intersexed people GENDER: means the entire collection of mental and behavioral traits, that to a greater or lesser degree, differ between males and females, (it’s the collection of psychological traits that differ between males and females) GENDER IDENTITY: a persons subjective sense of being male or female SEXUAL ORIENTATION: the direction of an individuals’s sexual feelings; seuxla attraction toward persons of the opposite sex (heterosexual), the same sex (homosexual) or both sexes (bisexual) TRANSGENDER: a person who identifies with the other sex GENDER ROLE: the expression of gender identity in social behavior COGNITIVE: related to the aspects of the mind that process knowledge or information PERSONALITY: the collection of mental and behavioral traits, especially those related to emotions and attitudes, which characterizes an individual GENDER CONSTANCY a child’s understanding that sex is a fixed attribute GENDER SCHEMA: a collection of ideas about gender that influences perception and judgment SEXUAL SCRIPTS: sexually negotiated roles that govern sexual behavior. TRANSEXUAL: a person who identifies with the other sex and who seeks to transition to the other sex by means of hormone treatment and sex reassignment surgery, Transexuals can be male to female or female to male GENDER DYSPHORIA: the unhappiness caused by discordance between a person’s anatomical sex and gender identity TRANS MAN a female to male transsexual TRANS WOMAN a male to female transsexual TRANSVETISM : wearing clothes of the other sex for purposes of sexual arousal. Sometimes applied to cross dressing for any reason AUTOGYNEPHILIA: a form of male-to female transsexuality characterized by a man’s sexual arousal at the thought of being or becoming a woman TRANSITIONING changing one’s physical sex and social gender REAL LIFE EXPERIENCE- a period of living in the role of the other sex as a prelude to sex reassignment SEX REASSIGNMENT SURGERY- surgery to change a persons genitals or other sexual characteristics METOIDIOPLASTY- surgical constructions of a small penis from a clitoris WOMEN outperform men in fine movements, verbal fluency, and some aspects of memory MEN outperform women in some cognitive traits, such as visuospatial skills PERSONALITY differences include greater aggressiveness in men In the area of SEXUALITY , men and women differ in frequency of masturbation (men masturbate more frequently), attitudes toward casual sex (men are more approving) , and styles of jealousy (women are more likely to experience sexual jealousy All these gender differences show considerable overlap between the sexes and their significance is debated MANY GENDER DIFFERENCES arise early in life Most children distinguish perceptually between males and females by 1 year of age Can identify their own sex by 2 to 3 years And understand the immutability of sex by 3 to 4 years MALES are more active than females BOYS are more aggressive than girls BOYS and girls prefer different toys BOTH prefer to associate with children of their same sex. SEX SPECIFIC interaction styles develop within these same sex groups DIFFERNCES in other cognitive traits emerge gradually during childhood BIOLOGICAL FACTORS INFLUENCE GENDER These include: GENES that have evolved to help men and women improve their reproductive success A role for sex hormones, especially during PRENATAL LIFE , is illustrated by experiments on animals, by observation of humans affected by endrocrinological disorders, and by the study of anatomical markers (such as finger length ratios) that are correlated with gender traits SOCIALIZATION INFLUENCES GENDER This can happen through the innumerable rewards and punishments that children receive form their parents and others. Imitation is also important mediator for gender learning A variety of cognitive development models stress the importance of children’s thought process in the development of gender. The understanding of gender develops sequentially in young children GENDER schemas are frameworks of beliefs that influence perception and that ten to encourage either or thinking about gender In sexual script theory, gender learning involves the social negotiation of roles, such as those to be played by the man and woman in heterosexual relationships TRANSGENDER PEOPLE are those whose gender identity does not match their biological sex. TRANSEXUALS are transgender people who seek to change their anatomical sex (m-f) or (f-m) All F-M transsexuals and some M-F transsexuals have a childhood history of strong gender noncomformity They dislike the bodily changes induced by puberty and may attempt to conceal them They are usually homosexual in the sense that they are sexually attracted to persons of the same birth sex as them They usually don’t identify as gay, but as heterosexual individuals Some heterosexual M-F transsexuals have a different development history; in which the desire to change sex develops out a wish to incorporate their sexual targets (women) into their own bodies (AUTOGYNEPHILIA) SEX REASSIGNMENT is a multistage process involving living for some period in the identiy of another sex followed by hormonal treatments and sometimes sex reassignment surgery GENITALS can be transformed into those of the other sex. But the procedure is expensive and particularly in the F-M reassignment, yields imperfect results. Nevertheless many transsexuals are satisfied with the result Other transgender people do not seek sex reassignment for a variety of reasons Some believe that sex reassignment would be unnecessary if society could be persuaded to loosen its rigid ideas about gender. All transgender people face discrimination and the risk of violence and most states and the deferral gov fail to ffer them specific protections LECTURE NOTES SEX AND GENDER DEVELOPMENT SEXUAL DIFFERENTIATION – developing as male or female Different ways to determine one’s sex CHROMOSAL – Identifying the choromosomes an individual has inherited GONADAL- the presence of the male or female’s gonads INTERNAL REPRODUCTIVE STUCTURES EXTERNAL GENITAL APPEARANCE Brain Differentiation Gender identity influences their sex CHROMOSOMAL SEX – determined by chromosomes an individual inherited Most human cells have 46 chromosomes 22 pairs of these chromosomes are AUTOSOMES THE AUTOSOMES carry genetic instructions for other features and functions of the body 23 pair of chromosomes are sex chromosomes, and differ in males and females. XX- female XY- male The amount of info carried on the X and Y chromosomes differs X chromosomes has 1500 genes Y has 90 genes Women can only pass an X chromosome but a male may pass an X or Y, so sex of baby is determined on what chromosome the sperm delivered SEX CHROMOSOMES- begin differentiation SRY gene (Sex- determining region of the Y) Hormones also key All embryos contain UNDIFFERENTIATED STRUCTURES meaning the structures have not specialized and become distinct male or female GONAD MULLERIAN DUCT WOLFFIAN DUCT GENITAL TUBERCLE GENTITAL SWELING URETHRAL FOLD MALE- GONAD becomes testis about WEEK 7 This development is controlled by the activation of SRY triggers production of testis determind factor (TDF) FEMALE- OVARIES develop at around weeks 10-11 Each Embryo has 2 sets of ducts- MULLERIAN DUCT becomes OVIDUCT, UTERUS, AND UPPER PART OF VAGINA WOLFFIAN DUCT becomes EPIDIDYMUS, VAS DEFERNS, AND EJACULATORY DUCT FEMALES: embryonic ducts Development of mullerian ducts promoted Wolffian ducts degenerate MALES: embryonic ducts PRODUCTION of ANTI MULLERIAN HORMONE (AMH) this hormone causes the Mullerian DUCT TO degenerate Promote development of Wolffian ducts EXTERNAL DEVELOPMENT External genital begin with the same embryonic structures Urethral folds Male: SHAFT/ Female: LABIA MINORA & OUTER PROTION OF THE VAGINA Genital tubercle Male: GLANS OF PENIS/ Female: GLANS OF CLITORIS Genital swelling Male: SCROTUM/ Female: LABIA MAJORA MALES: testosterone is coverted to 5x dihydrotestosterone (DHT) that promotes development of external structures FEMALES: development occurs without the influence of hormones or other signals DESCENT OF GONADS Females: OVARIES WILL MOVE AFTER BIRTH and to either side of the uterus Males: move form abdomen to scrotum during MONTH 6-7 in pregnancy. Prior to birth they will move to the scrotum Controlled by testosterone CYPTORCHIDISM: undescended testes SEXUAL DIFFERENTIATION AND HOMOLOGOUS STRUCTURES Homologous structures: Structures that develop form the same embryonic tissues HOMOLOGOUS STRUCTURES TESTES-OVARIES Male and Female brain differ in Structure: Male;s brain are larger, but are more proportional to increase in body size Cerebral hemispheres Same size in female, right larger in male Function: AMYGDALA- females use left male use right CHEMISTY: serotonin (mood regulation) produced higher in males DOPAMINE (has to do with pleasure) production higher in women These changes are caused by higher androgen levels during prenatal development TRANSGENDER and transsexual individuals (refer to book notes. Same) Cause: unknown 4 step process of GENDER REASSIGNMENT PROCESS 1. TRANSITONING- counseling and psychological evaluation 2., LIFE EXPERIENCE – live as their desired gender for 1 to 2 years 3. HORMONE THERAPY- the use of hormones to induce physical changes to gain characteristics of the desired sex 4. SEX REASSIGNMENT SURGERY Female to Male (FTM or TRANSMEN) involves the removal of INTERNAL FEMALE REPRODUCTIVE ORGANS A BREAST reduction surgery may be needed Male hormones cause an enlargement of the clitoris which is then formed into the glans of the penis Tissue from lower abdomen and labia create penis and scrotum Male-to female (MTF or trans women) includes the removal of the internal penile tissue and testes The skin including the genital end bulbs are moved into the newly constructed vaginal canal with the genital end bulbs to help maintain some sensitivity The skin of the scrotum is used to form the LABIA LECUTRE 2 DISORDERS OF SEX DEVELOPMENT (DSD) When one of the following variables of sex is ambiguous chromosomal, gonadal, internal organs, or the external genital appearance These individuals are referred to as INTERSEX since their sex is ambiguous in most cases NONDISJUNCTION: chromosomal DSD when the chromosomes pairs fail to separate during meiosis Meiosis is the cellular process by which the genital information of the parent is reduced by half in prep to be packaged in the gametes . when NONDISJUNCTION occurs or the sperm or egg carry an incorrect number of chromosomes If NONDISJUNCTION occurs during MEIOSIS 1 all gametes that result from that process will carry an incorrect number of chromosomes, either missing chromosomes or carrying extra information The problem occurs during the SECOND division, then some of the gametes will contain the correct number of chromosomes while others will either have missing or extra chromosomes KLINEFELTER’S SYNDROME When male inherits one or 2 extra X chromosomes (XXY or XXXY) This occurs 1 in every 1000 live births They are men but after puberty they develop some female characteristics like breast development and overall body shape Not diagnosed until adulthood often when they experience fertility issues TURNER;S SYNDROME When inherits a single sex chromosome, X It is not possible for an individual to only inherit a Y since the X chromosome carries genes which are vital to development and sustaining life Occurs 1 in 4000 births Lacking the Y chromosome without the SRY gene means they will be female with feminine characteristics although many of them don’t actually develop They will not have functioning ovaries A characteristic would be webbed neck and broad chest OTHER CHROMOSOAL DSD XYY syndrome Since they inherit the Y gene they have male characteristics but may suffer form infertility or male anomalies Intelligience affected because of the extra y chromosomes XXX SYNDROME women are infertile and defecits CONGENITAL ADRENAL HYPERPLASIA (CAH) when female emnbryo (XX) are expose to androgens It causes the masculinization of external genitalia since that is influenced by hormonal demands Internal she will still have female reproductive organs ANDROGEN INSENSITIVITY SYNDROME (AIS) Genetic male (XY) but doesn’t respond to androgens Mutation of androgens receptor gene External genitalia- female “testicular feminization” Internally lack incomplete or missing reproductive structures People with this usually identify themselves as women GONADAL INTERSEXUALITY where ovarian and testicular tissue are both present in the individual Most identify as female and are infertile 5x REDUCTASE DEFICIENCY Lack enzyme to convert testosterone into DHT This will prevent the external reproductive structures to form normally People with this are chromosomally male Their internal anatomy is male Since they lack DHT testes do not descend into scrotum And their external anatomy is ambiguous and somewhat female These individuals will experience drastic changes in puberty When testosterone levels surge after puberty, then they will have balls MICROPENIS: penis is less than 0.75 inches at birth LEADING CAUSE TO THIS CONDITION IS LINKED TO HOROMONAL EXPOSURE Initial phase is during the first trimester which initiate the development of genitals Lack of androgens Insensitivity to androgens – length of penis will not occur May experience trouble urinating, having sex, and may have a reduced sperm count reducing fertility This can be treated with hormonal therapy or surgery to lengthen it HYPOSPADIA: abnormal location of urethral meatus Occurs when the urethral folds fail to fuse along the midline of the penis to enclose the urethra Opening of urethra can be anywhere along the penis depending on where the fusion does not occur LECTURE 3 PUBERTY: sexual maturity and secondary sex characteristics During this time, the reproductive system matures resulting in the ability to reproduce and the development of secondary sex characteristics Puberty is TRIGGERED WHEN A CRITICAL WEIGHT IS REACHED : height and weight 120 lbs in boys 66 lbs in girls When certain weight is reached, a certain cells release a hormone called LEPTIN that communicated with the brain to begin to increase its output on GnRH This stimulates the pituitary to release gonadotrophins The gonadotrophins stimulate the development of the testes and ovaries which produce estrogen and testosterone These hormones will direct the development of secondary characteristics GENERAL CHANGES: pubic hair , development of sexual organs, and acne, PUBERTY: MALES Typically occur from 13-18 years Some of the most obvious and early changes are in the genitals Scrotum and tesicles enlarge before penis lengthens They may begin ejaculation with some immature sperm OTHER CHANGES: shoulders broaden, increase in bone and muscle mass, deepening of voice, body hair PUBERTY: FEMALES Typically is from 11-16 for girls One of the defining moments is menstruation, these early cycles may be inovulatory meaning a viable egg is not released to an ovary Breast development is another key change and is one of the earlier developments Wider hips, and changes internally including: STRAIGHTENING OF THE OVIDUCT , THICKENING OF VAGINAL WALL, ENLARGEMENT OF UTERUS, THE MATURATION OF FOLLICLES IN THE OVARY, AND THE INITIATION OF MUCUS FROM THE CERVIX o Problems ASSOCIATING WITH PUBERTY o PRECOCIOUS PUBERTY: when puberty begins early. 8 for girls 9 for boys o DELAYED PUBERTY: an early sign of puberty has no appeared for 13 for girls and 14 for boys o You can use hormonal therapy for this o GYNECOMASTIA is when males develop breast tissue during the later stages of puberty o Most often this will occur in obese people o In many cases, the breasts will disappear , but sometimes they will need to be surgically removed o AMENORRHEA; the lack of menstruation (primary: when she doesn’t menstruate before 18) secondary is ceasing period after they experience their period. Usually with a dramatic weightloss. Makes sense from survival standpoint because not enough resource and hormones from fat then it will not support a healthy pregnancy o
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