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anatomy

Reproductive by kam

QuestionAnswer
Sexual reproduction involves gonads that produce gametes ((haploid) and sex hormones ; Male gonad is testes, gamete is sperm Female gonad is ovary, gamete is secondary oocyte
Fertilization is the process results in the union of a male gamete with a female gamete
Pregnancy begins with fertilization a time when the fertilized egg undergoes implantation, embryonic and fetal development, and birth
Testes Paired male gonads in scrotum Contain seminiferous tubules that produce sperm during spermatogenesis Spermatogenic cells Begin sperm production at puberty
System of ducts Epididymis, ductus deferens, ejaculatory ducts, and urethra
Accessory glands Seminal vesicles, prostate, and bulbourethral glands
Supporting structures Scrotum and penis
Scrotum Loose skin and underlying hypodermis support testes in two sacs Normal sperm production in testes occurs at temperature a few degrees below body temperature Testes descend through inguinal canals during fetal development Cremaster and dartos muscles
Sertoli (Sustentacular) cells – seminiferous tubules (Testes) Nourish and control movement of developing sperm cells to release in lumen Form blood-testis barrier to prevent immune response Secrete inhibin hormone to decrease spermatogenesis Other functions?
Leydig (Interstitial) Cells – between tubules (Testes) Produce male sex hormone testosterone
Spermatogenesis Spermatogonia begin mitosis at puberty Some remain near basement membrane as stem cells Others move between Sertoli cells to become primary spermatocytes (diploid; 2n)
Spermatogenesis (Meiosis) Meiosis I – a primary spermatocyte divides into two secondary spermatocytes (haploid; n) with two chromatids of one of each pair of chromosomes Meiosis II – the two secondary spermatocytes divide forming four spermatids (n) (immature sperm)
last stage of spermatogenesis Influenced by testosterone Developing sperm form an acrosome and flagellum, shed excess cytoplasm, and increase mitochondria Elongated sperm cells are released into lumen of seminiferous tubule Sertoli cells secrete fluid to push sperm toward the ducts
acrosome: enzyme (filled vesicle),cap the sperm cell -needed to break protective barrier around the egg
flagellum: swim up female tract
Mature Sperm 300 million per day produced Once ejaculated, survive 48 hours in female reproductive tract Mature sperm structures Head – contains nucleus and haploid DNA Acrosome – enzymes for penetrating secondary oocyte Middle piece – mitochondria produce ATP T
Hormone Control of Testes At puberty, gonadotropin-releasing hormone(GnRH, hypothalamus) stimulates secretion of two anterior pituitary gonadotropin hormones Negative feedback regulation mechanism
male - Luteinizing hormone (LH) Stimulates Leydig cells to secrete testosterone
male - Follicle-stimulating hormone (FSH) With testosterone, stimulates Sertoli cells to secrete androgen-binding protein which keeps testosterone level high in seminiferous tubules
male - Inhibin (from Sertoli cells) Inhibits FSH to help regulate the rate of spermatogenesis
testosterone masculinizes the fetus-development of male organs -also stimulates the descent of testes into the scrotum-7 months gestation -failure to descend=cryptorchidism -leads to decrease sperm production and sterility because of
Ducts of the testes Seminiferous tubule lumen, straight tubules, rete testis
Epididymis Efferent ducts, ductus epididymis Site of sperm maturation, storage, degeneration
Ductus deferens (vas deferens) Ascends in spermatic cord, through inguinal canal, loops over ureter, and ends at dilated ampulla Stores sperm and conveys them to urethra
Ejaculatory ducts Union of ductus deferens and duct of seminal vesicles Empties sperm and seminal fluid into prostatic urethra
Urethra Shared by reproductive and urinary systems Prostatic urethra Membranous urethra (intermediate urethra) Spongy (penile) urethra (longest) External urethral orifice
Seminal vesicles Alkaline, viscous fluid with fructose, used by sperm for ATP production Secretion contributes to sperm viability contribute to most semen volume (60%) -secretion is alkaline (helps neutralize urethra and vagina) -fructose is nutrient for sperm
Prostate Surrounds prostatic urethra Secretion contributes to sperm motility and viability contributes about 25% of semen and is alkaline because it has citric acid (nutreint)
Bulbourethral glands (Cowper’s gland) Either side of membranous urethra Mucus for lubrication and alkaline fluid to neutralize acids from urine in urethra on pelvic floor
Semen Mixture of fluids Sperm and secretions from seminiferous tubules Secretions from seminal vesicles, prostate, and bulbourethral glands
Function of semen Fluid in which sperm are transported Supplies nutrients for sperm Neutralizes the acidity of the male urethra and female vagina
Ejaculation expulsion of semen from the urethra to the exterior of the body
Penis Support structure Contains urethra Passageway for ejaculation of semen and excretion of urine organ of copulation -intercourse -delivers sperm (in semen) into female tract
Body of penis Three erectile tissue masses Two corpora cavernosa penis One corpus spongiosum penis around urethra Glans penis expanded distal tip with sensory receptors
Erection engorgement of penile blood sinuses under influence of sexual excitement
Male Sexual Response Upon sexual stimulation (visual, tactile, auditory, olfactory, or imagined), sacral parasympathetic fibers initiate and maintain an erection
Under the influence of nitric oxide released from parasympathetic neurons (“neurogenic NO”,: arteries that supply the penis dilate and blood enters penile sinuses in the erectile tissue; NO also causes the smooth muscle within the erectile tissue to relax, resulting in widening of the blood sinuses
After an erection sympathetic stimulation is necessary for the rest of the sexual response, including ejaculation (-ejaculate volume is around 5 mm (teaspoon) The smooth muscle sphincter at the base of the urinary bladder must close, followed by semen being propelled into
Ovaries Paired female gonads in abdominal cavity Suspended on either side of uterus in peritoneal cavity, held in position by ligaments Broad ligament, ovarian ligament, and suspensory ligament Produce secondary oocytes Follicles in different stages of devel
Uterine tubes or oviducts Tubes transporting secondary oocyte to site of fertilization and zygote to uterus -not continuous with ovaries but partially cover ovaries -ends of oviducts will sweep the ovulated oocyte into the tube -are extended laterally from the uterus Cilia
Uterus Site of fetal development - opens up into the fallopian tubes it is a continuous pathway Major regions Fundus, body, and cervix
Vagina Passageway from cervix to exterior Receptacle for penis during sexual intercourse Outlet for menstrual flow Passageway for childbirth Rugae
Vulva collective external structures External genitals of female Include mons pubis, labia majora, labia minora, clitoris, vestibule, vaginal and urethral orifice (separate in female), hymen, paraurethral glands, and greater vestibular glands Many structures
Mammary glands Part of integumentary and reproductive systems Each breast anterior to pectoralis major and serratus anterior muscles -alveoli produce milk -myoepithelial cells contract because of oxytocin to cause milk let down (positive feedback); posterior pituita
male/female differences -male does not have uterus, female does not have prostate -female urethra shorter and wider and closer to other holes therefore they are more likely to develop infections (UTI); urethra only for urinary system -male risk has an increase of urinary sta
broad ligament: wide band of connective tissue that anchors uterus and ovaries in the pelvic cavity
suspensory ligament: attaches/suspends ovaries to the pelvic wall
ovarian ligament: attaches ovaries to uterus but not a passageway
secondary oocyte: released at day 14 through ovulation -ovulated in meiosis 2 -fertilization required to complete cell division (meiosis 2) which then becomes an ovum (egg)
Ovarian cortex Ovarian follicles surrounded by dense irregular connective tissue
Ovarian medulla Loosely arranged connective tissue with blood and lymph vessels and nerves
Histology of Ovary -female are born with gamete cells at first oocyte stage in primordial follicles -several degenerate during childhood: atresia -eventually menopause occurs -inner part of ovary is called medulla
Oogenesis Oogonia complete mitosis during fetal development Primary oocytes (diploid; 2n) formed before birth and many begin to degenerate (atresia) -oogenesis -oogonia (2n) -primary oocyte (2n) -arrested in meiosis 1 until puberty -in fetal developme
Oogenesis - Meiosis Meiosis I – a few primary oocytes enter prophase But arrested development until after puberty After puberty, complete meiosis I as follicle develops to produce secondary oocyte and polar body (unequal cytoplasm distribution) Usually one secondary oocyt
Primordial follicle Single layer of cells surrounding primary oocyte
Primary follicle Clear zona pellucida, multilayered granulosa cells
Secondary follicle Corona radiata, small antrum, more granulosa cells: secretes estrogen
Graafian follicle Mature follicle, large antrum: ruptures and ovulates
Corpus luteum Remnants after ovulation, produces hormones
Corpus albicans Degenerated corpus luteum; becomes fibrous scar
Infundibulum distal funnel shape end of tube, open to serous fluid of peritoneal cavity
Fimbriae fingerlike extensions sweep oocyte into infundibulum
Ampulla widest, longest portion, typically site of fertilization
Isthmus short, narrow connection to uterus
ectopic pregnancy -implantation outside of uterus -often in tube potentially fatal, if tube rupture + hemorrhage
Perimetrium outer protective layer, supported by broad, uterosacral, cardinal and round ligaments visceral peritoneum
Myometrium three smooth muscle layers important during labor receptors for prostaglandins + oxytocin
Endometrium Stratum functionalis - sloughs off - faces uterine cavity; sloughs off each month (menstrual flow)=tissue + blood -is replaced each month by proliferation of the stratum basalis Stratum basalis - produces new stratum functionalis after menstruation
Uterus functions: Menstruation and regrowth of sloughed-off lining Implantation of fertilized ovum Contribute to structure of placenta Support development of fetus during pregnancy Labor
Extensive blood supply Uterine, arcuate, radial, straight and spiral arteries
leiomyoma -fibroids -growth of myometrium
Mammary gland functions for lactation Modified sudoriferous gland that produces milk Lobules composed of alveoli separated by adipose tissue Myoepithelial cells contract to propel milk through ducts Secondary tubules, mammary ducts, lactiferous sinuses, and lactiferous ducts
Ovarian cycle Occurs in ovary during and after maturation of oocyte
Uterine cycle Concurrent changes in endometrium of uterus to prepare to receive fertilized ovum and support its development
Hormone Regulation of Female Cycle At puberty, gonadotropin-releasing hormone (hypothalamus) stimulates secretion of two anterior pituitary gonadotropin hormones
female - Follicle-stimulating hormone (FSH) Initiates follicular growth and estrogen secretion
female - Luteinizing hormone (LH) Stimulates further follicular development and estrogen Triggers ovulation and corpus luteum secretion of estrogen, progesterone, relaxin, and inhibin
female - Inhibin Inhibits FSH, and LH to lesser extent
female - Relaxin Relaxes uterine muscle and pubic symphysis
secondary female sex characteristics -enlarging breasts -widening breasts -development of pubic + axillary hair
female - Estrogen Stimulate development and maintenance of female reproductive structures and secondary sex characteristics Stimulates protein anabolism Decreases blood cholesterol levels
female - Progesterone Works with estrogen to prepare endometrium for implantation Prepares mammary glands for milk secretion
Menstrual phase menstruation -days 1-5 In ovaries, primordial follicle develop into primary, then secondary follicles In the uterus, stratum functionalis of the endometrium is shed, discharging blood tissue fluid, mucus, and epithelial cells
Preovulatory phase (days 6-13) In ovaries, a group of follicles begins to undergo maturation -One becomes dominant, and others degenerate -Graafian follicle secretes estrogens and inhibin, which decreases FSH and stops other follicles from growing In uterus, estrog
-female cycles -assume 28 days -variable in length of the preovulatory phase (days 1-13) -always 14 days for ovulation to the first day of the next cycle, which begins with menses
Ovulation -day 14 -release secondary oocyte High levels of estrogen exert positive feedback effect on anterior pituitary and hypothalamus Surge of LH causes rupture of Graafian follicle and release of secondary oocyte with zona pellucida and corona radiata cells into pelvic cavity
Postovulatory phase (days 15-28) In ovaries, the corpus luteum develops from the ruptured follicle Stimulated by LH, secretes progesterone, estrogens, relaxin, and inhibin In uterus, endometrium thickens in readiness for implantation Also begins secretion of nutrients to suppo
If fertilization and implantation do NOT occur In the ovaries, corpus luteum degenerates and levels of progesterone and estrogens decrease In the uterus, menstruation triggered by decreasing hormones Initiation of another reproductive cycle
If fertilization and implantation DO occur In the ovaries, human chorionic gonadotropin secreted by the implanted embryo maintains corpus luteum , so it continues to secrete progesterone and estrogens In the uterus, endometrium development continues in preparation for implantation by the zygote
vasectomy tube is cut therefore no sperm in semen
-tubal ligation fallopian tubes are cut therefore no egg to fertilize by the sperm
Fertilization Union of the genetic material from a haploid sperm and haploid secondary oocyte Male and female pronuclei form a single nucleus Typically occurs in uterine tube 12 to 24 hours after ovulation Sperm use flagella to swim from vagina through cer
Capacitation changes that prepare for penetration of corona radiata to zona pellucida
Acrosomal reaction release of acrosomal enzymes to digest path through zona pellucida
Polyspermy block fast and slow reactions prevent another sperm penetration
Fertilization Sperm entering oocyte triggers completion of meiosis II by oocyte, producing second polar body and diploid zygote secondary oocyte---penetrated by sperm and meiosis 2 occurs-----oocyte----pronucleus from sperm plus oocyte unite---zygote
Dizygotic (fraternal) if two secondary oocytes released and fertilized by two sperm
Monozygotic (identical) if single fertilized ovum separates into two embryos can share placenta or have their own (both have different complications)
Conjoined twins if developing ovum forms two embryos, but cells do not separate within 8 days
Embryo from fertilization to 8th week of development -teratogens can cross the placenta -substance that can development of the embryo/fetus -most damaging in embryonic stage-rapid cell division and establishment of organ systems -alcohol, viruses, X-rays
Cleavage (embryo) rapid cell division of zygote, producing blastomeres
Morula (embryo) solid sphere of cells
Blastocyst (embryo) hollow ball of differentiated cells Embryoblast – develops into embryo Trophoblast – becomes placenta and other support structures
Implantation Blastocyst attaches to the endometrium Endometrium becomes decidua basalis and later becomes the maternal part of placenta
Embryonic Period - Placenta is site of exchange between mother and fetus Fetal portion formed by chorionic villi Maternal portion formed by endometrium Functions for O2/CO2 exchange, protective barrier, stores nutrients, produces several hormones to maintain pregnancy Detaches and becomes the “afterbirth” after delivery
Embryonic Period - Umbilical cord connects placenta to embryo/fetus Forms from extraembryonic mesoderm surrounded by amnion Consists of two umbilical arteries (oxygen-poor blood) and one umbilical vein (oxygen-rich blood) Scar after delivery becomes umbilicus (navel)
Embryonic Period - Third to ninth week of embryonic development Three primary germ layers differentiate from the embryonic disc All major organs appear during fourth through eighth weeks of development All major body systems have begun development by end of eighth week, although most functions are minimal Fetal p
Ectoderm gives rise to nervous system and epidermis
Mesoderm gives rise to connective tissues and muscles
Endoderm gives rise to gastrointestinal tract, urinary bladder and urethra, and respiratory tract
Hormones of Pregnancy - Human chorionic gonadotropin Secreted by chorion to maintain corpus luteum until about 4th month, when placenta produces enough progesterone and estrogens
Hormones of Pregnancy - Progesterone and estrogens Secreted initially by corpus luteum, then chorion, and later placenta High estrogen level prepares myometrium for labor; progesterone ensures myometrium is relaxed and cervix tightly closed
Hormones of Pregnancy - Relaxin Secreted initially by corpus luteum, and later by placenta Increases the flexibility of pelvic ligaments and helps dilate cervix for delivery
Hormones of Pregnancy - Human chorionic somatomammotropin Secreted by chorion Prepares the mammary glands for lactation, increases protein synthesis for maternal growth, and influences maternal and fetal metabolism
Hormones of Pregnancy - Corticotropin-releasing hormone Secreted by the placenta Establishes timing of birth Increases secretion of cortisol, which is needed for maturation of fetal lungs and production of surfactant (surfactant is sufficient for about 35 weeks -gestation- it prevents the lungs from collapsi
Changes During Pregnancy Maternal abdominal organs get pushed superiorly against the diaphragm, while the ureters and urinary bladder are compressed Maternal weight gain, breast enlargement, and lower back pain resulting from lordosis (swayback) Metabolic changes to meet fetal
Labor Process by which fetus is expelled from the uterus through the vagina Controlled by complex interactions of several hormones Rising levels of estrogens stimulate release of prostaglandins by placenta, which cause softening of the cervix
True labor Uterine contractions at regular intervals and dilation of cervix, expulsion of fetus, and delivery of placenta
False labor Involves pain at irregular intervals that does not intensify
Lactation Secretion and ejection of milk from mammary glands
Prolactin Secreted by anterior pituitary gland Promote milk synthesis and secretion Inhibited by progesterone until maternal levels drop after delivery Suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus
Oxytocin Secreted by posterior pituitary gland Promotes milk ejection reflex and contraction of myoepithelial cells Suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus
benefits of vaginal birth -promotes removal of fluid from baby -contractions help uterus shrink after delivery -helps with let down of milk
Benefits of Breastfeeding Colostrum -Produced first few days after birth -Not as nutritious as true milk, but contains important antibodies to protect infant Ideal nutrition for infant Beneficial cells and molecules Decreased incidence of disea
Created by: 1228861590591703