The Reproductive System Flashcards
What are the functions of the reproductive system?
-Produce
-Nourish and transport the chromosome carrying cells
-Facilitate fertilization
-Sustain the growth of an embryo and fetus
What is the common goal of both the male and female reproductive systems?
Passing on genetic information and the continuation and procreation of the species
What are gonads?
Testes (male) and ovaries (female)
-Produce gametes and secrete sex hormones
What is a gamete?
male or female reproductive cells
What do ducts do?
store and transport the gametes
What do accessory sex glands do?
produce substances to protect the gametes and facilitate their movement
What do supporting structures do?
assist in gamete delivery and growth of embryo
What are the organs of the male reproductive system?
-Testes
-System of ducts (epididymis, ductus deferens, ejaculatory ducts and urethra)
-Accessory sex glands (seminal vesicles, prostate, bulbourethral)
-Supporting structures (scrotum, penis)
What is the scrotum?
-supporting structure for the testes that consists of loose skin and an underlying subcutaneous that hangs from the root of the penis
-divided by a septum that allows each testicle its own compartment
-skeletal muscle fibers exist within the scrotum and the scrotal septum that allow for the extension and retraction of the scrotal sac
-this allows for thermoregulation using body heat, in order to keep the testes 2-3C cooler than internal body temperature, required for adequate sperm production
What are testes (testicles)?
-A pair of oval shaped glands housed in the scrotum
-Internally, each testicle is divided into several lobules containing the seminiferous tubules, tightly coiled tubes where sperm is formed
-After the sperm is formed, it travels through a series of ducts that empty into a single ductus epididymis
What is spermatogenesis?
The process of sperm formation
What is mitosis?
nuclear cell division producing two identical cells
What is meiosis?
reproductive cell division that occurs in the gonads
What occurs in meiosis I?
a single diploid cell produces 2 haploid cells
What occurs in meiosis II?
the two haploid cells from meiosis I divide producing 4 haploid gametes that are genetically different from the original diploid cell
What is a diploid?
a cell having 2 sets of chromosomes (XX and XY)
What is a haploid?
a cell containing half the number of chromosomes
What is sperm (aka spermatozoa)?
the male gamete (reproductive sex cell) responsible to fertilization of a female ovum
What is sperm composed of?
Composed of a head (contains chromosomes, nucleus and other enzymes) and a tail (flagella - motility of the cell)
True or False:
Sperm can survive up to 24 hours in the female reproductive tract
False
Sperm can survive up to 48 hours in the female reproductive tract
What are the steps of spermatogenesis?
- Sperm cells start as spermatogonia (sperm stem cell) and undergoes mitosis within the seminiferous tubules to become primary spermatocytes
- The primary spermatocytes then undergo meiosis I, producing secondary spermatocytes
- The secondary spermatocytes undergo meiosis II producing spermatids
- The final stage of meiosis converts the spermatids into mature sperm cells
-One spermatogonia cell produces 4 spermatozoa (sperm cells)
What is the epididymis?
an organ that curves along the superior and posterior border of each testicle
What is the function of the epididymis?
The functional site for sperm maturation and storage, and it helps propel sperm into the vas deferens during sexual arousal
What is the ductus (vas) deferens?
the continuation of the epididymis and a passageway to transport sperm from the testes to the urethra during sexual arousal (achieved by peristaltic contractions)
What are spermatic cords?
a supporting structure that ascends out of the scrotum and contains:
-vas deferens
-arteries
-veins
-lymph vessels
-autonomic nerves
-the cremaster muscle (extension and retraction)
What are ejaculatory ducts?
-formed by the union of the seminal vesicle and the terminal end of the ductus deferens
-terminate in the prostatic urethra where they eject semen into urethral canal for ejaculation
What is the urethra (male reproductive)?
-shared terminal duct of the reproductive and urinary systems for males
-common passageway for urine and semen
What is the function of the accessory sex glands?
Responsible for producing and secreting the remaining substances that produce semen
What are the male accessory sex glands?
-seminal vesicles
-bulbourethral glands
-the prostate
What are the seminal Vesicles (aka seminal glands)?
-a pair glands that lye posterior to the base of the urinary bladder and secrete about 60% of the fluid in semen
-composed of fructose, prostaglandins and clotting proteins
-the alkaline fluid helps neutralize the acidic environment of the urethra and vaginal canal that would otherwise kill
What are the bulbourethral Glands (aka Cowper’s glands)?
-small, paired glands located inferior to the prostate
-during sexual arousal they secrete an alkaline mucous fluid to neutralize and lubricate the urethra and tip of the penis
What is the prostate?
-a singular gland located inferior to the urinary bladder and surrounds part of the urethra (prostatic urethra)
-secretes a milk and slightly acidic fluid that contributes to sperm motility and viability
What is semen?
-A mixture of sperm and seminal fluid with a slightly alkaline pH
-Provides sperm with a transport medium, nutrients and protection to promote fertilization with an ovum (egg)
-Typically contains approximately 50-150 million sperm cells per mL
What is the penis?
Contains the urethra and is a passageway for semen and urine
What does the structure of the penis consist of?
-Body: contains tissues that keep the urethra open and smooth muscle contraction and blood vessel dilation to promote an erection
-Glans penis: the distal end of the penis. Widens and provides an external opening for the urethra
-Root: connective tissue that anchor the penis in place
What occurs in hormonal control of the male reproductive system?
-During puberty, the hypothalamus begins producing more gonadotropin releasing hormone (GnRH)
-This stimulates the anterior pituitary gland to begin producing more luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
-LH stimulates cells within the seminiferous tubules to secrete testosterone
-FSH and testosterone work synergistically to stimulate spermatogenesis
What does testosterone do?
-Involved in prenatal development of the male reproductive system
-Development of male sex characteristics during puberty
-Enlargement of sex organs, muscular and skeletal growth, facial and chest hair growth, enlargement of the larynx (deepening voice), and increased sebaceous gland (oil) secretions
-Spermatogenesis and libido (sex drive)
-Stimulation of anabolism - protein synthesis
What are the organs of the female reproductive system
-Ovaries (female gonads)
-Uterine (fallopian) tubes (oviducts)
-Uterus
-Vagina
-External organs (vulva)
-Mammary glands (part of the integumentary and reproductive systems)
Where are the ovaries located?
Paired glands found lateral to the uterus and superior to the urinary bladder
What do the ovaries produce?
-Produce gametes (oocytes that mature into ova (eggs) after fertilization
-Produce hormones (progesterone and estrogens)
What is oogenesis?
the formation of gametes in the ovaries
True or False:
Spermatogenesis and oogenesis both occur through meiosis
True
Oogenesis occurs in the same fashion as spermatogenesis (meiosis) but starts before a female is even born (starts at puberty for males)
What is the process of oogenesis?
-Oogonia (diploid stem cells) undergo mitosis and produce primary oocytes
-The primary oocytes undergo meiosis I during fetal development but do not complete the phase until after puberty
-The primary oocytes are contained in ovarian follicles until maturation
-Following puberty, when the oocyte and follicle have matured and are ready for ovulation, the primary oocyte completes meiosis I - producing 2 haploid cells
-One of the 2 haploid cells is discarded, and the other becomes a secondary oocyte
-The secondary oocyte begins meiosis II but does not complete it until it is fertilized
-After completing meiosis II, there are two more haploid cells, one of them is discarded, the other is the ovum (mature egg)
What happens if the secondary oocyte is not fertilized?
If fertilization of the secondary oocyte does not occur, the cell degenerates
How many ovum are produced during oogenesis?
Unlike spermatogenesis, one primary oocyte produces a single ovum
What are the uterine (fallopian) tubes?
-Paired ducts that extend laterally from the uterus and provide a route for sperm to reach an ovum and transport secondary oocytes and fertilized ova from the ovaries to the uterus
-A ciliated epithelial layer and smooth muscle layer work together to propel a fertilized ova or secondary oocyte into the uterus
What are the functions of the uterus?
-the site of implantation of a fertilized ovum
-development of the fetus during pregnancy
-delivery of the infant (labor)
-it is also the source of menstrual flow and a pathway for sperm to reach the fallopian tubes
Where is the uterus located?
It is located between the urinary bladder and the rectum
How is the uterus anatomically divided?
Divided into:
-Fundus: curved superior surface of the uterus
-Body: tapering central portion
-Uterine Cavity: interior of the uterine body
-Cervix: inferior narrow portion; opens into the vagina
-Cervical Canal: interior of the cervix
-Internal Os: proximal opening of the cervical canal (into the uterus)
-External Os: distal opening of the cervical canal (into the vagina)
What are the 3 layers of the uterus?
-Perimetrium: outer layer and part of the visceral peritoneum
-Myometrium: middle muscular layer, responds to oxytocin during labor to initiate uterine contractions
-Endometrium: highly vascular inner layer. Outer layer of endometrium sheds and is replaced during each menstrual cycle
What is cervical mucous?
secreted by endothelial cells to provide a more hospitable environment for sperm during ovulation or thickens to produce a mucous plug and inhibit sperm motility at other times
What is the vagina?
A fibromuscular canal with a mucous membrane that extends from the exterior of the body to the uterine cervix
What is the function of the vagina?
-the receptacle for the penis during intercourse
-outlet for menstrual flow
-passageway for childbirth
What is the mucosa of the vagina?
-Continuous with the uterus and is arranged in transverse folds called rugae
-Present in the mucosa are antigen presenting cells (APCs) and glycogen stores that create an acidic environment to reduce microbial growth
What is the hymen?
-a thin fold of vascularized mucous membrane forms a border around and partially closes the inferior end of the vaginal orifice (opening to the exterior)
-usually ruptured during a first sexual experience, causing bleeding, and does not regrow
What is the vulva?
refers to all the external female genitals
What is the mons pubis?
anterior to the vaginal and urethral openings; elevation of adipose tissue covered by skin and pubic hair
What is the labia majora?
extend inferiority and posteriorly from the mons pubis; adipose tissue, sebaceous and sudoriferous glands
What is the labia minora?
medial to the labia majora; sebaceous glands that produce lubrication for sexual intercourse
What is the clitoris?
anterior junction of the labia minora; small mass containing nerves and blood vessels; enlargement on tactile stimulation; sexual excitation
What does the vestibule (region between the labia minora) include?
-Hymen (if still intact)
-Vaginal Orifice: vaginal opening to the exterior
-External Urethral Orifice: opening of the urethra to the exterior
-Several glands of varying function
What is the perineum?
-Diamond shaped area medial to the thighs and buttocks of both males and females
-Contains the external genitals and anus
What is an episiotomy?
During childbirth, if the stretching of the perineum becomes excessive, a physician may elect to perform a surgical cut between the vagina and the anus to prevent vaginal tearing and allow for a less traumatic delivery of a newborn
What are the mammary glands?
Within each breast, a modified sudoriferous gland that produces milk
What occurs in milk production?
-The functions of milk production and ejection are called lactation
-Production is largely stimulated by prolactin (anterior pituitary gland)
-Ejection is stimulated by oxytocin (posterior pituitary gland)
What is the ovarian cycle?
events occurring in the ovaries during and after the maturation of an oocyte
What is the uterine (menstrual) cycle?
concurrent changes in the endometrium of the uterus to prepare it for implantation of a fertilized ovum
What hormone regulates the ovarian and menstrual cycle?
-Gonadotropin-releasing hormone (GnRH) secreted by the hypothalamus regulates these cycles
-Stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland
What does follicle stimulating hormone do?
initiates follicular growth in the ovaries
What does luteinizing hormone do?
stimulates further development of the follicles
Both FSH and LH stimulate the ovarian follicles to secrete what?
Estrogens
What are estrogens?
-Primary female sex hormone
-Several different variations of estrogen exist, but functionally can be classified as one.
What are functions of estrogens?
-Promote development and maintenance of female sex characteristics
-Adipose tissue in breasts, mons pubis and hips
-Voice pitch
-Patterns of hair growth throughout the body
-Increase protein anabolism
-Lower blood cholesterol
-Promote the replacement of endometrial layer of the uterus
What does progesterone do?
-Secreted by the corpus luteum in the ovaries
-Works with estrogens to prepare and maintain the endometrium for implantation and prepares the mammary glands for milk secretion
What occurs in the menstrual phase?
-First 5 days of the 28 day cycle
-FSH influences the growth and development of follicles (may take several months to occur
-Sloughing off of part of the endometrial layer of the uterus
-Menstrual flow includes blood, mucous and epithelial cells from the endometrium
-Menstrual flow passes from the uterine cavity through the cervix and vagina to the exterior
What occurs in the preovulatory phase?
-The time between the end of menstruation and ovulation (days 6-13)
-Final development of the follicles in preparation for ovulation
-Developed or dominant follicle secretes estrogen
-Endometrial repair occurs
What occurs in ovulation?
-Rupture of the mature follicle releases the secondary oocyte into the pelvic cavity (day 14)
-High concentrations of estrogen stimulate increased release of GnRH from the hypothalamus and LH from the anterior pituitary
-GnRH stimulates anterior pituitary to release FSH and LH
-LH causes rupture of the mature follicle and expulsion of the secondary oocyte
-Ovulated oocyte is expelled into the pelvic cavity and typically swept into the fallopian tube
What occurs in the preovulatory phase?
-Time between ovulation and the next menses (day 15-28)
-Degradation of the ruptured follicle following ovulation
-Secretion of progesterone and estrogen
-Promote the repair of the endometrium
-Uterine preparation peaks approximately 1 week after ovulation (around the time a fertilized egg reaches the uterus)
-Progesterone and estrogen levels decline if fertilization does not occur, stimulates menstruation
What is pregnancy?
-a sequence of events that begins with fertilization, proceeds to implantation, embryonic development, fetal development, and finally the birth of a newborn
-the process should take approximately 38-40 weeks after the mother’s last menstrual period
What is the embryonic period?
the first 8 weeks of pregnancy
What is an embryo?
a developing human during the embryonic period
What is the fetal period?
week 9 until birth
What is a fetus?
a developing human during the fetal period
How is the time from fertilization to birth divided?
into 3 trimesters: 1st, 2nd, 3rd
What is the first trimester?
-most critical stage of development
-all major organ systems begin to form
What is the second trimester?
-nearly complete development of organ systems
-fetus assumes distinctly human features
What is the third trimester?
-rapid fetal growth
-early in the trimester, most organ systems are fully functional
What is fertilization?
genetic material from a haploid sperm cell and a haploid secondary oocyte merge into a single diploid nucleus
What occurs in the first week of the embryonic period?
-Of the approximately 200 million sperm introduced into the vagina, fewer then 2 million reach the cervix and only 200 reach the secondary oocyte
-Fertilization
-Normally occurs in the fallopian tube within 12-24 hours after ovulation
-Sperm remains viable for 48hrs, secondary oocyte is viable for 24hrs
-Pregnancy is most likely to occur during the 3-day window (2 days before and 1 after ovulation)
What occurs during fertilization?
-Sperm gather around a secondary oocyte until one of them successfully penetrates the two layers to enter inside the cell
-As soon a single sperm cell reaches the interior of the oocyte, a chemical reaction occurs that prevents other sperm cells from penetrating
-At this point the secondary oocyte must complete meiosis II
-The nucleus of the sperm cell and the nucleus of the mature ovum fuse together forming a zygote
What are dizygotic (fraternal) twins?
-produced by the independent release of two secondary oocytes and subsequent fertilization of each by two different sperm
-different genetic material, may be different sexes
What are monozygotic (identical) twins?
-when two sperm cells fertilize a single secondary oocyte and then separate into two embryos within 8 days
-same genetic material, always the same sex
What are conjoined twins?
when a monozygotic ovum does not separate into two embryos before 8 days
What occurs in cleavage of the zygote?
-Following fertilization, rapid mitotic cell division of the zygote occurs called cleavage
-One cell becomes 2, 2 becomes 4, 4 becomes 8, etc.
-The progressively smaller cells produced by cleavage are called blastomeres
-The successive cleavages eventually produce a solid sphere of cells called a morula
What occurs in formation of the blastocyst?
-By day 4/5, the morula will typically reach the uterine cavity where nutrient rich secretions (uterine milk) from the endometrium penetrate the membrane of the morula and aids in reorganizing the blastomeres
-This occurs at the 32-cell stage and the reorganized mass of cells is called a blastocyst
-The blastocyst cells eventually develop into the embryo and the beginnings of the placenta
-When this process is complete, the developing blastocyst “hatches” from its contained structure and is ready for uterine implantation
What occurs in implanation?
-The “hatched” blastocyst remains free in the uterine cavity for about 2 days before implantation in the endometrium occurs
-At about the 6th day post fertilization the blastocyst starts to adhere to the endometrium of the uterus
-Implantation of the blastocyst causes angiogenesis and enlargement of endometrial glands at the site
-The blastocyst will then burrow its way into the endometrium until it is completely surrounded by it, the endometrial tissue surrounding the implanted embryo is known as the decidua
What is the placenta?
-a temporary organ developed during pregnancy to provide a site of exchange of nutrients and wastes between the mother and the fetus
-adheres to the inner wall of the endometrium and is composed of tissue from the endometrium and tissues from the developing embryo
What does the placenta do?
-Allows O2 and nutrients to diffuse from maternal blood to fetal blood and returns CO2 and wastes from fetal blood to maternal
-It also functions as a barrier to guard the fetus against many microorganisms
What is the process of placental formation?
placentation
What is the umbilical cord?
-the connecting tissue between the placenta and the fetus
-contains 2 umbilical arteries that carry deoxygenated blood and wastes from the fetus to the placenta and 1 umbilical vein that carries oxygen and nutrients from the placenta to the fetus
What is afterbirth?
after delivery the placenta detaches from the uterine wall
When does the placenta develop?
Development occurs between weeks 2-12 before it is fully developed
What are the major events of the fetal period (week 9- birth)?
-Detection of heartbeat (week 9-12)
-Distinguishable gender (week 9-12)
-Formation of eyes and final alignment of features
-Rapid growth of fetus
-Development of lungs, nervous and cardiovascular systems (weeks 26-29)
-Fetal viability (in preterm birth) is thought to be around 21-24 weeks (we resuscitate anything ≥20 weeks gestation)
What are the hormonal maternal changes during pregnancy?
-During the first 3-4 months the ovaries secrete estrogen and progesterone to aid in maintaining the lining of the uterus and prepare the mammary glands
-The placenta secretes human chorionic gonadotropin (hCG), which stimulates the continued secretion of estrogen and progesterone and prevents menstruation from occurring and enhances embryonic attachment to the uterus (detected on home pregnancy tests)
-When the placenta is fully developed, it takes over the secretion of estrogen and progesterone and decreases levels of hCG
What are the maternal changes to the cardiovascular system?
-
What are the maternal changes to the respiratory system?
-Increased tidal volume (35%)
-Decreased expiratory reserve volume (40%) and functional residual capacity (25%)
-Increase minute ventilation (40%)
-Increased O2 consumption (15%)
What are the maternal changes to the digestive system?
-Increased appetite
-Decreased GI motility (constipation, nausea, vomiting, heart burn)
What are the maternal changes to the renal system?
-Increased frequency
-Increased GFR (40%)
What are the maternal changes to the integumentary system?
-Increased pigmentation of the face and areolae (nipples); stretch marks; hair
What are the maternal changes to the reproductive system?
-Edema and increased vascularity of the vulva and vagina
-Hormonal increase in libido
-The growing fetus can put pressure on the inferior vena cava towards the later months of pregnancy reducing preload and causing hypotension
-By the start of the 2nd trimester, the uterus now occupies most of the pelvic cavity and eventually extends higher into the abdominal cavity
What is amniotic fluid?
fluid contained in the amniotic sac that surrounds the fetus providing it with protection and thermoregulation
What is labour?
The process by which the fetus is expelled from the uterus, through the vagina - aka giving birth
Labour can be divided into what three stages?
-Dilation
-Expulsion
-Placental
What is the dilation stage?
-onset of labour until complete dilation of the cervix (6- 12 hours)
-includes regular and increasing uterine contractions and rupture of the amniotic sac
What is the expulsion stage?
time from cervical dilation to delivery of the baby (10mins to several hours)
What is the placental stage?
time from delivery of the baby to delivery of the placenta (5-30+ minutes)
How is labour hormonally regulated?
-As progesterone levels diminish, uterine contractions can begin (progesterone inhibits contractions)
-Estrogen levels rise (overpower progesterone function) and oxytocin is released by the PPG to stimulate uterine contractions
-Estrogen also stimulates the breakdown of fibres in the cervix that encourage it to relax and dilate
-Uterine contractions occur in waves (top to bottom) similar to peristalsis
What are postnatal fetal changes?
-After birth and the separation from the placenta, the baby’s own organ systems must take over, rather than being dependent on the mother for oxygen and nutrients
-Respiratory System: while in-utero, the fetal lungs are partially collapsed and filled with amniotic fluid
-After birth, the amniotic fluid is absorbed and CO2 levels begin to rise, this stimulates the baby to take its first breath, usually associated by some vigorous crying
What occurs in fetal circulation?
-Fetal circulation does not require blood to exit the right ventricle and travel through the lungs for gas exchange, the lungs are full of fluid
-An opening in the septum between the right atrium and left atrium exists called the foramen ovals, the majority of blood reaches systemic circulation due to this
-The blood that does travel to the right ventricle and through pulmonary circulation passes through the ductus arteriosus, a fetal vessel that connects the pulmonary trunk to the aorta
What postnatal changes are there to the cardiovascular system?
-Contractions of the smooth muscles in the ductus arteriosus close the opening and eventually this seals completely (3 months)
-The foramen ovale closes immediately at the moment of birth
