Reproductive System Flashcards
(124 cards)
1
Q
How do humans start off life?
A
- bipotential (ability to form male or female reproductive tract)
2
Q
What is sexual reproduction?
A
- involves fusion of gametes from two parents resulting in genetic variation among offspring
3
Q
Why is sexual reproduction necessary?
A
- creates genetic variation among a species/offspring
- enhances reproductive success in changing environments
- allows for variety of phenotypes
- genetic variation is needed to survive new pathogens and environments-> diversity driven by ability to survive disease
4
Q
What makes up the reproductive system in humans?
A
-gonads
- series of ducts for delivery of gametes and structures for copulation
5
Q
What are gonads?
A
- primary sex organs that produce gametes and secrete hormones
- male gonad (testes) produce sperm
- female gonad (ovaries) produce ova (eggs)
6
Q
What determines who is “named” male or female in a species?
A
- based on size of gametes
- Females have larger gamete
- Males have more gametes
7
Q
What are the primary structures of the male reproductive system?
A
- Testes
- Duct system (epididymis, vas deferens, urethra)
- Accessory glands (seminal vesicles, prostate, bulbourethral glands)
- External genitalia (penis, scrotum)
8
Q
What structures of the male reproductive system are shared with the urinary system?
A
- Accessory glands: seminal vesicles, prostate, bulbourethral glands
9
Q
What are the coverings of the testes
A
- tunica albuginea (capsule surrounding each testis)
- septa (extensions of the capsule that extend into the testis + divide it into lobules)
10
Q
Describe a lobule of the testes
A
- Each contains 1-4 seminiferous tubules (tightly coiled structures, function as sperm-forming factories, empty sperm into rete testis)
- Sperm travel through rete testis to epididymis
11
Q
What are Leydig (interstitial) cells>
A
- cells in the seminiferous tubules that produce androgens (generic term for sex hormone) such as testosterone + DHT (supercharged testosterone)
12
Q
What are the Ductus (Vas) Deferens?
A
- Carry sperm from epididymis to ejaculatory duct
- Passes through inguinal canal + over bladder
- Moves sperm by peristalsis (rhythmic cmooth muscle contractions)
- Spermatic cord includes ductus deferens, blood vessels, nerves in CT sheath
- Ends in ejeculatory duct which unites with urethra
- Expanded end is the ampulla
13
Q
When does ejaculation occur?
A
- When smooth muscle in walls of ductus deferens create peristaltic waves to squeeze sperm forward
14
Q
What is a vasectomy?
A
- Occurs by cutting/cauterizing ductus deferens at testes to prevent transportation of sperm through ejeculatory duct
- Sperm is reabsorbed into tissue instead
15
Q
What is the structure and function of the male urethra?
A
-Extends from base of urinary bladder to tip of penis
- Carries both urine + sperm
- Sperm enters from ejaculatory duct
- Regions of urethra: Prostatic urethra (surrounded by prostate); Membranous urethra (runs from prostatic urethra to penis); Spongy (penile) urethra (runs length of penis)
16
Q
What is semen?
A
- Mixture of sperm + accessory gland secretions from bulbourethral glands, seminal vesicles, and prostate
17
Q
What are the bulbourethral glands?
A
- pea-sized glands inferior to prostate
- produce thick, clear mucus known as pre-ejaculate (cleanses urethra of acidic urine, serves as lubricant during sexual intercourse, secreted into penile urethra)
18
Q
What are the seminal vesicles?
A
- Located at base of bladder
- Produces thick, alkaline, yellowish secretion (60% of semen):
- fructose to provide energy for ATP synthesis (neeeded for sperm to swim to egg)
- Vitamin C (potent antioxidant to prevent damage from cellular respiration)
- Prostaglandins to promote smooth muscle contraction
- Other substances that nourish + activate sperm in the oviducts
19
Q
What is the prostate?
A
- Encircles upper part of urethra
- Secretes milky fluid (helps activate sperm + enters urethra through several small ducts)
20
Q
What can occur when the prostate is enlarged?
A
- Can pinch urethra shut which can cause a need for frequent urination due to urine build up in the bladder
21
Q
What is the scrotum?
A
- Part of male external genitalia
- Divided sac of skin outside abdomen
- maintains testes at ~3 degrees C lower than normal body temp to protect sperm viability
- Can be used for heat-based contraception (stick testicles in boiling water to stop sperm from forming)
22
Q
What is the penis?
A
- Delivers sperm into female reproductive tract
- Regions of penis:
- Shaft
- Glans penis (enlarged tip)
- Prepuce (foreskin)- folded cuff of skin around proximal end that may be removed by circumcision
23
Q
What are descending testes?
A
- testes usually descend before birth around 32-36 weeks through the inguinal canal and end up in the scrotum (testes usually develop in abdomen)
- Undescended testes can occur in premature boys + can be corrected with surgery
24
Q
Describe the internal structure of the penis
A
- 3 areas of spongy erectile tissue around urethra (no baculum- penile bone)
- Erections occur when erectile tissue fills with blood during sexual excitement- run by parasympathetic NS
- Ejaculation driven by sympathetic NS input
25
What is spermatogenesis?
- The production of sperm cells
- Main function: Reduce number of chromosomes so offspring total is 46 not 92
- Begins at puberty and continues throughout life
- Occurs in seminiferous tubules
-Spermatogonia undergo rapid mitosis to produce more stem cells before puberty
26
What are the most important horomones of the testes? How are they produced?
Testosterone and DHT
- Produced by Leydig cells
- Luteinizing hormone (LH) activates Leydig cells when signaled by Gonadotropin hormone-releasing hormone (GnRH) from hypothalymus
- causes Leydig cells to produce testosterone
27
What are the functions of testosterone?
- Stimulate reproductive organ development
- Underlies sex drive
- Causes secondary sex characteristics (deepening of voice; increased hair growth; enlargment of skeletal muscles; thickening of bones)
28
What does exogenous testosterone do?
- Causes testes to shrink bc Leydig cells stop producing because there is already testosterone from steroid use
29
How are testosterone, FSH, and LH involved in reducing chromosome number in spermatogenesis?
- Testosterone + FSH directly modulate spermatogonia division
- LH regulates testosterone production (1 cell type produced is stem cell called type A daughter cell; other cell type produced becomes primary spermatocyte called type B daughter cell)
30
Describe the process of spermatogenesis
- Primary spermatocytes undergo meiosis
- One primary spermatocyte produces four haploid spermatids
- Spermatids have 23 chromosomes
- Late spermatids produced with distinct regions: head, midpiece, tail
- Sperm cells result after maturing of spermatids
- Spermatogenesis takes ~65 days
31
How is spermatogenesis regulated?
- Regulated by inhibin
- Inhibin secreted from Sertoli cells in seminiferous tubules inside the testes
- Testosterone + DHT stimulate inhibin production (helps locally regulate spermatogenesis)
- Testosterone, progesterone, estrogen synthesized from cholesterol + need carrier
32
Describe the anatomy of a mature sperm cell
- Only human flagellated cell
- Head (contains DNA, acrosome is a "helmet" protecting nucleus)
- Midpiece (contains mitochondria for ATP generation)
- Tail (allows for motion)
33
What is the purpose of follicles in the female reproductive system?
- Nurture eggs + produce sex hormones
- Located on the ovaries
34
What is the purpose of an orgasm?
- To cause an association between reproduction and pleasure
35
What is an ovary?
- Primary sex organ in females
- Composed of ovarian follicles (each follicle consists of a primary oocyte + follicular cells that surround oocyte)
36
What are the uterine tubes?
- Receive ovulated oocyte
- Procide site for fertilization
- attach to uterus
- little-no contact between ovaries + uterine tuves
- Supported + enclosed by broad ligament
37
What is the uterus?
- Hollow organ
- Located between urinary bladder + rectum
- Functions of uterus: Retain, receive, + nourish fertilized egg
38
What is the vagina?
-Part of the birth canal
39
What are fimbiae?
- Finger-like projections at distal end of uterine tube that receive oocyte from ovary
40
What are cilia?
- Located inside uterine tube + slowly move oocyte towards uterus (takes 3-4 days)
41
Where does fertilization occur?
- inside uterine tube since oocyte lives ~24 hours
42
What are the regions of the uterus?
- body = main potion
- fundus = superior rounded region above where uterine tube enters
- cervix = narrow outlet that protrudes into vagina
43
What are the three walls of the uterus and their purposes?
- Endometrium- inner layer (allows for implantation of a fertilized egg; sloughs off if no pregnancy occurs (mestruation))
- Myometrium- middle layer made of smooth muscle
- Perimetrium (visceral layer)- outermost serous layer
44
What is the mons pubis?
- fatty area overlying the pubic symphysis
- covered with the pubic hair after puberty
45
What is the labia?
- Skin folds
- Labia majora: hair-covered skin folds
- labia minora: dilicate, hair-free
46
What are the 3 orifices of the external genitalia?
1) Urethral orifice- pee
2) Vaginal orifice- reproduction
3) the anus
47
What are the greater vestibular glands?
- Bartholin's glands
- Secrete fluid that helps lubricate the vagina
48
What is the vagina?
- Extends from cervix to exterior of body
- Located between bladder + rectum
- Serves as birth canal + receives penis during intercourse
- hymen partially closes vagina until ruptured
49
What is the clitoris?
- Contains erectile tissue
- Corresponds to the male penis
- Hooded by a prepuce composed of sensitive erectile tissue + becomes swollen with blood during sexual excitement
50
What is the perineum?
- Diamond- shaped region between anterior ends of the labial folds, anus posteriorly, and ishcial tuberosities laterally
51
What is an episiotomy?
A cut through the perineum during childbirth to make head easier to fit through
- Not a good practice
52
When does meiosis begin in females?
- Before birth
- Primary oocytes inactive until puberty begins (frozen in prophase I)
53
What are Theca cells?
- Make up follicles along with granulosa cells
- Have receptors for LH
54
What are granulosa cells?
- Make up follicles along with theca cells
- secrete estrogen and inhibin
- Have FSH receptors
55
What is the corpus luteum?
- Forms after ovulation
- Secretes progesterone (inhibits FSH + LH by inhibiting GnRH)
- Secretes estrogen (secondary sex characteristics/maintains bonde density)
56
Describe the process of oogenesis and the ovarian cycle
- 28 days the hypothalamus signals anterior pituitary to secrete FSH + LH by releasing GnRH
- FSH causes one primary follicle to mature each month forming a seondary oocyte
- Cyclic monthly changes make up ovarian cycle
- Follicle development to the stage of vesicular follicle take ~14 days
- Ovulation of secondary oocyte occurs with release LH at 14 days
- Secondary oocyte ovualted + surrounded by corona radiata + zona pellucida
57
What occurs in the proccess of oogenesis?
- Primary oocytes from birth
- Meiosiss completed after ovulation if sperm penetrates + only one ovum + additional polar body is produced
- Formation of ovum allows 23 chromosomes to be combined with sperm chromosomes to form zygote
- If secondary oocyte isn't penetrated by sperm it dies + doesn't complete meisos to form an ovum
58
What is a polar body?
- garbage cans for extra chromosomes
59
Draw out a chart for the events of oogenesis
See slide 43
60
What is the ovarian cycle?
- includes changes in ovary that occur every 28 days
- Two phases: follicular + luteal
61
What is the menstural cycle?
- Involves changes that occur in the uterus over the same 28 days: menstural, proliferative, and secretory phases
62
What occurs during th follicular phase of the ovarian cycle?
- Days 1-14
- hypothalamus (GnRH) signals anterior pituitary to secrete FSH + LH
- FSH triggers growth of follicle
- As follicle grows it secretes estrogen with increses LH levels-> leads to ovulation
- estrogen starts positive feedback loop + ovulation ends it
- Inhibin inhibits FSH production but not secretion of GnRH from hypothalamus or LH from anterior pituitary gland
63
What is the vesicular follicle?
Growing follicle with a maturing oocyte
- ovulation occutes when egg is mature + follicle ruptures- increasing estrogen to start positive feedback loop
- maturing oocytes secrete estrogen
- ruptured follicle transforms into corpus luteum (secretes estrogen + progesterone)
64
What is progesterone?
- hormone secreted by corpus luteum
- Holds uterine lining in placde in case of fertilization + implantation
65
What occurs during the luteal phase?
- Days 14-28 in the ovaries
- Begins after follicle becomes corpus luteum
- Progesterone exerts negative feedback on hypothalamus + anterior pituitary (inhibit FSH + LH)
- Progesterone + estrogen levels decrease at end of ovarian cycle (lutolysis) + hypothalamus starts stimulating pituitary to secrete more FSH + LH
- new cycle begins through GnRH
66
What controls the menstrual cycle?
- Directly controlled by estrogen and progesterone
67
Which hormone maintains the uterine lining and prevents mensturation if fertilization occurs
hCG (human chorionic gonadotropin)
68
Why are hCG and progesterone levels elevated during pregnancy?
Needed to maintain a healthy pregnancy
69
When does luteolysis occur?
It occurs at the end of the luteal phase when there is no fertilization
70
Describe the phases that occur when fertilization does occur
The follicular phase (Days 0-14)-> Ovulation ~ Day 14 -> Implantation-> Pregnancy
71
What occurs during the mentrual phase of the menstruation cycle?
- Days 1-5 in uterus (same time as ovarian follicular phas)
- functional layer of endometrium is sloughed, bleeding occurs for 3-5 days
72
What occurs during the proliferative stage of the menstrual cycle?
- Days 6-14 (sametime as end of follicular phase)
- Regeneration of functional layer of the endometrium
- Estrogen levels rise
- Ovulation occurs at end of stage
73
What occurs during the secretory stage of the menstrual cycle?
- Days 15-28 (corresponds with luteal phase)
- Progesterone levels rise + increase blood supply to endometrium
- Endometrium increases in size + prepares for implantation
- If fertilzation does occur embryo produces hormone (hCG) that causes corpus luteum to continue producing its hormones (progesterone)
- if fertilization doesn't occur the corpus luteum degenerates + hormone levels decrease
74
What are the differences between spermatogenesis and oogenesis?
Spermatogenesis:
- Temp Sensitive
- Starts at puberty
- 2 month cycle
- no polar bodies
- 1 Spermatogonium: 4 Spermatids
- Tiny Gametes
Oogenesis
- Meiosis begins before birth + freezes in prophase 1 until puberty
- 28 cycle
- Females go through meiosis twice
- no functional gametes produced
75
What are the major roles of GnRH?
- Secreted by hypothalamus
- Regulates secretion of LH + FSH by pituitary
76
What is the main function of FSH?
- Secreted by anterior pituitary
- Stimulates growth of ovarian follicle
77
What is the main function of LH?
- Secreted by anterior pituitary
- Stimulates growth of ovarian follicle + production of secondary oocyte
- Promotes ovulation
- promotes development of corpus luteum and secretion of hormones
78
What is the main function of estrogen?
- Controls many secondary sex characteristics
- Secreted by ovarian follicle
- Low levels inhibit pituitary
- High levels stimulate hypothalamus
- Promotes endometrium
79
What are the main roles of estrogen and progesterone>?
- Secreted by corpus luteum
- Maintain endometrium
- High levels inhibit hypothalamus + Pituitary
- Sharp drops promote menstruation
80
What is progesterone's role during pregnancy?
- Helps maintain pregnancy by maintaining uterine lining
- Prepares breasts for milk production
81
What are the developmental aspects of the female reproductive system?
- breasts development signals puberty (~age 11)
- menarche- first menstrual period (caused by hormone leptin- provides energy for puberty through fat)
- menopause occurs when a year passes without mensturation (ovaries stop functioning as endocrine organs; childbearing ability ends)
82
How long are sex cells viable after ovulation/ejaculation?
- oocytes viable for up to 24 hours after ovulation
- sperm viable for up to 48 hours after ejaculation
- Intercourse must occur no more than 2 days before ovulation and no later than 24 hours after
- spem cells must make their way to uterine tube for fertilization to be possible
- Women fertile 10% of the time
83
Describe the process of fertilization
-sperm surface protein binds to egg receptor proteins
- Sperm + egg plasma membranes fuse + two nuclei unite
- Changes in egg membrane prevent entry of additional sperm (polyspermy)
- Fertilized egg develops into an embryo
84
What is capacitation?
The process in which the spermatozoon undergoes a series of changes that lead to its ability to fertilize an ovum (after it reaches the ampulla of the fallopian tube)
85
What is an ectopic pregnancy?
- an abnormal pregnancy that occurs outside the womb in the fallopian tube (called a tubal pregnancy)
86
What is cleavage?
- produces ball of cells from zygote through rapid series of cell divisions that results in a morula (solid ball)
- morula then becomes an early blastocye (hallowball with an inner cell mass)
- then becomes late blastocyst
- then becomes gastrula (ball with invaginations)
- morula can divide to become twins, triplets, etc
87
What is totipotent, pluripotent, multipotent, and unipotent?
- zygote starts off totipotent (can be entire organism)
- identical twins are monozygotic
-Fraternal twins are dizygotic
- blastocyst contains inner cell layer mass of pluripotent cells which become any tissue type (embryonic stem cells)
- Adults have unipotent + a few multipotent cells (blood stem cells can be blood but there are many types of blood cells)
88
What occurs in the early stages of development?
- fertilized egg undergoes early cleavage
- morula is a ball of cells + becomes early blastocyst
- Late blastocyst secretes hCG to induce corpus luteum to continue producing hormones
- late blastocyst forms after hatching from the zona pellucida + implants in wall of uterus
- Late blastocyst becomes gastrula
89
What are the functional areas of the blastocyst?
- Trophoblast- outer layer of the large fluid filled sphere
- inner cell mass is a cluster of cells to one side (will become fetus)
- cells of the inner cell mass will become us
90
What are the primary germ layers of the gastrula?
-ectoderm: becomes outside layer
- mesoderm: middle layer
- endoderm: inside layer
- archenteron: cavity of gastrula (GI tract)
91
What cells does the ectoderm become?
- skin cells of epidermis
- neuron of brain
- pigment cell
92
What cells does the mesoderm become?
- Cardiac muscle
- skeletal muscle cells
- tubule cell of. thekidney
- red blood cells
- smooth muscle (in gut)
93
What cells does the endoderm become?
- Lung cell
- thyroid cell
- pancreatic cell
94
What takes place during the first trimester of pregnancy?
- pregnancy begins when late blastocyst implants
- most rapid changes occur to the embryo during first trimester
- most important trimester
95
What are chorionic villi?
-Projections of the blastocyst
- develop and coopoerate with cells of the uterus to form placenta
96
What is the amnion?
- Fluid filled sac that surrounds embryo
97
What is the umbilical cord?
- Blood vessel containing stalk of tissue
- attaches embryo to placenta
98
What are the functions of the placenta?
- forms barrier between mother and embryo
- delivers nutrients and oxygen from mom
- removes waste from embryonic blood
- becomes an endocrine organ and takes over for corpus luteum by end of second month by producing estrogen, progestrone, and other hormones fro pregnancy maintainance
99
How is sex determined in humans?
- presence of Y chromosomes means functional SRY gene which leads to development of male XY
- SRY gene codes for presence/absence of testes
100
What does the SRY gene code for?
- Testes determining factory (TDF)
- Based on SRY gene ducts form:
- Mullerian ducts form female reproductive
- Wolffian ducts form male reproductive tract
- Female development is default pathway
- Gene is only used once
101
When does sex determination occur?
- SRY gene turns on for 11-48 hours at 7.5 weeks
- Wolffian duct/Mullerian duct forms ~10 weeks
- External genitalia become clear ~14 weeks
- Testes descend ~38 weeks
102
How does intersex occur?
- may develop if DHT levels aren't significant in utero
- Boys born with condition called guevedoces have low levels DHT so testes don't descend until puberty when there are high testosterone levels produced
103
What is androgen insensitivity?
- a case where intersex may develop
- androgen receptor is faulty
- genetically XY chromosomes, but female
- testes form + androgens produced but body doesn't respond to androgens because fo mutation of androgen receptor
- default pathway is to become female (blind-ending vagina; X-linked, sterile, no menstruation)
104
What can happen to a biological femake who uses exogenous testosterone?
- become more masculine
- hairier, smaller breasts
105
What occurs in fetal development beginning in the ninth week?
- embryonic induction initiates organ formation
- during induction adjacent cells + cell layers influence each other's differentiation via chemical signals
- all organ systems formed by end of eigth week
- activities of the fetus are growth and organ specialization
- major change in appearance occurs in this stage
106
What occurs during the second trimester?
- increase in size and refinement of human features
107
What occurs during the third trimester?
- birth of child brought about by series of rhythmic contractions of the uterus (labor)
108
When if a pregnancy considered full term?
At 40 weeks (range: 38-42 weeks)
109
What is labor
- rhythmic, expulsive contractions
- operates by positive feedback mechanism
110
What are Braxton- Hicks?
- false labor
- week irregular uterine contractions
111
How is labor initiated?
- estrogen levels rise, estrogen is permissive for oxytocin
- estrogen causes oxytocin receptors to be expressed on the uterine wall
- prostaglandins and oxytocin are released
- combination of oxytocin and prostaglandins produce uterine contractions
112
What is the process of childbirth?
1) Baby moves deeper into mother's birth canal
2) Pressoreceptors in cervix of uterus excited
3) Afferent impulses to hypothalamus
4) Hypothalamus sends efferent impulses to posterior pituitary where oxytocin is stored
5) Posterior pituitary releases oxytocin to blood + targets mother's uterine muscle
6) Uterus responds by contracting more vigorously
113
What are the three stages of labor?
1) dilation of cervix
2) expulsion of baby
3) delivery of the placenta
114
What occurs during the dilation stage?
- cervix dilates
- full dilation is 10 cm
- uterine contractions begin + increase
- cervix softens + effaces
- amnion ruptures (water breaking)
- lasts 6-12 hours
115
What occurs during the expulsion stage?
- infant passes through cervix + vagina
- can last for 50 minutes-2 hours in first birth 20 minutes in later births
- normal delivery is in cephalic position
- breech presentation is butt first
116
What does oxytocin do?
- causes mother to still love baby after it causes her extreme pain
117
What is the positive feedback loop that causes oxytocin to be released?
- estrogen induces oxytocin receptos on uterus
- oxytocin stimulates uterus to contract + stimulates placenta to make prostaglandins
- prostaglandins stimulate more uterus contractions
118
What occurs in the delivery stage?
- delivery of placenta
- withing 15 minutes after birth of infant
- afterbirth (placenta + attached fetal membranes)
- all placental fragments shoudl be removed to avoid post partum bleeding
119
What are different forms of contraception?
- Birth control pill
- Vasectomy
- Tubal ligation
- progestin minipill
- rhythm
- withdrawal
- condom (barrier)
- cervical caps
- diaphragms
- spermicidal foams
- gels
- sponges
120
How does sterilization as contraception work?
- uterine tubes cut
- vasectomy
121
What is rhythm as contraception?
- fertility awareness
- avoiding intercourse during period of ovulation or fertility
122
How does the birth control pill work?
- pill mimics pregnancy
- ovarian follicles don't mature + ovulation ceases, menstrual flow reduced, cervix coated with mucous
123
What do IUDs do?
- plastic/metal device inserted into uterus
- prevents ferilization of egg + may prevent implantation
- copper toxic to sperm
124
How does the morning after pill work?
Ella: Prevents ovulation/implantation taken within 5 days of unprotected intercourse
Plan B: similar to high levels of regular BC pills
- taken within 3 days of unprotected sex + disrupts hormonal signals to the point that fertilization/implantation is prevented
