Reproduction Flashcards
1
Q
What are the female primary sex characteristics:
A
Gonads (ovaries), oviducts, uterus, cervix, vagina, vulva
2
Q
What are the secondary female sex characteristics:
A
Minimal hair on face and body, prominent breasts, higher voice, rounded shoulders, wider hips, less muscle development
3
Q
Describe ovaries:
A
- Suspended by ligaments inside abdomen
- Site of oogenesis (egg production)
- Contains follicles where eggs mature (one follicle per month)
4
Q
Describe the fimbriae:
A
Finger-like projections (catcher’s mitt) that sweep the ovaries to collect eggs and direct them to the oviduct
5
Q
Describe the oviduct:
A
Carries the ovum (egg) from ovary to uterus
6
Q
Describe the uterus:
A
- Muscular organ
- Holds and nourishes fetus
- Size and shape of a pear
- Lined by endometrium – supplied by many blood vessels
7
Q
Describe the cervix:
A
Base of uterus – opening between uterus and vagina
8
Q
Describe the vagina:
A
Opening to female reproductive system – where sperm is deposited
9
Q
Describe the vulva:
A
Labia majora and minora are folds of skin that protect vaginal opening (also includes clitoris)
10
Q
What are ova?
A
- Ovaries produce only a limited number of ova (eggs)
- Single ovum develops in a single follicle each month
11
Q
Describe oogenesis:
A
- Oogonium develop into diploid primary oocytes stuck in prophase I (Girls are born with all of their 1° oocytes in Prophase I of meiosis – about 2 million)
- Every month after puberty until menopause, a 1° oocyte undergoes meiosis I (and part of meiosis II) to produce 1 haploid secondary (2°) oocyte (stuck in metaphase II) and 1 polar body
- Ovulation occurs at Metaphase II
- Meiosis II only proceeds through Anaphase II and Telophase II if the egg is fertilized
- Upon fertilization meiosis II creates a haploid ootid and a polar body
- The ootid quickly matures into an ovum and the 2 haploid nuclei (egg and sperm) fuse
- Oogenesis produces one ovum and two polar bodies (are just abosrbed)
12
Q
Describe ovulation:
A
- Follicle matures and ruptures
- Fimbriae pick up ovum and sweep it into oviducts
- Oviduct is cilia-lined and carries ovum to uterus
- Mature ovum is 20 times larger than sperm and has thick membrane
13
Q
Describe pre-natal development:
A
- Estrogen and progesterone cause prenatal development of female reproductive organs
- Also responsible for female secondary sex characteristics during puberty
14
Q
Describe mensuration:
A
- Coordinates ovulation and the readying of the uterus for implantation of fertilized egg
- Cycle is 28 days on average
- Cycle begins with menstruation and ends with the start of the next menstrual period
- A combination of ovarian and uterine cycle
- Periodic discharge of blood and fluid from uterus - caused by low levels of estrogen and progesterone at end of monthly cycle (hormone withdrawal)
15
Q
Describe the ovarian cycle:
A
- Female is born with about 2 million follicles, only about 400 will release a matured ovum
- Overview: follicle matures, releases an ovum, then follicle forms a corpus luteum (temporary endocrine gland)
- Two stages of ovarian cycle: follicular and luteal stage
16
Q
Day 1-5: Flow Phase (uterine)
A
- Lasts an average of five days
- Marked by the shedding of endometrial lining
- Triggered by a decrease in ovarian hormones (particularly progesterone) stimulates FSH and LH from pituitary
- Corpus luteum degenerates forming corpus albicans
17
Q
Day 6-13: Follicular Phase (ovarian)
A
- Increase in FSH from anterior pituitary
- Governed by estrogen released by developing follicle (which is stimulated by FSH)
- One follicle is stimulated to mature
- Estrogen inhibits FSH release -> FSH decreases (negative feedback)
- Estrogen stimulates the hypothalamus to release GnRH -> LH released from anterior pituitary (LH increases – positive feedback by estrogen)
18
Q
Day 14: Ovulation
A
- Estrogen peaks just before & LH and FSH levels peak
- LH triggers ovulation
Follicle erupts, ovum is released into fallopian tube - Female’s temperature peaks (may be used as a contraceptive method or to help in impregnation)
19
Q
Day 15 – 28: Luteal Stage (ovarian)
A
- LH causes the empty follicle to develop into a corpus luteum
- Governed by progesterone released by the corpus luteum (stimulated by LH)
- Corpus luteum secretes progesterone and estrogen
- Estrogen and progesterone inhibit anterior pituitary –> LH and FSH secretion decreased (negative feedback) —>
- Corpus luteum degenerates —> less estrogen and progesterone secreted
- FSH secretion not inhibited once drop in hormones —> back to follicular stage (new cycle)
20
Q
If implantation of a Fertilized Egg Occurs…..
A
- Embryo-supported membranes secrete a hormone called hCG
- Estrogen and progesterone secretion continues
- Progesterone maintains endometrium
- Estrogen stops ovarian cycle (so no more follicles mature)
21
Q
Describe the Uterine Cycle
A
- On first day of cycle, the corpus luteum has completely degenerated, estrogen and progesterone are low
- Estrogen released from developing follicle – by day six endometrium begins to thicken
- After ovulation, progestrone stimulates endometrium to thicken even more (doubles or triples by day 15-23)
- When corpus luteum degenerates and sex hormones drop, endometrium breaks down and menstruation begins
22
Q
Describe menopause:
A
- Number of functioning follicles decreases with age
- Hormone levels drop
- Menstrual cycle becomes irregular
- Takes a few years to stop altogether – menopause
- Decrease of sex hormones disrupts homeostasis of other hormone systems
23
Q
What are three things to remember about female hormones?
A
- Drop in progesterone =
menstruation or miscarriage - Peak/spike/increase in LH =
positive ovulation test (for trying to get pregnant) - Peak/spike/increase in HCG (human chorionic gonadotropin)=
positive pregnancy test
(Made by cells in the placenta; can be detected by urine test/blood test)
24
Q
Describe primary sex characteristics:
A
Structures that play a direct role in reproduction
25
Q
Describe secondary sex characteristics:
A
Characteristics that are unique to males or females but do not play a direct role in reproduction
26
Q
Describe the primary sex characteristics of males:
A
Testes (male gonads), scrotum, epididymis, ductus deferens, penis, seminal vesicles, prostate gland, Cowper’s gland
27
Q
Describe the secondary sex characteristics of males:
A
Facial hair, body hair, deep voice, narrow hips, muscle development
28
Q
What are testes?
A
- Organs where sperm are produced
- Scrotum contains the testes and helps regulate temperature – when cold outside, the scrotum pulls the testes closer; when warm, the testes hang lower – away from the body
29
Q
What are the parts of the testes?
A
- Ducts (Vas) deferens
- Epididymis
- Septum
- Seminiferous tubules
- Lobule
- Testis
30
Q
Describe the penis:
A
- Male organ for intercourse
- Transfers sperm to female reproductive tract
31
Q
What are the parts of the penis?
A
- Glans penis – enlarged tip
- Shaft – main component
- Foreskin – surrounds and protects the glans penis
- Both sperm and urine exit the body via a tube in the penis called the urethra
32
Q
Describe an erection:
A
- Flow of blood to spongy tissue of penis during sexual arousal
- Erectile tissue expands
- Veins carrying blood away from penis are compressed - more blood is trapped
33
Q
What is sperm?
A
- Sperm production is called “spermatogenesis”
- Each testis can produce 100 million sperm/day
- Tadpole-shaped structure 0.06 mm long
34
Q
What are the parts of sperm?
A
- Head – contains nucleus with 23 chromosomes
- Acrosome – cap of head – contains enzymes to penetrate egg
- Mid-piece (body) – contains mitochondria
- Tail – propels sperm forward
35
Q
Describe spermatogenesis:
A
- Sperm develop from specialized cells (spermatogonium) in the testes
- Meiosis I forms two haploid secondary spermatocytes
- Meiosis II forms four spermatids (haploid)
- Developing sperm cells are nourished by Sertoli cells in the seminiferous tubules
- Immature sperm are transferred to the epididymis (a duct on the testes)
- Sperm mature and become motile in the epididymis
36
Q
Describe sperm release?
A
- When ejaculation occurs, sperm travels from the epididymis to the ductus deferens (vas deferens), which carries sperm to the penis
- Sperm travels out of the penis via the urethra
- Muscle contractions help to expel the semen
- Sperm is carried in a supportive fluid called seminal fluid
37
Q
What is seminal fluid?
A
What is seminal fluid?- A mixture of fluids from the following glands that help to carry and nourish the sperm
- Seminal vesicle – produces mucous-like fluid containing fructose (helps to give the sperm energy)
- Prostate gland and Cowper’s (bulbourethral) gland – secrete mucous-like fluids that contain alkaline materials (neutralizes acids in the vagina)
38
Q
Describe how sex determination works:
A
- Androgens (male sex hormones) are triggered for release in an XY fetus
- A gene on the Y chromosome causes embryonic glands to develop as testes and secrete testosterone
- Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sex characteristics during puberty
- Male babies are born with a penis and testes (testes descend from abdomen shortly after birth) but cannot fertilize eggs until puberty
39
Q
Describe male puberty:
A
- Puberty begins at age 10-13 for males
- Hypothalamus increases production of gonadotropic releasing hormone (GnRH)
- GnRH causes anterior pituitary to release follicle stimulation hormone (FSH) and luteinizing hormone (LH)
FSH and LH stimulate sperm production and testosterone release from testes - Testosterone stimulates development of sex organs and secondary sex characteristics
40
Q
Describe regulation in the adult male - sperm production:
A
- GnRH triggers release of FSH and LH from anterior pituitary
- FSH causes cells in testes to produce sperm, also causes seminiferous tubules to release inhibin
- Inhibin acts on anterior pituitary to inhibit FSH
- A decrease in FSH means less inhibin will be released
- Negative feedback cycle continues to make sure sperm production is constant over time
41
Q
Describe regulation in the adult male - secondary sex characteristics:
A
- GnRH stimulates release of LH from anterior pituitary
- LH stimulates testes to release testosterone
- Testosterone promotes secondary sex characteristics (eg. Muscle development)
- Testosterone also inhibits LH release
- Negative feedback cycle keeps testosterone levels constant
42
Q
What is andropause?
A
- A decrease in testosterone beginning around age 40
- Can cause fatigue, depression, muscle and bone loss, drop in sperm production
43
Q
Describe fertilization:
A
- Occurs in the oviduct
- Egg takes about 4 days to travel down oviduct to uterus
- Fertilization must occur within 12-24 hours of release from ovary
- The successful sperm must therefore navigate the vagina —> cervix —> uterus —> most of the oviduct
44
Q
Describe the process of fertilization:
A
- Multiple sperm reach the egg
- Egg coating consists of outer corona radiata and the thicker zona pellucida
- When sperm hit corona radiata, acrosomes release enzymatic contents
- Enzymes begin to break down the zona pellucida, sperm keep pushing at egg
- Hundreds of sperm may be required to clear one path to egg
45
Q
What happens when one sperm gets into the egg?
A
- Egg membrane changes (depolarizes) (so no more sperm can bind to it)
- Sperm head collapses, and sperm nucleus fuses with egg nucleus (within 12 h)
- Resulting single cell with 46 chromosomes is called a zygote
- Takes several days to get to uterus but begins to divide while in oviduct
46
Q
Describe cleavage:
A
- Zygote begins to divide within 30 hours of fertilization
- Cells division occurs quickly with little time for growth, as a result zygote remains same size, just made of many small cells instead of one big one
- Division without overall growth is cleavage
47
Q
Describe morula:
A
- When zygote is 16 cells, becomes morula
- Morula enters uterus 3-5 days after fertilization
- Begins to fill with fluid from uterus – allows two groups of cells to form
48
Q
What is a blastocyst?
A
- When two groups of cells have formed
- Hollow structure
- Outer layer of cells is trophoblast
- Goes on to form chorion then placenta
- Inner is inner cell mass (embryoblast)
- Goes on to form embryo
49
Q
Describe implantation:
A
- Occurs around 10th to 14th day
- Trophoblast secretes enzyme to break down part of endometrium
- Blastocyst settles in to endometrium
- Woman is now officially pregnant
- Trophoblast starts to secrete hCG (human chorionic gonadotropin)
50
Q
Describe hormone regulation through pregnancy:
A
- hCG secretion continues for two months to maintain CL
- CL remains for pregnancy but placenta secretes most of estrogen and progesterone after first trimester
51
Q
Describe gastrulation:
A
- Process of forming the primary germ layers of the embryo
1. Space forms between inner cell mass and trophoblast – forms amniotic cavity
2. Inner cell mass flattens into disk-like structure – embryonic disk (short stalk connects embryonic disk to endometrium)
3. Two layers form in embryonic disk (ectoderm —> outer layer, endoderm —> inner layer)
4. Third layer forms, mesoderm —> middle layer - Ectoderm is closest to amnion, endoderm is closest to yolk sac
- All future body tissues are derived from these three germ layers
52
Q
When can a fetus be called an embryo?
A
Once the 3 layers are formed by gastrulation, it is now called an embryo
53
Q
How do identical twins happen?
A
Cell mass separates into two separate embryos before undergoing gastrulation
54
Q
How do conjoined twins happen?
A
The inner cells mass did not completely separate
55
Q
What does the ectoderm give rise to?
A
- Outside structure and the nervous system
- Epidermis
- Nervous tissue and sense organs
- Pituitary gland
- Adrenal medulla
- Tooth enamel
- Eye lens
56
Q
What does the mesoderm give rise to?
A
- Stuff that never sees the outside world
- Dermis
- Lining of blood vessels and body cavities
- Muscle
- Connective tissue
- Adrenal cortex
- Heart
- Kidneys
- Internal reproductive organs
- Spleen
57
Q
What does the endoderm give rise to?
A
- Stuff that sees the outside world
- Lining of digestive and respiratory tract
- Liver
- Gallbladder
- Pancreas
- Thymus
- Tonsils
- Parathyroid and thyroid
58
Q
Describe morphogenesis:
A
- Events that form distinct structures in organism
- Depends on differentiation – cellular process that allows cells to take on specific shapes and functions
59
Q
What happens at three weeks?
A
- A thick band of mesoderm cells along what will be babies back form notochord - forms basis for skeleton
- Nervous system (will form brain and spinal chord)
- Neuralization - process of forming neural tube
- Heart forms - begins to beat about day 18
- Gastrulation forms the gut
60
Q
Neurulation/ Organ Formation Week 4:
A
- Blood cells form and fill blood vessels
- Head visible
- Lungs and kidneys start to form
61
Q
Neurulation/ Organ Formation Week 5:
A
- Head very large compared to body
- Eyes open but don’t have lids or irises
62
Q
Neurulation/ Organ Formation Week 6:
A
- Brain developing rapidly
- Limbs are starting to lengthen
- Gonads producing hormones – influencing genaltalia
- Face, arms, legs, toes, fingers,internal organs, touch, movement, placental secretions, at seven weeks the sex is evident
63
Q
Neurulation/ Organ Formation Week 7:
A
- Organs formed
- Nervous system coordinating body activity
- Cartilage skeleton
- Lids over eyes
- Resembles human
64
Q
Neurulation/ Organ Formation Week 8:
A
- 90% of organs developed
- Moving from embryo to fetus stage
- About the size and mass of a paper clip
65
Q
Describe the estra-embryonic membranes:
A
- Protection, respiration, nutrition, excretion
- Allantois – foundation for umbillical cord
- Amnion – transparent sac that develops to completely envelop embryo
- Chorion – outer membrane —> forms placenta
- Yolk sac – produces blood cells and parts of organ systems (no nutritional function)
- Support structure
66
Q
Describe the placenta:
A
- Projections from chorion extend to uterine lining in 2nd week
- These projections (chorionic villi) become placenta
- Placenta is disk-shaped organ, well-vascularized, “connects” baby to mother
- Support structure
67
Q
Describe the “Connection” of Placenta to Uterus:
A
- Placenta sits in blood pools from mother in uterine lining
- Blood pools serve as connection between mother and baby
- Nutrient and waste exchange takes place here
68
Q
Describe the umbilical cord:
A
- Rope-like structure that connects navel area of fetus to placenta
- Contains two arteries – carry blood away from the fetus (oxygen poor)
- Contains one vein – carries oxygen rich blood from mother to fetus
69
Q
What is the difference between an embryo and fetus?
A
- In embryo organs are still forming
- In fetus, organs are formed, just need to develop
- Baby becomes a fetus at eight weeks
70
Q
Describe the first Trimester: weeks 1-12
A
- Learned about first eight weeks (embryo development)
- During next 4 weeks, body grows rapidly, growth of head slows
- Cartilage begins to harden to bone
- By end of 1st trimester, sex of baby is apparent
71
Q
Describe the second Trimester: Weeks 13-24
A
- Bones form
- Brain grows rapidly - nervous system starts to function
- Mother begins to feel movement
- Fifth month - Fetus becomes covered in hair (and oil) to protect skin
- Sixth month- baby appears skinny, hairy and wrinkled (little fat)
- Baby born at 24 weeks would have difficult surviving
72
Q
Describe the third trimester: weeks 25-38
A
- Fetal brain continues rapid development
- Digestive and respiratory systems mature last
- Maternal nutrition is extremely important during this time
73
Q
Describe teratogens:
A
- Substances that interfere with normal development resulting in structural abnormalities
- Includes:
- Infectious agents (rubella, cytomegalovirus, varicella, herpes simplex, toxoplasma, syphilis, etc)
- Physical agents (ionizing agents, hyperthermia)
- Material health factors (diabetes, maternal PKU)
- When the structure is encountered and the dose of the substance will influence the damage done
74
Q
Define parturition:
A
Birth
75
Q
Define labour:
A
Events associated with parturition
76
Q
Define lactation:
A
Secretion and formation of breast milk
77
Q
Describe Parturition Onset/ Maintenance:
A
- Uterine contractions during pregnancy are normal
- Stretching of cervix signals oxytocin release from posterior pituitary
- Oxytocin stimulates uterine muscles to contract (directly and through prostoglandins)
- Uterine contractions push the head against the cervix, stretch it more, more oxytocin relased
- Positive feedback cycle
78
Q
What are the three stages of parturition?
A
- Dilation
-Contractions and stretching cause cervix to open (dilate)
-Lasts 2 to 20 hours - Expulsion
- Baby moves through the birth canal
- Pushed by forceful contractions
- Lasts 0.5 to 2 hrs
- Placental
- Placenta and umbilical cord (afterbirth) are expelled
-10-15 minutes after baby born
- Placenta and umbilical cord (afterbirth) are expelled
79
Q
Describe prolactin:
A
- Stimulates milk production
- Hormone needed for milk production
- Secreted from anterior pituitary
- Suppressed by high levels of estrogen and progesterone during pregnancy
- Secretion begins after birth
80
Q
Describe milk secretion:
A
- Suckling stimulates nerve endings in nipples and areola (area around nipple)
- Hypothalamus is stimulated
- Posterior pituitary is signalled to release oxytocin
- Lobules in breast are stimulated to contract
- Alveoli in lobules contain milk – are squeezed and milk flows into ducts
81
Q
What does oxytocin do?
A
- Stimulates milk release (AKA milk let down) from breasts –> positive feedback
82
Q
Describe suckling and milk production:
A
- The more suckling, the more milk produced
- If suckling stops, milk production stops
- If suckling continues, milk production continues (sometimes for several years)
83
Q
Describe colostrum:
A
- First secretions from nipples right after birth
- Yellowish fluid
- Important source of antibodies for baby (important to get baby colostrum right after birth)
84
Q
What are the types of contraception?
A
- Barrier
- Hormonal
- Post fertilization
- Surgery
85
Q
Describe male infertility:
A
- Low sperm count
- Low testosterone levels and/pr FSH levels
- Poor sperm motility
- Absence/malformation of reproductive structure
86
Q
Describe female infertility:
A
- Failure to ovulate
- Blockage of reproductive tract
- Repeated miscarriages
- Absence/malformation of part of reproductive tract
- Hormone imbalance
87
Q
Describe artificial insemination:
A
- Man donates sperm
- Sperm is concentrated
Types:
1. IUI - intrauterine insemination- Uses catheter to deposit sperm into
- Intravaginal (at home procedure using a syringe)
- Sperm is inserted into a women’s vagina
- Uses catheter to deposit sperm into
88
Q
Describe in-vitro fertilization:
A
- Used in conjunction with Hormone therapy and Superovulation
- Hormones are given to stimulate the ovaries to produce numerous mature follicles
- Eggs are extracted surgically or via transvaginal ultrasound (ultrasound, probe, needle, aspirate, follicles)
- Sperm are donated (by father or unknown man)
- Egg and sperm and put into test tube/petri dish and will be stimulated to fertilize
- Zygote forms, undergoes cleavage, and is inserted via a catheter through the opening of the cervix
89
Q
Describe surrogacy:
A
- Used when female has fertility problems
- Ex: can’t produce eggs
- Ex: has had a hysterectomy (no uterus)
- Ex: can’t carry the fetus for other medical reasons
- Mother and father each donate egg & sperm
IVF - Embryo trasfer to surrogate mother
- Mother and father each donate egg & sperm
- Many controversial issues are associated with this
90
Q
How can doctors tell if a fetus has a disorder?
A
- Chorionic Villi Sampling – can happen early
- Amniocentesis – 2nd trimester
- Spina bifida detection
- karyotyping
- Trisomy
- (down symdrome)
- Monosomy
- Trisomy
91
Q
Who has fetal diagnostic test done?
A
- Pregnant mother over the age of 35
- Higher incidence of non-disjunction during meiosis
- Women are waiting to become pregnant to have their careers established
- Technology has evolved so that women this age can have babies.
- People who have a family history if genetics diseases in their families (Tay Sachs, etc)
