Reproduction Flashcards
(91 cards)
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
Describe secondary sex characteristics:
Characteristics that are unique to males or females but do not play a direct role in reproduction
26
Describe the primary sex characteristics of males:
Testes (male gonads), scrotum, epididymis, ductus deferens, penis, seminal vesicles, prostate gland, Cowper’s gland
27
Describe the secondary sex characteristics of males:
Facial hair, body hair, deep voice, narrow hips, muscle development
28
What are testes?
- 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
What are the parts of the testes?
- Ducts (Vas) deferens
- Epididymis
- Septum
- Seminiferous tubules
- Lobule
- Testis
30
Describe the penis:
- Male organ for intercourse
- Transfers sperm to female reproductive tract
31
What are the parts of the penis?
- 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
Describe an erection:
- 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
What is sperm?
- Sperm production is called “spermatogenesis”
- Each testis can produce 100 million sperm/day
- Tadpole-shaped structure 0.06 mm long
34
What are the parts of sperm?
- 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
Describe spermatogenesis:
- 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
Describe sperm release?
- 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
What is seminal fluid?
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
Describe how sex determination works:
- 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
Describe male puberty:
- 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
Describe regulation in the adult male - sperm production:
- 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
Describe regulation in the adult male - secondary sex characteristics:
- 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
What is andropause?
- A decrease in testosterone beginning around age 40
- Can cause fatigue, depression, muscle and bone loss, drop in sperm production
43
Describe fertilization:
- 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
Describe the process of fertilization:
- 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
What happens when one sperm gets into the egg?
- 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
Describe cleavage:
- 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
Describe morula:
- 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
What is a blastocyst?
- 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
Describe implantation:
- 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
Describe hormone regulation through pregnancy:
- 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
Describe gastrulation:
- 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
When can a fetus be called an embryo?
Once the 3 layers are formed by gastrulation, it is now called an embryo
53
How do identical twins happen?
Cell mass separates into two separate embryos before undergoing gastrulation
54
How do conjoined twins happen?
The inner cells mass did not completely separate
55
What does the ectoderm give rise to?
- Outside structure and the nervous system
- Epidermis
- Nervous tissue and sense organs
- Pituitary gland
- Adrenal medulla
- Tooth enamel
- Eye lens
56
What does the mesoderm give rise to?
- 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
What does the endoderm give rise to?
- Stuff that sees the outside world
- Lining of digestive and respiratory tract
- Liver
- Gallbladder
- Pancreas
- Thymus
- Tonsils
- Parathyroid and thyroid
58
Describe morphogenesis:
- Events that form distinct structures in organism
- Depends on differentiation – cellular process that allows cells to take on specific shapes and functions
59
What happens at three weeks?
- 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
Neurulation/ Organ Formation
Week 4:
- Blood cells form and fill blood vessels
- Head visible
- Lungs and kidneys start to form
61
Neurulation/ Organ Formation
Week 5:
- Head very large compared to body
- Eyes open but don’t have lids or irises
62
Neurulation/ Organ Formation
Week 6:
- 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
Neurulation/ Organ Formation
Week 7:
- Organs formed
- Nervous system coordinating body activity
- Cartilage skeleton
- Lids over eyes
- Resembles human
64
Neurulation/ Organ Formation
Week 8:
- 90% of organs developed
- Moving from embryo to fetus stage
- About the size and mass of a paper clip
65
Describe the estra-embryonic membranes:
- 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
Describe the placenta:
- 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
Describe the "Connection” of Placenta to Uterus:
- 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
Describe the umbilical cord:
- 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
What is the difference between an embryo and fetus?
- In embryo organs are still forming
- In fetus, organs are formed, just need to develop
- Baby becomes a fetus at eight weeks
70
Describe the first Trimester: weeks 1-12
- 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
Describe the second Trimester: Weeks 13-24
- 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
Describe the third trimester: weeks 25-38
- Fetal brain continues rapid development
- Digestive and respiratory systems mature last
- Maternal nutrition is extremely important during this time
73
Describe teratogens:
- 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
Define parturition:
Birth
75
Define labour:
Events associated with parturition
76
Define lactation:
Secretion and formation of breast milk
77
Describe Parturition Onset/ Maintenance:
- 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
What are the three stages of parturition?
- 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
79
Describe prolactin:
- 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
Describe milk secretion:
- 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
What does oxytocin do?
- Stimulates milk release (AKA milk let down) from breasts --> positive feedback
82
Describe suckling and milk production:
- The more suckling, the more milk produced
- If suckling stops, milk production stops
- If suckling continues, milk production continues (sometimes for several years)
83
Describe colostrum:
- First secretions from nipples right after birth
- Yellowish fluid
- Important source of antibodies for baby (important to get baby colostrum right after birth)
84
What are the types of contraception?
- Barrier
- Hormonal
- Post fertilization
- Surgery
85
Describe male infertility:
- Low sperm count
- Low testosterone levels and/pr FSH levels
- Poor sperm motility
- Absence/malformation of reproductive structure
86
Describe female infertility:
- Failure to ovulate
- Blockage of reproductive tract
- Repeated miscarriages
- Absence/malformation of part of reproductive tract
- Hormone imbalance
87
Describe artificial insemination:
- Man donates sperm
- Sperm is concentrated
Types:
1. IUI - intrauterine insemination
- Uses catheter to deposit sperm into
2. Intravaginal (at home procedure using a syringe)
- Sperm is inserted into a women's vagina
88
Describe in-vitro fertilization:
- 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
Describe surrogacy:
- 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
- Many controversial issues are associated with this
90
How can doctors tell if a fetus has a disorder?
1. Chorionic Villi Sampling – can happen early
2. Amniocentesis – 2nd trimester
- Spina bifida detection
3. karyotyping
- Trisomy
- (down symdrome)
- Monosomy
91
Who has fetal diagnostic test done?
- 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)
