Phys II- Reproduction Flashcards
What are Autosomes?
- 22 homologous pairs
- code for general human characteristics (not paired)
Testosterone
- steroid (cholesterol)
- sex and non sex effects
Spermatogenesis
- spermatogonia to spermatozoa
- stimulated by FSH
3 Steps of Spermatogenesis
- Mitotic Proliferation
- 46
- 2 mitotic divisions
- 4 spermatocytes
- Meiosis
- 23
- 2 meiotic divisions
- 16 spermatozoa
- Packaging
- head (nucleas/DNA)
- Acrosome (enzyme cap for penetration)
- midpiece (mitochondria)
- tail (mobility)
Sertoli Cells
- secrete fluid pushing sperm along
- release inhibin
- negative feedback for FSH
LH
- testosterone control
- spermatogenesis
- rapid rise and slow decline over 90 mins
FSH
- GnRH from anterior pituitary 9 min
- testosterone feedback to GnRH and LH producing cells
- inhibin inhibits FSH
Describe hormone levels before puberty
- GnRH is low
- thus Testosterone , LH, and FSH are too low to produce sperm before puberty
Describe the route of sperm during spermatogenesis
Seminiferous tubule- epididymis- ductus defrens
- movement caused by pressure gradient cerated by fluid from sertoli cells
What occurs in the epididymis
- motility, storage and fertilization by testosterone
What moves the sperm along the ductus defrens?
- peristaltic contractions
Seminal Vesicles
- fructose for energy
- prostaglandins (smooth muscle motility in M and F)
- fibrinogen
Prostate Gland
- alkaline fluid to neutralize acid in vagina
- clotting enzymes
- fibrinolysin
Bulbourethral Glands
- lubricating mucus
What physiologically causes an erection?
- NO from PNS
Ejaculation
- spinal reflex
- efferent SNS
- contraction of smooth muscle in epididymis, vas defrens, ejaculatory ducts, prostate, seminal vesicles, and urethra
- 2.5-3mls
Ovaries
- produce ova
- estrogen
- progesterone
Estrogen
- ova maturation and release
- secondary sex characteristics
- transports sperm from vagina to oviduct
- breast development
Progesterone
- suitable environment for fetus
- breast’s ability to produce milk
Oogonia
- undifferentiated germ cells in fetal ovaries
- 6-7 mill in 5th month of gestation
- mitotic division
Primary Oocyte
- diploid 46 replicated chromosomes
- meiotic arrest until ovulation
- surrounded by single layer of granulosa cells
Primordial Follicle
- reach maturity and ovulate
2. degenerate to form scar tissue
Describe the timing of meiotic divisions
- prior to ovulation
- second upon fertilization
Spermatogenesis vs Oogenesis
- each primary oocyte- one ovum 3 polar bodies
- each spermatocyte- 4 sperm
What are the two stages of the Ovarian cycle?
- Follicular Phase
2. Luteal Phase
Follicular Phase
- presence of maturing follicles
- oocyte enlarges
- estrogen secreted by granulosa
- one takes 14 days
- ruptures to produce oocyte
- oocyte enters oviduct
- increased FSH to increase estrogen
- increased estrogen decreases FSH
- increased LH leading to ovulation and LH surge
Mid Cycle LH Surge
- halts estrogen in follicular cells
- meiosis
- follicular cells become luteal cells
- LH maintains corpus luteum (more progesterone than estrogen)
Luteal Phase
- 14 days
- corpus luteum is fully functional 4 days after ovulation
- increase in size for 4-5 days
- if implantation does not occur corpus luteum degenerates in 14 days
- progesterone inhibits FSH and LH
- low LH causes degeneration and lowered progesterone
Three Stages of Menstrual Cycle
- Menstrual Phase
- Proliferation Phase
- Secratory/Progestational Phase
Menstrual Phase
- discharge of endometrium
- coincides with end of luteal and onset of follicular
- prostaglandin released by uterus
- vasoconstriction of endometrial vessels
- causing death mild contractions of myometrium
Proliferation Phase
- cocurrent with last part of follicular phase
- newly growing follicles secrete estrogen and endometrium prepares
- peak estrogen levels trigger LH surge for ovulation
Secratory/Progestational Phase
- after ovulation (new corpus luteum)
- corpus luteum secretes large amounts of progesterone and estrogen
- progesterone causes endometrium to become highly vascularized and glycogen-filled from glands
What is the ideal spot for fertilization?
- apulla of oviduct
Fertilization
- must occur within 24 hrs of ovulation
- sperm can survive 5 days in repro tract
When first sperm arrives at ovum…
- chemical changes in surface mem inhibiting more sperm from entering
- head of sperm pulled into cytoplasm
- within hour they nucleofuse (zygote)
- mitosis occurs
- blastocyst capable of implantation after one week
- uses enzymes released by tropoblasts that make hole in endometrium
- nutrients released from endometrium for embryo
Placenta
- develops after implantation
- organ of exchange between mom and baby
- finger- like projections into maternal blood
- forms fluid filled amniotic cavity
- umbilical vein carries nutrients and O2 to fetus from placenta
- arteries carry waste products to placenta
- secretes essential pregnancy hormones
HCG
- maintains corpus luteum (1st trimester)
- stimulates testosterone release in XY
Estrogen
- growth of myometrium
- increased uterine strength
- prepares mammary glands
Progesterone
- suppress uterine contractions
Relaxin
- softens cervix and pelvis for parturition
Gestation
- 38 weeks
- uterine enlargement
- breast enlargement and ability to make milk
- blood volume increase 30%
- weight gain
- increased resp activity 20%
- increased nutrition needed
Parturition
- dilation of cervical canal
- breakdown of collagen fibers (estrogen and PG)
- relaxin
- contraction of uterine myometrium
- positive feedback at start of labor to increase force of contractions
- pressure of fetus against cervix increases oxytocin
Oxytocin
- increases strength of contraction
- positive feedback increases until delivery
Three stages of parturition
- Cervical Dilation
- longest (up to 24 hrs)
- Delivery of Baby
- 30-90 mins
- Delivery of Placenta
- shortest
- myometrium contracts
Preparing Breasts for Lactation: Gestation
- placental estrogen and progesterone promote development
- inhibit prolactin action on mammary glands
Preparing Breasts for Lactation: Prolactin
- stimulates milk production in alveolar cells
- end of placental steroids after birth initiates lactation
Lactation
- suckling causes oxytocin and prolactin release to sustain milk production
Lactation: Oxytocin
squeezes milk through ducts
Lactation: Prolactin
stimulates milk production
