mod12 reprod Flashcards
sexual reproduction
organisms produce offspring by making germ cells (gametes)
fertilization
male gamete (sperm) unites with female gamete (ova) resulting in cell containing one set of chromosomes from each parent
gonad
reproductive organs; testes in males and ovaries in females; produce gametes (germ cells) and secrete sex hormones
functions of male reproductive system
testes produce sperm and male sex hormone T
ducts transport, store and assist in maturation of sperm
accessory glands secrete most of liquid portion of semen
Penis contains urethra; passageway for ejaculation of semen and excretion of urine
scrotum
pouch that supports testes; loose skin, superficial fascia and smooth muscle
sperm temperature
survives best at temperatures 2-3’C below body temp; scrotum maintains lowered temp (testes are raised toward pelvic cavity if it gets too cold)
testes
produce sperm and secrete hormones
semen
contains sperm and secretions provided by accessory sex glands
white fibrous capsule
covers testes; divides each testis into lobules
seminiferous tubules
tightly coiled tubule contained in lobules that produce sperm via spermatogenesis
spermatogenic cells
sperm-forming cells; line seminiferous tubuels
spermatogonia
stem cell precursor
sertoli cells
support, nourish and protect spermatogenic cells
phagocytize degenerating spermatogenic cells
secrete fluid for sperm transport
release inhibin to regulate sperm production
leydig cells
secrete testosterone from btw the seminiferous tubules
Meiosis
process of halving the chromosome number to produce gametes (each gamete must contain 23 chromosomes so that 46 will be present in zygote)
Spermatogenesis
process of gamete production in males; occurs in seminiferous tubules of testis and depends on supporting activites from sertoli cells and T
stages of spermatogenesis (earliest stages further from and final stages nearest to the lumen)
spermatogonia–>primary spermatocyte–>secondary spermatocyte–>spermatids–>sperm cells
process takes about 64 days
three stages of spermatogenesis
meiosis I, meiosis II, and spermiogenesis
Spermatogeonium
undifferentiated male germ cell; contains diploid number of chromosomes (46); after meiosis one splits into spermatogonium and the other into primary spermatocyte
Primary spermatocyte
diploid; after meiosis I, two secondary spermatocytes are formed from one primary (these secondary are HAPLOID (23) )
crossing over
part of meiosis I (prophase); exchange btw parts of nonsister chromatids resulting in genetic recombination
meiosis I results in :
two secondary spermatocytes (n); process begins with 2n and ends with two haploid (n)
meiosis II
each cell formed in meiosis I divides resulting in 4 HAPLOID GAMETES that are genetically different
spermatids
haploid cell formed form meiosis II
Spermiogenesis
final stage of spermatogenesis; each haploid spermatid develops into single sperm cell
spermATogensis vs spermEOgenesis
sperMATogenesis- entire process of meiosis
sperMEOgenesis- transition from spermatid to sperm cell
Sperm Head
produced: 300million/day
head: contains DNA and acrosome (vescile that contains enzymes that aid in penetration of sperm into oocyte)
sperm tail
consists of neck, middle piece, principal piece and end piece.
middle piece: contains mitochondria to produce ATP for locomotion
Where does sperm go after spermatogenesis?
pressure from release of sperm and fluid from sertoli cells propel sperm through seminiferous tubules and into epididymis
Ductus Epididymis
site of sperm maturation; occurs in about 14 days;
stores sperm and helps propel them during sexual arousal by peristaltic contractions
Ductus Deferens
at end of epididymis; 3 layers of muscle that stores sperm;
conveys sperm towards urethra via contraction of the muscles
spermatic cord
supports male reproductive system; accompanies vas deferens; contains blood/lymph and autonomic nerves
Ejaculatory duct
carries sperm into urethra; formed by union of ductus deferens and seminal vesicle
seminal vesicle (accessory gland)
secrete alkaline viscous fluid that contains fructose (for ATP), prostoglandins (motility and stimluate female contractions) and clotting proteins
neutralize enviro to protect sperm
**makes up 60% of semen
prostate (Accessory gland)
secretes milky, slightly acidic fluid that contains citric acid (ATP), acid phosphatase, several protein-digesting enzymes (PSA)
makes up 25% of semen
Bulbourethral gland (accessory gland)
secretes alkaline substance into urethra during sexual arousal
secrete mucus to lubricate end of penis and lining of urethra to protect sperm passing through
semen
sperm+ secretions from accesory glands (2.5-5ml ejaculated containing 50-500million sperm/ml)
infertile: below 20million/ml
contains antibiotics that kill bacteria
Hemospermia
presence of blood in semen; caused by inflammation of blood vessels lining the seminal vesicle
parts of the penis (5)
- root of penis
- body of penis (3 cylindrical masses of tissue)
- corpora cavernosa penis (dorsolateral masses)
- corpus spongiosum penis (midventral mass containing urethra)
- glans penis: opening of urethra; covered by foreskin
functions of female reproductive system
- ovaries produce secondary oocyte and hormones
- fallopian tubes transport oocyte to uterus (site of fertilization)
- uterus is site of implantation of fertilized ovum
- vagina receives penis; passageway for birth
- mammary glands produce milk/eject milk
ovaries
produce secondary oocytes that develop into mature eggs produce hormones (E,P, inhibin, relaxin)
ovarian follicle
each follicle consists of an oocyte and cells that nourish it
secrete E as follicle grows
mature graafian follicle
enlarged ovarian follicle; ruputes and expels secondary oocyte
corpus luteum
remenant of ovulated follicle; produces E, P, relaxin and inhibin
ovarian medulla
contains blood/lymph vessels and nerves; deep region of ovarian cortex
Oogenesis
formation of gametes in ovaries beginning before birth
oogania
diploid cell; formed in ovary in early fetal development
Meiosis I
primary oocytes begin process; starts during fetal development until puberty
occurs in mature graaffian follicle
primary oocytes
diploid formed from oogania; divide in meiosis I resulting in first polar body and secondary oocyte (larger of the two)
secondary oocyte
formed at puberty from primary oocyte; begins meiosis II; must be penetrated by sperm for fertilization to continue
if fertilized will split into 2 haploid cells (ovum and second polar body)
meiosis II
at ovulation (when graaffian follicle ruptures) secondary oocyte is expelled into pelvic cavity and swept into fallopian tubes
zygote
diploid; formed when sperm cell and ovum unite
Oogenesis vs spermatogenesis
each primary oocyte gives rise to a SINGLE gamete (secondary oocyte which becomes ovum)
in CONTRAST:
each primary spermatocyte produce FOUR gametes (sperm)
ovum
haploid; formed from secondary oocyte after fertilization
uterine (Fallopian) tubes
transport secondary oocyte from ovaries to uterus
after ovulation secondary oocyte is swept into tube and moved via peristalitic contractions and cilia
***usual site of fertilization
infundibulum
funnel shaped end of each fallopian tube; connect to upper and outer corners of uterus
uterus
pathway for sperm deposited in vagina to reach uterine tubes (fallopian)
site of implantation of fertilized ovum
cervix
narrow portion of uterus opening into the vagina
layers of the uterus
- perimetrium: visceral peritoneum
- myometrium: smooth muscle; help expel fetus
- endometrium: inner; mucous membrane that nourishes a growing fetus; sheds each month
vagina
btw urinary bladder and rectum; mucous contains glycogen that produces acids; this helps kill bacteria but is harmful to sperm
perineum
contains external genitalia and anus
vulva
external genitalia of female
clitoris
mass of erectile tissue and nerve; capable of enlargement upon sexual stimulation
