ch. 46 Flashcards
external male organs
scrotum and penis
testes
male gonads that consist of tightly coiled tubes surrounded by connective tissue
purpose of scrotum
sperm cannot be produced at body temperatures, so hangs outside abdominal cavity in mammals where temperature is lower
how long is each seminiferous tubule
70cm, 750 in each testis
where does sperm go after the seminiferous tubules
- coiled duct of epididymis
path of sperm in ejaculation
- sperm propelled through muscular vas deferens
- ejaculatory duct
- exits penis through urethra
semen
composed of 5% sperm and secretions from 3 sets of accessory glands
3 male accessory glands
- seminal vesicles
- prostate gland
- bulbourethral glands
seminal vesicles
contribute fructose
- 60% of total volume of semen
prostate gland
secretes alkaline products directly into urethra through several small ducts
bulbourethral glands
secrete alkaline, clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
how many types of erectile tissue in penis
3 cylinders of spongy erectile tissue
sexual arousal and penis
erectile tissue fills with blood from arteries (causes erection)
glans
head of penis, has thinner skin covering shaft
- more sensitive to stimulation
prepuce/foreskin
fold of skin surrounded glans
sexual reproduction
creation of offspring by fusion of haploid gametes to create diploid zygote
asexual reproduction
creation of offspring without fusion of egg and sperm
budding
simple form of asexual reproduction only found among invertebrates
- new ind. arise from outgrowths of existing ones
difference between sex and coitus
- sex - union of gametes
- coitus - physical union of female and male genitalia accompanies by rhythmic movements
binary fission
separation of parent into 2+ ind. of about the same size
- invertebrates
types of asexual reproduction
- budding
- binary fission
- fragmentation
- parthenogenesis
fragmentation
- breaking of body into pieces, some or all of which develop into adults
- accompanies by regeneration
parthenogenesis
development of a new ind. from an unfertilized egg
- mostly invertebrates
is finding a partner easy or difficult?
can be challenging
hermaphroditism
each ind. has both male and female reproductive systems
2 types of hermaphrodites
- synchronous
- sequential
synchronous hermaphrodites
ind. simultaneously male and female
sequential hermaphrodites
sex change
- protogynous and protandrous
protogynous hermaphrodites
egg products become sperm producers
protandrous hermaphrodites
sperm producers become egg producers
spotted hyena females
- bigger than males
- have pseudopenis (pseudophalluses)
- both sexes get erections when greeting each other
- give birth through “penis”
what are reproductive cycles related to
- environmental cues (seasons)
- hormones
ovulation
release of mature eggs at midpoint of female cycle
parthenogenesis of fish, amphibians, and lizards
- doubling of chromosomes after meisos
asexual whiptail lizards
- all females
- still exhibit mating behaviors (pseudo-copulation)
- parthenogenesis
twofold cost of sexual reproduction
sexual females have half as many daughters as asexual females
when is sexual reproduction beneficial
enhance reproductive success of parents when environmental factors change rapidly
when is asexual reproduction beneficial
in stable, favorable environments
fertilization
union of egg and sperm
external fertilization
eggs shed by female are fertilized by sperm in the external environment
favorable environment for external fertilization
moist habitat
- sperm can swim to egg
- prevents gametes from drying out
spawning
individual cluster in same area to release gametes into the water at the same time
- chemical and environmental signals
internal fertilization
enables sperm to reach an egg despite dry external environment
what does internal fertilization require
behavioral interactions and compatible copulatory organs
- often pheromones
characteristics of internal fertilization
- fewer gametes
- higher survivorship of zygotes
- protection of embryos
- parental care of young
purpose of shells for eggs of birds and reptiles
- protect against water loss
- protect against physical damage
where are gametes produced
precursor cells in:
- gonads
- undifferentiated tissue
what do elaborate gamete-producing systems include
sets of accessory tubes and glands that carry, nourish, and protect gametes/embryos
do insects have separate sexes
yes, each with complex reproductive systems
spermatheca
where sperm is stored in female insects during copulation
cloaca
common opening between external environment and the digestive, excretory, and reproductive systems
- common in nonmammalian vertebrates
monogamy
having one mate
- can decrease chance of mate mating w/ another ind.
- females sometimes influence reproductive success of mates
male external organs
scrotum and penis
male internal organs
- gonads - produce sperm and hormones
- accessory glands - secrete products needed for sperm movement
- ducts - carry sperm and glandular secretions
male gonads
testes
testes
consist of highly coiled tubes (seminiferous tubules) surrounded by connective tissue
where does sperm form
seminiferous tubules
female echidnas
- cloaca
- branches into different systems (2-branched reproductive tract)
female external reproductive structure
clitoris and two sets of labia
female internal organs
- pair of gonads
- system of ducts and chambers that carry gametes and house embryo/fetus
major vestibular glands
produce mucoid secretion that aids in vaginal and vulvar lubrication
how long does it take for the fertilized egg to travel to the uterus
6-12 days
sperm capacitation
set of natural physical changes that a spermatozoon undergoes to be able to fertilize ovum
- occurs in vivo following ejaculation when spermatozoa come into contact with different fluids of female genital tract
how long as sperm viable in the female reproductive system
5 to 6 days
how long are ovum viable after ovulation
6 hours
female gonads
ovaries - flank uterus in abdominal cavity
what does each ovary contain
follicles
follicles
consist of partially developed egg (oocyte) surrounded by support cells
path of egg from ovary to uterus
- leaves ovary
- travels through oviduct/fallopian tube by cilia
- enters uterus/womb
endometrium
uterus lining that contains many blood vessels
where does uterus narrow
cervix - opens into vagina
vagina
muscular but elastic chamber
- repository for sperm during copulation
- birth canal
vulva
where vagina opens to outside
- consist of labia major, labia minor, hymen, and clitoris
clitoris composition
- head - glans
- glans covered by prepuce - small hood of skin
- many nerve endings