B16 Sexual reproduction in humans Flashcards
Ovaries function
Where the egg is produced and produces 2 of the female sex hormones
Fallopian tubes (oviduct) function
Connect ovaries to uterus, where fertilization occurs
Uterus function
Site of implantation of embryo and fetus development
Cervix function
Narrow neck of uterus, dilates during labor
Vagina function
Accepts the penis during intercourse. The baby is passed through this during birth
Route of egg
1) Released by one of the ovaries approx. every 28 days
2) Passes into end of the Fallopian tube and moves downward
3) If egg met by sperm, fertilization occurs before or just after it reaches uterus
4) The sperm nucleus fuses with egg nucleus to form a zygote (conception)
5) If egg not fertilized, it passes out through vagina
Headpiece of sperm
Contains nucleus and bag of enzymes that help penetrate egg. (the acrosome and nucleus)
Midpiece of sperm
Has many mitochondria to generate energy for swimming (the mitochondrion)
Tail of sex cells
Egg- none
Sperm- Long flagellum that propels sperm in its swim to the egg
Sex cells mobility
Egg- Not mobile on their own; they are moved by small contractions of the oviducts
Sperm- long flagellum to propel it
Size of sex cells
Egg- 0.1mm in diameter
Sperm- Microscopic
Jelly coat of sex cells
Egg- Acts as protection to the ovum
Sperm- None
Mitochondria of sex cells
Egg- very few
Sperm- Many to generate energy for swimming
Nutrient reserve of sex cells
Egg- Very large, the egg may be in oviduct for several days. It also fuels early development of embryo
Sperm- None
Digestive enzymes of sex cells
Egg- None
Sperm- Helps it burrogh through egg
Number of sex cells released
Egg- usually one per menstrual cycle
Sperm- Millions
Adolescence/ puberty
The transition from a sexually immature child into a sexually mature adult
Male sex hormone
Testosterone
Female sex hormones
Progesterone and oestrogen
Zygote
A fertilized egg cell
Ovulation
The release of an egg from the ovaries which happens around 14 days into the menstrual cycle
Purpose of thick uterus lining
In preparation for fertilization and to acomodate a fetus
Corpus lutem
AKA yellow body, an empty follicle that develops 21 days into the menstrual cycle
Use of oestrogen
Causes uterus wall to thicken, and help causes ovulation
Use of progesterone
Maintains uterus wall and stops other eggs from developing. The fall in progesterone starts menstruation
Placenta
A temporary organ that allows the blood systems of the fetus and the mother to come in close contact without actually mixing.
Fetus
What the embryo and placenta are called after fertilization
Substances diffusing from mother to fetus
Oxygen, minerals, vitamins, glucose, amino acids
Substances diffusing from fetus to mother
Carbon dioxide, urea
Why are maternal and fetal circulations separated?
1) So the baby can rely on its own systems when born, not completely reliant on mother
2) Possibly different blood types
3) Blood pressure
Umbilical cord
Carries blood back to the placenta from the fetus
Amniotic fluid
Protects developing baby by cushioning against blows to the mother’s abdomen. Allows for easier fetal movement and promoting muscular/skeletal development
Length of pregancy
28-40 weeks
3 Stages of labor
1) Amnion ruptures and the cervix widens to diameter of 10 cm
2) Strong contractions of uterine muscle push baby out of uterus, through cervix and vagina
3) Placenta and umbilical cord expelled after baby born
Advantages of baby born headfirst
Prevent baby suffering brain damage when skull moves outwards
Oxytocin
Hormone produced right after birth that causes lactation and allows woman to breastfeed
HIV
Virus that damages immune system by infecting/destroying white blood cells.
AIDS
The final, life threatening stage of infection of HIV.
How is HIV transmitted?
Bodily fluids (blood, semen, breast milk), sexual intercourse, sharing needles
Testis function
Produces sperm. Are located outside of the body as sperm cannot be produced in too hot a temperature
Sperm duct function
Carries sperm from testes to urethra
Scrotum function
Pouch of skin containing the testes
Epididymis function
Coiled tube where sperm is stored
Urethra function
The duct that carries urine/sperm
Penis function
Transfers sperm into vagina
Seminal vesicle function
Produces fluid containing nutrients for sperm, makes up semen
Ureter function
Connects bladder to kidney
Prostate gland function
Produces alkaline fluid (to neutralize acidity of vagina) to add to sperm to make semen
Route taken by ejaculated sperm to oviduct of female
1) Testis
2) Epididymis
3) Sperm duct
4) Urethra
5) Vagina
How are sperm adapted to their function?
Pointed head to penetrate egg, long tail to help it swim faster, stream-like shape to decrease resistance
