15. Reproduction in humans Flashcards
State the functions of the male reproductive system
testes- organ that produce male gametes- sperm
scrotum- sac that contains testes
sperm ducts- tube that transports sperm from testis to urethra
prostate gland- organ that produces semen
urethra- tube that carries both sperm and urine at dif times
penis- organ containing urethra
State the functions of the female reproductive system
ovaries- organs that produce female gametes- eggs
oviducts- tube from ovaries to uterus
uterus- organ in which a fetus develops and embryo implanted
cervix- narrow opening from uterus to outside of the body
vagina- openings from uterus to the outside of the body
Describe fertilisation
the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell)
Adaptive features of sperm and egg cells
flagellum/ streamlined- swimming
mitochondria- respiration- energy- swim
acrosome containing enzymes- digest jelly coat
cytoplasm containing egg yolk- energy stores- development of embryo / mitosis / cell division
jelly coat- hardens to prevent other sperm from entering
Compare structures egg cells and sperm cells
size- large
structure- round, JC, nucleus w chromosomes, cytoplasm
motility- not capable of locomotion
numbers- thousands immature, 1 released every month
size- small
structure- flagellum, middle piece- mitochondria, head- nucleus containing mitochondria and acrosome
motility- capable of locomotion
numbers- millions
After zygote forms
the zygote divides by mitosis and forms an embryo which is a ball of cells that implants into the lining of the uterus
Development of the fetus:
placenta
umbilical cord
amniotic sac
amniotic fluid
As the embryo continue to divide & grow, the placenta also grows. Placenta is soft, dark red, and has finger like projections called villi. It is where substances are exchanged between mother’s blood and the embryo’s blood. the fetus’s & mother’s blood do not mix as they’re separated by the wall of placenta which is thin & has a large surface area for efficient diffusion due to difference in concentration gradients. some pathogens and toxins can pass across the placenta & affect the fetus.
The umbilical cord joins the fetus’s blood supply to the placenta for exchange of nutrients and removal of waste products It has too arteries & a vein. arteries take blood from fetus to placenta & veins - returns blood to fetus.
Mother to fetus - glucose, AA, fats; water, oxygen
Fetus to mother- CO2 & urea, excretory products
The fetus is surrounded by a strong membrane, called the amniotic sac which contains the amniotic fluid. It supports and protects the fetus, from mechanical injury. Embryo floats in fluid and is able to move its arms and legs, which helps the muscles and skeleton to develop correctly.
After birth
umbilical cord is cut - no nerves so no pain It is tied off to prevent bleeding. and shrivels up and falls off after few days leaving belly button behind.
Placenta detaches from uterus wall shortly after birth and is pushed out due to contractions in muscular wall of uterus. known as afterbirth
Process of menstruation
Inside the ovary, a follicle develops. The uterus lining is repaired
Ovulation- the follicle bursts releasing an egg cell from ovary into oviduct. before releasing, the uterus lining becomes thick and spongy, ready to receive a zygote.
Lining full of tiny blood vessel, which will supply the embryo with nutrients and O2. if fertilisation takes place.
The follicle turns into a corpus luteum. which secretes progesterone which keeps timing of uterus thick to receive a fertilised egg. corpus luteum break down if not fertilised.
Menstruation- As the egg hasn’t been fertilised, the thick uterus lining isn’t needed so It breaks down, and is gradually lost through the vagina.
Hormones in female reproductive system
Ovaries- oestrogen and progesterone
pituitary gland- FSH & LH
FSH stimulates development of egg in follicle.
Follicle secretes oestrogen which stimulates thickening and repair of uterus lining. & inhibits production of FSH and stimulates secretion of LH.
when follicle is fully developed, LH is released-causes ovulation, After ovulation secretion of LH decreases.
Follicle develops into corpus luteum and secretes progesterone - maintain thick & spongy lining, ready to receive a zygote (FSH and LH secretion stops) as no more follicles and embryo can implant into it until placenta is formed.
If egg is not fertilised, corpus luteum breaks down, secretion of progesterone decreases as menstruation occurs.
Describe STI
a sexually transmitted infection (STI)- an infection that is transmitted through sexual contact
human immunodeficiency virus (HIV) is a pathogen that causes an STI. HIV infection may lead to AIDS
Describe the methods of transmission of HIV and explain how the spread of STIs is controlled
sexual contact- fluids come in contact (never have more than one sexual partner, use a condom)
blood contact- during childbirth, share hypodermic needles (wear protective clothing)
breast feeding- passed on to baby through breast milk ( take antiretroviral drugs during pregnancy & while breast feeding)
Development controlled by hormones
development and regulation of secondary sexual characteristics during puberty is controlled by oestrogen and testosterone
female- breasts develop, body hair grows, hips grow wider, menstrual cycle begins
male- growth of facial hai and pubic hair, broadening shoulders, deepening voice, general muscle development, growth of penis and testes
