Reproduction in Humans Flashcards
State and identify functions of male reproductive systems (parts of the system)
- Testicles: produce male gametes - sperms
- Scrotum: a sac that keeps testes cool
- Sperm ducts: link testis to urethra: allow passage of semen containing sperm
- Prostate gland: produce alkaline fluid -> semen
- Urethra: urinate; pass semen (+sperm) through penis
- Penis: become firm, inserted into vagina during sexual intercourse -> transfer sperm
State and identify functions of female reproductive systems (parts of the system)
- Ovaries: contains follicles, produce
and stores eggs, produce oestrogen - Oviducts: carries ovum to uterus; Fallopian tubes = site of fertilisation
- Uterus – where fetus develops
- Cervix- a ring of muscles that separate the vagina from the uterus
- Vagina: receives sperm from erect penis during intercourse
Compare male and female gametes in terms of size, numbers and mobility
- Sperms: \+ Size: small \+ Movement: swims using tail (flagella) \+ Food store: has very little - uses sugar in seminal fluid \+ Number of chromosomes: 23 \+ Number produced: millions - Eggs: \+ Size: large \+ Movement: along the oviduct by cilia and peristalsis \+ Food store: protein and fat in cytoplasm \+ No. of chromosomes: 23 \+ Number produced: once a month
Explain the role of hormones in controlling
the menstrual cycle (including FSH, LH, progesterone and oestrogen)
- FSH: released from pituitary gland. Stimulates the development of follicle
- Oestrogen: released from follicle. Lining of uterus thickens, triggers LH
- LH: released from pituitary gland. Triggers ovulation
- Progesterone: released from the yellow body. Maintains uterus lining
Describe the menstrual cycle in terms of
changes in the uterus and ovaries
- During a menstrual cycle a follicle (small groups of cells + potential egg) develops inside the ovary and the lining of uterus thickens.
- Follicle grows and enlarges => bursts releasing eggs = ovulation. Follicle cells left behind = yellow body
- If implantation does not occur => lining of uterus breaks down
- One egg is released every month
Outline sexual intercourse
involves inserting the erect penis into the vagina.
- When stimulated, spongy tissue in the penis filled with blood and becomes erect.
- At the climax, semen is ejaculated from the penis into the neck of the vagina.
- Contractions of urethra help to propel the semen forward
- The sperms with their tails swim from the vagina, through the cervix and uterus into the oviduct
- Fluid made by vagina wall lubricates the movement of the penis
Describe fertilisation
the fusion of the nuclei of male gamete (sperm) and the female gamete (egg), to form a zygote
How is sperm adapted to its function?
- Acrosome releases enzymes to digest pathway through the jelly coat surrounding the egg
- Has tail => swims faster
- Has mitochondria which releases energy to power swimming of the tail
How is an egg adapted to its function?
- Has a large food store to last until implantation, provide food for embryo
- Forms membrane when fertilised so that no other sperm cells can enter
Outline early development of the zygote
Divides (by mitosis) once to form a 2-celled embryo. Then four, then eight. Cycle of divisions become less regular forming a ball of cells (embryo) that moves down the oviduct by peristalsis and becomes implanted in the wall of the uterus
Outline the development of the fetus
- 4 weeks: the heart is beating
- 8 weeks: it has a face, limbs, fingers and toes
- 16 weeks: fetus starts to kick
Describe the function of the umbilical cord
- Umbilical cord:
+ joins fetus to placenta; contains:
+ 2 arteries: blood from fetus -> placenta
+ 1 vein: returns blood -> fetus
Describe the function of placenta
- Blood from the fetus passes through the umbilical cord in the umbilical artery to the placenta.
- Here it comes close to the mother’s blood.
- transport O2 + nutrients (amino acids, glucose…) from mother -> fetus
- transport CO2 + wastes (urea… ) from fetus ->mother (through umbilical vein)
- prevents mother’s and child’s blood from mixing
Indicate the functions of the amniotic sac and
amniotic fluid
- Amniotic sac: membrane from embryo cells: encloses fetus, prevents entry of bacteria
- Amniotic fluid: supports, protects fetus from mechanical
damage; absorbs urine released by fetus.
Describe the ante-natal care of pregnant women
including special dietary needs and maintaining good health
- amino acids -> healthy grow and development
- calcium -> development of the skeleton
- iron -> red blood cell formation
- energy (carbohydrates/ fats) – help to move mother’s heavier body.
- gentle exercises
- avoid
+ drugs: aspirin, heroin
+ smoking: nicotine and CO
+ alcohol drinking