human reproduction

secondary sexual characteristics

characteristics that develop at puberty

male characteristics due to testosterone

deepening of the voice/ growth of body hair

female characteristics ( due to oestrogen )

development of breasts/ widening of hips

fsh - follicle stimulating hormone

secreted by the pituitary gland

stimulates development of the graafian follicle

stimulates secretion of oestrogen by the follicle cells

oestrogen

stimulates the lining of the uterus to repair and to become thick and vascular

stimulates secretion of LH by the pituitary gland

inhibits secretion of fsh

LH

stimulates ovulation

stimulates development of the corpus luteum from the graafian follicle

stimulates the corpuus luteum to secrete progesterone and oestrogen

progesterone

maintains the thickening of thee endometrium

inhibits secretion of fsh and LH

survival time for sperm and egg

sperm survives for up to 7 days in the female ; egg survives for up to 24 hours after ovulation

copulation

sexual intercourse

fertilisation

fusion of haploid nuclei of sperm and egg to form a diploid zygote occurs in the fallopian tube

pregnancy

stops the menstrual cycle

implantation

the embedding of the blastocyst in the endometrium ( 7 days after fertilisation )

primary germ layers

ectoderm- skin nervous system

mesoderm- muscle / skeletal and reproductive system

endoderm- gut lining / liver

the amnion

fluid filled sac or membrane that encloses and protects the embryo

formation of placenta

from tissues in the embryo and the uterus

functions of the placenta

transfer food , gases , excretory products between embryo and mother

prevents transfer of pathogens blood cells and hormones

secretes the hormones progesterone and oestrogen

the umbilical cord

connects placenta to the embryo

oxytocin

stimulates contraction of the muscles of the uterus

lactation

production of milk by the mammary glands

stimulated by prolactin secreted by the pituitary glad

biological benefits of breast feeding

correct nutrients / contains antibodies / helps uterus to contract / bonding

infertility

when a person cannot have children

male infertility

causes ;low sperm count , low sperm mobility , low level of testosterone

treatment ; in-vitro fertilisation

female infertility

causes; failure to produce eggs / failure to ovulate / blocked fallopian tubes

treatment ; hormone treatment / in-vitro fertilisation

in -vitro fertillisation

fertilisation outside the body

contraceptive

the prevention of fertilisation or implantation

4 methods of contraception

natural ; avoid sexual intercourse around time of ovulation

mechanical ; condom / diaphragm

chemical ; birth control pills/ spermicides

surgical ; women - tubal ligation - cutting oviduct / in men ; vasectomy - cutting the vas deferns

menstrual cycle disorder - fibroids

cause - unknown / may be hormonal

symptoms - benign tumours in uterus / large fibroids can cause heavy menstrual bleeding / removal of fibriods by surgery / pain / miscarriage / infertility

treatment ; hormones / removal of fibroids by surgery / hysterectomy