3.19 a and b

3.18 a and b

3.12 amniotic fluid

the developing embryo is protected by the amniotic fluid 

within the uterus, surrounding the embryo is a fluid called the amniotic fluid

one of the functions of the amniotic fluid is to protect the embryo, this is possible because the fluid is made largely of water which cannot be compressed

the fluid absorbs any pressure on the outside wall of the uterus preventing damage to the unborn child 

(it is hard to create great force within water) 

3.11 PLACENTA

the role of the placenta in the nutrition of the developing embryo

the placenta structure includes :

the umbilical cord, contains the umbilical arteries and the umbilical vein which connects the embryo to the placenta

the placenta grows out of the developing embryo not the mother, the blood vessels in the cord belongs to the baby

the placenta grows into the wall of the uterus

glucose, amino acids and fats in the mothers blood vessels-which is gained from food-travels into the wall of the uterus, and there the molecules will cross into the child's blood via the placenta.

the large surface area and thin barrier between the mother and the child makes this efficient.

nutrients that the child receives are taken from the mother

the child also produces molecules which exchanges into the maternal blood including CO2 and urea

3.9A The Male Reproductive System

the structure and functions of the male reproductive system

the male reproductive system includes the following structures:

BLADDER : used to store urine

TESTIS : used to carry out meiosis, which produces gamete known as sperm cells

EPIDIDYMIS : used to store sperm cells

VAS DEFERENS : used to carry sperm cells to the penis during sexual stimulation

PROSTATE : 20-30% of the volume of semen, it is known to contain sugars and is also alkaline which nuetralises the acidic secretions of the vagina

SEMINAL VESICLES : 70% of the semen which contains sugars and is alkaline.

URETHRA : joins left and right testis and the left and right vas deferens, it also takes the semen down the penis. it is also an exit to urine which is stored in the bladder

PENIS : carries sperm cells into the vagina during sexual intercourse