3.19 (a) and (b) Screen Capture

3.19a

3.19b

3.18 (a) and (b) Screen Capture

3.18a

3.18b

3.2 Fertilisation

Notes


Fertilisation = "fusion of male and female gamete to produce a zygote that undergoes cell division and develops into an embryo"

1. In both Adult male & Adult female:
-> Each is in terms of a Diploid (2n) (diploid = complete set of chromosomes, 46)
-> Diploids divide in testis to produce gametes (meiosis = sperm and egg)
    -> Diploid (2n) / 2 = Haploid (n)
    -> 23 per sperm/egg

2. Fertilisation = two cells are fused together (Sperm gamete & egg gamete) to form ONE CELL

In human:
-> Haploid (n = 23) + Haploid (n = 23) => Diploid (2n = 46) =  new cell known as ZYGOTE
-> Zygote combination of male and female cells but same no. of cells as adult human

3. Mitosis = cell divides (1-2-4-8-16, etc.), 2n -- mitosis --> 2n ALL CELLS CONTAIN DIPLOID (2n = 46) NUMBER OF CHROMOSOMES
-> Embryo = large collection of diploid cells

*Note: process is true for all sexually reproducing animals, variance in no. of chromosomes

3.9b Female Reproductive System

Notes

*before pregnancy, size of uterus = approx. orange

Ovary = meiosis (production of female gametes = eggs)

Oviducts (fallopian tube) = carries eggs to uterus BUT also location of where feritlisation may occur

*Fertilisation = occurs in oviducts NOT in uterus

Uterus = centre structure, wall of uterus which is a muscle stretches during pregnancy, contracts during birth

Lining of Uterus = develops fertilised eggs --> embryo --> child, placenta implants on wall of uterus

Uterus space = where embryo develops into unborn child, stretches to accommodate growing child

Cervix = where sperm cells from the penis enter, entrance to uterus, where sperm cells make way up to oviducts AND where eggs descend down towards

Vagina = collects sperm cells at top of vagina & allows sperm to enter through the cervix

3.9a Male Reproductive System

Notes


Bladder = stores urine

Testis = carry out meiosis produces gametes (sperm cells)

Epididymus = ('coil tube' system), stores sperm cells

Vas deferens = carry sperm cells to penis during sexual stimulation (during sex tube contracts and pushes sperm to penis)

Prostate = Adds 20% - 30% of volume of semen, contains sugars, alkali (alkali nature may neutralise acidic secretions vagina)

Seminal Vesicles = Adds remaining 70% of volume of semen so sperm can travel, produces sugar based secretion, alkali

*SEMEN = sperm cells + (seminal vesicle & prostate secretions)

Urethra = Runs length of penis, common tube joining R + L testis & vas deferens, exit for urine stored in bladder

Penis = Carry sperm cells into vagina during sexual intercourse

3.12 Amniotic Fluid

Notes


Amniotic fluid: Protects developing embryo, surrounds embryo in uterus space

-> Fluid (protection of developing embryo)
     -> Cannot be compressed, 
     -> Absorbs pressure when squeezed
= Prevents damage to embryo by absorbing forces on uterus wall
= Supports foetus as it cannot support own weight during development (bones = not calcified)

e.g. Trying to kick swiftly in water, but pressure (force) of kick is absorbed, slowing leg down

3.11 Placenta

Notes


Embryo: Unborn child, encompassed by uterus (amniotic fluid filled environment), with placenta on spinal side.

Placenta (provides nutrition to embryo)


-> Grows out of embryo in form of umbilical cord

-> Cord spreads out to form placental structure

-> Placenta grows into wall of uterus (past wall lining)

-> Glucose, amino acids & fats (maternal blood stream) --- crossing at (placenta) ---> embryo's blood stream

-> Efficiency/speed of blood/nutrition transfer:
   -> Large S.A. of placenta
   -> Very thin barrier (distance between) mother and embryo

-> Urea, carbon dioxide (embryo) --- crossing at (placenta) ---> maternal blood stream

** Placenta and placental blood vessels(including p. arteries & p. veins) belong biologically to embryo NOT mother