Grade 12 Life Sciences - Human Reproduction Summary
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Course
Life Sciences
Institution
12th Grade
This Grade 12 IEB Life Sciences summary covers the human reproductive system, detailing the male and female reproductive organs, their structures, functions, and processes such as gametogenesis, copulation, fertilization, and implantation. Perfect for students preparing for exams, this guide provid...
GAMETOGENISIS
-
The formation of gametes (sperm and eggs) in the sexorgans ,
these gametes are haploid (n)
-
There are 2 types of gametogenis :
> Spermatogenists
-
oogenists
NB . in males this starts at puberty and continues until death , and in females this starts at puberty and ends at Menopause
Spermatogenisis :
> formation of sperm from germinal epithelium cells that line seminiferous tubules
<
germinal epithelium divides by mitosis to form more germinal epithe/lum and some cells undergo melosis to form spermatozoa
SEMINIFEROUS
·
germinal epithelium (2n) O O
-
O
O
TUBULE
O y y
y
Meitosis y
O
y
y O
O
O
Spermatogonium (2n)
·
germinal
O
O
epithelium (2n) O
G
G
G O
O G G
growth O y
G O
Y G
S G
O
& O
y
spermatocyte (2n) G
primary
I
G
O O
S O O
y
G
G
O
-
↓
melosis I G O
O O
G
y
y O
O G O
G
O
J O
G y
y
O
O
secondary spermatocytes (n) O
O
O ·
O
y
· O
↓ Y
y O
y
meiosis i
O
y O
y J
O
spermatids (n)
z J ·
O
O
J
J
J J
sperm (n)
& 1 & y
sertoli cell :
support and give nutrition to the spermatids
While they differentiate into sperm cells
< After sperm is formed
,
It is not yet matures ready to fertilize an
ovum . The sperm matures in the epididymis where it is stored until it is
released or reabsorbed .
Structure of sperm
tall
d
head
I
[
>
contractive fibres
acrossme
W
whip-like motion for
digestive enzymes that
Contains s centriole mobility
digest outer layer of ovum for nucleus (n) makes the contractile Mitochondria
penetration fibres provide energy for
mobility
, sperm :
< 0 . 05 mm long
gets its nutrition from the secretions of the prostate gland and seminal vesicles
-
can last up to 48h in the female reproductive system
oogenisis :
- the formation of ove from the germinal epithelial cells
> the first stages of development occur before birth in the varies of the foetus
The primary jocytes are surrounded by follicle cells :
· germinal epithelium (2n)
The follide cells
MILOSIS
ore-birth
L
J
Secrete sestrogen (primary follicle)
jogonium (2n)
J ·
growth
birth ------
-------
Only one primary oocyte divides by melosis to form the
secondary oocyte. This primary follicle grows
·
primary socyte (2n) into the Graafian
follicle FHS IS
Melosis I
↓
L > follicle cells
&
secondary oocyte
·
J
Polar body
pubert L J J
Melosis I >
Cavity filled With fivid
L
J
J J
secondary oocyte
J L
ovum/egg
3 x polar bodies (n)
Call of this in Melosis I]
primary oocyte in
↑
OVARIAN CYCLE *
the primary follicle
②
↑ SH follicle stimulating hormone
3
:
LH :
luteinizing hormone follicle growing
D FSH stimulates
of
pri
orgonia
follice m ary
growth
&
-Gratian ③
secondary oocyte
follicle conan a
!
- ① LH
- triggers ovulation
⑧
S 8
degenerating -.
!
corpus luteum
⑤
↓ >
-
ovulation :
secondary oocyte
released from Graafian follicle
Corpus luteum secretes
and oestrogen
progesterone
I FSH is secreted from the pituitary gland . The FSH stimulates the sogonia to develop into primary follicles
containing primary oocyte
*
② one primary folide becomes dominant. The follicle cells secrete Destrogen
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