LIFE SCIENCES

GRADE 12
2023

TERM ONE

HUMAN REPRODUCTION
(PAPER 1: 41 marks)
MR S FENNI
BIOLOGICAL TERMS
The vesicle which contains enzymes found in the
Acrosome
head of a sperm cell
A fluid that protects the human embryo against
Amniotic fluid
injuries and large-scale temperature changes
Blastocyst/blastula A hollow ball of cells formed from the zygote
The outermost membrane found around the
Chorion
embryo/foetus
The introduction of the male sex organ into the
Copulation
female sex canal, followed by a discharge of semen.
The inner lining of the uterus where implantation of
Endometrium
the embryo occurs
Part of the female reproductive system where
Fallopian tube
fertilisation occurs
BIOLOGICAL TERMS
When the nucleus of the sperm cell fuses with the
Fertilization
nucleus of the ovum
Follicle stimulating The hormone responsible for the development of
hormone/FSH follicles in the ovary
The period between fertilization and birth when the
Gestation
foetus develops in the womb
The attachment of the fertilized ovum or blastocyst to
Implantation
the wall of the uterus at the start of pregnancy.
Luteinising The hormone responsible for ovulation and the
hormone/LH formation of the corpus luteum
The hormone that causes the thickening of the
Oestrogen
endometrium and is produced by the Graafian follicle
Oogenesis The production of female gametes through meiosis
BIOLOGICAL TERMS
A hormone produced by the pituitary
Prolactin gland/hypophysis that stimulates milk production in
human females
The stage in humans when sexual maturity is
Puberty
reached in males and females
Spermatogenesis The production of male gametes through meiosis
A hormone that stimulates the maturation of sperm
Testosterone
and stimulates puberty in males
The male reproductive tube that connects the testis
Vas deferens
with the urethra
The diploid cell formed by the process of
Zygote
fertilisation
INTRODUCTION
LIFE CYCLE OF HUMANS
ACTIVITY 1
STRUCTURE OF THE MALE
REPRODUCTIVE SYSETM
STRUCTURE OF THE MALE REPRODUCTIVE SYSTEM
 1. THE TESTIS
 There are a pair of testes referred to
as male sex organ (male gonads)
 Testes produce sperm cells and the
hormone testosterone
 The testes lies outside the abdominal
cavity covered by the scrotum.
 Scrotum:
1. protects the testes
2. holds the testes ‘outside’ the body, at
a temperature that is 2°C below 37°C
which is the best temperature for the
production of sperm.
1. THE TESTIS
• The inside of each testis has seminiferous tubules.
• The seminiferous tubules are lined with germinal epithelial cells which
produce the sperms by spermatogenesis.
• The specialized cells called Sertoli cells are rich in glycogen which
serve as nutrients for the spermatids as they develop into sperm or
spermatozoa.
2. EPIDIDYMIS
• Epididymis is a coiled tube
lying outside each testis within
the scrotum.
• Leads off of the seminiferous
tubule
• Epididymis: Stores sperm
temporarily before sending it to
the vas deferens.
3. VAS DEFERENCES
 The vas deferens is also known
as the sperm duct.
 The vas deferens transport the
sperms from the epididymis to
the ejaculatory duct.
4. EJACULATORY DUCTS
• The two ejaculatory ducts join
the urethra just after it leaves
the bladder.
• Contractions of the muscular
walls of the ejaculatory duct
forces the semen through the
urethra.
5. URETHRA
• Urethra is a tube which runs
through the penis and opens at
the tip of it.
• Urethra transports urine and
semen.
TUBES RESPONSIBLE FOR CARRYING SPERMS

Stores sperms temporarily Transports the sperm

before sending them to the cells from the
vas deferens. epididymis through
the abdomen into the
ejaculatory duct

Contractions of the
ejaculatory duct forces Transports semen from
the semen through the the ejaculatory ducts.
urethra.
6. ACCESSORY GLANDS
1. Seminal vesicles-
produce nutrient rich
seminal fluid to provide
energy for
transportation of the
sperm cells
2. Prostate gland-
secretes a clear,
slightly alkaline fluid
that neutralises the
acids in the vagina that
would kill the sperm
3. Cowper’s glands-
Secrete mucus that
helps with movement of
the sperm
6. PENIS
 The penis is the external male
reproductive organ.
 It is made up of spongy
tissue.
 The penis becomes erect
when the tissue fills with
blood.
 This occurs before the penis
is inserted into the vagina.
 The function of the penis is to
transfer the semen to the
female.
CLASSWORKS
ACTIVITY 1-6
 STRUCTURE OF THE
FEMALE REPRODUCTIVE
SYSETM
STRUCTURE OF THE FEMALE REPRODUCTIVE SYSTEM

Consists of:
1. A pair of ovaries
4. Vagina
2. The fallopian tube/oviduct
5. The vulva
3. The uterus
1. THE OVARIES
• Female sex organs.
• Found in lower part of abdominal cavity.
• Held in place by ligaments.
• Made up of a covering of germinal
epithelium with a large number of
follicles in it.
• Germinal epithelium produces follicles.

FUNCTIONS OF THE OVARIES

• Oogenesis takes place within follicles to
produce ova.
• Follicles secrete oestrogen and
progesterone
THE STRUCTURE OF THE OVARY
2. THE FALLOPIAN TUBES/OVIDUCT
 There are 2 fallopian tubes.
 They lead from the ovary to
the uterus.
 They transport the ovum from
the ovary to the uterus.

FUCTIONS OF THE OVIDUCT

• It is the site of fertilisation
• Connects the ovaries to the
uterus
• Transports OVA from the ovary
3. THE UTERUS
• Pear shaped, hollow organ with
muscular walls.
• Endometrium lines the uterus and
is richly supplied with blood
vessels
• Neck of uterus is called the cervix
and extends into the vagina

FUNCTIONS OF THE UTERUS

• Serves for implantation of the
embryo if fertilization takes place.
• Carries the embryo and foetus
during pregnancy
3. THE VIGINA
 Cylindrical sheath like structure
that leads from the cervix to the
outside forming the vulva.
 During copulation the penis is
inserted into the vagina where
semen is released.

FUNCTIONS OF THE VIGINA

• The vagina serves as the birth
canal.
• Receives the penis and semen
during copulation
• Serves as a passage for blood
during menstruation.
4. CERVIX
• Lower, narrow part of uterus.
• It stretches to allow the baby through during childbirth
ACTIVITY 6
ACTIVITY 7
ACTIVITY 8
ACTIVITY 9
PUBERTY STAGE
PUBERTY STAGE
• Puberty is a time of life when a person becomes sexually mature.
• Physical changes occur between 10 and 14 in girls and 12 and 16 for
boys
• It begins when the hypothalamus in the brain starts releasing
gonadotropin-releasing hormone (GnRH)
PUBERTY IN MALES
• Puberty in males starts when GnRH stimulates the anterior pituitary
gland to secrete:
– Follicle Stimulating Hormone (FSH) – which stimulates the testes
to produce sperm
– Luteinising hormone (LH) – which stimulates the testes to produce
testosterone
– Secondary sexual characteristics (caused by testosterone)
SECONDARY SEXUAL CHARACTERISTICS BY TESTOSTERONE
1. Development of pubic hair, this is the growth of hair around the
scrotum AND penis.
2. Growth of hair in the armpits and beard.
3. Deepening of the voice
4. Development of muscles and broadening of the shoulders.
5. Enlargement of the penis
6. Rapid increase in height, size and strength of muscles
PUBERTY IN FEMALES
• Puberty in females starts when GnRH stimulates the anterior pituitary
gland to secrete:
– Follicle Stimulating Hormone (FSH) – stimulates a follicle in the
ovary to develop and secrete oestrogen
– Luteinising hormone (LH) – stimulates the development of the
corpus luteum in the ovary to secrete progesterone (not
responsible for secondary sexual characteristics)
– Secondary sexual characteristics (caused by oestrogen)
SECONDARY SEXUAL CHARACTERISTICS BY OESTROGEN
1. Rapid increase in height and breast development
2. Hair growth in the pubic area and armpits
3. Increase in size of the vagina
4. Uterine and endometrial growth
5. Onset of menstruation
6. Increase in body fat
GAMETOGESIS
EXAMINATION GUIDELINES
GAMETOGENESIS
Gametogenesis is the formation of gametes by meiosis.

THERE ARE 2 TYPES OF GAMETOGENESIS

1. Spermatogenesis: the formation of sperm cells by meiosis from the
germinal epithelial of the testes.
2. Oogenesis: the formation of ova by meiosis from the germinal
epithelial of the ovaries.
1. SPERMATOGENESIS
• Under the influence of testosterone
• The diploid cells in the seminiferous tubules of the testes undergo
meiosis
• to form FOUR haploid sperm cells
STRUCTURE AND FUNCTIONS OF THE PARTS OF A SPERM CELL
• Acrosome: Contains enzymes to digest walls of ovum for fertilisation
• Nucleus: Contains 23 chromosomes
• Mitochondria: Provide energy for swimming
• Tail: Enables the sperm to swim
2. OOGENESIS
• Diploid cells in the ovary undergo mitosis to form numerous follicles.
• At the onset of puberty and under the influence of FSH, one cell inside
a follicle enlarges and undergoes meiosis.
• Of the four cells that are produced, only one survives to form a
mature, haploid ovum.
• This occurs in a monthly cycle.
STRUCTURE AND FUNCTIONS OF THE PARTS OF THE OVUM
• The nucleus bears the genetic material from the mother
• The cytoplasm serves as nutritive material to nourish the future
zygote.
• The ovum is enclosed in a vitelline membrane.
• One ovum is produced and released every 28 days.
ACTIVITY 6
ACTIVITY 7
ACTIVITY 8
ACTIVITY 9
MENSTRUAL CYCLE
EXAMINATION GUIDELINES
MENSTRUAL CYCLE
 The menstrual cycle refers to the
changes that occur in the ovary and
uterus of a female over a period of 28
days.

THERE ARE TWO CYCLES OF

MENSTRUAL CYCLE
1. Ovarian cycle: the changes that
occur within the ovary during the
development and release of the
ovum within the Graafian follicle.
2. Uterine cycle: the changes that
occur in the walls of the uterus as it
thickens until menstruation occurs.
EVENTS IN THE OVARIAN CYCLE
Day 1-7
• Pituitary gland secretes FSH
• FSH stimulates the development of
the Graafian Follicle in the ovary
Day 8 – 13
• FSH increase in blood as the Follicle
grows and matures
• The mature follicle is called Graafian
follicle
• The Graafian follicle secretes
oestrogen
• The oestrogen prepares the
endometrium for implantation by
making endometrium to become
thick and more vascular
EVENTS IN THE OVARIAN CYCLE
Day 12
• Pituitary gland stops secreting
FSH and starts secreting
Luteinizing Hormone (LH)
Day 14
• The Graafian follicle ruptures
• The ovum is released
• The release of the ovum is called
ovulation
• The LH stimulates the formation
of Corpus Luteum from the
Graafian follicle
EVENTS IN THE OVARIAN CYCLE
Day 15 – 22
• The Corpus Luteum secretes
progesterone
• The progesterone along with
oestrogen this increases the
thickness of the endometrium
EVENTS IN THE UTERINE CYCLE
Day 23-28
If fertilisation takes place
• The corpus luteum
remains active in the ovary
and continues to secrete
progesterone
• No more follicles develop
in the ovaries
• No menstruation takes
place
EVENTS IN THE UTERINE CYCLE
Day 23-28
If fertilization does not occur
then:
• Levels of LH drop causing
the Corpus Luteum to
shrink and degenerate
• The levels of oestrogen and
progesterone in the blood
drop.
• Day 28: This causes the
endometrial lining of the
uterus tears away
• The cycle begins again
HORMONAL CONTROL OF THE MENSTRUAL CYCLE
NEGATIVE FEEDBACK MECHANISM BETWEEN FSH AND PROGESTERONE
NEGATIVE FEEDBACK MECHANISM BETWEEN FSH AND PROGESTERONE
FERTILISATION AND DEVELOPMENT
OF
ZYGOTE TO BLASTOCYST
DEFINITIONS OF COPULATION AND FERTILIZATION

Copulation: The introduction of the penis into the vagina followed by a

discharge of semen.
Fertilization: The haploid nucleus of the sperm cell fuses with the
haploid nucleus of the ovum to form a diploid zygote.
 PROCESS OF FERTILISATION
• During copulation the sperms are
deposited into the vagina.
• Sperm move by spiral movements
towards the ovum in the fallopian
tubes
• The head of one sperm cell
penetrates the membranous barrier
around the ovum
• Enzymes from the acrosome
hydrolyse these barriers
• The sperm loses its tail.
• The membrane becomes
impenetrable to other sperm cells
• The nucleus of the sperm and ovum
fuse to form a zygote
DEVELOPMENT OF ZYGOTE TO BLASTOCYST
• The zygote divides by mitosis for form a ball of cells called morula.
• Morula further divides by mitosis to form a hollow ball of cells called
blastula/blastocyst.
IMPLANTATION, GESTATION
AND THE ROLE OF THE
PLACENTA
IMPLANTATION
Implantation: The attachment
of the fertilized egg or
blastocyst to the wall of the
uterus at the start of
pregnancy.
After implantation the embryo
forms extra-embryonic
membranes :
1. Amnion: which fills with
fluid (amniotic fluid)
2. Chorion: The outer most
covering which form finger
like projections into the
endometrium called
chorionic villi
THE ROLE OF OESTROGEN AND PROGESTERONE
OESTROGEN
The oestrogen makes the endometrium to be:
1. More thick,
2. More vascular and
3. glandular in order for implantation to occur.

PROGESTERONE
 Progesterone maintains pregnancy by ensuring that the embryo
remains attached to the uterine wall.
 Progesterone inhibits the secretion of FSH by pituitary gland to
prevent the development of new follicles in the ovary.
THE DEVELOPING FOETUS IN THE UTERUS: GESTATION
• Gestation: The period of development of the foetus in the uterus
which takes place from conception to birth.
• Pregnancy: all the changes (hormonal, physical, emotional) that take
place in the body of a female as a result of the developing foetus.
FUNCTIONS OF CHORION AND CHORIONIC VILLI
1. The Chorion
 The chorion is the outmost
membrane.
 It forms the chorionic villi.
2. The Amnion
 It is found on the inside of the
chorion.
 It forms a cavity called the
amniotic cavity.
 The amniotic cavity is filled
with amniotic fluid.
FUNCTIONS OF THE AMNIOTIC FLUID
1. It acts as a shock absorber,
thus protecting the embryo
against mechanical injury.
2. It prevent the foetus from
drying out.
3. It protects the foetus against
temperature changes.
4. Allows for the free movement
of the foetus.
THE UMBLICAL CORD
 The placenta is attached to the embryo
by means of the umbilical cord.
 The umbilical cord is a hollow rope like
tube.
 The umbilical blood vessels are found
within the umbilical cord.
1. Umbilical artery: carries deoxygenated
blood with nitrogenous waste from the
foetus to the placenta
2. Umbilical vein: carries blood rich
oxygenated blood from the placenta to
the foetus.
 THE FUNCTIONS OF THE PLACENTA
1. Attaches the foetus to the mother.
2. Allows for the diffusion of dissolved food,
as well as oxygen from mother to foetus.
3. It allows for the diffusion of nitrogenous
waste from the foetus to the mother.
4. It also allows for the diffusion of the carbon
dioxide from the foetus to the mother.
5. It secretes its own progesterone after 12
weeks of pregnancy.