ONLINE ASSIGNMENT

SUBMITTED BY:

LUBENA BASHEER

REG NO:13367008

HUMAN REPRODUCTION

• Sexual reproduction is the process involving the joining of

the male and female sex cells • Gametes- sex cells, produced in the sex organs • Gonads- sex organs • Fertilization- the fusion of male gametes and female gametes • Zygote- single cell • Primary sex organs- gonads- produce gametes • Secondary sex organs- store the gametes, bring them together for

fertilization and support the developing baby

MALE REPRODUCTIVE SYSTEM

• Males gametes (sperm) are produced in the gonads or testes

which are held in the scrotum. • This holds the testes outside the body cavity because the

production and development of sperm requires a temperature that

is about 2 degrees lower then the normal body temp. therefore to

enable sperm production, the testes lie outside the body

Part description function

Testes • Oval in shape Produce sperm and hormones

• 4.5cm long, 2.5cm wide

and 3cm thick

Lobules • compartments 200-300 Compartments that hold tubes • filled with fine tubes

called seminiferous

tubules

Seminiferous tubules • lined with cells Produce male gametes (sperm) • between the

seminiferous tubules are

clusters of interstitial

cells

Interstitial cells • between the Secrete male hormone testosterone

semininferous tubules

• they are clusters

Epididymis • highly, folded tubule that Stores sperm while they finish maturing (for a

is against the rear surface month)

of each testes

Vas deferens • tubule of epididymis Carries sperm to urethra forms this and joins to

form urethra

• Semen or seminal fluid is used to transport the sperm to the females body.

It also nourishes and aids the sperm

Semen is made from a mixture of secretions from three glands • Seminal vesicles- pair of pouch like organs and 5 cm. The fluid is rich

in sugars and about 60% of volume of semen • Prostate gland- 2 vaso deferens join the urethra. It is a single gland and it

surrounds the urethra just below the bladder. Secretes a thin, milky

alkaline fluid that becomes part of the semen

• Cowper’s glands (bulbourethral glands) – 2 small yellow glands located

beneath prostate. Secretes clear mucous which acts as lubricant and

most precedes the emission of seminal fluid

• The urethra- transports urine and semen • The penis contains connective tissue with a very rich blood supply (erectile

tissue) and it contains many sponge like spaces which fill with blood

during sexual arousal • This causes in an erect and stiff penis, and it can be successfully introduced

into the vagina

FEMALE REPRODUCTIVE SYSTEM

Part Description Function Ovaries Female gonads Ova is produced

Almond shaped gland

3cm in length located in

body Stroma Connective tissue found in Contains germ cells

ovary

Surrounded by germ cells Germ cells Surrounds the stroma

Enclosed in a follicle Follicle Contains germ Surrounds and matures ova

cells(surrounds germ cells)

Numerous follicles

As a follicle matures it

moves to the surface of the

ovary and ruptures

Spermatogenesis

SPERMATOGENESIS • Occurs in seminiferous tubules of the testes • Immature sperm cells line the seminiferous tubules called spermatogenesis • They contain 46 chromosomes(diploid) • They divide by mitosis – provide a continuous source of new cells for the

production of sperm • Primary spermatocyte- some spermatogenia are pushed away from the

edge and they grow • These cells undergo the 1

st stage of meiosis (reduction stage), to form 2

daughter cells with half the chromosome number (haploid) and are called

2nd

spermatocyte

• A further meiotic division produces two spermatids each –total of four

daughter cells • Spermatids have no tail and move towards the centre of the tubule as

they mature into spermatozoa • Maturing sperm are nourished by cells in the tubules called nurse cells • Takes about 72 days and continues through puberty

OOGENESIS

• Production of ova in the ovaries • Begins before and after baby is born • Oogonia develop in the ovaries. These are diploid cells • At birth the ovary contains several hundred thousand oogonia which have

grown to become primary oocytes • Primary oocytes begin the first phase of meiosis but stop at prophase

until puberty • Each primary oocyte is surrounded by a single layer of cells forming a primary

follicle • At puberty follicles begin to mature

• The primary oocyte completes its 1st

division of meiosis to form two haploid cells. These are uneven in size. The larger one receives most of the cytoplasm

and is called the secondary oocyte. The smaller one is called 1st

polar body • The secondary oocyte immediately begins the 2

nd meiotic division but stops

at metaphase • When ovulation occurs the follicle ruptures and the secondary oocyte is

released • If it is fertilised by a sperm, meiosis is quickly completed • The 2

nd stage of meiosis also produces cells of uneven size, and again the

smaller one is the 2nd

polar body. The larger of the two develops into mature ovum

• The 1st

polar body may also complete its 2nd

meiotic division and produce 2 more polar bodies

• All polar bodies disintegrate • A female only produces 1 ovum from every primary oocyte • And males produces for sperm from every primary oocyte

Differences between O and S

• Spermatogenesis takes place in the testes of males, oogenesis takes place in

the ovary of the females. • Spermatogenesis produces small, motile spermatozoa whereas in oogenesis

the ovum is spherical, not motile and is much larger with more food reserves and

cytoplasm. • Spermatogenesis involves a metamorphosis stage called spermiogenesis,

in oogenesis there is no metamorphosis stage. • In spermatogenesis, 4 gametes are produced from each meiotic division, whereas

in oogenesis there is only 1 gamete produced from each division as the unequal

cytokinesis leads to the formation of polar bodies. • Spermatogenesis occurs in males (human males) continuously from puberty to

death whereas oogenesis starts in females at puberty and then occurs on a monthly

basis until the menopause. It takes 70 days for sperm to be produced in males.

Ovarian cycle

• It is a series of events that occurs in the ovaries under the control of

hormones from the pituitary gland situated in the brain • At birth a females ovaries contain about 400000 immature eggs

which remain in a resting phase until puberty • At puberty some primary follicles begin to enlarge and divide creating

a layer of cells around the developing ovum • These layers of cells secrete fluid unto the follicle causing it to continue

to enlarge • It then begins to move to the surface of ovary. Now is called secondary

follicle • Primary follicle secondary follicleovummature

folliclefluidruptured follicle corpus luteum corpus albicans • Ovulation- mature follicle bursts releasing ovum • After ovulation the ruptured follicle falls and forms an endocrine

gland called the corpus luteum (secretes hormones which influence the

development of endometrium) • If no fertilization corpus luteum degenerates into corpus albicans (mass of

fibrous scar tissue) • If fertilization occurs, corpus luteum develops and ovarian cycles cease

The menstrual cycle

• Changes in the lining of the uterus (endometrium) • Menstruation is the monthly shedding of the lining of a women’s uterus (more

commonly known as the womb) Stages

• Menstruation (1-4 days) Uterine bleeding and shredding of endometrium (glands, blood vessels) • Pre ovulation\proliferation (5-12 days) Endometrium repairs, then thickening. Ovarian follicles develops (developing of

a new lining ) • Ovulation (13-15 days)

Rupturing of a mature follicle

• Secretion (16-20 days) Secretion of water mucous by endometrium glands, cervix and uterine

tubes Unfertilized egg breaks down and corpus luteum develops

Uterus is ready for implantation • Pre menstruation (21-28 days)

Detoriation of endometrium

Corpus luteum degenerates

2 stages in an ovary

Follicular phase (0-14) - development of follicles - forming of glands and blood vessels in endometrium - and is the menstrual and proliferative stage - secretion of oestrogen by the ovarian follicle (follicular cells) - In the menstrual and proliferation stage in the uterus

Luteal phase (14-28) - development of corpus luteum

- secretion of oestrogen and testosterone - secretion of mucous from glands - in the secretory phase of stage in uterus

Link between ovarian cycle and reproductive hormones

1. When Follicle stimulating hormone released – the follicle matures, grows

and produces (helps ovarian cycle)

2. Release Oestrogen – in endometrium FSH levels decrease

Lutenizing hormone increases

3. When LH is released – ovum ruptures (ovulation), follicle changes to corpus

luteum and changes into a gland

4. Progesterone is produced by CL and oestrogen is produced

LH levels decrease

FSH levels decrease

5. If implantation occurs CL supports pregnancy for 3 months

6. If no implantation CL degenerates, menstruation occurs and lowers oestrogen

levels

Puberty

• When a person reaches sexual maturity Females (11-14)

• Oestrogen – responsible for : Breasts Broadening of hips

Female contours

Voice deepens a little Pubic hair- armpits and groin

Sex organs enlarged Males (15-16)

• Testosterone Facial and chest hair

Increase in size of larynx

Lengthning of vocal cords

Pubic hair- armpits and groin

Sex organs enlarge Sexual intercourse

Male

When sexual arousal has occurred, the sperm in the epididymis move to the prostate

gland and the seminal vesicle via the vas deferens. They are nourished at the prostate

and seminal vesicle and then by the contracting of the epididymis, prostate, and vas

deferens the sperm move out of the penis via urethra into the cervix of vagina.

(ejaculation) Female

When arousal in female occurs the erectile tissue fills with blood near vaginal

opening. This reduces the size of the opening which increases stimulation for penis.

Increase in mucous secretions for use as lubricant for penis

The sperm is ejaculated through the cervix and into the uterus where they make

their way to the uterine tubes. Muscular contractions and the beating of the cilia on

the lining of the cells of the tubes help move the ovum down the tubes

Fertilization

• Cells of corona radiata are held together by an acid • The head of the sperm contains an enzyme that breaks down the acid of

the corona radiata • Many sperm needed for the break down of the corona radiata • When one sperm penetrates egg, egg forms a ‘fertilization membrane’ so

no sperm can enter • The male pro nucleus (head of sperm) moves towards females pro nucleus • The ovum completes its 2

nd meiotic division and nucleus of egg develops

into female pro nucleus • Male pro nucleus fuses with female pro nucleus to form single nucleus with

diploid number of chromosomes (46) • Fertilized egg called a zygote

Implantation

• Process in which the egg implants into the uterus wall and its journey to the

uterus and in the uterus • Within a few hours of conception, tiny hair-like structures called cilia

push the zygote towards the uterus. During this journey to the uterus, the

zygote starts the process of cell division

• At around 4 days, the zygote is a 16-cell mass and it enters the uterus where

it floats freely for about 2 days • Cleavage is the term used for the rapid division of cells that happens in

the first 24-48 hours after fertilization. • At around 6 days, the zygote has become mass of more than 100 cells called

a Blastocyst and it has the shape of a hollow ball with inner and outer layers.

The out layer will become the placenta and the inner layer will become the

feotus.

• The zygote implants (attaches) to the wall of the endometrium at around

10 days. After implantation, the zygote is officially known as an embryo.

Embryonic membranes – two month –foetus

• protect and nourish

embryo Four membranes • Amnion secretes amniotic fluid

protection (shock absorber)

maintain constant temp

baby can move freely

• Chorion Surrounds embryo and other 3 membranes Made from the outer cells of blastocyst and mesodermal cells Becomes the main part of the featul position of the placenta

Placenta

• Substances are exchanged between the foetal and maternal blood supplies

by diffusion and active transport

The umbilical cord contains 2 umbilical arteries- They carry the deoxygenated blood

from foetus to mother • A single umbilical vein- carries oxygenated blood from the mother to foetus • Blood from mother enters the placenta though the uterine arteries, and flows

through the blood spaces where he exchange of substances occurs and

leaves again through the uterine veins • Oxygen and nutrients from mother diffuse into foetal blood and wastes leave

foetus by diffusing into maternal blood • Many villi for large SA of exchange • Umbilical cord attaches placenta to baby

1st

trimester (1-12 weeks)

• No period • Swelled breasts • Enlarged nipples • Nausea • Pressure on bladder

2nd

trimester (13-28 weeks)

• Enlarged uterus • Blood volume and heart rate increase • Movement of baby week 18

3rd

trimester (29-40 weeks)

• Sharp pains due to kicking • Uncomfortable • Lower back pain • More rest needed for big weight

Maternal diet

Requirement Reason Food source

Folic acid Cell division Whole grain breads,

Protein production cereals, leafy green veges Calcium Bone growth and baby Dairy

teeth

Vitamin A Normal cell growth Yellow and green veges

Iron Blood cell production Red meat, green veges

Protein Structural materials Meat, dairy, nuts

Avoid- raw fish, unfresh foods, soft cheese, pre packed food

Teratogenic agents • Substance that causes physical defects in embryo • E.g. some hormones, antibiotics, drugs

Watching baby

Ultra sound

• High frequency sound waves to produce image of baby • Probe placed on abdomen and sound waves reflected from feotel tissue to

obtain echoes of what is inside uterus • Determines sex of baby, and any defect e.g. spina bifida

Fetoscopy

• Looking at foetus from telescope like instrument • Inserted into uterus through abdominal wall • Foetus examined for – missing ears, absent

limbs Hormonal intervention

• If progesterone levels drop due to inadequate progesterone production then

a premature delivery or miscarriage could result • Women affected are given progestin – helps mother retain foetus

3 stages of labour

Stage 1 of labour

• contractions of the uterus wall opens up the uterus 10 cm • 10-12 hours approx • amniotic sac breaks • cervix opens wide enough for babys head to pass through • a show- discharge of mucus mixed with blood which has come away from

the cervix where it has formed a plug • regular and strong contractions

Stage 2 of labour

• baby passes through birth canal • the uterus, cervix and vagina are now a continious birth canal • pushing of babies head • babies head emerging from vagina (crowning) • when baby is out mucus must be cleared from nose and mouth of baby • baby must start to breathe and cry • episiotomy- small cut made to widen opening of vagina to prevent tearing

Stage 3 of labour

• baby is a separate person • once baby Is breathing the umbilical cord is cut of • contractions continue until the placenta is expelled • the mother may be given an injection of syntometrine to speed up process

and to prevent excess loss of blood

• left side pump O blood to body • right side pump DO to lungs

• foetal blood returns to heart through liver and inferior vena cava • most of the blood bypasses liver and flows through vessel called ductus

venosus and inferior vena cava • blood flows into the right atrium of heart and it may- Flow into right V and then to lungs From from RV though ductus arteriosus(lung bypass to aorta) (carries O2 blood to

body)

Flow through opening called foremen ovale and in LA Motor development

• Cephalocaudal Head to foot development e.g. raise head, grasp • Proximodistal

Outwards development. Movements of part of limb closest to body comes first

e.g. control forearm then fingers

• Gross to specific Larger muscle movements then the finer movements e.g. whole arm movement, then grasp a ball with hand, then picking up

object between thumb and finger

Socilisation- learning to behave in a manner accepted by others Infertility

• Infertility is the inability to conceive a child after 12 months of regular

sexual intercourse without the use of birth control. There are two types of

infertility; primary infertility and secondary infertility • Causes in females - Pelvic inflammatory disease, endometriosis • Causes in males- Autoimmunity, Chronic prostate infections

Artificial insemination • Success rate- 70-80% • Major risk- transmission of disease from the donor to the receiver • All donors are screened for STI’s, genetic diseases, mental problems

or general health • The physical characteristics of the donor are the closest to the partners • When ovulation is expected a women visits the doctor. The next 3-4 days the

donors semen is injected into the upper vagina of the women • 3 seminations per month for 3 months are necessary for successful conception • insemination is done on day of ovulation and this is detected by testing the

LH surge in the blood or urine

In vitro fertilization • mature eggs are removed from the mother by laparoscopy • sperm are added to an egg which is stored in a glass dish in a lab (fertilization) • it is incubated until it grows (3 days) • after fertilization the dividing cells are implanted into the uterus • excess embryos are frozen for future use

Gamete intrafallopian transfer • it is a variation of IVF • the sperm and the egg are mixed together and are then immediately transferred

into the uterine tubes • it is done in one procedure- not in 2 like IVF • it is a natural way of fertilization