Human Reproductive System Chapter 10

What is sexual reproduction?

The process involving the fusion of nuclei of male and female gametes to form a zygote and the production of genetically dissimilar offspring.

What is puberty?

The period of rapid growth and development during which a person becomes sexually mature and capable of reproducing

At what age does puberty usually begin in females?

Around 10–11 years old.

At what age does puberty usually finish in females?

Around 15–17 years old.

At what age does puberty usually begin in males?

Around 12–13 years old.

At what age does puberty usually finish in males?

Around 16–18 years old.

What are the physical changes during puberty in females?

Growth spurt

Hair starts to grow in the pubic region and armpits

Breast and uterus enlarge, and hips broaden

Menstruation and ovulation begin.

What are the physical changes during puberty in males?

Growth spurt

Facial hair starts to grow, hair starts to grow in the pubic region and armpits

Voice-box enlarges, and voice deepens

The penis and testes increase in size

Production of sperms begins, and ejaculation occurs

What are the overall changes?

Dramatic physical, emotional and social changes occur

What are the gametes of the male and the female?

Sperm

Ovum (or plural, ova)

What are the male and female individuals called?

Parents/

Who can produce these gametes/reproductive cells?

Sexually mature male and female organisms.

What are the external male reproductive organs?

Scrotum and penis.

What are the internal organs of the male reproductive system?

Gonads (produce sperm, hormones)

Accessory glands

What are the main organs of the male reproductive system?

Scrotum

Penis → erectile tissue

Urethra

Testes

Vas Deferens/Sperm Duct

Epididymis

Urinary Bladder

Ureter

Bulbourethral gland (cowper’s gland)

Prostate pland

Seminal vesicle

What is the structure of a testes

Gonads of the male

Oval in shape

Suspended in the scrotum

Why is it suspended in the scrotum?

outside the body cavity (kept 2-3oC cooler than the rest of the body – optimum temperature for sperm production)

What is the function of the testes?

Produces male gametes (sperms)

- Produce male sex hormone (testosterone)

What is the scrotum?

A sac formed by the skin that encloses the testes.

What is the function of the scrotum?

Protects the testes and keeps it 2-3oC cooler than the rest of the body - optimum temperature for sperm production)

What is the structure of the urethra?

Tube passes through the penis

What is the function of the urethra?

Carries urine and semen at different times through the penis

What is the penis?

An erectile organ

What is the function of the penis?

Carries urine and semen out of the body

-Becomes stiff and erect as copulation occur and releases sperm into the vagina

What is the structure of the vas deferens?

Tube connecting the coiled tube (epididymis) with the urethra.

What is the vas deferens function?

Transports the sperm from the epididymis to the urethra during copulation (sexual intercourse)

What is the structure of the sex (prostate) gland

A gland located at the part of urethra where the two sperm ducts join

What is the function of the prostate gland

Produces seminal fluid containing nutrients and enzymes, which keeps the sperm alive and helps them to swim vigorously.

(sperm + seminal fluid → semen )

What is the structure of the epididymis

A long coiled tube that connects the testis to the sperm duct.

What is the function of the epididymis?

Site of sperm maturation

Storage of inactive, mature sperm before they are released into the sperm ducts.

What is the structure of the ureter

Tube connecting the kidney to bladder

What is the function of the ureter?

Carries urine from the kidney to the urinary bladder.

What is the structure of the urinary bladder?

Distensible, muscular bag

What is the function of the urinary bladder?

Stores urine.

What is the path taken by sperm during ejaculation?

Testis → Epididymis → Sperm duct → Urethra → Vagina.

Where are sperm stored before entering the sperm duct?

Epididymis.

What are the three main parts of a mature sperm?

Head, middle piece and tail.

What does the head of a sperm contain?

A nucleus containing 23 chromosomes and an acrosome (vacuole containing enzymes)

What is the function of the sperm nucleus?

Contains 23 chromosomes carrying genetic information.

What is the function of the acrosome?

Contains enzymes that help the sperm penetrate the egg during fertilisation.

What does the middle piece of a sperm contain? Why?

Mitochondria (provides energy for movement)

What is the function of the sperm tail? (flagellum)

Propulsion, allowing the sperm to swim.

Is a sperm motile or non-motile?

Motile.

How does a sperm move?

Its tail propels it towards the oviduct.

What are the internal organs of the female reproductive system? What is their function? (overall)

Pair of gonads

System of ducts and chambers

→ carry gametes and house the embryo and fetus

What are the main organs of the female reproductive system?

Ovaries,

oviducts, (Fallopian tube)

uterus,

endometrium

cervix,

vagina and

vulva

Bladder

Ureter

Urethra

What are the female gonads? Where are they located?

Ovaries.

In the abdominal cavity.

What do the ovaries contain?

Many follicles containing partially developed eggs called an oocyte surrounded by support cells (follicular cells)

How long does it take for the oocyte develop into an egg?

Once a month, an oocyte develops into an ovum (egg)

What hormones are produced by the ovaries? What do they do?

Oestrogen and progesterone. Act together to promote fertilisation of the ovum and to prepare the female reproductive tract for pregnancy.

What is the vagina?

A thin-walled chamber that is the repository for sperm during copulation and serves as the birth canal

What is the vulva?

External female genitals

What are the internal female genitals?

Vagina
Uterus

What is the function of the oviduct? What helps it do so?

Carries the ovum towards the uterus (VIA MUSCULAR WALL CONTRACTIONS HELP MOVE THE OVUM TOWARDS UTERUS)

Site of egg fertilisation.

Cilia - conveys egg to the uterus

What is the structure approaching the cervix?

Uterus narrows at the cervix, and opens into the vagina

What is the structure of the ovaries?

• Oval in shape

• Attaches to the dorsal body wall below the left and right kidney

What is the function of the ovaries

Releases an ovum every 28 days into the oviduct (per menstrual cycle)

Produces female sex hormones (oestrogen and progesterone)

Structure of the oviducts is?

A narrow tube with a funnel-shaped opening lying close to the ovary (uterine/fallopian tube)

Contains Fimbriae - no contact between ovary and oviduct

Function of oviduct is?

Helps move the ovum towards the uterus through muscular wall contractions

Site of egg fertilisation

What is the uterus?

A pear-shaped organ lying behind and slightly above the bladder.

What is the function of the uterus?

Site for foetus development and the smooth inner lining is adapted for the implantation of the embryo

(implants in the uterine lining)

What is the structure of the cervix

A ring of muscles at the lower end of the uterus

What is the function of the cervix

Helps keep the baby in the uterus until it is ready to be born

What is the structure of the vagina?

A thin-walled tube that opens to the outside through the vulva.

What are the functions of the vagina?

An opening for the entry of the penis during copulation

An outlet for the birth of a baby

The site where sperms are deposited

What is the endometrium?

The lining of the uterus.

What is special about the endometrium?

It contains many blood vessels.

What happens during menstruation?

Endometrium breaks down

What is the cell (contents) structure of an ovum?

Nucleus with 23 chromosomes

Cytoplasm (Mitochondria and other organelles)

Cell surface membrane with adaptation to allow for sperm binding

Outer membrane

Follicular cells surrounding ovum

Differences btween sperm and ovum

Size

Quantity

Mobility

Shape

Sex chromosomes

Sperm:

Extremely small

Several millions per ejaculation

Has a tail that enables it to propel towards the oviduct (Motile)

Differentiated into head, middle piece and tail when matured

Carries an X-chromosome or Y-chromosome

Numerous sperms produced throughout life from puberty onwards

Ovum:

Large

One ovum per 28 days during ovulation

Unable to move on its own - Passive movement of egg along oviduct due to the action of cilia and peristalsis of the oviduct wall. (Non-motile)

Round

Carries an X-chromosome

Number of eggs is determined at birth (about 500 mature eggs a life from both ovaries)

Is an ovum motile or non-motile?

Non-motile.

How does an ovum move along the oviduct?

Passive movement of egg along oviduct due to the action of cilia and peristalsis of the oviduct wall.

What is the menstrual cycle?

The cycle of events that takes place in the female reproductive organs every month.

How long is a typical menstrual cycle?

About 28 days.

What alternates during the menstrual cycle?

Menstruation and ovulation, and fertile and infertile periods.

What happens during days 1–5 of the menstrual cycle?

Menstruation occurs.

What happens during days 6–13 of the menstrual cycle?

After the uterus wall has recovered, the spongy uterine lining repairs and thickens and a follicle develops.

What normally occurs around day 14?

Ovulation.

What happens during days 15–28?

The uterine lining thickens further and becomes more vascular, in preparation for implantation.

How long does menstruation usually last? After what?

About five days.

Two weeks after ovulation

Which hormone is dominant in the first half of the menstrual cycle?

Oestrogen.

What is the effect of oestrogen on the uterine lining?

It helps repair and thicken the uterine lining.

Which hormone is dominant in the second half of the menstrual cycle?

Progesterone.

What is the effect of progesterone on the endometrium?

Causes the endometrium to thicken and become supplied with blood capillaries.

What is menstruation?

The bloody discharge from the vagina, caused by the breakdown of the endometrium together with blood.

Menstrual periods take place____ at intervals of about 28 days

Fairly regularly

Once the uterine lining has recovered, what happens?

It begins to rebuild its spongy lining under the influence of oestrogen from the ovary

Meanwhile, a new ovum is maturing in the ovary

What is ovulation?

The release of a mature ovum from the ovary into the fallopian tube

Ovum is moved along the fallopian tube towards the uterus

What happens to an unfertilised ovum? What happens next?

It eventually disintegrates, and the lining of the uterus wall breaks down

The uterine lining and blood flows out through the vagina 2 weeks after ovulation, signalling the start of the next menstrual cycle.

What happens when an ovum is fertilised?

If an ovum is fertilised with a sperm, a zygote is formed. It undergoes cell division to form the embryo, and attaches itself to the endometrium(uterine lining) from which food and oxygen are obtained.

What happens to the gametes during the fertile phase after being released into the female reproductive system?

Ovum lives up to 24 hours after ovulation

Sperm remains active for three to five days after being released into the female reproductive system

Fertilisation occurs when sperm is released into the female reproductive system during this period

What is the fertile phase in a typical 28-day cycle? What happens if sperm is released now?

Approximately day 10 to day 15.

If sperm is released into the female reproductive system during this period, there is a higher chance for fertilisation to occur

Why can intercourse before ovulation still lead to pregnancy?

Sperm can remain alive for 3–5 days and may still be present when the ovum is released.

What are the two infertile phases in the slides?

Day 1–9 and day 16–28.

What happens from day 1 to day 9?

The uterine lining breaks down and is slowly repaired again.

What happens from day 16 to day 28?

The uterine lining thickens and is maintained, with blood vessels and glands developing in preparation for an embryo.

Does intercourse during the so-called infertile phase guarantee that pregnancy cannot occur?

No, because the exact timing of ovulation can vary.

Does the fertile period mean pregnancy will definitely occur?

No, it only means there is a higher chance of pregnancy.

So when can the egg be fertilised?

During both the fertile and infertile periods

What is fertilisation?

The fusion of the nucleus of the male gamete with the nucleus of the female gamete to form a zygote, leading to the production of genetically dissimilar offspring.