UNIT 3: The Human Reproductive System

Question 1

penis

Answer 1

muscular organ through which urine and semen travel. It can also fill with blood, becoming erect. This occurs during sexual arousal, enabling the penis to be inserted into the vagina.

Question 2

sperm ducts

Answer 2

there are 2 sperm ducts that carry sperm from the testes to the urethra.

Question 3

prostate gland

Answer 3

exocrine gland located just underneath the bladder. It secretes fluid contributing to semen.

Question 4

cowper’s gland

Answer 4

pair of exocrine glands that also secrete fluid contributing to semen.

Question 5

seminal vesicles

Answer 5

pair of exocrine glands that also secrete fluid contributing to semen.

Question 6

epididymis

Answer 6

sperm storage organs that are located on top of each testis. Sperm mature in the epididymis before being released during sexual intercourse. If sperm is not released, it is broken down and absorbed by the cells of the epididymis.

Question 7

testes

Answer 7

pair of exocrine and endocrine glands located outside of the body in a sac called the scrotum. They are responsible for producing sperm (exocrine secretion) and the hormone testosterone (endocrine secretion). Testosterone is produced by the testes in response to luteinising hormone (LH), which is secreted by the pituitary.

Question 8

scrotum

Answer 8

pouch in which each testis are located. They hold the testes outside the body as sperm production required a temperature of 35

Question 9

sperm production

Answer 9

The testes produce sperm in response to the hormone follicle-stimulating hormone (FSH, which is secreted by the pituitary).
Sperm are produced by meiosis.
Sperm are highly specialised cells containing three parts: head, midpiece and tail

Question 10

Sperm: head

Answer 10

contains the nucleus with 23 chromosomes (human haploid number) and an acrosome - needed to penetrate the egg cell at fertilisation.

Question 11

Sperm: midpiece

Answer 11

contains many mitochondria that produce energy needed for movement of the sperm cell towards the egg cell.

Question 12

Sperm: tail

Answer 12

responsible for propelling the sperm cell

Question 13

vulva

Answer 13

consists of a number of external genital organs, forming the entrance to the vagina and function in sexual arousal.

Question 14

vagina

Answer 14

muscular organ approximately 7cm long. It is also known as the birth canal and receives the penis during sexual intercourse.

Question 15

cervix

Answer 15

located at the top of the vagina - it is the junction between the vagina and uterus.

Question 16

uterus (womb)

Answer 16

muscular organ responsible for holding the developing embryo/foetus/baby during pregnancy. The internal lining of the uterus is called the endometrium and undergoes a series of changes throughout the female’s 28 day menstrual cycle.

Question 17

fallopian tubes

Answer 17

also known as the oviducts, they form the tubes that carry the egg / fertilised egg from the ovaries to the uterus.

Question 18

ovaries

Answer 18

2 exocrine and endocrine organs located within the abdomen at the end of the fallopian tubes. They release 1 egg (exocrine secretion) per menstrual cycle and hormones progesterone and oestrogen (endocrine secretion) directly into the bloodstream.

Question 19

egg cell development

Answer 19

• eggs are present in the female ovaries at birth.
• eggs begin to be ovulated (released from the ovary) at puberty in the female (about the age of 13).
• usually only 1 egg is released (ovulated) per 28 days (the length of the female menstrual cycle).

Question 20

meiosis

Answer 20

a nuclear division leading to 4 daughter cells each with half the chromosomes as the parent cell.

Question 21

role of meiosis in gamete formation

Answer 21

Meiosis is required for gamete formation so that following fertilisation, the new individual will have the correct number of chromosomes in its cells. Meiosis also created variation in the gametes, so that no 2 gametes are the same genetically, and therefore, no two offspring are the same (unless they resulted from the same zygote).

Question 22

secondary sexual characteristics

Answer 22

those features that distinguish males from females, but are not part of the reproductive system.

Question 23

male secondary sexual characteristics

Answer 23

• facial hair
• pubic hair
• enlarged larynx
• broad shoulders and chest
• large musulature

Question 24

female secondary sexual characteristics

Answer 24

• pubic hair
• breasts
• wide hips

Question 25

role of testosterone

Answer 25

Produced in the male body by the testes in response to the pituitary hormone luteinising hormone (LH). It functions in maintaining male secondary sexual characteristics and plays a role in the production of sperm

Question 26

role of oestrogen

Answer 26

Produced in the female body by the ovaries in response to follicle stimulating hormone (FSH). It functions in the formation and maintenance of female secondary sexual characteristics and the repair of the endometrium during the menstrual cycle.

Question 27

role of progesterone

Answer 27

Produced in the female body by the ovaries (corpus luteum) following ovulation. It functions in maintaining the endometrium during the menstrual cycle and during pregnancy. Inhibits FSH / LH and prolactin

Question 28

menstrual cycle

Answer 28

a series of changes that occur in the female reproductive tract over the period of 28 days. It begins in the female at puberty and continues every 28 days until menopause (approx. age 45). It can be divided into 3 separate phases: - follicular phase and menses - ovulation - luteal phase

Question 29

follicular phase and menses

Answer 29

- this phase begins with menses - which is the shedding of the lining of the uterus (endometrium) - usually occurring over the first 5 days of the cycle. - it is caused by low levels of estrogen and progesterone. - low levels of the female sex hormones removes the inhibition of these hormones on the pituitary and therefore, follicle-stimulating hormone (FSH) levels begin to increase once again. - As FSH increases, new follicles begin to form within the ovaries and they start secreting estrogen. - Eventually, one of these follicles becomes dominant and is called the Graafian follicle. - The Graafian follicle continues to grow from days 6-13, increasing in size and secreting increasing amounts of estrogen. - Increasing amounts of estrogen helps to repair the lining of the uterus. - Increasing amounts of oestrogen also inhibits FSH secretion from the pituitary, ensuring no further follicles develop during the cycle.

Question 30

ovulation

Answer 30

- oestrogen levels reach a critical level in the blood stream just before ovulation (approx. day 14). - this critical level of oestrogen stimulates the pituitary to secrete a burst or surge of luteinising hormone (LH). - the surge of LH levels causes ovulation - the release of an egg cell from the ovary into the fallopian tube.

Question 31

luteal phase

Answer 31

- once the graafian follicle has released its egg, it becomes the corpus luteum or yellow body and oestrogen levels drop. - the corpus luteum secretes increasing amounts of progesterone. - progesterone maintains the endometrium and thickens it further in readiness for a potential pregnancy. - towards the end of the luteal phase, progesterone and oestrogen levels drop.

Question 32

endometriosis

Answer 32

where the cells lining the uterus (endometrium) move and grow outside the uterus.

Question 33

symptoms of endometriosis

Answer 33

pain in the pelvic area and infertility

Question 34

treatment of endometriosis

Answer 34

pain medication, hormonal drugs to treat any hormonal imbalance, or surgery in severe cases.

Question 35

stages of sexual intercourse: sexual arousal

Answer 35

- in males, blood flows into the penis, which becomes erect so that it can be inserted into the vagina. - in females, secretions from the vagina and blood flowing into the vagina causing it to elongate. - increases in heart rate and breathing occur in both sexes.

Question 36

stages of sexual intercourse: copulation

Answer 36

copulation is the insertion of the erect penis into the vagina

Question 37

stages of sexual intercourse: orgasm

Answer 37

orgasm occurs when sexual arousal reaches a maximum (climax). Orgasm in males is accompanied by ejaculation. Ejaculation is the release of semen from the penis during sexual intercourse.

Question 38

fertilisation

Answer 38

the fusion of a sperm cell with an egg cell to form a diploid zygote

Question 39

survival time of sperm and egg cells

Answer 39

Sperm survive anywhere from 0-7 days in the female reproductive tract. Egg cells survive up to 48 hours after ovulation.

Question 40

location of fertilisation

Answer 40

always occurs in the fallopian tubes

Question 41

fertile period

Answer 41

the time at which the female is most likely to become pregnant.

Question 42

implantation

Answer 42

implantation is the embedding of the embryo into the lining of the uterus.

Question 43

placenta formation

Answer 43

placenta: - formed from the trophoblast of the blastocyst - composed of uterine and embryonic tissue. - fully formed and functional after 3 months. - attached to the foetus via the umbilical cord. functions of the placenta: - secretes progesterone, taking over from the corpus luteum. - allows nutrients, water, oxygen, antibodies, drugs and hormones to pass from the mother's bloodstream into the baby's bloodstream. - allows waste produced by the baby such as carbon dioxide and urea, to pass to the mother's bloodstream for excretion. - keeps mother's blood separate from baby's blood

Question 44

development of the embryo

Answer 44

- at fertilisation, the zygote starts to divide by mitosis. - a ball of cells called a morula is formed. - the morula moves down the fallopian tube towards the uterus. - mitosis continues in the morula which then becomes a blastocyst around day 7. - mitosis continues in the blastocyst producing an inner cell mass with 3 layers: 1. ectoderm 2. mesoderm 3. endoderm - a protective sac, called the amnion, forms around the developing embryo. - amniotic fluid fills the sac and acts as a shock absorber to protect the developing embryo. - at the end of the 8th week of pregnancy, all the major internal organs have been formed and the embryo is known as a foetus. - at the 12th week, the placenta is fully formed and functional. - as pregnancy progresses, the foetus increases in size and the internal organs mature in readiness for life outside the uterus.

Question 45

morula

Answer 45

a ball of undifferentiated cells that forms as a result of mitosis.

Question 46

blastocyst

Answer 46

a fluid-filled sac containing an inner cell mass that gives rise to the embryo

Question 47

ectoderm

Answer 47

gives rise to the skin and nervous system

Question 48

mesoderm

Answer 48

gives rise to the musculoskeletal system, kidneys, lungs and heart

Question 49

endoderm

Answer 49

gives rise to the liver, pancreas and inner linings of the breathing, digestive and excretory systems.

Question 50

childbirth

Answer 50

divided into 3 stages: 1. labour 2. parturition 3. afterbirth

Question 51

labour

Answer 51

- ranges from 1-72hours. - walls of the uterus begin to contract caused by secretion of the hormone oxytocin from the pituitary. - the amniotic sac breaks

Question 52

parturition

Answer 52

- the process of the baby being born (passing through the birth canal). - the baby is usually delivered through the birth canal head first. - the umbilical cord is clamped, cut and sealed to prevent excess blood loss.

Question 53

afterbirth

Answer 53

involves the passing of the placenta from the uterus,

Question 54

lactation

Answer 54

the production and secretion of milk by the breasts of the female. - the production of milk by the breasts is controlled by a pituitary hormone, prolactin. - in the days after childbirth, the breasts secrete a thick yellow substance called colostrum - a nutritious and concentrated form of milk that contains antibodies that protect the baby in the first few weeks and months of life.

Question 55

advantages of breastfeeding

Answer 55

- contains all the correct nutrients in the correct proportions. - contains antibodies. - correct temperature. - sterile - contain no bacteria or viruses. - promotes a strong bond between mother and baby. - helps the mother's body recover quicker after pregnancy. - thought to reduce the chances of developing breast cancer in later life.

Question 56

birth control

Answer 56

procedures taken to limit the number of offspring produced

Question 57

abortion

Answer 57

the physical removal of a foetus from the uterus.

Question 58

contraception

Answer 58

the intentional prevention of pregnancy by stopping fertilisation or implantation from occurring.

Question 59

natural contraception

Answer 59

the couple avoid sexual intercourse during the female's fertile period (rhythm method).

Question 60

mechanical contraception

Answer 60

a barrier is used to prevent the sperm from reaching and fertilising the egg cell e.g. the use of a condom, diaphragms and domes.

Question 61

chemical contraception

Answer 61

using spermicides or hormones. Condoms, domes and diaphragms are often coated in a spermicide that kills the sperm as soon as they come into contact with it. Hormones are used as contraceptives in the form of the 'contraceptive pill' - the woman takes one pill per day - which prevents her ovulating

Question 62

surgical contraception

Answer 62

involves the ligation (tying and cutting) of the fallopian tubes in females (tubal ligation) and of the sperm ducts in males (vasectomy).

Question 63

infertility

Answer 63

the inability to contribute to conception

Question 64

male infertility causes

Answer 64

- low sperm count - low sperm mobility - endocrine gland failure

Question 65

female infertility causes

Answer 65

- fallopian tube blockage | - endocrine gland failure

Question 66

corrective measures for infertility

Answer 66

- hormonal treatment - surgery - IVF (in-vitro fertilisation)

Question 67

Gonad

Answer 67

An organ that produces sex cells in animals

Question 68

Semen

Answer 68

Fluid containing sperm and seminal fluid

Question 69

Menstruation

Answer 69

The discharge of the lining of the uterus and the unfertilised egg

Question 70

Insemination

Answer 70

The release of semen into the vagina just outside the cervix

Question 71

In-vitro fertilisation

Answer 71

Removing eggs from an ovary and fertilising them outside the body

Question 72

Germ layer

Answer 72

Basic layers of cells in the blastocyst from which all adult tissues and organs will form

Question 73

Gestation

Answer 73

The length of time spent in the uterus from fertilisation to birth