Reproductive System

Question 1

What is asexual reproduction?

Answer 1

Produce offspring genetically identical to their parents

Question 2

What is sexual reproduction?

Answer 2

Produces offspring genetically different from their parents - new individual formed by fusion of haploid gametes to form diploid zygote

Question 3

What are the gametes?

Answer 3

Haploid cells
Male: sperm
Female: ova

Question 4

Characteristics of asexual reproduction

Answer 4

1 parent, gametes not produced, genetically identical offspring, cell divisions are mitotic, large number of offspring in short time

Question 5

Characteristics of sexual reproduction l

Answer 5

2 parents, gametes produced, genetic variation of offspring, produced by meiotic division and zygote developed by mitotic division, less offspring

Question 6

What are haploid cells?

Answer 6

Diploid cells replicate and divide twice via meiosis - half the number of chromosomes as it’s parent cell

Question 7

What is fertilisation?

Answer 7

Fusion of 2 haploid gametes to produce a diploid zygote.

Question 8

What is it meant by humans being diploid organisms?

Answer 8

Require 23 chromosomes from father 23 from mother - 46 chromosomes - 22 autosomal and 1 sex-linked

Question 9

What is meiosis?

Answer 9

Cell division reduces the no. of chromosomes in parent cell by half and produces 4 gamete cells

Question 10

What is mitosis?

Answer 10

Cell division resulting in 2 daughter cells - same number of chromosomes as the parent cell

Question 11

What do autosomal chromosomes control?

Answer 11

Development of the human body & variable characteristics e.g. hair colour, blood type

Question 12

What do the sex chromosomes code for?

Answer 12

Development of internal & external sex organs

Question 13

What are sex organs composed up?

Answer 13

The gonads, internal genitalia, external genitalia

Question 14

What are gonads?

Answer 14

Organs that produce gametes
Males:testes
Females:ovaries

Question 15

What is Müllerian Inhibiting Substance/ anti-Müllerian hormone?

Answer 15

Secreted by foetal testis causes regression of the Müllerian ducts to prevent differentiation of female reproductive organs in males

Question 16

Name and explain an X-linked trait?

Answer 16

Colour blindness - confuse colours, colours aren’t as bright, no colours at all - inherited but can arise due to Brian & eye damage - Ishihara test

Question 17

What is intersex?

Answer 17

People born with parts of both males & females reproductive system (complete/incomplete parts) - 1.7%

Question 18

What is the Mayer Rokitansky Kuster Hauser Syndrome?

Answer 18

Females born without all their reproductive organs

Question 19

What are the 4 functions of the reproductive system?

Answer 19

1. Produce sperm/ova
2. Transport cells
3. Sustain these cells
4. Nurture the developing offspring

Question 20

Male reproductive system explained.

Answer 20

Male gonads are the testes which are suspended in the scrotum. Sperm are produced in the testes, mature in the epididymis and then enter the vas deferns. Vas deferns empties sperm into an ejaculatory duct that enters the urethra. Fluid produced by seminal vesicles, bulbourethral glands, prostate glands

Question 21

During ejaculation how is* sperm transported?

Answer 21

Sperm leaves in a fluid known as semen. Contains basic solution, fructose, and prostaglandins
>400 million sperm/ 3.5ml in ejaculation

Question 22

What are the parts of the sperm?

Answer 22

Head - covered by acrosome stores enzymes for penetration
Middle/body - mitochondria for energy
Tail - swimming

Question 23

Cells of testes?

Answer 23

Spermatogonia cells - varius stages of sperm production
Sertoli cells - regulate sperm development
Leydig cells - interstitial tissue between seminiferous tubules - secrete testosterone

Question 24

What cells are in the seminiferous tubules?

Answer 24

Spermatogonia cells & Sertoli cells

Question 25

Explain testes structure.

Answer 25

Paired ovoid structure 5cm x 2.5cm - tough other fibrous capsule encloses masses of seminiferous tubules(250-300 - 80% of mass) - 0.3-1 m in length

Question 26

Hormonal regulation in males

Answer 26

Hypothalamic GnRH promotes the release of LH & FSH from anterior pituitary - stimulate testes - FSH targets Sertoli cells (sperm & inhibin) - LH targets Leydig cells (testosterone - 1° & 2° sexual characteristics) - testosterone & inhibin exert negative feedback on the hypothalamus & anterior pituitary

Question 27

Explain the female reproductive system?

Answer 27

Oviducts (fallopian/uterine tubes) extend from uterus to ovaries - fimbriae sweep over ovary & move egg into tubes
Uterus - thick walled muscular organs, 5cm wide stretch to 30cm, lined by endometrium formation of placenta & varies in thickness during stages of the menstrual cycle, enters vagina at right angle

Vagina - 45° to small of the back

Question 28

What are the 3 stages of the ovarian cycle?

Answer 28

Follicular phase, ovulation luteal phase

Question 29

What is the menstrual cycle?

Answer 29

Females produce gametes in monthly cycles (28 days) - changes in follicles in the ovary & the endometrial lining

Question 30

What is the follicular phase?

Answer 30

Follicular growth in ovary - most variable in length lasts from 10 days - 3 weeks

Question 31

What is ovulation?

Answer 31

1+ follicles ripened, ovary release oocyte

Question 32

What is the luteal phase?

Answer 32

Transformation of a ruptured follicle into a corpus luteum - secretes hormones that prepare for pregnancy - if pregnancy doesn’t occur corpus luteum ceases to function after 2 weeks & cycle begins again

Question 33

What age is optimal fertilisation

Answer 33

30

Question 34

What is the uterine cycle?

Answer 34

Oetrogen & progesterone affect the endometrium causing events in a 28 day cycle

1-5 menses - low levels of hormone cause endometrium to disintegrate

6-13 increased production of oestrogen - new ovarian follicle - endometrium thickens & becomes more vascular & granular = proliferative phase

14 ovulation

15-28 increased production of progesterone by corpus luteum - endometrium doubles/triples in thickness & gland secrets a mucous = secretary phase

Question 35

What is conception?

Answer 35

Secondary oocyte(mature ovum) releases to the uterus: 4-7 days - fertilisation must occur 24 hours after ovulation - few hours after fertilisation ovum undergoes cell division to produce 2 haploid cells - bigger cell fuses with nucleus of sperm - fertilisation complete when a diploid zygote is formed - embryonic development begins

Question 36

Female hormones control

Answer 36

Controlled by GnRH (hypothalamus), FSH and LH (anterior pituitary) & Oestrogen, progesterone and inhibin from the ovary.
Follicular phase = oestrogen Luteal phase + progesterone

Ovarian cycle controlled gonadotrophic hormones: FSH and LH in various amounts during cycle.
Follicular phase FSH - development of a follicle in the ovary - secretes oestrogen and some progesterone. Negative feedback on pituitary

increased oestrogen causes a sudden surge of GnRH from hypothalamus - LH from anterior pituitary - ovulation

Luteal phase = LH development of corpus luteum (progesterone and some oestrogen) Progesterone causes endometrium to build up & negative feedback on anterior pituitary secretion of LH so corpus luteum degenerate.

luteal phase ends = menstruation