Reproductive System Flashcards
What is asexual reproduction?
Produce offspring genetically identical to their parents
What is sexual reproduction?
Produces offspring genetically different from their parents - new individual formed by fusion of haploid gametes to form diploid zygote
What are the gametes?
Haploid cells
Male: sperm
Female: ova
Characteristics of asexual reproduction
1 parent, gametes not produced, genetically identical offspring, cell divisions are mitotic, large number of offspring in short time
Characteristics of sexual reproduction l
2 parents, gametes produced, genetic variation of offspring, produced by meiotic division and zygote developed by mitotic division, less offspring
What are haploid cells?
Diploid cells replicate and divide twice via meiosis - half the number of chromosomes as it’s parent cell
What is fertilisation?
Fusion of 2 haploid gametes to produce a diploid zygote.
What is it meant by humans being diploid organisms?
Require 23 chromosomes from father 23 from mother - 46 chromosomes - 22 autosomal and 1 sex-linked
What is meiosis?
Cell division reduces the no. of chromosomes in parent cell by half and produces 4 gamete cells
What is mitosis?
Cell division resulting in 2 daughter cells - same number of chromosomes as the parent cell
What do autosomal chromosomes control?
Development of the human body & variable characteristics e.g. hair colour, blood type
What do the sex chromosomes code for?
Development of internal & external sex organs
What are sex organs composed up?
The gonads, internal genitalia, external genitalia
What are gonads?
Organs that produce gametes
Males:testes
Females:ovaries
What is Müllerian Inhibiting Substance/ anti-Müllerian hormone?
Secreted by foetal testis causes regression of the Müllerian ducts to prevent differentiation of female reproductive organs in males
Name and explain an X-linked trait?
Colour blindness - confuse colours, colours aren’t as bright, no colours at all - inherited but can arise due to Brian & eye damage - Ishihara test
What is intersex?
People born with parts of both males & females reproductive system (complete/incomplete parts) - 1.7%
What is the Mayer Rokitansky Kuster Hauser Syndrome?
Females born without all their reproductive organs
What are the 4 functions of the reproductive system?
- Produce sperm/ova
- Transport cells
- Sustain these cells
- Nurture the developing offspring
Male reproductive system explained.
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
During ejaculation how is* sperm transported?
Sperm leaves in a fluid known as semen. Contains basic solution, fructose, and prostaglandins
>400 million sperm/ 3.5ml in ejaculation
What are the parts of the sperm?
Head - covered by acrosome stores enzymes for penetration
Middle/body - mitochondria for energy
Tail - swimming
Cells of testes?
Spermatogonia cells - varius stages of sperm production
Sertoli cells - regulate sperm development
Leydig cells - interstitial tissue between seminiferous tubules - secrete testosterone
What cells are in the seminiferous tubules?
Spermatogonia cells & Sertoli cells
Explain testes structure.
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
Hormonal regulation in males
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
Explain the female reproductive system?
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
What are the 3 stages of the ovarian cycle?
Follicular phase, ovulation luteal phase
What is the menstrual cycle?
Females produce gametes in monthly cycles (28 days) - changes in follicles in the ovary & the endometrial lining
What is the follicular phase?
Follicular growth in ovary - most variable in length lasts from 10 days - 3 weeks
What is ovulation?
1+ follicles ripened, ovary release oocyte
What is the luteal phase?
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
What age is optimal fertilisation
30
What is the uterine cycle?
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
What is conception?
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
Female hormones control
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
