Sexual Reproducion In Humans Flashcards
Name the parts of a female reproductive system and explain their function
Ovaries = Produce egg cells in follicles
Fallopian Tubes = Transport an egg cell from ovary to uterus
Uterus = Where embryos develop
Cervix = Separates uterus from vagina, protects fetus
Vagina = Leads from the cervix to outside the body
Name the parts of the male reproductive seen and explain their functions
Testes = Production of sperm cells and testosterone
Vas Deferens = Carry sperm from testes to urethra
Prostate Gland = Secretes alkaline fluid to counteract vaginal acidity
Urethra = Allows excretion to urine
How does the human body produce gametes ?
Via gametogenesis
Describe the structure of a sperm cell
Head (5 um)
- Acrosome containing protease enzyme to digest the cells of the corona radiata
- Nucleus in the head
Mid Section
- Mitochondria in mid-section produces ATP to power microtubule that move tail
Axial filament in tail
- Whiplash movement of tail propels the spermatozoa
What are the 2 types of gametogensis ?
Spermatogensis - formation of sperm in the testis
Oogenesis - formation of ova in the ovary
Describe spermatogenesis
-Takes place in the seminiferous tubules
- The diploid (2n) germinal epithelium divides by mitosis to form
- Spermatogonia (2n ) also divide by mitosis resulting in cells that increase in size- forming
- Primary Spermatocytes (2n)
- Primary spermatocytes divide by meiosis to from haploid
- Secondary Spermatocytes after the first division and eventually
- Spermatids (n) after the second division meiotic division
- Spermatazoa mature and differentiate into a head, middle piece and tail adjacent to the lumen of the tubule
What do the Sertoil cells do?
Provide nutrients to the developing spermatazoa
What do the Leydig cells do and where are they found?
In between seminiferous tubules secrete testosterone to stimulate spermatogenesis
Outline the stages of Oogensis
- germinal epithelium cells divide to form diploid follicle cells making primary follicles
- Primary oocytes (2n) present at birth are stoped in prophase of meiosis 1
- Secondary oocytes (n) and small polar body (n) are formed when the primary oocyte completes meiosis 1. This happens from puberty onwards
- The secondary follicle containing haploid secondary oocyte matures into a Graafian follicle
- One Graafian follicle migrates to the surface of the ovary and bursts releasing the secondary oocyte. This is ovulation
- Meiosis 2 begins but stops at metaphase 2 until fertilisation
What is a polar body?
A haploid cell produced during meiosis in females that does not have the ability to be fertilised
Describe the structure of the secondary oocyte
Corona radiata = outer layer of follicle cells
Zona Pellucida = coating above cytoplasm that prevents polyspermy and hardens when cortical granules release chemicals
Haploid nucleus = fertilisation restores diploid chromosome number
Define fertilisation
In sexual reproduction sperm are released into the vagina
Outline capacitation and the acrosome reaction
1) Sperm swim to the fallopian tube
2) Capacitation of the membrane in from of the acrosome
3) The acrosome releases proteases that digest the corona radiata
4) The acrosome membrane ruptures releasing hydrolase enzymes which digest the zona pellicuda on contact
5) The membranes of the sperm and secondary oocyte fuse and the genetic material of the sperm enters the secondary oocyte.
Describe the cortical reaction
6) Cortical granules fuse with the cell membrane and alter the zona pellicuda to form the fertilisation membrane; this prevents polyspermy
7) Meioisis 2 completes forming the ovum and the second polar body
8) Sperm and ovum nuclei fuse. A diploid zygote nucleus is formed
How does implantation occur?
Following fertilisation, mitosis divisions of the zygote occurs - called cleavage.
A hollow ball of cells called a blastocyst is produced and implants into the endometrial lining of the uterus
How does the placenta form?
From the outer blastocyst layer
It is a temporary organ attached to the lining of the uterus during pregnancy
Define implantation
Early stage of pregnancy in which the blastocyst adheres and sinks into the endometrium
What hormones are involved in the functioning of the female reproductive system
- Follicle Stimulating Hormone (FSH)
- Luteinising Hormone (LH)
- Oestrogen
- Progesterone
