Sexual reproduction - Term 4

Basically, this is what I have learned:

Males

1) Testes
- Produces sperms
- Produces Testerone
- Receives blood from blood vessels in spermatic cord
- Stores inactive sperms in epididymis, a narrow coiled tube, before they enter the sperm ducts

2) Scrotum
- Testes are in them
- Outside the main body cavity
- At a lower temperature than the body

3) Sperm Duct
- Loops over a uretera
- Opens into the urethra
- Sperms travel through sperm duct after they are released from testes

4) Seminal Vesicle
- Opens into each sperm duct
- Stores sperms temporarily before they are released through the urethra

5) Prostate Gland + Cowper Gland + Seminal Vesicle
- Secrete slippery fluid which mixes with sperms
- Fluid contains nutrients and enzymes which nourish the sperms and activates them
- Mixture of fluid and sperms called Semen

6) Urethra
- Tube which passes from bladder through center of penis to the outside of the body
- Sphincter muscle at the base of bladder prevents urine from coming out during ejaculation

7) Penis
- Numerous spaces that can be filled with blood
- Contains erectile tissue
8) Sperm
- Head about 2.5 micrometers wide, contains haploid set of chromosomes, an acrosome containing enzymes that break down part of the egg membranes for teh sperm to penetrate it
- Middle body contains a lot of mitochondria, to provide energy for the sperm to "swim" to the egg
- Beating movement of tail/flagellum enables sperm to "swim" towards the egg.
- Motile

Females

1) Ovary
- Produce eggs and female sex hormones
- When eggs become mature, they are released from the ovaries

2) Oviducts / Fallopian Tubes
- Narrow mascular tube leading from ovary to uterus
- Funnel-like opening lying close to the ovary
- Egg normally fertilised in oviducts

3) Uterus
- Where fetus develops
- Shaped like upside down pear
- Elastic muscular walls
- Smooth muscle tissue in walls contract to push baby out during birth
- Soft, smooth inner lining (uterine lining/endometrium) is where embryo is implanted at
- Broken down and flows out monthly if no zygote implanted

4) Cervix
- Circular ring of muscle at lower narrow end of uterus
- Enlarges for fetus to pass through during birth

5) Vagina
- leading from cervix to outside
- Opening is called vulva
- Semen deposited in it during sexual intercourse

7) Ovum
- Female gametes
- female born with all potential ova she will ever have
- For humans: about 70k potential egg cells present at birth, only about 500 mature
- about 120 micrometers wide
- contains haploid set of chromosomes
- has abundant cytoplasm which may contain a small amount of yolk
- Surrounded by a cell surface membrane, which is surrounded by an outer membrane

Menstrual cycle

Day 1-5 (Menstrual Flow Stage)
- Uterine lining breaks down and flows out of body through the vagina
- Anterior pituitary gland secretes follicle-stimulating hormone (FSH) into the bloodstream

Day 6-13 (Follicle Stage)
- FSH stimulates the development of the follicles in the ovary
- Stimulates follicles in the ovaries to secrete oestrogen
- Oestrogen causes the repair and growth of the uterine lining (it becomes think and spongy with blood vessels)
- When a high concentration of oestrogen is present, FSH production is stopped, and the pituitary gland to secrete luteinising hormone (LH)

Day 14 (Ovulation)
- LH causes ovulation
- causes the formation of corpus luteum, which secretes progesterone and some oestrogen

Day 15-28 (Corpus Luteum Stage)
- Progesterone causes uterine lining to thicken further and be supplied with blood capillaries
- Prepare lining for implantation of embryo
- Inhibits ovulation
- Inhibits production of FSH