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Sunday, May 17, 2015

Sexual Reproduction in Humans

Male Reproductive System consists of:

 
1.Testes:
  - produce sperm + hormones
  - under the influence of pituitary gonadotrophins, FSH +LH
  - contains scrotum 
  - kept 2 °C <normal body temperature
  - optimal for sperm production (spermatogenesis).

2. Ducts:
  - vasa efferentia + vas deferens
  - transport sperm to urethra
 
3. Glands:
  - prostate gland, Cowper’s gland, seminal vesicles
  - contribute fluid to semen.

4. Sperm (in seminal fluid)
  - discharged from body thru penis ( intromittent organ).

5. Each testis:
  - consists of about a thousand seminiferous tubules.

6. Each tubule:
  - lined by germinal epithelium
  - which divides to give rise to sperm
  - + two months.

 
 
1. Interstitial cells:
   - between seminiferous tubules
   - contain Leydig cells 
   - produce testosterone
   - influence of LH (in pituitary gland).
 
2. Testosterone:
   - stimulates development + maintenance of male secondary sexual
     characteristics + accessory sex organs.
 
3. Spermatogenesis:
    - starts at puberty
    - when FSH stimulates series of cell divisions
    - of germinal epithelium
    - of seminiferous tubules.
 
4. Spermatozoan cell:
    - cytoplasm disappeared during development.
 
 
 
 
 
 
 
 
 
 
 
 


5. Acrosome:
    - large lysosome
    - enzymes to digest outer membranes of the egg (female gamete)
 
6. Mitochondria - provide energy for locomotional flagella movement.


Human female reproductive system consists of:


















1. Pair of ovaries:
   - which produce ova
   - carried by Fallopian tubes (oviductus)
   - to uterus.

2. cervix - muscular ring at outer end of uterus.

3. vagina – opening to outside of body.


















 

1. At birth:
   - ovaries contain about two million follicles
   - which started to divide by meiosis,
   - but stopped at prophase I (primary oocytes).
   - subsequent development at monthly intervals (menstrual cycle).
 
2. Oogenesis is regulated by the pituitary hormones FSH + LH
 
3. Ovulation + development of secondary sexual characteristics
   + uterine changes in preparation for implantation of a fertilised egg
   - controlled by the ovarian hormones (oestrogen + progesterone).
 
4. Fertilisation:
   - occurs in the Fallopian tubes
   - and the zygote is transported to the uterus
   - by the action of cilia lining.
 
5. Development of the zygote + embryo is viviparous