Reproduction 2 (sperm development) Flashcards
What are the 3 main parts of a sperm cell?
- Head
- Midpiece
- Tail
What does the head of a sperm cell contain?
- Chromosomes
- Acrosome –> cont. enzymes necessary for breaking down membrane of egg
What does the midpiece of sperm cells contain?
Mitochondria –> bank of ATP
What does the tail of the sperm cell do?
Whiplike movements propel sperm
What are the stages on spermatogenesis?
Spermatogonium
Chromosome replicate
- 2 primary spermatocytes with 2n
Meiosis I
- Two secondary spermatocytes with 2 x n
Meiosis II
- Four spermatids - 1 x n
Differentiation
- Spermatazoa 1 x n
Where does spermatogenesis happen in the testis?
From basement membrane to lumen
Following mitosis, one spermatagonia stays to produce more
What are the 3 stages in sperm maturation?
- Spermatazoa released into lumen of seminiferous tubules
- Move to epidiymis by peristaltic contractions & flow of lumenal fluid
- Move to vas deferens by peristalsis
What happens during sperm maturation when spermatazoa are released into lumen of seminiferous tubules?
- Immotile
- 20 days
What happens during sperm maturation when sperm move to epidiymis by peristaltic contractions & flow of lumenal fluid?
Acquire motility
What happens during sperm maturation when sperm move to vas deferens by peristalsis?
Remain in vas deferens until ejeculation
What is sexual response in males controlled by?
The autonomic NS
(Something about spinal reflexes)
What are the 3 phases of sexual response in males?
- Erection
- Emission
- Ejaculation
What are the phases of sexual response in males controlled by?
- Erection
- Emission
- Ejaculation
- Erection = parasympathetic
- Emission = sympathetic
- Ejaculation = sympathetic
What are the stimuli of sexual responses in males?
- Mechanorecpetors of penis & erogenous zones
- Descending signals from higher brain centres
Refer to the flow chart of male sexual repsonses
Thanks
What happens between erection to emission?
Neural activity shifts from para control to sympathetic control
What is the process of emission?
- Response to mechnical stimulation continues from erection to emission
- Contractions of epididymis, vas deferens & ejaculatory duct
- Secretions form seminal vesicles & prostate
- Result = movement of semen (sperm & fluid) into urethra
What is the average sperm counts?
- Average volume of semen - 2.75ml (range 2-6ml)
- 66 million sperm/ml
- 180 million sperm (120 - 400 million normal range)
(Sperm count on avg in the UK are constantly dec)
What is an infertile sperm count number?
<20 million/ml
What is the overall function of male reproductive tracts?
- Production of sperm (spermatogenesis)
- Delivery of sperm to the female
What is the overall function of the female reproductive tracts?
- Production of ova (oogenesis)
- Reception of sperm
- Transport of the sperm & ovum to common site for union (fertilisation or conception)
- Maintenance of the developing fetus until it can survive in the outside world
- Giving birth (partution)
- Nourishing the infant after birth (lactation)
(Much more complex than male)
