Reproduction 2 (sperm development)

Question 1

What are the 3 main parts of a sperm cell?

Answer 1

• Head
• Midpiece
• Tail

Question 2

What does the head of a sperm cell contain?

Answer 2

• Chromosomes
• Acrosome –> cont. enzymes necessary for breaking down membrane of egg

Question 3

What does the midpiece of sperm cells contain?

Answer 3

Mitochondria –> bank of ATP

Question 4

What does the tail of the sperm cell do?

Answer 4

Whiplike movements propel sperm

Question 5

What are the stages on spermatogenesis?

Answer 5

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

Question 6

Where does spermatogenesis happen in the testis?

Answer 6

From basement membrane to lumen

Following mitosis, one spermatagonia stays to produce more

Question 7

What are the 3 stages in sperm maturation?

Answer 7

• Spermatazoa released into lumen of seminiferous tubules
• Move to epidiymis by peristaltic contractions & flow of lumenal fluid
• Move to vas deferens by peristalsis

Question 8

What happens during sperm maturation when spermatazoa are released into lumen of seminiferous tubules?

Answer 8

• Immotile
• 20 days

Question 9

What happens during sperm maturation when sperm move to epidiymis by peristaltic contractions & flow of lumenal fluid?

Answer 9

Acquire motility

Question 10

What happens during sperm maturation when sperm move to vas deferens by peristalsis?

Answer 10

Remain in vas deferens until ejeculation

Question 11

What is sexual response in males controlled by?

Answer 11

The autonomic NS

(Something about spinal reflexes)

Question 12

What are the 3 phases of sexual response in males?

Answer 12

• Erection
• Emission
• Ejaculation

Question 13

What are the phases of sexual response in males controlled by?

• Erection
• Emission
• Ejaculation

Answer 13

• Erection = parasympathetic
• Emission = sympathetic
• Ejaculation = sympathetic

Question 14

What are the stimuli of sexual responses in males?

Answer 14

• Mechanorecpetors of penis & erogenous zones
• Descending signals from higher brain centres

Question 15

Refer to the flow chart of male sexual repsonses

Answer 15

Thanks

Question 16

What happens between erection to emission?

Answer 16

Neural activity shifts from para control to sympathetic control

Question 17

What is the process of emission?

Answer 17

• 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

Question 18

What is the average sperm counts?

Answer 18

• 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)

Question 19

What is an infertile sperm count number?

Answer 19

<20 million/ml

Question 20

What is the overall function of male reproductive tracts?

Answer 20

• Production of sperm (spermatogenesis)
• Delivery of sperm to the female

Question 21

What is the overall function of the female reproductive tracts?

Answer 21

• 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)