S5) Sexual Function and Fertilisation Flashcards Preview

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Flashcards in S5) Sexual Function and Fertilisation Deck (40)
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1

Describe the composition of semen

- Spermatozoa + 

- Seminal plasma 

2

Identify 3 functions of the semen

- Transport medium

- Nutrition

- Buffering capacity 

3

Where is seminal plasma derived from?

Accessory glands of the male reproductive tract:

- Prostate gland

- Seminal vesicles 

- Bulbourethral gland

4

What is the usual site for fertilisation?

Ampulla of uterine tube 

5

Identify the 4 phases in the sexual response

- Excitement phase

- Plateau phase

- Orgasm phase

- Resolution phase

6

What sort of stimuli trigger the excitement phase?

Psychogenic and / or somatogenic stimuli 

7

What happens after the resolution phase in the sexual response?

Return to haemodynamic norm followed by a refractory period (males)

8

Identify the 2 stimulants of the male sexual response – erection

- Psychogenic

- Tactile (sensory afferents of penis and perineum) 

9

Identify the 2 efferent nerves in the male sexual response – erection

Somatic and autonomic efferents:

- Pelvic nerve (PNS)

- Pudendal nerve (Somatic) 

10

Which three processes are required for an erection to occur?

- Sinusoidal relaxation

- Arterial dilation

- Venous compression 

11

Identify the nerves involved in the parasympathetic innervation of the penis

- Pelvic nerve and pelvic plexus

- Cavernous nerve

12

Describe 3 neurophysiological events which produce an erection

- Inhibition of sympathetic arterial vasoconstrictor nerves

- Activation of non-adrenergic, non-cholinergic, autonomic nerves to arteries

- Release of Nitric Oxide (NO) 

13

In five steps, describe the events leading to the release of NO in an erection

⇒ Post-ganglionic fibres release ACh

⇒ ACh bonds to M3 receptor on endothelial cells

⇒ Rise in [Ca2+]i activates NO synthase and formation of NO

⇒ NO diffuses into vascular smooth muscle and causes vasodilation

⇒ NO is also directly released from nerves

14

Identify 4 causes of erectile dysfunction

- Psychological

- Tears in fibrous tissue of corpus cavernosa

- Vascular 

- Drugs 

15

Describe the psychological cause for erectile dysfunction

Psychological – descending inhibition of spinal reflexes

16

What sort of neural control governs emission and ejaculation?

Sympathetic Nervous System

17

Which 2 events occur in the male sexual response – emission?

- Movement of semen into prostatic urethra

- Contraction of smooth muscle in prostate, vas deferens and seminal vesicles 

18

What occurs in the male sexual response – ejaculation?

Expulsion of semen:

- Contraction of smooth muscle in glands and ducts 

- Bladder internal sphincter contracts 

- Rhythmic striatal muscle contractions

19

Why does the bladder internal sphincter contract in ejaculation?

To prevent retrograde ejaculation 

20

Which structures are involved when the striatal muscles contract in ejaculation?

- Pelvic floor

- Perineal muscles

- Ischiocavernosus muscle

- Bulbospongiosus muscle

21

Describe the hormonal influence over the changes of the character of cervical mucus in the menstrual cycle

Oestrogen: thin, stretchy cervical mucus

- Oestrogen & progesterone: thick, sticky cervical mucus (forms a plug)

22

What is the site of sperm deposition?

Cervix

23

Describe the process which occur as part of capacitation in the female reproductive tract?

- Further maturation of sperm (6-8 hours)

- Sperm cell membrane changes to fuse with oocyte

- Sperm tail movement changes to a whip-like action

- Acrosome reaction can now occur

24

State the fertility windows for the sperm and oocyte respectively

Spermatozoa: 48 - 72hr

- Oocytes: 6 - 24 hr 

25

What is the fertile period?

Fertile period: sperm deposition up to 3 days prior to ovulation or day of ovulation 

26

Distinguish between the transport of the gametes

Oocyte: beating cilia & peristalsis of uterine tube

- Sperm: own propulsion 

27

Describe the origin, structure and function of the acrosome

- Origin: derived from golgi region of developing spermatid

- Structure: contains enzymes

- Function: necessary for fertilisation 

28

Which 2 events trigger the acrosome reaction?

- Sperm pushes through corona radiata

- Binding of sperm surface receptor to ZP3 glycoprotein of zona pellucida 

29

What is the result of the acrosome reaction?

30

Which 2 processes lead to fertilisation?

- One sperm penetrates leading to fusion of plasma membranes

- Cortical reaction occurs (blocks polyspermy)