Male Reproduction I

Question 1

Reproduction

Answer 1

Biological process by which a new individual organisms are produced from their parents = asexual and sexual

Question 2

Asexual reproduction

Answer 2

Offspring originates from a single organism and inherits the parents’ gene

Question 3

Gemmation

Answer 3

formation of small buds on the surface of the progenitor which can develop into a new individual

Question 4

Fragmentation

Answer 4

New organism is growing from fragments of the progenitor

Question 5

Parthenogenesis

Answer 5

Parthenos = virgin
Genesis = birth
Offspring develops from unfertilised eggs e.g. in arthropods, some fish and amphibians

Question 6

Asexual reproduction advantages

Answer 6

Very quick - no gamete formation necessary
Small populations in secluded areas
Not very complex, requires less energy compared to sexual reproduction
Survival in a stable environment

Question 7

Asexual reproduction disadvantages

Answer 7

Offspring is clone of parent
Little genetic diversity
Environment usually not stable = long term want to have diversity to be able to adapt to different environments
Often struggle for existence as well as overcrowding

Question 8

Sexual reproduction in animals

Answer 8

-Consists of gamete formation, fertilisation and development of the zygote
-Gametes: haploid chromosome set
-Primary sex organs: male testes (production of spermatozoa) and female ovaries (production of ova)
-Secrete sex hormones: males (androgens) and females (oestrogen and progesterone)
Fertilisation: leads to a diploid zygote

Question 9

Sexual reproduction advantages

Answer 9

Introduces genetic diversity and survival in a changing environment

Question 10

Sexual reproduction disadvantages

Answer 10

Cost intensive (a lot of energy) 
Only 50% of the genome contribute to the offspring and few offspring

Question 11

Penis

Answer 11

• male copulatory organ
• roof, shaft, glans penis, foreskin
• corpus sponglosum surrounds urethra
• corpus cavernosa: paired dorsal erectile bodies

Question 12

Erection

Answer 12

Avascular, sexual arousal
Nerves in penis release nitric oxide
Vasodilation: increased blood flow to corpora cavernous

Question 13

Scrotum

Answer 13

Sac of skin and superficial fascia
Hangs outside abdominopelvic cavity
Contains paired testes
Midline septum divides scrotum into two compartments, one for each testis

Question 14

The testes

Answer 14

• Combined within the scrotum
• each testis is surrounded by two tunics
• Tunica vaginalis: outer layer derived from peritoneum
• tunica albuginea = inner layer fibrous capsule
• Septa divide tests into 250 lobules
• Each lobule contains one to four seminiferous tubules
• produce sperm in seminiferous tubules
• sperm ripens from a spertagonium to mature sperm
• produce hormones in interstitial tissue

Question 15

Semen

Answer 15

Milky-white of stem and accessory gland secretions

• 2-5mL ejaculated contains 20-150 sperm/mL
• contains fructose for ATP production, protects and activates sperm and facilitates sperm movement
• alkaline fluid neutralises acidity of male urethra and female vagina and enhances mobility

Question 16

Sperm

Answer 16

• Take 74 days for sperm to mature
• Young men make 300 000 sperm a minute = 400 million/day
• Average sperm count it 50/120 – million sperm/mL
• Sperm count <25 million/mL = infertility

Question 17

Temperature control in testes

Answer 17

• temp is kept constantly 3 degrees lower than core body temp
• lower temp is necessary for sperm production
• two sets of muscles contract the scrotum and can draw the testes towards the abdominal cavity when the testes are cold

Question 18

Dartos muscle

Answer 18

Smooth muscle, wrinkles scrotal skin, pulls scrotum close to the body

Question 19

Cremaster muscles

Answer 19

bands of skeletal muscle that elevate testes

Question 20

The pampiniform plexus

Answer 20

testicular artery entering the scrotum form the abdomen and the testicular been entering the abdomen from the scrotum lie in the tortuous plexus

Question 21

Countercurrent heat exchange

Answer 21

• blood entering the scrotum from the abdomen is warmer than blood leaving the testes
• heat exchange from blood in the testicular artery to blood the plexus, decreases the temperature of blood entering the testes
• blood leaving the testes is warmed by contraction

Question 22

Cryptochidism

Answer 22

• undescended testes
  Absences of one or both testes from the scrotum
• descend to scrotum at 28 weeks of foetal life
• most common genital problem
  3-4% of infant boys born with at least one undescended
• production of testosterone is not affected by temperature
• treated when 6 months
  if not treated: infertility, testicular torsion, cancers

Question 23

Spermatogensis

Answer 23

production of viable sperm, is greatly affected by the temperature of the testicle

Question 24

Ducts of the testes

Answer 24

• sperm delivered to exterior through system of ducts
• epididymis -> vas (ductus deferens) -> ejaculatory duct -> urethra
• seminiferous tubules
• straight tubules
• rete testis
• efferent ductules
• epididymis
• vas deferens

Question 25

Epididymis

Answer 25

• single highly coiled tube
• about 6m long
• maturation of sperm
• passage of sperm 2-6 days
• microvilli absorb testicular fluid and pass nutrients to stored sperm

Question 26

Vas deferens

Answer 26

Ductus deferens

• sperm transport: smooth muscle in walls propels sperm from epididymis to urethra
• sperm storage
• palpable
• 45cm long

Question 27

Vasectomy

Answer 27

cutting and ligating ductus deferens as a form of birth control

Question 28

Accessory glands (3)

Answer 28

Prostate, seminal vesicles, bulbourethral gland

Question 29

Prostate

Answer 29

encircles urethra interior to bladder
size of a peach pit
singe gland 
contributes 30% of spinal fluid
contains enzymes
secretes milky, slightly acidic fluid

Question 30

Seminal vesicles

Answer 30

Paires glands
on posterior bladder surface
contribute to 65% of seminal vesicle
alkaline
prostaglandins, clotting protein and fructose
contains a smooth muscle that contraction during ejaculation
duct of seminal gland joins ductus deferens to form ejaculatory duct

Question 31

Bulbourethral gland

Answer 31

AKAK cowper's glands
pea-sized glands inferior to prostate 
paired glands
contribute 5% of seminal fluid 
lubricate glans penis 
neutralises traces of acidic urine in urethra
alkaline
pre-ejaculatory fluid
produce thick, clear mucus during sexual arousal

Question 32

Other ducts

Answer 32

ejaculatory duct

urethra