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Biology > Grade 12 Human Reproduction Part 1 Male reproductive organs > Flashcards

Grade 12 Human Reproduction Part 1 Male reproductive organs Flashcards

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1
Q

What makes up the male reproductive organs?

A
  • Primary sex organs - the testis / testes in scrotum
  • Ducts - epididymis, sperm duct (vas deferens) and urethra
  • Accessory glands e.g. prostrate
  • External genitalia - penis

To simplify: Testes, Tubules for the transport of sperm, accessory glan

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2
Q

What is the scrotum and what is its function?

A

**A sac of skin that ecloses the testis.

**Functions: **
* Temperature regulator - keeping testis 2 - 3 degrees lower than body temperature ( for formation of fertile sperm).
* Protects the testis

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3
Q

What is the testis?

A
  • Primary male sex organs - pair of **testes **
  • Two oval structures, suspended outside the body in the scrotum
  • Oval shaped gland, about 5cm in length
  • Divided internally into compartments or small lobules
  • Each lobule contains several closely packed, convoluted seminiferous tubules - 250m in each testis
  • Tubules - lined with special cells, namely germinal epithelium.
  • Epithelium cells can divide and give rise to sperm (male gametes) in a process called - spermatogenesis
  • Between the tubules (connective tissue) are groups of endocrine cells - the interstitial cells / cells of Leydig = Produce male hormone testosterone
  • A few germinal epithelium cells develop into l**arger columnar cells - Sertoli cells = provide food for sperm
    I
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4
Q

Discuss the function of the testis:

A
  1. Sperm production
  2. Testosterone - male sex hormone - development of secondary sexual characteristics
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5
Q

List the tubules for the transport of sperm (4)

A
  • Epididymus
  • Vas deferens (sperm duct)
  • Ejaculatory duct
  • Urethra
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6
Q

What is the epididymus?

A

Seminiferous tubules join to form the epididymis where they:
* mature to become motile and fertile
* are stored for several months (after which they are broken down by the epithelial cells of the epididymis and re-absorbed into the body
* situated at the back of the testes and lined with a mucous membrane

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7
Q

Explain the function of the epidiymis: (2)

A
  1. Stores sperm produced in testes - mature inside until ready to become motile and fertile and fertilise ovum
  2. Mucous membrane lining epididymis secretes a substance that, together with peristaltic movements of tubule walls, facilitate movement of sperm
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8
Q

What is the sperm duct / vas deferens?

A
  • Muscular sperm duct = continuation of epididymis, which passes through abdominal cavity and opens in urethra
  • Forms a swelling just before it joins the urethra = ampulla
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9
Q

What is hte function of the sperm duct / vas deferens?

A
  • Transports sperm - by means of peristaltic movements, from epididymis to urethra
  • Ejaculation
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10
Q

What is the ejaculatory duct?

A

The ampulla of the vas deferens leads to a muscular tubule, the ejaculatory duct.

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11
Q

What is the function of the ejaculatory duct?

A

The smooth muscle fibres in the duct contract, forcing the contents of the duct (semen) along the urethra to the exterior.
I.e. to ejaculate

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12
Q

What is the urethra?

A

The duct at the end of the uro-genital system leading to the exterior.

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13
Q

What is the function of the urethra?

A
  • Forms a common duct for the transportation of semen and urine.
  • These two processes never occur together.
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14
Q

LIst the accessory glands:

A
  • Seminal vesicles
  • Prostate gland
  • Cowper’s glands
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15
Q

Explain seminal vesicles:

A
  • Two sac-like structures connected by a tubule to the lower end of the ampulla.
  • Lined with a mucous membrae that secretes a yellow-ish, sticky substance.
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16
Q

What is the function of the seminal vesicles?

A

Secretion of mucous membrane provides fructose, main source of food for sperm.

17
Q

What is the prostrate gland?

A
  • **Plumb-sized **
  • Surrounds urethra at the base of the bladder - where ejaculatory ducts join the urethra
  • Conical gland
  • Secretes a milky alkaline liquid, the prostrate fluid, which gives semen its characteristic smell
18
Q

Discuss the function of the prostrate gland:

A

Secretes prostrate fluid - that:
1. ensures maximum sperm motility (certain enzymes)
1. protects sperm against low pH (acidity) in the urethra and vagina

19
Q

What are Cowper’s glands?

A

**Two small glands on either side of the urethra - just below the prostrate gland.

20
Q

What are the functions of Cowper’s glands?

A
  1. Secretion = greater motility of sperm
  2. Clears the urethra of urine residue - neutralise acidic urine
  3. Lubricates the head of the penis - prevents mechanical damage during ejaculation
21
Q

Explain what the penis is:

A
  • Male sex organ
  • Consists of shaft + head region
  • Cone-shaped head - glans penis
  • Partially covered by foreskin - remove through circumcision
  • Shaft is divided up into three columns of erectile tissue - Corpus carvernosa (2 columns) , corpus spongiosum
  • Erectile tissue in these columns become filled with blood during arousal due to increased blood pressure and blood flow = erection
22
Q

Explain the three columns that the shaft of the penis is divided into:

A
  • **Corpus cavernosa **- 2 columns of erectile tissue that form the upper part of the penis
  • Corpus spongiosum - 1 smaller column of erectile tissue that surrounds the urethra on the lower part of the penis. Ensures that the urethra remains open during erection for the passage of semen.
23
Q

What mechanism brings about an erection of the penis?

A
  • Dilation of the dorsal and central arteries supplying blood to the penis.
  • This allows more blood to fill the three spongy erectile tissue chambers (columns), causing the penis to lengthen and stiffen.
24
Q

What is the function of the penis?

A
  • **Deposits semen with sperm **into the female’s vagina during copulation.
  • Sperm are brought **closer to the egg **for fertilisation - increases chances of fertilisation.
25
Q

What is distinctive about the HUMAN penis?

A
  • Human male has no erectile bone (baculum) in the penis - relies on engorgement / filling up with blood to reach erect state.
  • **Not attached to abdominal wall **but hangs free - in contrast to other mammals
26
Q

What is semen?

A

Consists of:
* Sperm - from the testis
* Seminal fluid from the sperm duct and accessory glands e.g. prostate

27
Q

What is average volume of semen for an ejaculation?

A

2.5 - 5ml semen
50 million - 150 million sperm per ml!
Thus around 700million per ejaculation.
If less than 20 million per ml - infertile

28
Q

What is the difference between erection and ejaculation?

A

Erection = stiffening of the penis
Ejaculation = expulsion of semen

29
Q

Discuss puberty in boys:

A
  • Time period during which sex organs develop and gametes are produced in a boy
  • Puberty starts around 12 years
  • Hypophysis secretes the **hormone LH (luteinising hormone) **- which stimulates the cells of Leydig to produce male hormone, testosterone
  • Hypophysis also releases the **hormone FSH (follicle stimulating hormone) **- stimulates the process of **spermatogenesis **together with testosterone.
30
Q

What effect does testosterone have re secondary sexual characteristics?

A
  • Increased muscle mass
  • englargement of skeletal muscle and broadening of shoulders
  • deeper voice - increase in size of larynx
  • enlargement of penis and testes
  • sperm production
  • sexual drive
  • sweat production
  • increase in facial and body hair - moustache, chest hair, armpit and pubic and leg hairs (about 13 - 14)
  • oily skin (may develop acne)
  • growth spurt - appetite
  • behavioural changes - mood, emotional outbreaks, changed sleeping patters
31
Q

List, in order, all the structures a sperm travels through from where it is made until its release from the body. Also mention the gland it passes through. (See Page 92 - Mind Action) (5 marks)

A
32
Q

Name distinctive human male sexual activities:

A
  • Sexually fertile all th time unlike most mammalian species
  • Nocturnal emissions - wet dreams
  • Mating not confined to period of female ovulation - to increase pair bonding, care for young

Biology (25 decks)

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