H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Assignment 9C: Reproduction
Male reproductive system
Figure 1-
Labelled
diagram of
the male
reproductive
system
Hormones
Testosterone
Testosterone is one of the primary male reproductive hormones which is
produced by the testes in the male reproductive system. This hormone is
responsible for the development of secondary sex characteristics during puberty,
e.g. growth and development of sexual organs, voice breaking, etc. The target
organ for testosterone is mainly the reproductive organs along with the bones
and muscles. Reproductive organs, e.g. testes, tend to grow and develop as a
result of testosterone being produced. The bones and muscles are affected by
testosterone as the bone density increases as well as muscle mass. The release
of this hormone can also stimulate the production of sperm which is key to the
process of conception – discussed on pages 6-7. Men can produce too little or too
much testosterone which leads to implications such as infertility, the triggering
of puberty before the age of 9 years. This can be treated using testosterone
supplements and/or testosterone replacement therapy (TRT).
As men age, the levels of testosterone decrease and this can be referred to as
late-onset hypogonadism. In recent years, this has been identified as a
recognised medical condition and has several symptoms:
- Fatigue
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
- Depression
- Mood changes
- Decreased body hair
- Decreased muscle mass and strength
Late-onset hypogonadism has also been associated with metabolic disease as
well as sexual dysfunction. There are statistics that state around 4 in 10 men
have hypogonadism by the time they reach 45 years old and by the age of 60,
the low levels of testosterone would lead to a diagnosis of hypogonadism in
younger men. Overall, an increased number of men see the effects of age-
related testosterone depletion.
Follicle-stimulating hormone (FSH)
FSH is another male reproductive hormone which is produced by the pituitary
gland, located at the base of the brain, below the hypothalamus. FSH is classed
as one of the gonadotrophic hormones and is produced in combination with LH
(luteinising hormone). This hormone has an important role in pubertal
development as well as the functioning of the male testes. In men, FSH works on
the testes in order to stimulate the production of sperm (spermatogenesis) and
also is involved in the regulation of testosterone levels. The target organ for FSH
is the testes as it involved in spermatogenesis and promotes the production of
sperm. If levels of testosterone are high, this is detected by nerve cells in the
hypothalamus so that secretion of FSH is decreased. The reverse happens when
levels of testosterone are high and this regulation of testosterone levels is
controlled by negative feedback.
If FSH levels are too high, it is a sign of malfunction of the testes and is referred
to as hyper-gonadotrophic-hypogonadism. It is also associated with testicular
failure in men and is seen in a condition known as Klinefelter’s syndrome in men.
If FSH levels are too low, lack of puberty and infertility can occur as a result of
the lack of sperm. Having partial FSH deficiency can lead to delayed puberty and
limited sperm production, however if the lack of FSH happens after puberty,
there will be a similar loss of fertility.
Luteinising hormone (LH)
LH is a male reproductive hormone which is also classed as a gonadotrophin-
releasing hormone and is also produced by the pituitary gland, specifically the
anterior pituitary. This hormone plays an important role in regulating the
operation and function of the testes as well as supporting sperm development.
The target organ for this hormone is also the testes as it is involved with the
secretion of testosterone. A surge in this hormone can cause infertility in men
along with some genetic conditions, e.g Klinefelter’s syndrome. Similarly, if there
is a large drop in LH, it can also cause infertility in men as an optimum level of
LH is required for the testes to function normally. In some cases, the rare genetic
disorder, Kallmann’s syndrome, can be developed which is involved with
gonadotrophin-releasing hormones not being produced enough.
Gonadotrophin-releasing hormone
2
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
Assignment 9C: Reproduction
Male reproductive system
Figure 1-
Labelled
diagram of
the male
reproductive
system
Hormones
Testosterone
Testosterone is one of the primary male reproductive hormones which is
produced by the testes in the male reproductive system. This hormone is
responsible for the development of secondary sex characteristics during puberty,
e.g. growth and development of sexual organs, voice breaking, etc. The target
organ for testosterone is mainly the reproductive organs along with the bones
and muscles. Reproductive organs, e.g. testes, tend to grow and develop as a
result of testosterone being produced. The bones and muscles are affected by
testosterone as the bone density increases as well as muscle mass. The release
of this hormone can also stimulate the production of sperm which is key to the
process of conception – discussed on pages 6-7. Men can produce too little or too
much testosterone which leads to implications such as infertility, the triggering
of puberty before the age of 9 years. This can be treated using testosterone
supplements and/or testosterone replacement therapy (TRT).
As men age, the levels of testosterone decrease and this can be referred to as
late-onset hypogonadism. In recent years, this has been identified as a
recognised medical condition and has several symptoms:
- Fatigue
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 9: Human Regulation and Reproduction
- Depression
- Mood changes
- Decreased body hair
- Decreased muscle mass and strength
Late-onset hypogonadism has also been associated with metabolic disease as
well as sexual dysfunction. There are statistics that state around 4 in 10 men
have hypogonadism by the time they reach 45 years old and by the age of 60,
the low levels of testosterone would lead to a diagnosis of hypogonadism in
younger men. Overall, an increased number of men see the effects of age-
related testosterone depletion.
Follicle-stimulating hormone (FSH)
FSH is another male reproductive hormone which is produced by the pituitary
gland, located at the base of the brain, below the hypothalamus. FSH is classed
as one of the gonadotrophic hormones and is produced in combination with LH
(luteinising hormone). This hormone has an important role in pubertal
development as well as the functioning of the male testes. In men, FSH works on
the testes in order to stimulate the production of sperm (spermatogenesis) and
also is involved in the regulation of testosterone levels. The target organ for FSH
is the testes as it involved in spermatogenesis and promotes the production of
sperm. If levels of testosterone are high, this is detected by nerve cells in the
hypothalamus so that secretion of FSH is decreased. The reverse happens when
levels of testosterone are high and this regulation of testosterone levels is
controlled by negative feedback.
If FSH levels are too high, it is a sign of malfunction of the testes and is referred
to as hyper-gonadotrophic-hypogonadism. It is also associated with testicular
failure in men and is seen in a condition known as Klinefelter’s syndrome in men.
If FSH levels are too low, lack of puberty and infertility can occur as a result of
the lack of sperm. Having partial FSH deficiency can lead to delayed puberty and
limited sperm production, however if the lack of FSH happens after puberty,
there will be a similar loss of fertility.
Luteinising hormone (LH)
LH is a male reproductive hormone which is also classed as a gonadotrophin-
releasing hormone and is also produced by the pituitary gland, specifically the
anterior pituitary. This hormone plays an important role in regulating the
operation and function of the testes as well as supporting sperm development.
The target organ for this hormone is also the testes as it is involved with the
secretion of testosterone. A surge in this hormone can cause infertility in men
along with some genetic conditions, e.g Klinefelter’s syndrome. Similarly, if there
is a large drop in LH, it can also cause infertility in men as an optimum level of
LH is required for the testes to function normally. In some cases, the rare genetic
disorder, Kallmann’s syndrome, can be developed which is involved with
gonadotrophin-releasing hormones not being produced enough.
Gonadotrophin-releasing hormone
2
