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BIOL155 > Sperm Production and Delivery > Flashcards

Sperm Production and Delivery Flashcards

1
Q

How many cells in the human body have a flagellum

A

Only one! Sperm cells are the only cell in the human body that have flagellum

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2
Q

What is the main job of a sperm cell

A

Main job: To fuse/fertilize an ovum
- deliver the necessary materials to fertilize an egg

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3
Q

Are sperm fully mature and functional in the testes

A

Anatomically, sperm LOOK mature/functional in the testes

However, they are not functionally mature in the testes

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4
Q

What are the internal genitalia of the male reproductive system

A

Internal genitalia include the testes (gonads), and a series of ducts and glands that help to support and move sperm to the external genitalia

  1. TESTES
  2. SERIES OF DUCTS AND GLANDS
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5
Q

What are the external genitalia of the male reproductive system

A

External genitalia include the urethra and penis, which deliver sperm, and the scrotum, which keeps the testes outside of the abdominopelvic cavity

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6
Q

What are the functions of the internal genitalia

A

Gonads - produce gametes (sperm cells)
Series of ducts and glands - help support and move sperm to the external genitalia

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7
Q

What are the functions of the urethra and penis (internal or external?)

A

Urethra and penis are EXTERNAL genitalia

  • deliver sperm
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8
Q

What is the function of the scrotum

A

Keeps the testes outside of the abdominopelvic cavity

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9
Q

Why is the scrotum kept outside of the body

A

Scrotum keeps the testes outside of the abdominopelvic cavity
- acts as a temperature regulator for sperm
- temperature difference allows sperm to be in its optimal environment for sperm development

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10
Q

What is the function of the male reproductive system

A

Manufacture gametes known as sperm and deliver them to an ovum in viable form

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11
Q

Trace the path of the male reproductive system

A
  1. Testes
  2. Ducts and glands
  3. Urethra and penis
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12
Q

Upon tracing the path of the male reproductive system, briefly discuss what happens at each step/structure

A
  1. Testes
    - makes the sperm
  2. Ducts and glands
    - contribute to the maturation of sperm
    - secretes fluids to help keep sperm viable
  3. Urethra and penis
    - responsible for depositing sperm in the female reproductive tract (and for most of the pleasurable sensations associated with performing this function - basically sex)
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13
Q

Recall: What is SRY

A

A gene present on Y (and sometimes X chromosomes) that drive the development of male sex characteristics/reproductive organs

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14
Q

What is TDF (SOX9)

A

TDF(SOX9) is the testes-determining factor/gene that drives the development of male testes

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15
Q

The testes develop from a __________ gonad during the embryonic period

A

BIPOTENTIAL

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16
Q

Everyone starts with a bipotential gonad with two ducts (Wolffian and Mullerian): Which one degrades and which one becomes the male reproductive ducts

A

Mullerian duct degrades
Wolffian duct develops into the male reproductive system
- including the epididymis, vas deferens, ejaculatory duct, and seminal vesicle

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17
Q

From a bipotential gonad, what causes the development of the testes and internal system of cords/ducts for males

A

Due to SRY and TDF (SOX9) expression, as well as ANDROGEN SECRETION

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18
Q

What kind of tissue acts as the band that eventually pulls the testes through the abdominal wall into the scrotum by the end of the term

A

Connective tissue band!

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19
Q

What is the scrotum

A

Skin, muscles layers, and fascia that support the testes

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20
Q

What are the two tubules that are part of the tubular system of the male reproductive system

A

Rete testis - central web
Seminiferous tubules - highly coiled tubes
(Epididymis is a coiled bunch of tubes closer to the top of the teste)

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21
Q

What is the role of membrane and fascia layers in the male reproductive system

A

Tissues that allow the testes to move within the scrotum and keep the tubular lobes separated

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22
Q

Although the testes are pushed out of the abdominopelvic cavity during embryonic development, they remain mobile, particularly in response to temperature. Why?

A

Testes are housed in the scrotum OUTSIDE of the body because body temperature inside the body can become TOO WARM for sperm development

  • remaining mobile allows the testes to move away or closer to the body as needed to adjust temperature for sperm developmentW
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23
Q

What is one potential trade off for having the testes outside of the body

A

If they are farther from the body, they are easier to damage
- trade off!!

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24
Q

Where are sperm formed?

A

Formed from germ cells within the SEMINIFEROUS TUBULES of testes

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25
Q

What are the three classes of functional cells in gonads

A
  1. Steroid-secreting cells
  2. Support (“nurse”) cells
  3. Germ cells
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26
Q

What are the three classes of functional cells specifically in the testes

A
  1. Steroid-secreting cells = Leydig cells
  2. Support (“nurse”) cells = Sertoli cells
  3. Germ cells = Spermatogonia
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27
Q

What are Sertoli cells and where can they be found (function/properties)

A

Location: testes
- have tight functions
- similar to BBB
- prevent pathogens from getting into seminiferous tubules
- act like a testes barrier

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28
Q

What are Leydig cells and where can they be found (function/properties)

A

Location: testes
- sit in the interstitial space
- release androgens (testosterone)
- found outside of the seminiferous tubules

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29
Q

What are Spermatogonia and where can they be found (function/properties)

A

Location: testes
- form sperm inside the seminiferous tubules

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30
Q

Compare a peanut M&M analogy to the order in which the three functional classes of cells can be found in the testes

A

Peanut = centre = spermatogonia
Chocolate = middle = sertoli cells
Crunchy coating = outside = leydig cells

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31
Q

Which of the following are found inside and outside of the seminiferous tubules

A

Inside = Sertoli cells, spermatogonia
Outisde = Leydig cells

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32
Q

What is spermatogenesis

A
  • process of generating sperm from spermatogonia
  • germ cell becomes a sperm
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33
Q

What are the four cellular stages in which germ cells become a sperm

A
  1. Spermatogonium / spermatogonia = germ cell differentiating (start closest to basale layer, furthest from lumen, differentiates to become spermatocyte)
  2. Spermatocyte = two types (primary or secondary, depending on which stage of mitosis/meiosis it is in)
  3. Spermatid
  4. Sperm = mature sperm cell
34
Q

What are spermatogonia

A
  1. Spermatogonium / spermatogonia = germ cell differentiating (start closest to basale layer, furthest from lumen, differentiates to become spermatocyte)
35
Q

What are spermatocytes

A
  1. Spermatocyte = two types (primary or secondary, depending on which stage of mitosis/meiosis it is in)
36
Q

What is sperm

A
  1. Sperm = mature sperm cell
37
Q

What is gametogenesis

A

the process in which cells undergo meiosis and mitosis to form gametes
- involves spermatogenesis

38
Q

Differentiate mitosis from meiosis

A

Mitosis = regular cell division
= produces exact duplicates (each with 23 paired chromosomes = 46 chromosomes)
= produces diploid cells

Meiosis = germ cell division
= meiosis 1 and meiosis 2
= get formation of tetrads (46 chromosomes)
= some genetic code in some offspring cells (23 chromosomes)
= end up with gametes
= allows for genetic variety
= produces haploid cells

39
Q

Breakdown the steps of spermatogenesis

A
  1. Mitosis of a spermatogonium (46)
    - start with 1 spermatogonium
    - end up with 1 primary spermatocyte (diploid)
  2. Meiosis I (46)
    - start with primary spermatocyte (DNA replication)
    - divides into two secondary spermatocytes (tetrads)
  3. Meiosis II (23)
    - start with two secondary spermatocytes (tetrads)
    - tetrads are split between four offspring cells
    - produces 4 spermatids (haploid)
  4. Spermiogenesis
    - 4 sperm cells
    - 4 haploid gametes
40
Q

Breakdown the timeline for spermatogenesis

A

Mitosis
= 16 days

Meiosis I
= 24 days

Meiosis II
= Hours

Spermiogenesis
= 24 days

Total time = ~64 days

40
Q

How long does spermatogenesis take

A

~ 2 months to complete

40
Q

What are the five features of anatomically mature sperm

A
  1. Acrosome - contains enzymes needed to penetrate an ovum during fertilization
  2. Head - contains compacted DNA/haploid chromosomes
  3. Neck - also contains mitochondria
  4. Middle piece - contains mitochondria which generates ATP to keep the tail moving/swimming
  5. Tail - flagellum = a motile organelle that moves the sperm
40
Q

Spermatogenesis involves movement of the developing sperm toward the lumen of the seminiferous tubule: Explain this path

A

As developing gametes progress from
spermatogonium -> spermatocyte -> spermatid -> sperm

They move from the basal layer of the seminiferous tubules towards the lumen, while maintaining contact with Sertoli cells
- not just undergoing division, but physically moving through the testes

41
Q

Testicular cancer almost always originates from abnormal spermatogonia or spermatocytes, not Sertoli nurse cells or Leydig cells
- What do you think might explain this pattern

A

Spermatogonia or spermatocytes undergo cell division more frequently compared to Sertoli cells or Leydig cells
- they are more prone to getting mutations that can lead to them developing into cancer

42
Q

What is the acrosome of a sperm

A

contains enzymes needed to penetrate an ovum during fertilization
- layer at the tip of sperm head that comes from golgi apparatus
- contains enzymes and proteins needed to penetrate ovum

43
Q

Trace the path of sperm development

A
  1. Starts as germ cells (spermatogonia) in the seminiferous tubules and develops into sperm
  2. Still attached to sertoli cells until the end of development into anatomically mature sperm
  3. Detaches from sertoli cells and enters the rete testis (web like)
  4. Sperm may be anatomically mature but is not necessarily functionally mature
44
Q

Where does physiological maturation of sperm occur

A

Occurs in the reproductive tract, starting in the epididymis
- functional maturation of sperm is completed in epididymis
- cilia on the epididymal epithelium help propel immotile sperm through the epididymis

45
Q

Where does anatomical maturation of sperm occur

A

Occurs in the seminiferous tubules

46
Q

How long is transit time for a typical sperm through the epididymis

A

in order to travel from the testes (seminiferous tubules -> rete testis -> epididymis) to as deferencs

= takes about 10-15 days
= takes a long time for it to travel

47
Q

What is immobilin and which type of cell secretes it

Why is important for sperm to be kept immotile until necessary

A

Epididymal cells secrete immobilin which keeps sperm immotile
- flagellum is powered by ATP and is not actively moving/whipping
- would not be energy efficient to always be mobile

48
Q

Epididymal cells also secrete factors which promote maturation processes, such as:

A
  1. Compaction of genetic material
  2. Alteration of sperm plasma membrane
  3. Maturation of acrosome proteins
49
Q

After leaving the seminiferous tubules and into the epididymis, where does sperm go

A

Sperm are transported from the epididymis through the vas deferens/ductus deferens and can also be stored there

50
Q

Where are sperm stored if needed to be stored for several months

A
  • sperm travels through the ductus deferens while they are inactivated or held in suspended animation
  • they can also be stored in the AMPULLA for several months
51
Q

True or False:

The reproductive tract joins with the urinary tract in the male reproductive system

A

True!

The reproductive tract joins the urinary tract just posterior and inferior to the urinary bladder

52
Q

What is capacitation

A

Process by which sperm becomes motile and the process by which they become capable of fertilization

  • MOTILE
  • ABLE TO FERTILIZE
53
Q

When does capacitation begin

A
  • capacitation of sperm begins when they are mixed with secretions from the seminal glands
54
Q

Where does capacitation begin

A

occurs in the ejaculatory duct when sperm mixes with seminal fluid that is secreted from seminal glands (vesicles)

55
Q

Trace the path of sperm to the stage of capacitation

A
  1. Spermatogonia in seminiferous tubules becomes mature sperm
  2. Attached to sertoli cells until anatomically mature, then travels to retes testis and then epididymis
  3. Travels from epididymis to vas deferens
  4. Reaches ejaculatory duct and mixes with seminal fluid secreted from seminal glands
56
Q

Describe the composition of semen

A
  1. sperm
  2. fluid/fructose
  3. seminalplasmin and other enzymes
  4. mucous, antibodies, alkali
57
Q

What is semen

A

Substance secreted by the male reproductive system

58
Q

Where do each of the following components of sperm come from

A
  1. sperm 5%
    = FROM TESTES
  2. fluid/fructose 60-65%
    = FROM SEMINAL GLANDS
  3. seminalplasmin and other enzymes 20-30%
    = FROM PROSTATE GLAND
  4. mucous, antibodies, alkali ~1%
    = BULBOURETHRAL GLANDS
59
Q

Match all the following:

  1. PROSTATE GLAND
  2. BULBOURETHRAL GLANDS
  3. TESTES
  4. SEMINAL GLANDS

a. SPERM
b. SEMINALPLASMIN, OTHER ENZYMES
c. FLUID/FRUCTOSE
d. MUCOUS, ANTIBODIES, ALKALI

i. ~1%
ii. 20-30%
iii. 5-10%
iv. 60-65%

A
  1. PROSTATE GLAND
    b. SEMINALPLASMIN, OTHER ENZYMES
    ii. 20-30%
  2. BULBOURETHRAL GLANDS
    d. MUCOUS, ANTIBODIES, ALKALI
    i. ~1%
  3. TESTES
    a. SPERM
    iii. 5-10%
  4. SEMINAL GLANDS
    c. FLUID/FRUCTOSE
    iv. 60-65%
60
Q

What is the role of the penis

A

Conduct semen and urine to the outside of the body

61
Q

Describe the anatomy of the penis

A
  • surrounds the distal portions of the urethra
  • consists of different tissues
  • has skin (dartos) and smooth muscle within the dermis
  • dorsal veins, arteries and nerve sit within an elastic tissue layer
  • erectile tissue in the corpora cavernosa and corpus spongiosum consists of vascular tissue, elastic connective tissue, and smooth muscle which are CONTRACTED at rest
  • two skeletal muscles connecting the base of the penis to the pelvic floor
62
Q

How is penile tissue influenced by the (parasympathetic) autonomic nervous system

A
  • parasympathetic fibers innervate erectile tissue
  • at rest, smooth muscle in erectile tissue is CONTRACTED and keeps blood out
  • when excited, smooth muscles RELAX and blood can pool = causes an erection
  • during arousal, parasympathetic fibers release nitric oxide which relaxes smooth muscle in the tissue, allowing increased blood flow that fills the vascular spaces, causing an erection
63
Q

How is penile tissue influenced by the somatic nervous system

A
  • lumbosacral somatic motor neurons
  • innervate skeletal muscles at the base of the penis
  • during ejaculation, a spinal reflex produces rhythmic contractions in these muscles (orgasm)
  • orgasm/rhythmic contractions help push semen out of the urethra
  • muscles contract rhythmically when ejaculation occurs
64
Q

At rest, smooth muscles in the penis are:

When excited, smooth muscles in the penis are:

A

At rest = CONTRACTED

Excited = RELAXED

65
Q

How is penile tissue influenced by the (sympathetic) autonomic nervous system

A
  • innervates the epididymis, vas deferens, and seminal vesicles
  • become active during stimulation and causes sperm and secretions to move into the urethra
66
Q

Identify the true statements about the functions of the male genitalia:

A. Most of the volume of semen is
produced by the seminal vesicles.

B. Erection involves enhanced contraction of smooth muscle, pushing blood into the erectile tissue.

C. The prostate gland is involved in
maintaining erection.

D. A spinal cord injury in the cervical spine would permanently destroy all male sexual response.

A

A. TRUE = seminal vesicles release fluid/fructose into semen, making up 60-65% of it

B. FALSE = contraction involves the RELAXATION of smooth muscles

C. FALSE = prostate gland contributes secretions to semen, but does not involve itself with erection… Erections are caused by erectile tissue relaxing

D. FALSE = spinal cord injury would impair the male sexual response but would not permanently destroy all responses = can still respond to some sensory stimuli

67
Q

Which axis contains spermatogenesis and testicular hormonal secretions

A

HPG axis
= hypothalamus, pituitary, gonads

68
Q

Which two pituitary gonadotropins have distinct effects on the testes

A

FSH and LH

69
Q

How does FSH and LH affect the testes

A
  1. Leydig cells = stimulated by LH
    = activation directs androgen synthesis and release
  2. Sertioli cells = stimulated by FSH
    = get activated to start spermatogenesis -> spermatogonia to final sperm
    = sertoli cells also produce a regulatory hormone, inhibin
70
Q

Which of the three functional classes of cells produce the regulatory hormone inhibin in the testes

A

SERTIOLI CELLS

71
Q

Describe the regulation of GnRH in a typical male

A

GnRH is secreted from the hypothalamus in a regular, pulsatile manner

  • synaptic and hormonal influences on GnRH neurons in the hypothalamus create regular bursts of activity
72
Q

How often do bursts of activity occur in the masculinized brain

A

These bursts of activity create pulses of increased LH and FSH secretion from the anterior pituitary, which occur about once every TWO hours

73
Q

What happens if the rhythm of pulsatile GnRH secretion is disrupted

A
  • Testicular functions are impaired
  • if there isn’t a regular release of GnRH, there is no regular release of LH or FSH which can lead to impairment of the testes
74
Q

What kind of hormones do Sertoli cells release

A
  • inhibin
  • ABP
75
Q

How do sertoli cells enhance sperm function

A
  • maintain blood-testis barrier
  • maintain spermatogonia numbers
  • direct spermatocytes to complete meiosis
  • promote adhesion and development of spermatids
76
Q

True or False:

Spermatogonia and sperm express androgen receptors

A

FALSE

Spermatogonia and sperm DO NOT actually express androgen receptors

77
Q

How do gonadal hormones interact with the HPG axis (what type of feedback loop)

A

Gonadal hormones provide negative feedback to the HPG axis
- happens at the level of the hypothalamus and anterior pituitary

78
Q

How does androgen provide negative feedback on the HPG axis

A
  • androgenic negative feedback appears to occur mostly at the hypothalamus
79
Q

How does inhibin provide negative feedback on the HPG axis

A
  • inhibin has a major role in inhibiting the secretion of gonadotropes found in the anterior pituitary

BIOL155 (34 decks)

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