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PHGY 216 Mod 2 > Section 2 > Flashcards

Section 2 Flashcards

1
Q

Where are the testes located in the male reproductive system?

A

The testes are located outside the abdominal cavity and within the scrotal sac.

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2
Q

When do the testes typically descend into the scrotum?

A

In most males, the testes will descend into the scrotum in the last months of fetal life.

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3
Q

What is the term for the condition when testes fail to descend during gestation?

A

When testes fail to descend during gestation, the condition is called cryptorchidism.

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4
Q

What typically happens for the majority of premature male babies regarding the descension of the testes?

A

For the majority of premature male babies, the testes will descend in early childhood.

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5
Q

What is cryptorchidism, and what are its consequences?

A

Cryptorchidism is the condition where the testes remain undescended into adulthood. This condition results in sterility.

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6
Q

Describe what you would predict to be the significance of the location of the testes.

A

The location of the testes is physiologically important to one of the primary roles of the testes,
spermatogenesis*.

The temperature within the scrotum averages several degrees Celsius less than normal body (core) temperature. Descent of the testes into this cooler environment is essential, because spermatogenesis is temperature sensitive and cannot occur at normal body temperature.

Therefore, an individual with cryptorchidism is unable to produce viable sperm.

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7
Q

What two muscles play a role in varying the position of the scrotum in relation to the abdominal cavity?

A

The cremaster muscle and dartos muscle play a role in varying the position of the scrotum in relation to the abdominal cavity.

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8
Q

What is the role of the cremaster muscle and dartos muscle in regulating testicular temperature?

A

The cremaster muscle and dartos muscle, along with a spinal reflex mechanism, play an important role in regulating testicular temperature by adjusting the position of the scrotum.

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9
Q

How do the scrotal muscles (cremaster and dartos muscles) respond when the testes are too cold for spermatogenesis?

A

When the testes are too cold for spermatogenesis, the scrotal muscles contract (cremaster and dartos muscles) to bring the testes closer to the body, retaining heat.

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10
Q

What is the response of the scrotal muscles when the testes are too hot for spermatogenesis?

A

When the testes are too hot for spermatogenesis, the scrotal muscles relax to move the testes away from the body, allowing them to cool down.

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11
Q

What is the structural composition of the majority of the testes?

A

The majority of the testes consists of coiled seminiferous tubules, which are structures where sperm are produced.

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12
Q

Where are Leydig cells located, and what is their function?

A

Leydig cells are located within the connective tissues between the seminiferous tubules in the testes. They produce and secrete testosterone.

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13
Q

Where does most of the testosterone secreted by Leydig cells go, and what does it support?

A

Most of the testosterone secreted by Leydig cells enters the lumen of the seminiferous tubules, where it supports sperm production.

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14
Q

What are the five categories of actions of testosterone?

A

The actions of testosterone can be grouped into five categories: effects before birth, effects on sex-specific tissues after birth, other reproductive effects, effects on secondary sexual characteristics, and non-reproductive actions.

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15
Q

What are some effects of testosterone before birth?

A

Before birth, testosterone causes the masculinization of the reproductive tract and external genitalia and facilitates the descent of the testes into the scrotum.

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16
Q

What are the effects of testosterone on sex-specific tissues after birth?

A

After birth, testosterone maintains the reproductive tract throughout adulthood, promotes spermatogenesis, and supports the maturation of the reproductive system at puberty.

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17
Q

What reproductive effects does testosterone have during puberty?

A

Testosterone during puberty develops sex drive and controls the secretion of gonadotropin hormone.

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18
Q

What are some secondary sexual characteristics influenced by testosterone?

A

Testosterone causes the voice to deepen, the development of male pattern body hair, and promotes muscle growth (protein anabolism).

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19
Q

What non-reproductive actions does testosterone have?

A

Testosterone promotes bone growth at puberty, plays a role in the closing of the epiphyseal plates, and may induce aggressive behavior.

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20
Q

Where does spermatogenesis take place within the testes?

A

Spermatogenesis takes place within the highly-coiled seminiferous tubules within the testes.

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21
Q

What are the two main cell types present in the majority of seminiferous tubules?

A

The two main cell types present in the majority of seminiferous tubules are germ cells and Sertoli cells.

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22
Q

What is the primary function of seminiferous tubules?

A

Seminiferous tubules are the location of spermatogenesis, the process of sperm cell development.

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23
Q

What is spermatogenesis, and what is the chromosome count in the final sperm cells?

A

Spermatogenesis is the process in which diploid primordial germ cells are converted into motile sperm cells with a haploid set of chromosomes (23 chromosomes).

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24
Q

What are the primordial germ cells called, and where are they located?

A

The primordial germ cells are called spermatogonia, and they are located in the outermost layer of the seminiferous tubule.

25
Q

Describe the process of mitotic proliferation in spermatogenesis.

A

Spermatogonia continuously undergo mitotic division to create a constant supply of new germ cells.

After each division, one daughter cell remains at the outer edge, and the other migrates toward the lumen of the tubule. The migrating cell will undergo two more mitotic divisions to produce four identical primary spermatocytes, which enter a resting phase in preparation for meiosis I.

26
Q

What happens during meiosis in spermatogenesis?

A

Each primary spermatocyte forms two secondary spermatocytes, each with 23 double-stranded chromosomes. During meiosis II, each secondary spermatocyte results in two spermatids, each with 23 single-stranded chromosomes.

27
Q

How many spermatids can be produced for each spermatogonium in spermatogenesis?

A

For each spermatogonium, 16 spermatids can be produced.

28
Q

What is the final maturation process in spermatogenesis, and what happens during this phase?

A

The final maturation process in spermatogenesis is packaging. During this phase, spermatids mature into spermatozoa by being stripped of all non-essential components, such as cytosol and most organelles.

29
Q

Determine whether each of the following is a haploid OR diploid cell, with single OR double stranded chromosomes

Spermatogonium
Spermatogonia
Primary spermatocytes
Secondary spermatocytes
Spermatids
Spermatozoa

A

Spermatogonium:
DIPLOID, SINGLE

Spermatogonia:
DIPLOID, SINGLE

Primary spermatocytes:
DIPLOID, DOUBLE

Secondary spermatocytes:
HAPLOID, DOUBLE

Spermatids:
HAPLOID, SINGLE

Spermatozoa:
HAPLOID, SINGLE

30
Q

What is the main component of the head of a mature spermatozoa?

A

The head of a mature spermatozoa consists of the nucleus.

31
Q

What is the function of the acrosome in a mature spermatozoa?

A

The acrosome is an enzyme-packed vesicle at the tip of the head of a mature spermatozoa, and it is needed to penetrate the ovum during fertilization.

32
Q

What is the primary role of the midpiece in a mature spermatozoa?

A

The midpiece of a mature spermatozoa is packed full of mitochondria to provide energy for locomotion.

33
Q

What is the function of the tail (flagellum) in a mature spermatozoa?

A

The tail (flagellum) of a mature spermatozoa provides propulsion, and the movement requires a significant amount of ATP (adenosine triphosphate).

34
Q

What makes up the walls of the seminiferous tubules, providing structural support for spermatogenesis?

A

A single layer of Sertoli cells makes up the walls of the seminiferous tubules.

35
Q

How are Sertoli cells connected to their neighboring cells?

A

Sertoli cells are connected to their neighboring cells by tight junctions.

36
Q

What happens to developing sperm cells during spermatogenesis as they migrate towards the lumen of the seminiferous tubules?

A

During spermatogenesis, developing sperm cells pass between Sertoli cells as they migrate towards the lumen.

37
Q

What role do Sertoli cells play in the migration of developing sperm cells?

A

Developing sperm cells are essentially engulfed by Sertoli cells as they migrate towards the lumen. The sperm head remains embedded in the Sertoli cells until it is mature.

38
Q

What is the function of the tight junction formed by Sertoli cells in spermatogenesis?

A

The first function of Sertoli cells is to form tight junctions, creating the blood-testes barrier. This barrier allows Sertoli cells to control the intratubular environment, optimizing it for developing spermatozoa.

39
Q

What are the six functions of Sertoli cells?

A
  1. Form tight junctions to create the blood-testes barrier, allowing control of the intratubular environment for developing spermatozoa.
  2. Nourish sperm cells.
  3. Absorb developing sperm cytoplasm and remove defective germ cells.
  4. Secrete seminiferous tubule fluid into the lumen to flush released sperm into the epididymis for storage.
  5. Secrete androgen-binding protein, concentrating testosterone in the lumen.
  6. Serve as the site of action for testosterone and FSH to regulate spermatogenesis.
40
Q

What hormones control the testes, and where are they produced?

A

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) control the testes. These hormones are produced in response to gonadotropin-releasing hormone (GnRH) released from the hypothalamus.

41
Q

What is the role of LH in males, and which cells does it stimulate?

A

In males, LH stimulates Leydig cells to secrete testosterone.

42
Q

What is the role of FSH in males, and which cells does it act on?

A

FSH acts on Sertoli cells to stimulate spermatogenesis and to secrete inhibin.

43
Q

What is the direct negative-feedback pathway of testosterone in hormonal regulation?

A

Testosterone has a direct negative-feedback pathway at the level of both the hypothalamus to decrease GnRH release and at the anterior pituitary to decrease LH and FSH release.

44
Q

What is the role of inhibin in hormonal regulation, and which cells release it?

A

Inhibin, released by Sertoli cells, feeds back to the anterior pituitary to decrease FSH release.

45
Q

_____________: Released by Sertoli cells, feeds back to the anterior pituitary to decrease FSH release

A

Inhibin

46
Q

_____________: Stimulates the Leydig cells to secrete testosterone

A

LH

47
Q

_____________: Has a direct negative-feedback pathway at the level of both the hypothalamus and the anterior pituitary

A

Testosterone

48
Q

_____________: Acts on the Sertoli cells to stimulate spermatogenesis and to secrete inhibin

A

FSH

49
Q

_____________: Stimulates the anterior pituitary to release LH and FSH

A

GnRH (gonadotropin-releasing hormone)

50
Q

What is the primary function of the epididymis in the male reproductive tract?

A

The epididymis serves as a tightly coiled tube around 5m in length, where sperm produced in the seminiferous tubules are swept. Sperm, upon entering the epididymis, are not initially motile, mainly due to the low pH in this region.

51
Q

What structure forms from the convergence of epididymal ducts, and where does it empty?

A

The ductus deferens forms from the convergence of epididymal ducts, and it empties into the urethra.

52
Q

How long can sperm be stored in the epididymis?

A

Sperm can be stored for months in the epididymis.

53
Q

What are the three primary accessory sex glands in males, and what is the main function of their secretions?

A

The three primary accessory sex glands in males are responsible for producing secretions that make up the bulk of semen. These secretions function to provide support for the continuing viability of sperm inside the female reproductive tract.

54
Q

How many seminal vesicles are there, and where do they empty their contents?

A

There are two seminal vesicles, with each one emptying into each of the ductus deferens just before the urethra.

55
Q

What are the primary purposes of seminal vesicles in the male reproductive system?

A

The primary purposes of seminal vesicles are to:

  • provide the bulk of the semen
  • supply fructose as an energy source for ejaculated sperm
  • secrete prostaglandins to cause smooth muscle contractions in both the male and female reproductive tracts
  • ## secrete fibrinogen.
56
Q

What is the definition of fibrinogen?

A

Fibrinogen is a precursor of the protein fibrin, which forms the meshwork of a clot.

57
Q

Where is the prostate gland located in the male reproductive system?

A

The prostate gland is a large gland that surrounds the ejaculatory ducts and urethra.

58
Q

What are the two primary purposes of the prostate gland?

A
  1. The prostate glands, also referred to as Cowper’s glands, are a pair of glands that empty into the urethra, one on each side, before the urethra enters the penis.
  2. They secrete a clear substance during sexual arousal, and this fluid helps to lubricate the urethra for sperm to pass through.
59
Q

What are the primary functions of the bulbourethral glands in the male reproductive system?

A
  1. To secrete an alkaline fluid to neutralize the acidic environment of the vagina.
  2. To secrete clotting enzymes that act on fibrinogen from the seminal vesicles, producing fibrin to clot the semen and keep it within the female reproductive tract.

PHGY 216 Mod 2 (7 decks)

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