Week 4; SPERMS AND THEIR ORIGINS

Question 1

State the functions of the male reproductive system

Answer 1

*Spermatogenesis
*Delivery of the sperm to the female

Question 2

Briefly describe the process of sperm production

Answer 2

*Spermatogonia undergoes mitotic division forming several cells,
*Half of the cells form spermatocytes while the rest remain as stem cells to insure there is consistent supply of sperm cells
*Primary spermatocytes undergo meiosis to form secondary spermatocytes
*Secondary spermatocytes form spermatids
*Spermatids then form spermatozoa

Question 3

Describe how a spermatid matures

Answer 3

1. Appearance o acosomal vesicle and flagellum in the spermatid
2. Growth of acrosome and flagellum
   3.Shedding of excess cytoplasm

Question 4

What is the unction of the acrosome in a sperm?

Answer 4

It contains enzymes with break down the outer membrane of the ovum, allowing the sperm to fertilize the ovum

Question 5

State the changes that occur during adolescence

Answer 5

*enlargement and maturation of gonads
*development of secondary sexual characteristics
*achievement of fertility
*Growth and maturation of the reproductive tract
*attainment of libido ( sex drive)

Question 6

State the effects of testosterone on the reproductive system before birth

Answer 6

*results in masculinization of the reproductive tract
*Promotes development of external genitalia
*Promotes descent of the testis into the scrotum

It then ceases after birth until puberty starts

Question 7

What is castration?

Answer 7

Surgical removal of the testis

Question 8

State the other reproduction related effects of testes

Answer 8

Develops the libido at puberty
Controls gonadotropin hormone secretion

Question 9

State the effects of testosterone on secondary sexual characteristics

Answer 9

*hair growth: beard,chest hair
*Deep voice caused by enlargement of the larynx and thickening of vocal cords
*Thin skin
*The male body configuration ( broad shoulders, heavy arm and leg masculature) as a result of protein disposition

Question 10

What is a Eunuch?

Answer 10

A man castrated before puberty.

He does not mature sexually and does not develop secondary sexual characteristics

Question 11

State the non reproductive effects of testosterone

Answer 11

*Exerts a protein anabolic effect
*Promotes bone growth at puberty
*Closes the epiphyseal plates after being converted to estrogen by aromatase
*May induce aggressive behavior

Question 12

Testosterone is converted to estrogen,a female sex hormone.Name the enzyme catalyzing this process

Answer 12

Aromatase

Question 13

Where is aromatase abundant?

Answer 13

In the adipose tissue

Question 14

State the 3 parts of a spermatozoa

Answer 14

*Head: acrosome, nucleus

*Midpiece: mitochondria

*Tail: microtubules
-The bundle of microtubules that span the entire length of the tail is critical for flagellar beating.

Question 15

Throughout their development, sperm remain intimately associated with Sertoli cells.
Sertoli cells form tight and gap junctions with the developing sperms.
Name the process of the final release of a spermatozoa from Sertoli cells which requires the breakdown of the gap and tight junctions

Answer 15

Spemiation

Question 16

What does ADAM stand for?

Answer 16

Androgens Deficiency in Aging Males

Question 17

State the 7 roles of Sertoli cells in Spermatogenesis

Answer 17

*Produce Mullerian inhibiting hormone (Antimullerian hormone)
*Regulates Spermatogenesis through acting as a site for action of FSH and testosterone
*Forms the blood testis barrier
*Nourishes the sperm cells
*Maintains high levels of testosterone to sustain sperm production in the seminiferous tubules by having Androgen binding receptors
*Secretes a fluid which flushes the released sperm from the tubule into the epididymis for storage and further processing
* Carry out phagocytic function,They engulf the cytoplasm extruded from the spermatids during their remodeling and destroy defective germ cells that fail to successfully complete all stages of spermatogenesis

Question 18

In what form is glucose taken up by the GLUT 1 symporter converted to before being transfered to the sperms cells for energy for energy source?

Answer 18

Lactate

Question 19

What is the function of Luteinizing hormone in Spermatogenesis regulation?

Answer 19

It regulates testosterone release in Leydig cells

Question 20

What is the role of FSH in spermatogenesis?

Answer 20

Acts on Sertoli cells and induce spermatogenesis

Question 21

Name the hormone from the pituitary gland that stimulates FSH and LH secretion by the Anterior pituitary gland

Answer 21

Gonadotropin releasing hormone

Question 22

How does testosterone regulates the secretory rate of LH?

Answer 22

Through negative feedback
When in high amounts,it inhibits the Gonadotropin releasing hormone in the hypothalamus
It also acts directly on the anterior pituitary gland to reduce LH secretion

Question 23

Name the hormone released by Sertoli cells that control FSH secretion that acts directly on the anterior pituitary gland.

Answer 23

Inhibin

Question 24

How can the arcuate nucleus regulates FSH secretion?

Answer 24

They have Kiss1 neurons which secretes kisspeptins which are neurotransmitters that stimulates Gonadotropin Releasing Hormone

Question 25

How is the stimulation of the Gonadotropin Releasing Hormone by the Kiss1 neurons in the arcuate nucleus regulated?

Answer 25

Testosterone acts on the Kiss1 neurons and inhibits their excitatory action on Gonadotropin Releasing Hormone secretory neurons.

Question 26

Why don’t kiss 1 neurons act directly on the Gonadotropin Releasing Hormone secretory neurons when regulating FSH and LH levels during spermatogenesis?

Answer 26

Gonadotropin Releasing Hormone secretory neurons do not have Androgen receptors

Question 27

How does the Sertoli cells maintain high testosterone levels in the seminiferous tubules?

Answer 27

It has Androgen Binding Receptors which retains the testosterone produced locally by the Leylig cells in the seminiferous tubules

Question 28

State the two hormones that are involved in spermatogenesis and their functions

Answer 28

Testosterone: facilitates mitosis and meiosis of the germ cells
FSH: is needed in spermatids remodeling

Question 29

State the functions of Growth hormone and Activin on sperm production.

Answer 29

GH –stimulates spermatogenesis.
Activin- stimulates FSH release.

Question 30

State the effects of melatonin and leptin in Gonadotropin hormones

Answer 30

Melatonin:has an anti-gonadotopic effect
Leptin: plays an important role in puberty onset in females

Question 31

What is capacitation?

Answer 31

The enhancement of the sperm’s capacity to fertilize in the male reproductive duct and by the exposure to secretions in the female reproductive tract .

Question 32

What is vasectomy?

Answer 32

A surgical removal of a small segment of the vas deferens after it passes the testis but before it enters the inguinal canal, thus blocking exit of sperms from the testis.

Question 33

What is benign prostatic hypertrophy (BPH) ?

Answer 33

A condition in which the prostate enlarges in middle age to older age

Question 34

What is semen?

Answer 34

A mixture of sperms, accessory sex gland secretion and mucus.

Question 35

State the functions of Growth hormone and Activin on sperm production.

Answer 35

GH –stimulates spermatogenesis.
Activin- stimulates FSH release.