Week 4; SPERMS AND THEIR ORIGINS Flashcards
State the functions of the male reproductive system
*Spermatogenesis
*Delivery of the sperm to the female
Briefly describe the process of sperm production
*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
Describe how a spermatid matures
- Appearance o acosomal vesicle and flagellum in the spermatid
- Growth of acrosome and flagellum
3.Shedding of excess cytoplasm
What is the unction of the acrosome in a sperm?
It contains enzymes with break down the outer membrane of the ovum, allowing the sperm to fertilize the ovum
State the changes that occur during adolescence
*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)
State the effects of testosterone on the reproductive system before birth
*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
What is castration?
Surgical removal of the testis
State the other reproduction related effects of testes
Develops the libido at puberty
Controls gonadotropin hormone secretion
State the effects of testosterone on secondary sexual characteristics
*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
What is a Eunuch?
A man castrated before puberty.
He does not mature sexually and does not develop secondary sexual characteristics
State the non reproductive effects of testosterone
*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
Testosterone is converted to estrogen,a female sex hormone.Name the enzyme catalyzing this process
Aromatase
Where is aromatase abundant?
In the adipose tissue
State the 3 parts of a spermatozoa
*Head: acrosome, nucleus
*Midpiece: mitochondria
*Tail: microtubules
-The bundle of microtubules that span the entire length of the tail is critical for flagellar beating.
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
Spemiation
What does ADAM stand for?
Androgens Deficiency in Aging Males
State the 7 roles of Sertoli cells in Spermatogenesis
*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
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?
Lactate
What is the function of Luteinizing hormone in Spermatogenesis regulation?
It regulates testosterone release in Leydig cells
What is the role of FSH in spermatogenesis?
Acts on Sertoli cells and induce spermatogenesis
Name the hormone from the pituitary gland that stimulates FSH and LH secretion by the Anterior pituitary gland
Gonadotropin releasing hormone
How does testosterone regulates the secretory rate of LH?
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
Name the hormone released by Sertoli cells that control FSH secretion that acts directly on the anterior pituitary gland.
Inhibin
How can the arcuate nucleus regulates FSH secretion?
They have Kiss1 neurons which secretes kisspeptins which are neurotransmitters that stimulates Gonadotropin Releasing Hormone
How is the stimulation of the Gonadotropin Releasing Hormone by the Kiss1 neurons in the arcuate nucleus regulated?
Testosterone acts on the Kiss1 neurons and inhibits their excitatory action on Gonadotropin Releasing Hormone secretory neurons.
Why don’t kiss 1 neurons act directly on the Gonadotropin Releasing Hormone secretory neurons when regulating FSH and LH levels during spermatogenesis?
Gonadotropin Releasing Hormone secretory neurons do not have Androgen receptors
How does the Sertoli cells maintain high testosterone levels in the seminiferous tubules?
It has Androgen Binding Receptors which retains the testosterone produced locally by the Leylig cells in the seminiferous tubules
State the two hormones that are involved in spermatogenesis and their functions
Testosterone: facilitates mitosis and meiosis of the germ cells
FSH: is needed in spermatids remodeling
State the functions of Growth hormone and Activin on sperm production.
GH –stimulates spermatogenesis.
Activin- stimulates FSH release.
State the effects of melatonin and leptin in Gonadotropin hormones
Melatonin:has an anti-gonadotopic effect
Leptin: plays an important role in puberty onset in females
What is capacitation?
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 .
What is vasectomy?
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.
What is benign prostatic hypertrophy (BPH) ?
A condition in which the prostate enlarges in middle age to older age
What is semen?
A mixture of sperms, accessory sex gland secretion and mucus.
State the functions of Growth hormone and Activin on sperm production.
GH –stimulates spermatogenesis.
Activin- stimulates FSH release.
