The Male Reproductive System Flashcards
What is role does the testis have in the male reproductive system ?
Testis: An organ which produces spermatozoa (male reproductive cells)
What is the epididymis and what is its function ?
The epididymis is a coiled tube behind the testis that connects the testicles to the vas deferens, which transport sperm to the urethra.
Function: Collects and stores sperm, and helps sperm mature before ejaculation
What affect does overheating have on the testes?
Overheating of testes reduced sperm count
Meiosis in males: what happens during the interphase ( S-phase) in meiosis?
Each chromosome is duplicated
What are tetrads?
Tetrads (group or set of 4) are two pairs of sister chromatids (sister chromatids)
Meiosis in males: what happens in prophase? (2)
the chromosomes condense (they become shorter and fatter) and the nuclear envelope disintegrates.
The centrioles move to opposite poles of the cell and form spindle fibres.
Meiosis in males: what happens in metaphase I? (3)
Tetrads align at the metaphase plate (equator), each connected to the spindle fibre via their centromeres.
Crossing over occurs leading to different combinations of genes
Centrioles contract-> sister chromatids move to opposite poles of the cell
Meiosis in males: what is the result of meiosis I ?
After meiosis I, each cell has one pair of sister chromatids that are no longer identical due to crossing over.
Meiosis in males: what is the result of meiosis II?
MII is another cycle of cell division in which the sister chromatids separate to give a single unique chromosome in each daughter cell.
4 genetically different daughter cells each contains one chromosome ( haploid)
What is spermatogenesis?
Spermatogenesis: the process by which spermatogonia (germ/stem cells) undergo meiosis to produces primary spermatocytes which further differentiate into mature haploid spermatozoa
Where is spermatogonia found ?
spermatogina (germ cells/stem cells) are found on the basement membrane of the seminiferous tubules
- What does mitosis of spermatogonia produce?
- What does meiosis of spermatogonia produce ?
- More spermatogonia
- Primary spermatocytes
What happens to primary spermatocytes ?
Primary spermatocytes move into the adluminal compartment between adjacent Sertoli cells and undergo meiosis I.
Meiosis II occurs to give 4 haploid spermatids (23 single chromosomes).
Round spermatids then differentiate into elongated spermatids. Mature spermatozoa are extruded into the lumen
What hormone does the hypothalamus release that plays an important role in the male reproductive system?
The Hypothalamus produces Gonadotrophin Releasing Hormone (GnRH) which is a 10 amino acid long dipeptide. It is released in pulses from the hypothalamus and travels to the pituitary gland where it is secreted to stimulate the release of LH and FSH from the pituitary gland.
What effect does pulsating vs continuous release of GnRH have on LH and FSH ?
Pulsatile GnRH secretion : stimulates LH and FSH secretion
Continuous GnRH secretion: decreases LH and FSH secretion
What are group of hormones do FSH and LH belong to ?
FSH and LH are glycoprotein hormones collectively known as Gonadotrophins
What is the difference between Gonadotrophin hormones FSH and LH
Gonadotrophin hormones are heterodimeric peptides which a common alpha-subunit and hormone specific beta-subunit
( beta strands are different lengths )
What is the role of FSH in the males?
.FSH stimulates the gonads (testes) - for growth and sperm production
.FSH maintains healthy testicular cells and regulates spermatogenesis
What is the role of LH in males?
. LH causes the testes to produce testosterone and other androgens
What are Gonadotrophins used for in pharmacology?
. stimulate the gonads, primarily in cases of infertility or subfertility. They are commonly used in females especially for ovulation induction or in IVF cycles.
What is the main sex steroid in men
Testosterone
How many carbons are in progestogens (female) vs androgens (male)?
Progestogens- 21 carbons
Androgens- 19 carbons
What nervous system pathway is responsible for erections ?
Parasympathetic nervous system
What causes an erection ? (2)
Parasympathetic derived acetylcholine binds to muscarinic receptors on endothelium causing release of nitric oxide which diffuses to arterial smooth muscle causing relaxation and vasodilation. = swelling
Greater blood flow into the penis compresses the veins causing partial constriction of the venous return.
What nervous system pathway is responsible for ejaculation?
Sympathetic nervous system
What causes ejaculation ? (3)
.Co-ordinated smooth muscle contractions of vas deferens, glands and urethra.
•Movement of sperm into epididymis, vas deferens, penile urethra (emission).
•Expulsion of the glandular secretions & evacuation of urethra (ejaculation).
How do antagonists of GnRH work ?
Antagonists of GnRH bind to GnRH receptors without stimulating it . This blocks GnRH from stimulating FSH and LH- acts as a puberty blocker
What do all sex steroids have in common?
All sex steroids (progestogens and androgens) are derived from cholesterol
What does viagra do?
Inhibits phosphodiesterase meaning less cGMP is converted back into GMP -> increases relaxation of arterial smooth muscle -> increased vasodilation=erection
