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Male Repro Physio
Male Reproductive Physiology
Term | Meaning |
---|---|
Interstitial cells | within the testes are the site of testosterone production (aka Leydig cells) |
Leydig cells / interstitial cells | secrete testosterone from stimulation of LH from the anterior pituitary. These cells lie in the soft connective tissue surrounding the seminiferous tubules |
Testosterone | a steroid sex hormone that is responsible for the growth and development of masculine characteristics and enhances sperm development in the seminiferous tubules |
Effects of testosterone | 1)stim descent of testes before birth, 2)controls growth and dev of male sex organs, 3)stim bone growth and protein anabolism, 4) stim development of male secondary sex characteristics (more muscle, deep voice, narrow hips, etc) |
Seminiferous tubules | located within the testes is the site of sperm production |
Spermatogenesis | the production of sperm cells within the seminiferous tubules is by a special type of cell division called meiosis, stimulated by FSH; produces 4 spermatozoa (sperm cells) |
Stages of Spermatogenesis | Spermatogonium, spermatocytes (primary then secondary), spermatid, spermatozoan |
Spermatogonium | are located in the seminiferous tubules and contains 46 chromosomes (diploid) |
Primary spermatocyte | produced from spermatogonium, it divides into two (2) secondary spermatocytes |
Secondary spermatocyte | produced from primary spermatocytes, it divides into four (4) spermatids |
Spermatid | produced from secondary spermatocytes, it has 23 chromosomes but needs to undergo spermiogenesis to mature it further (haploid) |
Spermatozoan | a sperm cell that contains 23 chromosomes; it has a head (contains the nucleus and a helmet-like acrosome), a midpiece (contains mitochondria, for ATP), and a tail (flagellum) for locomotion |
Sertoli cells / Sustentacular cells | located between the developing sperm in the seminiferous tubules are stimulated by FSH to begin spermatogenesis and inhibin secretion |
Inhibin | exerts a negative feedback to hypothalamus adjust FSH secretion. If inhibin level is high, the hypothalamus lowers sperm production by reducing FSH, if level is low, the hypothalamus increases sperm production by increasing FSH |
Sertoli cell function | 1)forms “blood testes barrier” to protect sperm from recognition by B and T cells, 2) protect and nourish developing sperm, 3)secrete inhibin, to inhibit the release of FSH by the anterior pituitary to control rate of spermatogenesis |
FSH | Hormone that promotes sperm production |
LH or ICSH (interstitial cell secreting hormone | Hormone that promotes testosterone production. LH binds to the interstitial cells and stimulates them to secrete testosterone. |
Erection | enlargement and stiffening of the penis results from engorgement of the erectile bodies with blood |
Erection physiology | sexual excitement triggers parasympathetic to release of nitric oxide locally, which relaxes vascular smooth muscle, causing these arterioles to dilate and fill the erectile bodies with blood. This expansion compreses drainage veins. |
diploid | contains 46 chromosomes; has two copies of each chromosome |
haploid | contains 23 chromosomes |
acrosome | contains hydrolytic enzymes that enable the sperm to penetrate and enter an egg |
Factors that can suppress sperm formation | common antibiotics such as tetracycline, radiation, lead, certain pesticides, marijuana, and excessive alcohol |
Variocele | a condition that hinders drainage of the testicular vein, results in an elevated temperature in the scrotum that interferes with normal sperm development |
Meiosis | reduction division; 46 chromosomes divide into 23 chromosomes; occurs only in certain reproductive organs |
Mitosis | process during which the chromosomes divide into two daughter nuclei; nuclear division; Consists of prophase metaphase, anaphase and telphase. |
Inhibin production | a protein hormone produced by the Sertoli cells regulates the rate of spermatogenesis |
Testicular hormones | testosterone and inhibin; exert a negative feedback control on the hypothalamus and anterior pituitary |
GnRH | Gonadotropin-releasing hormone, controls the release of the anterior pituitary gonadotropins, FSH and LH |