BSC2086 1st Edition Lecture 24 Outline of Last Lecture I Introduction to the reproductive system II Structures of the reproductive system III Male reproductive functions Outline of Current Lecture I Male Reproductive Functions continued II Female Reproductive System III Structures of Reproductive System IV Oogenesis V Ovarian Cycle VI Uterine Tubes Current Lecture I Male reproductive functions continued a Spermatozoon i Head 1 Has a nucleus and chromosomes 2 Acrosome cap like compartment found at the tip of the head a Has enzymes needed for fertilization ii Neck 1 Attaches head to middle piece iii Middle piece 1 Has mitochondria which provides ATP to move tail iv Tail 1 ONLY flagellum in the human body 2 Whip like organelle 3 Moves cell from one place to another a Complex corkscrew motion v Mature spermatozoon 1 Does not have a Endoplasmic reticulum b Golgi apparatus c Lysosomes and peroxisomes d Inclusions e Other intracellular structures 2 Organelles not present to reduce sperm size and mass 3 Plasma membrane contains antigens not present in somatic cells 4 Sperm must absorb nutrients such as fructose from the surrounding fluid b Sperm maturation i Testes make physically mature spermatozoa which cannot fertilize an oocyte ii Other parts of the reproductive system are responsible for functional maturation nourishment storage and transport iii Spermatozoa 1 Detach from nurse cells 2 Found free in lumen of seminiferous tubules 3 Functionally immature therefore incapable of locomotion or fertilization 4 Moved by cilia into the epididymis iv Epididymis 1 Start of male reproductive tract 2 Coiled tube almost 7 meters or 23 feet long 3 Bound to the posterior border of the testes 4 Functions to both store and protect spermatozoa received from testes 5 Recycle damaged spermatozoa 6 Monitors adjusts fluid composition in the seminiferous tubules 7 Mature sperm can leave the epididymis but must go through capacitation before they can swim v Capacitation 2 steps 1 Spermatozoa become motile when mixed with seminal gland secretions 2 Spermatozoa become able to fertilize an oocyte when exposed to the female reproductive tract 3 The epididymis secretes substances that prevents early capacitation c Ductus deferens vas deferens 1 Part of the spermatic cord that starts at the tail of the epididymis 2 Ascends through inguinal canal 3 Curves under the bladder toward the prostate and seminal glands 4 Lumen enlarges into ampulla 5 Wall made of thick layer of smooth muscle which performs peristaltic contractions to propel the spermatozoa and fluid 6 Able to store spermatozoa for several months in a state of suspended animation where they have low metabolic rates d Ejaculatory duct 1 Short passage 2 cm or less than an inch 2 Penetrates the wall of the prostate gland 3 Empties into urethra e Urethra f 1 Used by urinary and reproductive system in males 2 18 20 cm or 7 8 inches long from the urinary bladder to the tip of the penis 3 Divided into a Prostatic b Membranous c Spongy Accessory glands i Makes semen mixture of secretions from many glands 1 Each secretion has a distinctive biochemical characteristic ii Important glands are 1 Seminal gland 2 Prostate gland 3 Bulbo urethral glands iii Functions of male glands 1 Activate spermatozoa 2 Give nutrients to spermatozoa needed motility 3 Propel spermatozoa and fluids along the reproductive tract a Mainly by peristaltic contractions 4 Produce buffers which counteract acidicity of the environments of the urethra and vaginal environments iv Seminal glands 1 Make seminal fluid which makes up about 60 of semen volume a Empties into prostatic urethra 2 Same osmotic concentration as blood plasma but different composition a High fructose which is easily metabolized by spermatozoa b Smooth muscle contractions stimulated by prostaglandins i In both males and females c Fibrinogen makes a temporary clot in the vagina 3 Slightly alkaline to neutralize acids in the vagina and prostate gland 4 Seminal fluid a Starts the first step in capacitation i Spermatozoa start beating flagella and become highly motile b Discharged into the ejaculatory duct at emission when peristaltic contractions begins c Sympathetic nervous system controls contractions v Prostate gland 1 Small muscular organ about 4 cm or 1 6 inches in diameter 2 Encircles the proximal portion of the urethra found under the bladder 3 Surrounded by smooth muscle fibers 4 Prostatic fluid a Makes 20 30 of semen volume b Ejected into prostatic urethra by peristalsis of prostate wall c Slightly acidic d Seminalplasmin may help prevent UTIs in males vi Bulbourethral glands 1 Aka Cowpers glands 2 Compound tubular mucous gland a Empties into spongy urethra 3 Found at base of penis a Duct of each gland travels next to the penile urethra and empties into the urethral lumen 4 Thick alkaline mucus secreted to help neutralize urinary acids in urethra a Lubricates the glans of penis g Semen i 2 5 mL released in a typical ejaculation ii Abnormally low volume may indicate problems with prostate gland or seminal glands iii Sperm count 1 Usually 20 100 million spermatozoa mL of ejaculate 2 In order to determine this semen is collected after 36 hours of sexual abstinence iv Ejaculate 1 Contains spermatozoa seminal fluid and enzymes a Enzymes include i Protease ii Seminalplasmin iii Prostatic enzyme causes semen to coagulate by converting fibrinogen to fibrin a few minutes after ejaculation iv Fibrinolysin after about half hour it liquefies the clotted semen h External genitalia i Penis tubular organ in which distal portion of urethra passes 1 Conducts urine to exterior 2 Introduces semen into females vagina 3 Root fixed portion attaches penis to body wall a This attachment occurs in the urogenital triangle under the public symphysis 4 Body or shaft tubular movable portion of the penis a Composed of 3 cylinder columns of erectile tissue 5 Glans expanded distal end of penis that surrounds the external urethral orifice 6 Dermis of penis a has layer of smooth muscle which is a continuation of dartos muscle b underlying areolar tissue allows the skin to move freely c subcutaneous layer contains superficial veins arteries and lymphatic vessels 7 Prepuce foreskin a Fold of skin surrounding tip of penis attaches to neck and continues over the glans 8 Erectile tissue a Located in body of penis b Has network of vascular channels which are incompletely separated by partitions of elastic connective tissue and smooth muscle fibers c In the
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