Male Reproductive System PDF

Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. endocrine function of gonads MALE REPRODUCTIVE SYSTEM TABLE OF CONTENTS I. II. III. IV. V. Functions Anatomy & Physiology A. Gonads B. Reproductive Tract...

Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. endocrine function of gonads MALE REPRODUCTIVE SYSTEM TABLE OF CONTENTS I. II. III. IV. V. Functions Anatomy & Physiology A. Gonads B. Reproductive Tract & Accessory Organs Hormones and Secretions Sexual Role/Act Dysfunctions FUNCTIONS 1. Production of gametes — sperm or oocytes 2. Fertilization — mature sperm meets mature oocytes 3. Development — Primary and secondary sexual characteristics 4. “Endocrine” role → production of reproductive hormones a. Estrogen, progesterone, testosterone General Overview 1. Gonads a. Testes 2. Reproductive Tract a. Epididymis b. Vas Deferens c. Ejaculatory Duct d. Urethra (prostatic, membranous, penile) 3. Accessory Organs a. Seminal Vesicles b. Prostate Gland c. Bulbourethral Glands Gonads Endocrine function: testosterone and gametogenesis - Located in scrotum: 2 degrees lower than body temp - Enclosed by tunica albuginea MALE REPRODUCTIVE ANATOMY & PHYSIOLOGY 1. Gonads (testes) a. Production of gametes and androgens 2. Reproductive Tract and Accessory Glands a. Storage, development, secretion, transport to external b. Development is dependent on the Two compartments: 1. Intratubular Compartment - Spermatogenesis - Sertoli cells (Nurse cells) 2. Peritubular Compartment Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - Leydig cells → testosterone formation vaginalis disintegrate while lower portion becomes tunica vaginalis → Gubernaculum → scrotal ligament Compartments → Combined length of seminiferous tubule = half a mile → Empty into straight tubule → Rete testis → Efferent ductules → Epididymis Intratubular Compartment: Seminiferous Tubules Spermatogenesis - Descent of Testes 8th Weeks of Gestation - Retroperitoneal Organ → Connected to “scrotum” by gubernaculum 7th to 9th Month of Gestation Moves through the inguinal canal into the scrotum →Testis is preceded by process vaginalis, outpocketing of the peritoneum → Connected to “scrotum” by gubernaculum 9th Month: 98% of the time Testis is in the scrotum → Upper portion of process - Highly complex temporal event: Undifferentiated diploid cell highly specialized haploid cell (sperm) Unique male gamete Immature sperm cells at base, while most mature at luminal side Androgen dependent (Testosterone) Steps 1. Spermatocytogenesis: spermatogonia (stem cells; 2N) undergo mitosis (spermatocytogenesis) - Some daughter cells remain as a stem cell, other daughter cells will undergo meiosis 2. Meiosis I: primary spermatocyte (diploid; 4N) → secondary spermatocyte (haploid; 2N) Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. 3. Meiosis II: secondary spermatocyte spermatids (haploid; 1N) 4. Spermiogenesis: spermatids spermatozoa - Decrease nucleus size, (-) cytoplasm, (+) tail - Acrosome: membrane-enclosed structure; (+) lysosome and hydrolytic enzymes fertilization - It takes 5 weeks 5. Spermiation: Sertoli cells release mature sperm into the lumen - composed of condensed nucleus with the anterior 2/3 covered by the acrosomal cap 2. Midpiece: - abundance of mitochondria → Motility 3. Tail: - central cytoskeleton of 11 microtubules (axoneme) flagellum - Moves at a velocity of 1 – 4 mm/min Sertoli Cells (Nurse Cells) - - Spermatozoa 1. Head - Structural support: provide adherens and gap junctions with all sperm cell stages - Guide sperm cells toward lumen Tight junctions between Sertoli cells form the blood-testis barrier - Restrict the movements of substances between the blood and sperm cell which would allow the Sertoli to control the availability of nutrients to the germ cells - Creates a specialized, immunologically safe microenvironment for developing sperM Essential for sperm viability and development Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - - - - Express androgen receptor and an FSH receptor Produce androgen-binding protein (ABP) to maintain high androgen (testosterone) levels in the testis Produce fluid as bathing medium for sperms and assist moving immotile sperm from ST to epididymis Phagocytic function engulfing residual bodies or the excess cytoplasm from spermiogenesis Also secretes: - Inhibin for negative feedback to FSH production - Mullerian-inhibiting substance (MIS) during embryonic development - Aromatase to convert testosterone to estradiol Peritubular Compartment 1. Leydig Cells → Testosterone formation - Steroidogenic stromal cells - Express LH Receptor produces testosterone (from cholesterol) - Contains enzymes necessary for biosynthesis of androgens - Provides both intratesticular and peripheral - Intratesticular T: indirectly affects sperm development (spermatogenesis) by regulating Sertoli cell function; 100X concentrated than peripheral Check Point 1. What are the different parts 2. 3. 4. 5. of the male reproductive tract? Enumerate the timeline of descent of the testis. Arrange and define the following steps in spermatogenesis a. Spermiogensis b. Spermatocytogenesis c. Spermiation What are the functions of the Sertoli Cells? What are the functions of the Leydig Cells? Male Reproductive Tract 1. 2. 3. 4. Epididymis Vas Deferens Ejaculatory Duct Urethra (prostatic, membranous, penile) Epididymis Anatomy - Head, body and tail - Pseudostratified columnar epithelium with stereocilia Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. Functions: - Final sperm maturation for a month; improves unidirectional motility of sperm - Dependent on luminal testosterone-Androgen binding protein complexes Vas Deferens - From tail of epididymis to join with duct of seminal vesicle ejaculatory duct - Part of the spermatic cord: blood vessels and nerves that supply the testis - Pseudostratified columnar with thick smooth muscle Function: - Propel its contents into the prostatic urethra during emission - Storage site similar to epididymis Penis - - - Male organ of copulation Three columns of erectile tissue - 2 dorsal side – corpora cavernosa - 1 ventral side that contains urethra – corpus spongiosum Glans penis: distal end; expansion side → most sensitive part “Foreskin” or prepuce – covers glans penis - Removed thru circumcision Accessory Glands 1. Seminal Vesicles 2. Prostate Gland 3. Bulbourethral Glands (Cowper’s Gland) Seminal Vesicles Role: Responsible for 60-70% of the semen volume Fructose- nutrient for sperm Semenogelins- induce semen coagulation (to block capacitation) Prostate Gland Anatomy: - Glandular and muscle tissue; walnut shaped - At the base of urinary bladder and surrounds the prostatic urethra - Fibrous connective tissue capsule - Pseudostratified or simple columnar epithelium Role: - 20-30% of semen volume - Alkaline - Prostate-specific antigenliquefies coagulated semen Bulbourethral Glands (Cowper’s Gland) Role: Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - Secretes mucus-rich secretion (for lubrication) before emission and ejaculation Biosynthesis - Check Point 1. Trace the pathway of sperm. 2. What is the importance of epididymis, vans deferens? 3. What are the male accessory glands for reproduction? And its role? 4. What is acrosomal reaction? HORMONES & SECRETIONS Androgens - Refer to any steroid hormone that promotes the development and maintenance of the male sex characteristics Effects - Has CYP11A1, 3β- hydroxysteroid dehydrogenase (3β-HSD), CYP17, and 17β-hydroxysteroid dehydrogenase type 3 to convert cholesterol into testosterone 5α-reductase DHT Aromatase Estradiol (at adipose tissue) Several tissues besides the testes—including adipose tissue, brain, muscle, skin, and adrenal cortex Dihydrotesterone - 5α-reductase Type 1: skin - Sebaceous gland activity 5α-reductase Type 2 - Male urogenital tract, genital skin, hair follicle and liver - Masculinization of the external genitalia in utero and for many of the changes associated with puberty, including growth and activity of the prostate gland (secondary sexual characteristics) Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. Transport Metabolism - - - 60% of circulating T bind to sex hormone-binding globulin - 38% to albumin, 2% free Metabolized in liver via conjugation with sulfate or gluconate Approximately 50% of excreted androgens are found as urinary 17-ketosteroids - 30% are from testis Loop Hole - - There are two pools of T (peripheral and intratesticular T), but feedback is only from peripheral T Thus, exogenous androgens can cause excess negative feedback and cause deficiency in intratesticular T - Explains the sterility that occurs in steroid abuse Semen Hypothalamic-Pituitary-TesticularAxis - Composed of sperms (10%) and seminal plasma (90%) Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - - - Secretions from seminal vesicles, prostate, epididymis and bulbourethral glands Usually 2.5-3.5 mL after several days of abstinence Sperm count: 75 to 400 M sperm cells/ml of semen Volume and sperm count decrease rapidly with repeated ejaculation Highly viscous and initially coagulate (Semenogelins) Prostate Specific Antigen SEXUAL ROLE/ACT Erection - - - - A central psychoneuroendocrine and peripheral neuro-vascular event Produced by arteriolar dilation and increased blood flow to erectile tissue Under parasympathetic control (Sacral SC) → release of NO and VIP → relaxation of cavernous smooth muscle Cavernous engorgement presses on veins in the penis thus reduces venous drainage Lubrication - - - Still under parasympathetic control Secretion of urethral and bulbourethral glands - Mucus or “pre-cum” → aid in lubricating during the sexual act Most of the lubrication of coitus is provided by the female sexual organs rather than by the male Lubrication is important; no lubrication= pain= inhibited sexual sensations Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - The mucus also decreases the vaginal acidity - Emission - - - Neural activity shifts from parasympathetic to sympathetic control (T12-L2) Refers to the movement of ejaculate (vas deferens) into the proximal part of the urethra Involves: - Peristaltic contractions of the vas deferens (ampullary portion), seminal vesicles, and prostatic smooth muscles - Secretions of the seminal vesicles and prostate - Internal sphincter of bladder constricts to prevent retrograde ejaculation orgasm then male sexual excitement disappears almost entirely within 1 to 2 minutes and erection ceases, a process called resolution (flaccid state) DYSFUNCTIONS Cryptorchidism - Failure of testis to descend - Failure of processus vaginalis to disintegrate Ejaculation - - - Forceful expulsion of secretions to the exterior; mediated via spinal ejaculation centers (sympathetic) Rhythmic muscular contractions involving the muscles of the pelvic floor and anal sphincter propel the semen to exterior This entire period of emission and ejaculation is called the male Enlarged Prostate Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. Abnormal Spermatogenesis - Andropause - - - Gradual decline in testosterone sperm production - Starts at age 50 - No distinct age - No loss of function unlike in females Male climacteric - decrease libido and sexual function, insomnia, hot flashes, impaired memory and concentration Increase LH and FSH Abnormal Sperm Count - - Men with sperm counts below 20 million/mL, Less than 50% motile sperm, or less than 60% normally Forward progression Conformed sperm are usually infertile. May be due to several factors, e.g. - Damage to tubular epithelium - Excessive temperature to the testes - Cryptorchidism 50% abnormal sperm morphology= infertile Erectile Dysfunction - - Inability to develop or maintain an erection May be due to multiple factors (e.g. hormonal, neurovascular, anatomical, psychogenic, medications/drugs) May be treated using cGMP phosphodiesterase inhibitors (e.g. sildenafil) Human Anatomy and Physiology with Pathophysiology LUNA SOLEIL B. BUENO MT1A // University of the East Ramon Magsaysay Memorial Medical Center Inc. - - - Ejaculation that occurs prior to or within ~1 minute of vaginal penetration Inability to delay ejaculation on all or nearly all vaginal penetrations Negative personal consequences, as distress, bother, frustration, and/or the avoidance of sexual intimacy Check Point 1. Describe the 4 stages of the male sexual act 2. How do cGMP-phosphodiesterase inhibitors help treat erectile dysfunction Retrograde Ejaculation - - - Occurs when the internal urethral sphincter fails to constrict. May result from any process that interferes with the innervation of the vas deferens and bladder neck Presence of 15 sperms/HPF in urine after ejaculation Causes include diabetes, multiple sclerosis, surgery, trauma, etc. Premature Ejaculation