Reproductive Physiology PDF

Dr. Mariam Alawadhi (Pharmacy 2024) 1 Dr. Mariam Alawadhi (Pharmacy 2024) 2 Objectives At the end of these lectures, students should be able to: Understand the mechanism of sex differentiation in the fetus. Describe the function of different parts of the male and female reproductive system Understan...

Dr. Mariam Alawadhi (Pharmacy 2024) 1 Dr. Mariam Alawadhi (Pharmacy 2024) 2 Objectives At the end of these lectures, students should be able to: Understand the mechanism of sex differentiation in the fetus. Describe the function of different parts of the male and female reproductive system Understand the process of spermatogenesis and oogenesis REPRODUCTIVE PHYSIOLOGY Understand the hormonal control of testicular and ovarian steroidogenesis Understand the endocrine background of the menstrual cycle Describe the process of fertilization, stages of pregnancy and parturition Dr. Mariam Al-Awadhi Department of Physiology 3rd floor- Room 334a E-mail: [email protected] Describe the function of the placenta Describe the triggering and maintenance of lactation Dr. Mariam Alawadhi (Pharmacy 2024) 3 Dr. Mariam Alawadhi (Pharmacy 2024) Fetal Sex Determination Development of Internal Genitalia - Males Before 6 wks gestation BOTH DUCTS exist in both sexes Between 6 – 8 weeks: in male, testes develop (SRY gene) nai females In males once the testes develop: SERTOLI CELLS: secrete anti-mullerian hormone (AMH/MIF/MIS) → to regression of the mullerian duct CELLS: secrete testosterone messes LEYDIG which lead to the growth & development of the Wolffian duct. This duct will give rise to the male internal genitalia (epididymis, vas deferens, seminal vesicle, ejaculatory duct) ann Fetal Sex Determination Development of Internal Genitalia - Females O O sina.am nuenotestes Itai In females: The internal genitalia are: fallopian tubes, uterus and upper third of vagina. The absence of testosterone and AMH will lead to female internal genitalia o 4 Dr. Mariam Alawadhi (Pharmacy 2024) 5 Development of External Genitalia 9-12 weeks Dr. Mariam Alawadhi (Pharmacy 2024) 6 Summary - Fetal Sex Determination In males: T.is Testosterone 5a-reductase 5a-dihydrotestosterone n male external gentalia (penis, prostate, scrotum and penile urethra) In females: absensers The external genitalia are: clitoris, labia majora and minora and lower two thirds of the vagina Doing 027 If 5α-reductase is deficient in a male, the external genitalia may be mistaken for a female me *Sex determining region Y (SRY gene) is the testis determining gene located on the short arm of the Y chromosome Paromosome Dr. Mariam Alawadhi (Pharmacy 2024) 7 Dr. Mariam Alawadhi (Pharmacy 2024) Male Reproductive System 8 Testes Testes consist of 2 Parts: 1. Seminiferous tubules: Germinal cells: sperms Sertoli cells “nursing cells”: have FSH (follicular stimulating hormone) receptors 2. Interstitial tissue: Leydig cells have LH (luteinizing hormone) receptors ➔ testosterone 85 Organ Function Testes Produce sperms and sex hormones Epididymis Sites of maturation (ability to swim [motility], resistance to changes in pH & temperature) and some storage of sperm Vas deferens Conduct and store the mature sperm Urethra Conducts sperm (and urine) Penis Organ of copulation (sexual intercourse) I Dr. Mariam Alawadhi (Pharmacy 2024) 9 Is't osis205 Spermatogenesis I3 10 Dr. Mariam Alawadhi (Pharmacy 2024) Spermatogenesis Starting at ~13 yrs of age. Occurs in the seminiferous tubules upon LH & FSH stimulation. Takes on average 74 days to complete. no 120 million sperm are produced/day 23 (~ 60 - 150 million/day). Dr. Mariam Alawadhi (Pharmacy 2024) 11 Dr. Mariam Alawadhi (Pharmacy 2024) 12 Ezones Spermiogenesis as o Spermiogenesis: The last step in spermatogenesis. It results in transformation of spermatids to sperms. Immure Eve Spermatogenesis Spermiogenesis Sperm (spermatozoa) contain 3 parts: Mediated by Sertoli cells that are responsible for eliminating most of the spermatid cytoplasm to give spermatozoa. E Gigg is 1. Head: contains a nucleus covered by an acrosome (stores digestive enzymes to penetrate egg) I E 2. Middle piece: contains mitochondria wrapped around microtubules of the flagellum (mitochondria provide energy for movement) g 3. Tail: contains microtubules as components of flagellum; its movements propels sperm Dr. Mariam Alawadhi (Pharmacy 2024) Dr. Mariam Alawadhi (Pharmacy 2024) 13 Mariam Al-Awadi- Human Reproduction -2019 14 Mariam Al-Awadi- Human Reproduction -2019 At the completion of spermatogenesis: Spermatozoa will be released into the lumen of seminiferous tubules (non motile). F ET In the epididymis, sperms become mature and gain motility. Sperms also become more resistance to change in pH and temperature. Most of the sperms are then stored in the vas deferens. Gland Function Seminal vesicles 60% of the semen; thick viscous fluid containing nutrients (fructose) for use by sperm. Contains prostaglandins that stimulate smooth muscle contraction along male and female reproductive system. Prostate gland 30% of the semen; secretes alkaline secretion that increase motility of sperm. Prostatic hypertrophy Bulbourethral glands Produce clear viscous secretion known as pre-ejaculate that clear the urethra from urine residues. 15 Dr. Mariam Alawadhi (Pharmacy 2024) 5 E Dr. Mariam Alawadhi (Pharmacy 2024) Control of Male Sex Hormone Secretion Mariam Al-Awadi- Human Reproduction -2019 Hypothalamicpituitary-testes axis Exogenous androgen Anabolic steroids testicular atrophy During ejaculation the sperms of vas deferens obtains fluid secretions of seminal a vesicle and prostate, and together with the sperms the semen is carried by the ejaculatory duct to the urethra. C Semen (seminal fluid) is a thick whitish fluid that contains sperm (5%) and glandular secretions. 16 Androgenbinding proteins Luminal fluid spermatogenesis Dr. Mariam Alawadhi (Pharmacy 2024) Functions of Testosterone It is the main sex hormone in males. Important for development and function of male reproductive glands and organs. Essential for the maturation of sperm. Essential for development of male secondary sex characteristics: Oil and sweat glands secretion leading to acne and body odor. Enlargement of larynx and vocal cords; deepening of voice. Triggers baldness if appropriate genes are present. Development of hair on face, chest and back. Tallness, longer legs, broad shoulders. Sex drive and aggressiveness. Greater muscle strength (athletes, anabolic steroids) 17