UNIT 2 ANATOMY and PHYSIOLOGY of REPRODUCTIVE SYSTEM and DEVELOPMENT of FOETUS Structure

UNIT 2 ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM AND DEVELOPMENT OF FOETUS Structure 2.0 Objectives 2.1 Introduction 2.2 Anatomy and Physiology of Reproductive System 2.2.1 The Female Reproductive System 2.3 Menstrual Cycle 2.4 Structure and Functions of Breasts or Mammary Glands 2.4.1 External Structure 2.4.2 Internal Structures 2.5 Female Pelvis 2.5.1 The Bony Pelvis 2.5.2 Part of the Bony Pelvis 2.5.3 Diameters of the Brim 2.5.4 The Pelvic Cavity 2.6 Pelvic Floor 2.6.1 Functions of Pelvic Floor 2.6.2 Injury to Pelvic Floor During Labour 2.7 Foetal Skull 2.8 Anatomy and Physiology of Male Reproductive System 2.8.1 Structure and Functions of Male Reproductive Organs 2.8.2 Spermatogenesis 2.9 Conception 2.9.1 Definition and the Process of Fertilization 2.10 Development of Embryo 2.10.1 Development of the Fertilized Ovum 2.10.2 The Placenta 2.10.3 The Foetal Membranes 2.10.4 Liquor Amnii (Amniotic Fluid) 2.10.5 Umbilical Cord (Funis) 2.11 The Foetus, Foetal Growth and Foetal Circulation 2.12 Let us Sum Up 2.13 Answers to Check your Progress 2.14 Further Readings 2.0 OBJECTIVES After completing this unit, you will be able to: l describe the Anatomy and Physiology of both Female and Male Reproductive systems; l discuss the structure and functions of breasts; l explain the female pelvis, pelvic floor and fetal skull and identify their significance for child birth; l describe the development of fertilized ovum; and l explain the foetal circulations and identify the normal changes at birth. 2.1 INTRODUCTION Over the past decade the role of nurse in the care of woman and neonate has changed dramatically because of socio-economic changes, consumer’s education, scientific and 19 technological advancement. Strengthening the knowledge of reproductive health orients Maternal Health and Nursing you in anticipating problems, mastering procedures, identifying complications, responding Intervention to emergencies, reviewing laboratory investigations, planning nursing intervention for client and her family based on nursing process. Reproductive health care explores the basic health concerns that bring women into contact with health care professionals. To provide the knowledge base, it is essential to have a thorough understanding of reproductive anatomy and physiology of both female and male, conception and foetal development. 2.2 ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM You have already learnt in General Nursing the anatomy and physiology of Reproductive System of both female and male. Let us now review the structure and functions, so that you will have deeper understanding about Reproductive Health. Within this Unit you will review your knowledge about the female organs of regeneration such as vagina, uterus, fallopian tube and ovaries. You will also learn about the menstrual cycle, the breasts. Further, you will learn about the male genito urinary organs including spermatogenesis. Let us discuss first the Female Reproductive organs. 2.2.1 The Female Reproductive System The female reproductive system consists of internal organs, located in the pelvic cavity and supported by the pelvic floor and external genitals located in the perineum. The female’s internal and external reproductive structures develop and mature in response to oestrogens and progesterone, starting in foetal life and continuing throughout puberty and the child bearing years. External Reproductive Organs The external female genitals are located in the perineum. The external structures are presented in the following orders (from anterior to posterior) l Mons pubis (mon veneris) l Labia majora and labia minora (sing. Labia majus) l Clitoris l Vestibule l Fourchette l Perineum External genitals are illustrated in Fig. 2.1. Mons veneris Labium majus Clitoris Vestibule Labium minus Urethral meatus Vaginal orifice Hymen Fourchette Central part of perineum Anus Fig. 2.1: External female genitals 20 Mons Pubis Anatomy and Physiology of Reproductive System and The mons pubis or mons veneris is the rounded pad of subcutaneous fatty tissue and loose Development of Foetus connective tissue over the symphysis pubis. It contains many sebaceous glands and develops course dark, curly hair at puberty, about 1-2 years before the onset of menses. Menarche occurs on an average at 13 years of age. The functions of the mons are to play a role in sensuality and to protect the symphysis pubis during coitus. Labia Majora The labia majora are two rounded lengthwise folds of skin-covered fat and connective tissues that merge with the mons. They extend from the mons downwards round the labia minora ending in the perineum in the midline. The labia majora functions as a protection for the labia minora., urinary meatus and vaginal introitus. In the women who has never experienced vaginal childbirth, the labia majora come together in the midline, obscuring the vaginal introitus. Some labial separation and even gaping of the vaginal introitus follow childbirth and perineal or vaginal injury. The medial surface of the labia majora are smooth, thick and without hair. Labia Minora The labia minora, located between the labia majora, is narrow lengthwise folds of hairless skin extending downward from beneath the clitoris and merging with the fourchette. Whereas the lateral and anterior aspects of the labia are usually pigmented, their medial surfaces are similar to vaginal mucosa: pink and moist. Their rich vascularity gives them a reddish colour and permits marked turgescence of the labia minora. With emotional or physical stimulation the glands in the labia minora also lubricate the vulva. A rich nerve supply make them sensitive, enhancing their erotic function. Clitoris The clitoris is a short, cylindrical, erectile organ fixed just beneath the arch of the pubis. The tip of the clitoral body is called the glans and is more sensitive than its shaft. When sexually aroused, the glans and shaft increase in size. The clitoris contains many nerve endings and is the homologue of the penis of the male. Its main function is to stimulate and elevate levels of sexual tension. Vestibule Vestibule is a triangular area between the labia minora laterally, from clitoris at the apex to fourchette anteroposterioraly. There are four openings into the vestibule: i) External urethral opening This is a midline anteroposterior slit with two lateral lips lying behind clitoris and just in front of vaginal orifice. Paraurethral ducts (Skene’s ducts) open on either side of external urethral meatus or on its posterior wall inside the orifice. ii) Vaginal orifice (introitus) It is a median slit behind urethral opening. It is completely guarded by a septum of mucous membrane called hymen. In a virgin, hymen has a small accentric opening not usually admitting the finger tip. On coitus it gets ruptured. Following child-birth per vagina hymeneal tags (crunculae myrtiformes) are visible. Hymen is composed of double layer of stratified squamous epithelium with intervening vascular connective tissues. Vaginal introitus gets dilated on coitus and childbirth. iii) Two opening of Bartholin glands ducts Bartholin glands are pea sized mucous secreting oval glands. Each gland is situated posterior to vestibule. The duct is about 2 cm long and opens in the groove between hymes and labia minora. The gland and duct are lined by single layer of columnar epithelia, except for the duct opening which is lined with stratified squamous epithelium. On sexual excitement bartholin glands secrete alkaline mucus that lubricate the vaginal introitus to facilitate coitus. The gland can become infected and lead to bartholinitis or bartholin abscess. Fourchette The fourchette is a thin, flat, transverse fold of tissue formed where the tapering labia majora and minora merge in the midline below the vaginal orifice. A small depression, the fossa naviculoris, lies between the fourchette and the hymen. 21 Maternal Health and Nursing Perineum Intervention The perineum is the skin covered muscular area between the vaginal introitus and the anus.The perineum forms the base of the perineal body. Internal Reproductive Organs Internal structure consists of: l Vagina l Uterus l Fallopian tubes l Ovaries Fundus Uterine tube Ovary Fimbria Ligament of ovary Isthmus Endometrium Myometrium Internal os Vagina Cervical canal External os Fig. 2.2: Female internal genital organs Vagina The vagina is a fibromuscular distensible tube joining vestibule of vulva with Uterus. It forms the lowest vestibule of vulva with uterus. It forms the lowest part of internal genital tract to provide canal for menstrual blood outflow from the uterus, coital canal and birth canal. The vaginal canal is directed upward and backward towards sacrum making an angle of 45 degrees with horizon in erect posture of a woman. Cervix projects into the upper end of the vagina is called a vault. The anterior wall of vagina is 7.5 cm long, posterior wall 9 cm. Four fornices are formed due to projection of uterine cervix into the vagina–one anterior, two laterals and one posterior. Normal uterus can be palpated through fornices. Anterior upper half of vaigna is related to base of urinary bladder and lower half with urethra. Posteriorly lower third of vagina is related to perineum, middle third to rectovaginal septum and anterior rectal wall and upper third to Pouch of Douglas. The vagina consists of four layers: l Mucous membrane the innermost layer of stratified squamous epithelium. It has numerous rugae. l Submucous layer with vascular loose areolar tissue. l Muscular layer – inner circular – outer longitudinal 22 l Fibrous layer with rich blood supply. Vagina has rich blood supply from cervicovaginal branch of the uterine artery, vaginal Anatomy and Physiology of branches of Internal iliac artery and Internal podendal artery of internal iliac artery. Vein Reproductive System and Development of Foetus and lymphatics follow the arteries.

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