lecturenotes42-45

lecturenotes42-45 - Lecture 42: Principles of Reproductive...

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Lecture 42: Principles of Reproductive Physiology Reading: chapter 20, pgs 731-739 (5 th edition 749-756) Reproductive system - Does not contribute to homeostasis - Is not essential for survival of the individual - Is essential for perpetuating the species - Influences individual’s psychology and emotional makeup - Has profound social ramifications i.e. population density and resource management Reproductive physiology – The interactions among the reproductive organs, hypothalamus, anterior pituitary, and target cells of the sex hormones that collectively lead to the production and union of male and female gametes, and ultimately the production and nourishment of offspring. Primary reproductive organs (gonads) 1) produce gametes: sperm in males, ova (eggs) in females 2) secrete sex hormones: testosterone in males, estrogen and progesterone in females Secondary sexual characteristics External characteristics not directly involved with reproductive physiology e.g. body configuration and hair distribution Functions and anatomy of the reproductive tracts Males ( Figure 20-1 ): 1) spermatogenesis and semen production: - scrotum and testis - accessory sex glands: seminal vesicles, prostate gland, bulbourethral glands 2) deposition of sperm/semen in female: - penis - epididymis, ductus vas deferens, ejaculatory duct, urethra Females ( Figure 20-2 ): 1) oogenesis: ovaries 2) reception of sperm: vagina, cervical canal 3) fertilization (conception): oviducts 4) gestation (pregnancy): uterus, placenta 5) parturition (labor and delivery): uterus, cervix, vagina 6) lactation: mammary glands
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Chromosomal distribution in sexual reproduction Autosomal and sex chromosomes ( Figure 20-1 ) - males are XY - females are XX Homologous recombination during meiosis Sex differentiation ( Figures 20-4, 20-5 ) 1) Genetic sex : determined by sex chromosomes 2) Gonadal sex: - SRY (sex-determining region) of the Y chromosome masculinizes the gonads by stimulating H-Y antigen secretion from early gonadal cells - Without H-Y, undifferentiated gonadal tissue develops into ovaries (9 th week) 3) Phenotypic (anatomical) sex: - undifferentiated genitalia: genital tubercle, urethral folds, genital swellings - differentiation into male genitalia induced by androgens (testosterone) - Wolffian and Mullerian ducts - males - fetal testes secrete testosterone and Mullerian-inhibiting factor - testosterone induces development of Wolffian duct into male reproductive tract - DHT induces differentiation of the external genitalia into penis and scrotum - Mullerian-inhibiting factor causes regression of the Mullerian ducts - females in the absence of testosterone and Mullerian-inhibiting factor, the Wolffian ducts regress and the Mullerian ducts develop into the female reproductive tract, and undifferentiated genitalia differentiate into female external genitalia.
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Lecture 43: Male Reproductive System / Intercourse Reading: chapter 20, pgs 739-752 (5 th edition 756-770) Male Reproductive System
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lecturenotes42-45 - Lecture 42: Principles of Reproductive...

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