BSCI342-lec1notes - Lecture 1 There are 11 organs in the...

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Lecture 1 There are 11 organs in the body, 10 which are present and functional at birth. The reproductive tract becomes functional once it is activated by puberty. "Life is a continuum. It has no beginning, no end." Reproductive system is the only system used for homeostasis Reproduction: Continuity of Life 2 Types of Reproduction 1. Asexual - mitosis (identical offspring to the parent. . genetically identical clones) Ex: fission, budding, pathenogenesis Advantage: fast, easy, simple. .. only 1 individual is involved Disadvantage: in the face of harsh environmental conditions, all clones will die and the species will become extinct 2. Sexual - involves the fusion of a male sex cell and a female sex cell to form a zygote (both are haploids, and fuse to become diploid. .. aka zygotes) Advantage: genetic variation in offspring [during meiosis, formation fo sex cells (gametes), tetrad formation and crossing over result in the production of sex cells (gametes) that are genetically different from the parents] * the key to genetic variation is tetrad formation genetic variation allows for natural selection in the face of harsh environmental conditions some individuals of the species will survive (survival of fittest) to continue on with the species to avoid extinction Disadvantage: slow, tedious, a greater chance of mutations in the formation of the sex cell
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Human Reproduction - reproductive parts are found in pelvic region Male Reproduction - gonads = testes, are the site of gamete production and sex hormones Female Repoduction - gonads = ovaries Male Reproductive System (2 brances) 1. Primary Organs (male gonads = testes) - produce androgens (sex steroid hormone) - produce spermatozoa (sperm, which are male sex cells/ true gametes) through process called spermatogenesis - testes are ovoid shape and located outside body in scrotum hanging from perineum to keep at 3 C below body temp (below 38C) 2. Accessory structures (ducts and glands) Female Reproductive System (2 branches) 1. Primary Sex Organs (gonads = ovaries) - produce estrogens and progesterone (sex steroid hormone) - produce ova (eggs, which are female sex cells/ gametes) 2. Accessory reproductive structures (ducts and vulva) Reproductive Endocrinology What: the endocrine system is made up of endocrine glands that secrete chemicals called hormones into the extracellular fluid ( blood plasma and interstitial fluid) How: it releases hormones in response to stimuli most hormones work thru negative feedback, working to negate the stimuli that caused their release… these work to establish homeostasis Naming Hormones: Based upon 3 methods 1. Organ of origin (the endocrine gland that releases it) Ex: testosterone (hormone is released by testes) 2. Function Ex: follicle stimulating hormone (FSH) stimulates development of ovarium follicles 3. Structures or chemical class Ex: testosterone (steroid hormone released by the testes) * the site of release determines if something is a hormone or a neurotransmitter
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BSCI342-lec1notes - Lecture 1 There are 11 organs in the...

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