REPRODUCTIVE System
Vocabulary
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Homologous chromosomes
Diploid Haploid Asexual reproduction Sexual reproduction Reproduction |
Gonad
Gamete ovum sperm spermatogenesis oogenesis polar bodies semen |
synapsis
disjunction tetrad fertilization zygote embryo fetus |
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Although reproduction is one of the life processes it is not vital to an individuals survival but rather to the survival of the species. Some organisms are able to reproduce without the fusion of gametes, (sex cells) this is called asexual reproduction. This produces offspring nearly identical to that of the parent. Most complex organisms reproduce by fusing gametes to produce a zygote, this is called sexual reproduction. When a Sperm and an Ovum fuse it is called fertilization.
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sexual vs Asexual reproduction
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SEXUAL reproduction involves the fusion of gametes to produce offspring
Offspring are genetically different from either parent. Pros: Variation Cons: Longer process must find a mate |
ASEXUAL reproduction DOES NOT involve the fusion of gametes to produce offspring.
Offspring are genetically identical to the parent Pros: very fast beneficial traits are preserved no need to find mate Cons: Little to no variation |
Diploid vs Haploid
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Diploid cells contain homologous pairs of chromosomes. All body cells are diploid and the symbol for diploid is 2n. In a diploid cell, one complete set of chromosomes is given by each parent
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Haploid cells only contain one chromosome from each homologous pair. ONLY gametes are haploid and the symbol for haploid is n.
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Meiosis
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Meiosis is the production of haploid gametes. Meiosis only occurs in the gonads.
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SpermatogenesisThe process by which the male gamete (sperm) is produced is called Spermatogenesis. Spermatogenesis occurs in the male gonad (testes) which are located in the scrotum. The Male testes are located outside of the body because spermatogenesis must take place 2 degrees below body temperature (34-36 C). The producing of sperm is constant and at a rate of about 1,000 sperm per minute. Once the immature sperm cells are formed they travel to the epididymis to mature. Sperm take about 18 days to mature and can be stored in the epididymis for 2-3 months before being reabsorbed.
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OOgenesisThe process by which the female gamete (ovum) is produced is called oogenesis. Oogenesis occurs in the female gonad (ovary) which are located in the abdomen. This process differs from spermatogenesis because only 1 gamete is produce and 3 polar bodies are then reabsorbed by the female body. Oogenesis is also regulated by the hormones of female menstrual cycle, occurring approximately once a month (28 days).
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Major differences:
- Spermatogenesis produces sperm, Oogenesis produces Ova
- Spermatogenesis produces 4 gametes, Oogenesis produces 1 ovum and 3 polar bodies
- Spermatogenesis takes place below body temp., Oogenesis takes place at body temperature
- Spermatogenesis occurs constantly in males, Oogenesis occurs once a month in females
Puberty
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Reproductive Anatomy
FemaleOvary- The female gonad. Responsible for the production of estrogen and progesterone, two hormones key in female development and the menstrual cycle. Each Ovary contains 400,000 undeveloped eggs and every 28 days one egg develops and is released.
Oviduct- also known as the fallopian tube, is responsible for transporting the mature egg to the Uterus. Fertilization occurs here. Uterus- Commonly called the womb, this is where the fetus develops Cervix- the opening of the uterus. The cervix is responsible for blocking or allowing sperm to enter the uterus. Urethra- in females the urethra is only used to excrete urine. Vagina- the vagina is the birth canal and the area in which intercourse occurs. Vulva- the external anatomy of the vagina |
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MaleScrotum- Loose pouch like sac that contains the testes. It is key for regulates the temperature of the testes which must be kept slightly cooler than body temperature for sperm production
Testicle- the male gonad, responsible for testosterone and sperm production. Epididymis- where the sperm mature, located on the back/top of the testes. Vas Deferens- carries the mature sperm from the epididymus to the urethra and past the glands that add fluids to the sperm. Seminal Vesicles- Glands that add fluid containing nutrients to sperm, creating semen. Penis- responsible for delivering the sperm Urethra- responsible for both excretion of urine and ejaculation of semen. Semen- contains enzymes, sugars and other substances that promote the survival of the sperm. |
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menstrual cycle
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Menstrual cycle is the cycle of changes that occurs in the uterus and ovary for the purpose of sexual reproduction. It is essential for the production of eggs and for the preparation of the uterus for pregnancy. The menstrual cycle occurs only in fertile female humans and other female primates.
In humans, the length of a menstrual cycle varies greatly among women (ranging from 21 to 35 days), with 28 days designated as the average length. Each cycle can be divided into four phases based on events in the ovary or in the uterus. The menstrual cycle consists of the follicular phase, ovulation, luteal phase and menstruation if fertilization does not occur. |
Hormones from the Pituitary
FSH (follicle stimulating hormone) -stimulates the follicle growth and maturation of ovum. LH (luteinizing hormone) -signals ovulation and maintains the corpus luteum Hormones from the Ovary Estrogen -builds the uterine lining Progesterone -maintains the uterine lining |
fertilization
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Fertilization is the fusion of gametes to initiate the development of a new individual organism. In animals, the process involves the fusion of an ovum with a sperm, which creates a zygote and eventually leads to the development of an embryo.
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Development
click the picture above to open an interactive activity
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REPRODUCTIVE technology
Remedial
Artificial Insemination- is the deliberate introduction of semen into a female's vagina or oviduct for the purpose of achieving a pregnancy through fertilization by means other than copulation (sexual intercourse).
In vitro fertilization- (IVF) is a process by which an egg is fertilized by sperm outside the body: in vitro. IVF is a major treatment for infertility and involves monitoring and stimulating a woman's ovulatory process, removing ovum or ova (egg or eggs) from the woman's ovaries and letting sperm fertilize them in a fluid medium in a laboratory. The fertilized egg (zygote) is cultured for 2–6 days in a growth medium and is then transferred to the mother's uterus with the intention of establishing a successful pregnancy. Surrogacy Traditional surrogacy: in which the surrogate either undergoes artificial insemination or IVF with sperm from the male or from a sperm donor. The surrogate herself provides the eggs and is therefore genetically related to the child. This form of surrogacy is the older method and because of the genetic link between the surrogate and the baby there is some downside risk to this form of surrogacy. Gestational surrogacy: in which the surrogate carries a pregnancy and delivers a child that is created from the egg and the sperm of the intended parents and /or donor egg and /or donor sperm and/or donated embryos in any combination. The key to this type of surrogacy is that the gestational surrogate is not genetically related to the child and acts only as a gestational carrier for the pregnancy. cesarean section- (c-section) is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver a baby |
PreventativeVasectomy- is a surgical procedure for male sterilization and/or permanent birth control. During the procedure, the vas deferens of a man are severed, and then tied/sealed in a manner such to prevent sperm from entering into the seminal stream (ejaculate).
Tubal ligation-(tubes tied) is a surgical procedure for sterilization in which a woman's fallopian tubes are clamped and blocked, or severed and sealed, either method of which prevents eggs from reaching the uterus for fertilization. Tubal ligation is considered a permanent method of sterilization and birth control. birth control (hormonal) Intrauterine devices- is a small contraceptive device, often 'T'-shaped, often containing either copper or levonorgestrel, which is inserted into the uterus.
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