Human reproduction

Reproduction?

The production of offspring by parents through sexual or asexual methods

Compare asexual and sexual reproduction?

• Parents : Asexual = 1 Sexual = 2

• Meiosis : Asexual = no (mitosis) Sexual = Yes

• Offspring : Asexual = Genetically identical Sexual = Genetically different

• Genetic variation = Asexual = no Sexual = YeS

• Environment : Asexual = Doesn’t respond to environmental changes Sexual: Responds to environmental changes

Outline the role of meiosis in the sexual life cycle?

Meiosis maintains the correct number of chromosomes

Outline the role of fertilization in the sexual life cycle?

Fertilization fuses the two haploid gametes to form a diploid zygote

Sexual reproduction results in……

Genetic variation

Compare male and female gametes?

• Size : Female = large Male = smaller

• Motility : Female = Non motile Male = Motile

• Production rate : Female = Few produced Male = Large numbers produced

• Energy reserves : Female = large energy reserves to support fertalization Male = low energy reserves

Scrotum?

Sac protecting the testes

Testes?

Produce sperm

Epididymis?

Long coiled tube on top of each testies were sperm mature

Vas deferens?

Transports mature sperm to the urethra for ejaculation

Seminal vesicles?

Glands that produce fluid high in fructose

Prostate gland?

Adds alkaline ph to semen to neutralize the acid ph of vagina

Urethra?

Narrow tube that moves urine and semen to the exterior of the body

Penis?

Male external genitalia

Ovaries?

Small oval shaped glands located on either side of the uterus that produce eggs and make hormones

Oviducts?

Tubes that serve as a passage between the ovary and the uterus

Uterus?

Hollow muscular organ that nourishes and develops the fetus

Cervix?

Lower portion of the uterus that connect the uterus to the vagina for mensturation and birth

Vagina?

A muscular canal lined with mucus membranes connecting the uterus and cervix to the outside of the body

Vulva?

All of the structures that make the female external genitalia

Ovarian cycle?

The series of changes in the ovary during which the follicle matures and releases an egg

What are the two main phases of the ovarian cycle?

• The follicular phases

• The luteal phase

Follicle stimulating hormone(FSH)?

Rises in the first 10 days of mensturation cycle stimulating the development of follicles each containing an egg and follicular fluid

Luteinizing hormone (LH)?

Rises to a sharp on day 14 of the cycle stimulating the maturation of the oocyte and ovulation

Estrogen?

Rises to a peak in the second week of the cycle stimulating repair and thickening of the endometrium and increases of FSH receptors

Progesterone?

Rises following ovulation reaching a peak then dropping back to a low level by the end of the menstrual cycle

Describe the negative feedback loop that regulates FSH during the cycle?

Oestradiol lowers the level of FSH and LH being secreted through the hypothalamus. subsequently lowering the level of oestradiol produced

Describe the positive feedback loop that regulate the secretion of LH during the ovarian cycle?

Oestradiol switches from day 12-14 to provide positive feedback to the hypothalamus causing and increase in LH leading to ovulation

Fetalaization?

The fusion of a sperm with an egg to form a zygote

Describe the process of fertalization?

The sperm move from the cervix to the uterus, swimming to the egg, directing their movement to the egg based on temperature (thermotaxis) and chemical gradients (chemotaxis). Sperm digests cells en route through glycophorins to reach the plasma membrane of egg cells. Once a sperm reaches the egg the spems’s plasma membrane binds to the egg cell’s plasma membrane through proteins causing a fusion of membranes (minus the sperm tail and mitochondria). The zona pellucida around the gg hardens preventing entry form other sperm, the sperm and egg zygote remain seperate untile mitosis the both nucelus breakdown.

In vitro fertalization?

Occurs through medically assisted reproduction outside the body in a lab

Outline the process of IVF?

• Downregulation

• FSH injection

• HCG injection

• Egg collection

• Fertilization

• Endometrial preparation

• Embryo transfer

Embryo transfer?

Embryos are placed in the uterus and progesterone is given to ensure the lining is maintained

Endometrial preparation?

Oestradiol and progesterone prescribed to stimulate thickening of endometrium

Fertilization?

Egg is mixed with sample sperm in dish then incubated for 1-2 days

Egg collection?

Surgical procedure using a micro pipette and ultrasound to drain eggs

HCG injection?

Follicles are stimulated to mature when 18mm in diameter

FSH injection?

Injection given for 7-12 days to stimulate follicles to develop (super ovulation more FSH)

Downregulation?

Injections given to stop secretion of FSH and LH