The Human Reproductive System * Body Parts and Functions

Female Reproductive System

Female Reproductive System

Female reproduction system Fallopian tubes Extend from the ovaries to the uterus Carry the mature ova to the uterus Inner walls with cilia which propel the egg to the uterus Has two parts: fimbria and ampulla Fimbria: envelopes the ovary and catches the egg at the time of ovulation (when egg is realesed) Ampulla: Tube where fertilization takes place (when the sperm enters the egg)

2. Uterus The main reproductive organ (pear shaped) Walls are 1cm thick, lined with tissue called uterine lining Expandable The site where the embryo is brought to maturity Reforms each month in preparation of receiving a fertilized egg

3. Vagina Cavity that receives sperm and allows the passage of the fetus Capable of considerable dilatation

4. Ovaries 4. Ovaries There are two ovaries, which are almond shaped sacs 3cm x 2cm Responsible for bringing ova to maturity Contains the eggs, about 700 000 at birth Between ages 12 to 50, about 400 eggs mature Stops functioning at menopause.

Vulva (external glands) Labia majora Large external folds Labia minora Two folds that cover the vaginal opening. Clitoris Small, erectile structure with many blood vessels and nerve endings

Hyman Membrane which covers the vaginal opening Different forms, may be minimal or absent all together Bartholian glands Secretes a lubricating substance

Female Puberty At the onset of puberty, the pituitary gland (in the brain) produces two hormones, FSH and LH These hormones stimulate the ovaries to produce other hormones: estrogen and progesterone These hormones produce a number of changes

Physiological Changes Growth of body hair Growth of breasts Widening of hips Development of genital organs Beginning of menstruation

The Menstrual Cycle The role of the menstrual cycle is to bring an egg to maturity so that it can be fertilized by a sperm. Endometrium: The lining of the inner surface of the uterus A soft protection “bed” that supports and nourishes the embryo. If the egg is not fertilized by a sperm, the lining is shed.

Four Phases Phase 1 – The Menstrual Phase Day 1 to Day 4-7 Bleeding (release of the endometrium) to flush unfertilized eggs out of the system Phase 2 – The Follicular Phase Up to Day 14 FSH (follicle stimulating hormone) is released from the brain in order to develop a new egg in the ovary Follicle grows and releases estrogen. The walls of the uterus also thicken (endometrium) in preparation of the possible arrival of a fertilized egg

Ovulation Phase 4 – Luteal Phase Day 14 A follicle releases an ovum into the Fallopian tubes If fertilized, the egg will implant itself in the uterus Phase 4 – Luteal Phase Day 15 to Day 28 Progesterone from ovary is released to maintain the endometrium until it is determined if the egg is fertilized. The non-fertilized egg(s) degrades and hormonal changes lead to menstruation

Cowper’s glands

Male Reproductive System Penis Erectile organ that ejaculates semen during intercourse Includes the glans (end of the penis) and foreskin (fold of skin around the glans) Testicles (two) About the size of egg yolks Located inside the scrotum Produce testosterone (hormone) and spermatazoa The epididymis extends to form the vas deferens

Seminal vesicles (two) Epididymis Long tube about 6m in length coiled on top of each testicle Vas deferens Tubes connecting the testicles to the urethra Collect sperm and store them between ejaculations Seminal vesicles (two) Produce a liquid that forms 30% of semen Secretes a thick, transparent liquid into the vas deferens in which the sperms are suspended.

Ejaculatory duct Prostate Cowper’s glands Urethra Connects the vas deferens to the urethra Receives secretions from the seminal vesicles and sperm from the vas defrens. Prostate Produce a milky liquid that forms 60% of semen Cowper’s glands Produce a liquid that forms 5% of semen Urethra Extends from the bladder to the end of the penis Receives urine from the bladder and sperm from the ejaculatory ducts

Male Puberty At the onset of puberty, the pituitary gland (in the brain) produces two hormones, FSH and LH These hormones stimulate the testicles to produce hormones called androgens (such as testosterone) Androgens produce a number of changes, in addition to the production of spermatazoa

Spermatazoa

Physiological Changes Growth of body hair Deepening of voice Development of muscle Changes to genital organs

TWINS Identical twins 30% of all twins are identical Develop from one egg & one sperm The fertilized egg divides into two separate zygotes These twins have the same sex, blood type & hereditary characteristics

Twins Fraternal twins 70% of all twins are fraternal 2 eggs are released by one ovary or each ovary releases 1 egg A different sperm fertilizes each egg Different hereditary characteristics.

Procreation

Assisted Reproduction Artificial insemination Cryopreservation (freezing) Sperm/egg donation Fertility drugs In vitro fertilization Surrogacy

Ethical Issues What to do with unused eggs and sperm… Should surrogate mothers be paid for their “work”? Should a child made by artificial insemination be allowed to find out who his/her “parents” are?