Reproductive System

Question 1

Sexual Reproduction

Answer 1

• the genetic material of two organisms
• combines and results in a genetically unique offspring
• occurs via the fusion of two gametes, specialized sex cells produced by each parent

Question 2

Gonads

Answer 2

• this is where gametes are produced
• the male gonads are testes - produce sperm in the tightly coiled seminiferous tubules
• the female gonads are the ovaries - produce oocytes (eggs)

Question 3

Gametogenesis

Answer 3

• this is the production of functional cells
• in males, it is called spermatogenesis
• in females, it is called oogenesis

Question 4

Fertilization

Answer 4

the union of the egg and sperm nuclei to form a zygote with a diploid number of chromosomes

Question 5

Male Reproductive System

Answer 5

• the testes are located in the scrotum
• sperm passes from the testes through the vas deferens and the ejaculatory duct and then to the urethra
• the testes are also the sites of production of testosterone

Question 6

Spermatogenesis

Answer 6

• occurs in the seminiferous tubules
• spermatogonia differentiate into diploid cells called primary spermatocytes, which undergo a meiotic division to yield two haploid secondary spermatocytes
• a second meiotic division produces four haploid spermatids of equal size
• after meiosis the spermatids undergo a final series of changes that increase their inability resulting in mature sperm - spermatoza

Question 7

Female Reproductive System

Answer 7

• ovaries are found in the abdominal cavity below the digestive system
• ovaries consists of follicles
• approx once a month, an immature ovum is released from the ovary to the fallopian tubes
• each fallopian tube opens into the upper end of the uterus
• the lower narrow end of the uterus is called the cervix
• the cervix connects with the vaginal canal

Question 8

Oogenesis

Answer 8

• the production of female gametes, occurs in the ovarian follicles
• primary oocytes - at birth all that a female will produce in her lifetime
• secondary oocytes - a small cell known as a polar body. It is expelled from the follicle during ovulation
• the oocytes cell membrane is surrounded by two layers of cells, Inner layer: zona pellucida layer. Outer layer: Corona Radiata layer
• Meiosis II is triggered when these two layers are penetrated by a sperm cell
• the mature ovum is a large cell containing cytoplasm, RNA, organelles, and nutrients needed by the developing embryo

Question 9

Female Sex Hormones

Answer 9

• ovaries synthesize to secrete female hormones
• the secretion of both estrogens and progesterone is regulated by leutinizing hormone (LH) and follicle stimulating hormone (FSH), which are regulated by gonadotriptin-releasing hormone (GnRH)

Question 10

Estrogen

Answer 10

• steroid hormones necessary for female maturation
• stimulate the development of the female reproductive tract
• responsible for the thickening of the endometrium
• secreted by the ovarian follicles and the corpus luteum

Question 11

Progesterone

Answer 11

• a steroid hormone secreted by the corpus luteum during the luteal phase of the menstrual cycle
• stimulates the development and maintenance of the endometrium in prep for implantation

Question 12

The Menstrual Cycle

Answer 12

1. Follicular Phase: begins with the cessation of the menstrual flow from the pervious cycle
2. Ovulation: midway through the cycle ovulation occurs - a mature ovarian follicle bursts and releases an ovum
   - caused by a surge in LH and a peak in estrogen levels
3. Luteal Phase: after ovulation, LH maintains the
   remnant of the ruptured follicle - corpus luteum
   -the corpus luteum secretes estrogen and progesterone
   -progesterone causes the glands of the endometrium that prepare it for the implantation of the embryo
4. Menstruation
   - if the ovum is not fertilized, the corpus luteum atrophies
   - the drop of progesterone and estrogen level gives rise to the menstrual flow
   - if fertilization occurs, the developing placenta produces hcG, maintaining copus leteum
5. Fertilization
   - occurs in the lateral, widest portion of the fallopian tube
   - sperm must travel through the vaginal canal, cervix, uterus, and into the fallopian tubes to reach the ovum
   - sperm must first penetrate the corona radiata
   - the acrosome is responsible for penetrating the zena pellucida
   - once in contact with the membrane, the sperm forms a tube-like structure called the acrosomal process, which extends to the cell membrane and penetrates it
   - the acrosomal reaction triggers a cortical reaction in the ovum - calcium ions into the cytoplasm - results in the formation of the fertilization membrane - prevents multiple fertilizations

Question 13

Monozygotic (Identical Twins)

Answer 13

• results when a single zygote splits into 2 embryos

- same sex, blood type, etc

Question 14

Dizygotic (Fraternal Twins)

Answer 14

• result when two ova are released in one ovarian cycle and are fertilized by 2 different sperm
• develops its own placenta, amnion, and chorion
• develop from 2 different zygotes