BIOL Lab 11: Reproductive and Excretory Systems

Question 1

Ovary

Answer 1

In females, the almond shaped ovaries produce eggs and the female sex hormones, estrogen and progesterone.

Question 2

Oviduct

Answer 2

The ovaries are capped by the flared ends of the oviducts (fallopian tubes). Cells lining the oviducts are covered with cilia. These cells sweep the egg along, after their release from the ovary, to the uterus.

Question 3

R & L Uterine Horns

Answer 3

The points where the uterus and the fallopian tubes meet.

Question 4

“Body” of Uterus

Answer 4

The uterus is a pear-shaped muscular organ that houses the developing embryo and, at birth, contracts to expel the child.

The lining of the uterus, the endometrium, grows in thickness by adding a rich supply of blood vessels during the female’s monthly cycle.

If pregnancy occurs, the embryo implants into the uterine lining and is surrounded by the endometrial tissue.

If pregnancy does not occur, the endometrium is sloughed off as menstrual flow.

At the lower end of the uterus is the cervix, an opening into the vagina.

Question 5

Vagina

Answer 5

A muscular tube between the cervix and the external genitalia. It receives the penis during copulation and serves as a birth canal.

The female external genitalia (vulva) consist of the clitoris (homologous to the penis with a similar nerve supply), the labia minora (flaps of tissue protecting the vaginal opening), and the labia majora (external flaps of tissue protecting the labia minora and the urethral opening).

Question 6

Scrotal Sac

Answer 6

Contains the testes. Also called scrotum. Located outside body cavidty.

In most mammals, the internal body temp is too warm for sperm to develop properly. Scrotum allows the testes to hang away from body so that the sperm can develop at a lower temp.

Question 7

Testis (-es)

Answer 7

Source of the male gametes (sperm).

Also secrete testosterone, which maintains the male reproductive organs and secondary sexual characteristics such as, facial hair and a deep voice.

The testes produce sperm in tiny tubes called seminiferous tubules.

Question 8

Epididymis

Answer 8

The seminiferous tubules coalesce to form a coiled tube, the epididymis, where mature sperm is stored.

Question 9

Spermatic Cord

Answer 9

Leads from testes through abdominal wall. Contains vas deferens, artery, vein, lymphatic vessels.

Question 10

Seminal Vesicles

Answer 10

Gland below uniary bladder in males. It secretes fructose, an energy source for the sperm.

Question 11

Penis

Answer 11

The male copulatory organ. It is comprised of three, spongy cylinders of erectile tissue. During erection, the arteries of the penis dilate and the tissue swells. Impotence is a failure to have an erection. Sterility is failure to produce viable sperm. The head of the penis is the glans penis, a highly sensitive organ. In uncircumcised males, the foreskin protects the glans penis.

Question 12

Ductus Deferens

Answer 12

Also called vas deferens, a long tube that travels from the scrotum into the body cavity. During ejaculation, muscular contractions force the sperm through this tube.

It enters upper portion of the urethra.

Question 13

Bulbourethral Gland

Answer 13

Gland that secretes an initial lubricating fluid that is released during sexual arousal.

Question 14

Prostrate Gland

Answer 14

Secretes prostaglandins, hormones that stimulate muscular contractions in the female tract thereby facilitating sperm conduction to the egg.

Question 15

Asexual and Sexual Reproduction

Answer 15

Most animals reproduce sexually by producing gametes, eggs, and sperm, in gonads (ovaries and testes). Some animals can reproduce asexually by budding (e.g. hydra), patthenogenesis (e.g. some insects and lizards), or regenerating body parts following injury (e.g. planaria), forming two complete organisms. In addition, some animals are hermaphrodites (but usually are not self-fertile) with some species exhibiting sequential hermaphroditism (e.g. earthworms and some fish).

Question 16

Spermatogenesis

Answer 16

Spermatogenesis is the process by which male primordial germ cells, called spermatogonia undergo meiosis.

The first division is mitotic, producing two primary spermatocytes (2N).

The meiotic division of each primary spermatocyte produces two secondary spermatocytes (1N).

Finally, the meiotic division of each secondary spermatocyte produces two spermatids (a.k.a. spermatozoa, 1N).

The entire process results in four spermatozoa.

Question 17

Corpus Luteum

Answer 17

In mammals, this structure develops following release of a secondary oocyte from the follicle during ovulation. This mass of glandular connective tissue produces progesterone and estrogen to inhibit release of another egg and to thicken the endometrium of the uterus for implantation of a fertilized egg. The corpus luteum deteriorates if pregnancy does not occur. The decreased horomonal signals allow other oocytes to complete maturation.

Question 18

Oogenesis

Answer 18

Oogenesis is the process by which a mature egg is produced in the ovary. The process begins with an oogonium (2N) which undergoes mitosis to produce a primary oocyte (2N).

The primary oocyte (2N) undergoes meiosis I producing a secondary oocyte (1N) and the first polar body that is discarded.

The secondary oocyte (1N) undergoes Meiosis II to produce an ovum (1N) and the second polar body that is discarded. Meiosis II is halted at metaphase II until fertilization occurs.

Question 19

Abstinence

Answer 19

The most reliable form of birth control is to abstain from sex. In addition to preventing pregnancy, this method virtually eliminates the risk of sexually transmitted diseases (STD’s) such as genital herpes, chlamydia, gonorrhea, syphilis, and AIDS.

Question 20

Rhythm Method

Answer 20

Consists of avoiding intercourse on days of the menstrual cycle when eggs might be fertilized. A woman generally produces one egg each cycle, around the 14th day of a 28-day cycle (counting day 1 as the onset of menstruation). The egg spends the first 24-48 hours traveling through the oviduct and uterus, and it is only fertile during this short period. Sperm are viable for 24-48 hours in the female tract. In all, there are approximately 96 hours a month when sex can result in pregnancy, 48 hours before the release of the egg (ovulation), and 48 hours after. To predict ovulation more accurately, a woman can keep a calender of her menstrual cycle and note the thinning of vaginal discharge or slight elevation in body temp (about 0.75 F) that follows ovulation. The temp should be taken at the same time each day, preferably immediately on waking up in the morning. This is done using a rectal thermometer and plotting the daily temp on a graph.

Question 21

Condom

Answer 21

Has been in use since 1500s, where it was made to prevent spread of syphilis. It acts as a physical barrier by preventing sperm from entering the female reproductive tract. Condoms made of latex are also effective in preventing the spread of STD’s. Those make of sheepskin have been proven less effective in preventing the spread of viral STD’s, such as AIDS. Condoms can be tested for leaks by blowing them up like a balloon and testing for escaping air.

Question 22

Diaphragm

Answer 22

A round rubber dome that covers the woman’s cervix like a cap. It acts as a physical barrier to prevent sperm from traveling beyond the cervix and for proper fit it, must be measured by a doctor. Spermicidal jelly is spread on the inside of the diaphragm before insertion to kill any sperm that may slip around the edge of the diaphragm. Spermicide must be added prior to each act of sex, and the diaphragm must be left in place for 8 hours after sex.

Question 23

Spermicides

Answer 23

These are creams, jellies, and foams that are applied prior to sex. They are more effective when used in combo with a physical barrier-type contraceptive.

Question 24

The pill/patch

Answer 24

Most birth control pills contain synthetic progesterone and estrogen, the female sex hormones (minipills contain only progesterone). These hormones inhibit the release of the pituitary hormones (FSH and LH) that promote the development and release of eggs. Therefore pregnancy is prevented because there is not egg for the sperm to fertilize. Pills and the patch must be prescribed by a doctor and used as directed to provide effective protection.

Question 25

Implants

Answer 25

This contraceptive device is a surgical implant (e.g. Norplant) that releases female sex hormones gradually over a period of five years. Once implanted by a doctor, the device prevents pregnancy without need for any further precautions. When pregnancy is desired, a physician must remove the implant.

Question 26

Vasectomy

Answer 26

The most common means for sterilization in men. Generally, the vas deferens from each testicle is cut and tied off in a surgical procedure in the physician’s office. Sperm are still produced by the testes but, since they cannot exit, the body reabsorbs them. Intercourse and ejaculation can occur normally since the bulk of the male’s semen is supplied by the glandular secretions, which are unaffected by a vasectomy.

Question 27

Tubal Ligation

Answer 27

Female sterilization usually involves cutting and tying off each fallopian tube so they cannot carry the egg to the uterus. This is a more serious operation than vasectomy, however, it can be done on an outpatient basis.

Question 28

Excretory Systems

Answer 28

All operate of the premise of three processes. Filtration (Bowman’s capsule), selective reabsorption (collecting duct), secretion (ureter).

For simple animals, nitrogenous waste is simply eliminated either across the body surface of along with the food waste via the gastrovascular cavity (eg. Hydra and Planaria). Planarians also have cells specialized for the elimination of nitrogenous waste and osmoregulation. These are the protonephridia (often called “flame cells”) in planarians. These cells are connected by tubules and empty via pores in the body surface. The beating cilia in the protonephridia give the appearance of a flickering flame.

In crayfish, the green gland serves the excretory function. In bony fish, such as the perch, dilute urine is produced by the kidney and quickly excreted via the urinary bladder. In fish, the gills also function in the excretion of ammonia. In animals such as the fetal pig and humans, more complex kidneys and urinary systems have evolved. The nephron is the functional unit of the kidney along with extensive capillary networks surrounding each nephron.

Question 29

Glomerulus

Answer 29

Capillary bed that forces wastes out of the bloodstream.

Question 30

Bowman’s Cpasule

Answer 30

Epithelial layer surrounds glomerulus that receives filtrate from glomerulus.

Question 31

Proximal Convoluted Tubule

Answer 31

Tubules that selectively remove nutrients from nephron to the bloodstream.

Question 32

Loop of Henle

Answer 32

Long extension of nephron tubule that forms concentration gradient to remove wastes and make urine.

Question 33

Distal Convoluted Tubule

Answer 33

Tubules that slective remove H2O and NaCl but absorb K.

Question 34

Collecting duct (tubule)

Answer 34

Nephrons that further concentrates urine while passing it along to ureter.