Solutions To Exercises Lesson

1. The human urogenital systems are made up of the urinary organs, which produce the fluid called urine, and the genital, or reproductive, organs of male and female humans, which together can produce a new human. (para 8-1)

2. The urinary system is specialized to remove certain nitrogenous waste products from the circulating blood. These result from the body's use of proteins.

3. The major parts of the human urinary system are two kidneys, two ureters, one urinary bladder, and one urethra. (para 8-2b)

4. On the concave, medial side of each kidney there is a notch called the hilus. Through this notch pass the ureter and the NAVL which service the kidney. (para 8-3a(2))

5. If we compare the structure of the kidney with that of a cantaloupe, the structure corresponding to the hard rind would be the renal cortex. The structure corresponding to the edible flesh of the melon would be the renal medulla. Corresponding to the hollow center (after removal of the seeds) would be the renal sinus. The pyramids of the renal medulla form peaks called papillae, which empty into the renal sinus. (para 8-3b)

6. The functional unit of the human kidney is the nephron. Its main subdivisions are the renal corpuscle and a tubular system. (para 8-3c)

7. The renal corpuscle is composed of the glomerulus and the renal capsule. Blood enters by way of the afferent arteriole, passes through the tangled mass of capillaries called the glomerulus, and leaves by way of the efferent arteriole. Leaving the blood, fluid is first collected in the double-walled sac called the renal capsule. (para 8-3c)

8. The first coiled portion of the renal tubule is known as the proximal convoluted tubule. The hairpin-shaped portion of the renal tubule is known as the renal loop (of Henle). The second coiled portion is known as the distal convoluted tubule. (para 8-3c(2))

9. The distal convoluted tubules of several nephrons empty into a collecting tubule. The urine is then passed from the collecting tubule at the papilla of the medullary pyramid. Several collecting tubules are present in each pyramid. There is a hollow sac within the sinus of the kidney called the renal pelvis. The ureter then drains the urine from the renal pelvis. (paras 8-3d, e)

10. Ureters are tubes which connect the kidneys to the urinary bladder. The mechanism used by ureters to move urine is peristalsis. (para 8-4)

11. The urinary bladder is a muscular organ for storing the urine. The triangular base of the urinary bladder is known as the trigone. The two posterior corners of the trigone are the points where the ureters empty into the bladder. The anterior corner of the trigone is the opening of the urethra. Nerve endings stimulated by the stretching of the bladder walls are known as stretch receptors. (para 8-5)

12. The urethra is a tube conducting urine from the urinary bladder to the outside of the body. It begins at the anterior base of the urinary bladder. There is an internal urethral sphincter and an external urethral sphincter. The internal urethral sphincter is located in the floor of the urinary bladder. It is controlled by nerves of the autonomic nervous system. The external urethral sphincter is more inferior, in the area of the pelvic floor. It is controlled by nerves of the peripheral nervous system. (para 8-6a)

13. The female urethra is short and direct. The male urethra is much longer and has two curvatures. The female urethra serves only a urinary function. The male urethra serves both the urinary and reproductive functions. (para 8-6b)

14. Since there are different genital systems for males and females, genital systems are an example of sexual dimorphism. (para 8-7)

15. Primary sex organs produce sex cells (gametes). Primary sex organs also produce sex hormones. What do secondary sex organs do? Secondary sex organs care for the product of the primary sex organ. Secondary sexual characteristics help to ensure mating by making males and females more attractive to each other. (para 8-9)

16. The primary sex organ of the human female is the ovary. The ovaries are located to the sides of the upper end of the uterus. They are anchored to the posterior surface of the broad ligaments. The broad ligaments are sheets or folds of peritoneum enclosing the uterus and uterine tubes and extending to the sides of the pelvis. The ovary produces the egg cell or ovum. The ovary produces chemicals called female sex hormones (estrogens and progesterone). One ovum is released in each menstrual period. (para 8-10)

17. Uterine tubes are two muscular tubes which extend to either side of the uterus and open at the outer ends. Fringe-like appendages encircle the ovaries. At their medial ends, the uterine tubes open into the uterus. The function of a uterine tube is to pick up the ovum when it is released from the ovary and hold it until (a) it is fertilized, or (b) the nutrient is used up and the ovum dies. (para 8-11a)

18. The uterus is the site for all but the first few days of the development of the embryo and fetus. The uterus is shaped like a pear. The stem, or cervix, faces downward and to the rear. It opens into the upper end of the vagina. The uterus leans anteriorly with the body slightly curved as the body passes over the top of the urinary bladder. (para 8-11b)

19. The inner lining of the uterus is called the endometrium. The muscular wall of the uterus is called the myometrium. (para 8-11b(2))

20. The vagina is a tubular canal connecting the cervix of the uterus with the outside. The vagina serves as a birth canal and as an organ of copulation. (para 8-11c)

21. The external genitalia of the human female include the mons pubis, the labia majora, the labia minora, the clitoris, and the vestibule. (para 8-11d)

22. The mons pubis is a mound of fat tissue, covered with skin and hair, in front of the symphysis pubis. (para 8-11d(1))

23. The labia majora are two folds of fatty tissue and skin which extend back from the mons pubis and encircle the vestibule. The outer surfaces are covered with hair. The inner surfaces are moist and smooth. (para 8-11d(2))

24. The labia minora are two folds of skin lying within the labia majora and also enclosing the vestibule. (para 8-11d(3))

25. The clitoris is a small projection of erectile tissue corresponding to the male penis. (para 8-11d(4))

26. During the first eight weeks of pregnancy, the developing organism is known as an embryo. Thereafter, the developing organism is known as a fetus. At the time of birth, the second delivery is that of the placenta and fetal membranes.

27. The secondary sexual characteristics of females include growth of pubic hair, development of mammary glands, development of the pelvic girdle, and deposition of fat in the mons pubis and labia majora. (para 8-12)

28. The primary sex organ of the human male is the testis. The testes are shaped like eggs. Their location is within the scrotum. The scrotum is a sac of loose skin attached in the pubic area of the lower abdomen. The scrotum provides a site cooler than body temperature to maintain the viability of the spermatozoa. When the air is too cold, muscles and muscular fibers draws the testes and scrotum closer to the body to maintain warmth. Otherwise, the scrotum hangs loosely. The testis produces male sex cells called spermatozoa. The testis also produces chemicals, or male sex hormones, called androgens. (para 8-14)

29. The epididymis is a coiled tube whose function is to aid in the maturation of spermatozoa. Its lining secretes a nutritive medium for spermatozoa. As the spermatozoa pass through the nutrient, they mature. (para 8-15a)

30. The ductus deferens is a transporting tube which carries the mature sperm from the epididymis to the prostate. Each tube enters the abdomen through the inguinal canal. Each tube passes over a ureter to reach the back of the urinary bladder and then down to the prostate gland. (para 8-15b)

31. Lying alongside each ductus deferens as it crosses the back of the bladder is a tubular structure called the seminal vesicle. (para 8-15c)

32. The prostate gland is a chestnut-size gland that surrounds the first inch of the urethra as it leaves the urinary bladder. It provides an additional fluid to be added to the spermatozoa and seminal vesicle fluid. (para 8-15e)

33. The penis is the male organ of copulation. Passing through the penis is the urethra. The penis has a central cylinder of erectile tissue called the corpus spongiosum. Each end of this cylinder is bulb-shaped. The sensitive anterior end is known as the glans. The corpora cavernosa are a pair of cylinders of erectile tissue overlying the corpus spongiosum. When present, a covering of skin for the glans is called the prepuce or foreskin. (para 8-15f)

34. The secondary sexual characteristics of males include growth of facial, pubic, and chest hair; growth of the larynx to deepen the voice; and deposition of protein to increase muscularity and general body size. (para 8-16)

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