1. DO Are You Ready? Pg

3. 1. Adult humans have developed from a single fertilized egg into a complex organism composed of many types of cells.
(a) How does one cell grow into a multicellular organism?
(b) If all the cells in your body came from the same fertilized egg cell, why don’t they all look alike?
(c) Why are there more of some cell types than others?

4. 2. A quaking aspen located near Salt Lake City, Utah, may be the world’s largest organism, according to Dr. Stewart Rood at the University of Lethbridge.What appears to be a grove of individual aspen trees is actually one organism with a common root system. The single organism covers 43 hectares! The tree-like shoots develop from runners (horizontal roots) that grow above or below the ground.
(a) What are the advantages of reproducing by runners?
(b) Do all the trees have the same genetic information since they are one organism? Explain why or why not.
(c) List three other plant species that reproduce through runners.

5. 4. The time that unborn young spend developing in the uterus is called the gestation period. In mammals, the gestation period ranges from 16 days for golden hamsters to 650 days for elephants (Figure 2). Identify the advantages and disadvantages of short and longer gestation periods.

6. 5. On April 25, 1978, the birth of a young girl, Louise Brown, caused people around the world to stop in amazement. She was the first baby ever conceived outside of the human body. A sperm cell fertilized an egg cell within a glass Petri dish in the laboratory (Figure 3). This revolutionary technique heralded the beginning of the new field of reproductive technology.
(a) Could a woman give birth to a baby who carries none of her genetic information? Explain your answer.
(b) Is it possible, through reproductive technology, for a 60-year-old woman to have a baby?
(c) What ethical problems might arise because of research in this field?

7. Reproduction

8. Introduction Reproduction ensures the survival of a species
Asexual reproduction involves only one individual, requires less energy, and produces more offspring
Sexual reproduction involves the fusion (or fertilization) of male and female sex cells (egg and sperm) to produce a zygote

9. Introduction
Fusion of sex cells yields more diversity and thus greater chance of species survival
Male and female sex organs develop in the same region of the embryo and are indistinguishable until the third month (the clitoris and penis develop from the same cells)

10. Introduction
Females produce about eggs which are present at birth. About 400 mature between the ages of
Males can produce sperm cells every day from age

11. Male Reproductive System (Figure 1 Nelson, pg. 512)11 10 5 9 5 9 8 8

13. Male Reproductive System
TESTES - male gonads produce male sex hormones and sperm. Drop from the abdominal cavity to the scrotum in the last two months of fetal development. The testes must be outside of the body where it is cooler to produce sperm. (hernia)
EPIDIDYMIS - Located outside of the testes. Store sperm cells.
 VAS DEFERENS - tube which takes sperm to urethra (vasectomy). Regulated by the ejaculatory duct which allows semen to enter the urethra if the urinary sphincter is closed.

14. Male Reproductive System
SEMINAL VESICLES - add fructose and prostaglandins (hormone) to the semen
 PROSTATE GLAND - adds an alkaline buffer to the semen to protect sperm from the acidic environment of the vagina. (cancer of the prostate gland is very common and can be detected with a rectal exam, early detection can prevent spread to other areas of the body)
 COWPER’S (BULBOURETHRAL) GLAND - adds mucus to the semen to protect the sperm.
 ERECTILE TISSUE - fills the penis with blood during sexual excitement. Controlled by a parasympathetic nerve.

15. Development of Sperm Cells
Pg 515 Nelson
Human Sperm Cell
Figure 17.3 Nelson

16. Testes and Spermatogenesis
Sperm Cell – VERY WELL DESIGNED TO SWIM
Small amount of cytoplasm for high mobility
Flagellum- propels the sperm
Acrosome- cap on sperm that expel enzymes to digest outer coating of egg

17. Testes and Spermatogenesis
Seminiferous Tubules
Twisting tubes that fill each testis, 250m long
SERTOLI CELLS in the testes nourish developing sperm cells.
Lined with spermatogonia (sperm producing cells)
Meiosis occurs to produce spermatocytes which have only 23 chromosomes rather than 46
Spermatocytes then differentiate into spermatids and then to sperm
Sperm then head to the epididymis to mature and be stored
At body temperature, sperm live only 1-3 days outside the male’s body

18. Seminal Fluid
In an ejaculation (approx. 3-4 mL) there are 500 million sperm in the seminal fluid. There are also other secretions from the:
SEMINAL VESICLE- secretes a fluid that contains prostaglandins (signals female muscle contractions to facilitate movement of sperm in reproductive tract) and fructose (provides the sperm with energy)
PROSTATE GLAND- secretes an alkaline secretion that protects the sperm from the acidity in the vagina
COWPER’S GLAND- secretes mucous to protect sperm from acidity in male urethra and to facilitate movement in vagina

19. Hormonal Control of Male Reproductive System
Testosterone
Produced by INTERSTITIAL CELLS between the seminiferous tubules
stimulates spermatogenesis and
stimulates development of secondary sex characteristics in males such as
maturation of the testis and penis,
facial & body hair,
deepening of voice,
strengthening of muscle, and
sex drive
Testosterone is used to make anabolic steroids used illegally by some athletes and body biulders

20. Hormonal Control of Male Reproductive System
Negative FEEDBACK:
Hypothalamus secretes GnRH (Gonadotropin Releasing Hormone) which activates the…
Anterior pituitary to secrete
1. FSH (follicle stimulating hormone ) which stimulates the production of sperm cells in the seminiferous tubules and
2. LH (luteinizing hormone ) which promotes the production of testosterone by interstitial cells
Once high levels of testosterone are detected by the hypothalamus a negative feedback system is activated and GnRH is decreased thereby decreasing the release of LH and ultimately decreasing sperm production
Testosterone is used to make anabolic steroids used illegally by some athletes and body biulders

21. Hormonal Control of Male Reproductive System
Sertoli Cells (in testes) secrete a hormone called inhibin that is a part of the negative feedback loop for sperm/testosterone. It is triggered by high levels of sperm. It sends a message to pituitary to reduce FSH and to the hypothalamus to reduce GnRH.

22. Hormonal Control of Male Reproductive System
GnRH
Write beside the bubbles: sertoli cells and interstitial cells
Sertoli Cells in seminiferous tubules
Interstitial Cells