1. The Human Organism &The Perpetuation of Life
Chapter 5
The Human Organism &The Perpetuation of Life
The Elements of Life
Elements make up everything around us including the trees, bacteria, air, rocks and you.
All life is made up of small compartments called cells.
Cell: is the basic unit of life.
All living things must be able to:
Breathe
Eliminate waste
Grow
Reproduce

2. Human Genome: made up of ~25 000 genes.
Gene: segment of DNA that contains the genetic information required to carry out a particular job. Ex: certain segments code for the manufacturing of proteins: hormones, enzymes, repairing wounds, etc.
Human Genome: made up of ~ genes.
Your genes make you who you are from how your body works to your specific characteristics.
Genetic Diversity:
Every individual has different genes except for identical twins.
Every gene can exist in different variations and forms. Ex: genes for eye colour: blue, green brown, hazel, etc. or hair colour.
The total # of possible genetic combinations make up the genetic diversity of a species.
Sexual reproduction increases genetic diversity of a species.

3. 2. Cell Division in Humans
3 Reasons:
increase cell count for growth
to regenerate damaged or broken tissue
make sexual reproduction possible by producing sex cells
Cell Division: is a process that is essential to the production of new cells for the purpose of growth, tissue repair and sexual reproduction.
The period when cells are not dividing is called Interphase: period when doing their ‘job’

4. Interphase Before mitosis a cell is in a phase called Interphase.
Interphase: is when a cell is performing its regular functions, “job”.
Towards the end of Interphase DNA replication occurs preparing the cell for Mitosis. Therefore there will be 92 chromosomes in a cell at the end of Interphase.
Replication: DNA uncoils and separate, each DNA strand serves as a template for building a new complementary strand. Forms two identical helixes.

5. Cell Division
1) Mitosis: increases the number of cells for growth and tissue repair.
** End of Mitosis two daughter cells are produced and they are genetically identical.

6. *Male sex cells: male gametes or spermatozoa
2) Meiosis: creates the sex cells (haploid). -haploid cells contain one copy of each gene. -parent cell (diploid) divides twice producing four daughter cell containing ½ the genetic information (DNA) of the parent cell. - crossing over (exchange pieces of DNA) increases genetic diversity -Result of meiosis is 4 genetically different haploid daughter cells not identical to the parent cell. -Allows for sexual reproduction to occur.
Two types of sex cells:
*Male sex cells: male gametes or spermatozoa
*Female sex cells: female gametes, eggs or ova

7. Reduction Division Meiosis reduces the # of chromosomes by half.
There are two divisions: Meiosis I and Meiosis II.
The result: 4 haploid daughter cells each containing 23 chromosomes that are genetically different from each other and the parent cell.

8. SEXUAL REPRODUCTION
The production of offspring through meiosis and the union of a sperm and an egg.
Gametes (haploid)￫ a reproductive cell. Ex: sperm (spermatozoan), egg (ovum)
Offspring are genetically different from the parents.
Meiosis and Fertilization are the 1st two steps of development.

9. Fertilization
when two gametes (sperm and egg) meet to form a zygote (diploid): a single cell.
A zygote contains genetic information from both parents.
A zygote is the 1st cell of every human.
The zygote will divide by mitosis and eventually form an embryo.
Sexual reproduction gives an evolutionary advantage enabling species to adapt quickly to new conditions.

11. Puberty: a process where physical changes occur developing a child’s body to an adult’s, capable of reproduction.
~10-14 yrs. old.
production of sex hormones.
Hormones: chemical messengers that are secreted by glands.
transported by the blood
control the activity of one or more organs.
growth is accelerated
Sexual Development
Hormones and their glands are part of the endocrine system. It regulates body activities, growth, regulation of metabolic processes, reproduction, bodies responses to stress, etc.

12. Hormones Triggering Puberty
Pituitary Gland located at base of the brain secretes two hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
FSH and LH stimulate
maturation of ova; beginning of fertile phase
Stimulate ovaries to produce female sex hormones: estrogen and progesterone.
FSH and LH
stimulate production of spermatozoa.
Stimulate testicles to produce male sex hormone: testosterone.
Sex hormones initiate primary and secondary sex characteristics in both males and females.

13. The Primary physical changes in boys
Physical Changes of Males
The Primary physical changes in boys
Development of testicular size, function and fertility (Production of sperm)
Development of genitalia
Body , facial, underarm and pubic hair appear
Voice change; becomes deeper (larynx enlarges)
Height growth
Body shape: skeletal musculature and bone density increases
Body odour, skin changes, acne
Psychological changes occur
General hairiness
The Secondary physical changes in boys

14. Physical Changes of Females
Primary physical changes of puberty in girls
Development of genital organs: vagina, uterus, ovaries
Menstrual and Ovarian Cycle: Menstruation and fertility [Maturation of egg(s)]
Secondary physical changes of puberty in girls
Breast development
Hair (Pubic, underarms)
Wider pelvic shape
fat distribution (rounded figure: mainly hips and breasts)
Body odour, skin changes, and acne
Psychological changes
General hairiness

15. Female Reproductive System
prepares the ova/eggs for possible fertilization.
The ovaries are located in the lower abdominal cavity
fallopian tubes: connected to each ovary; lined with cilia and fluid; leads to uterus: site of attachment for fertilized ovum.
The uterus (womb) is a hollow, inverted, pear-shaped organ located in a woman's lower abdomen between the bladder and the rectum.
The inner layer of the uterus (endometrium) goes through a series of monthly changes known as the menstrual cycle.
Cervix: opening to the uterus.

17. Oogenesis: maturation of the ova
The primary reproductive organs of the female reproductive system are the ovaries.
the female gonads (ovaries) produce gametes. 
Ovum: the female gamete (egg); pl. ova (haploid)
Oogenesis is the process of ovum production by meiosis.
Females born with ~ cells (oocytes: diploid) in ovaries that can become ova. ~400 oocytes will become ova.
Each cycle an oocyte matures, becomes ovum (haploid) which is highly complex and is ~ times larger than a sperm.

18. Oocyte Development: Beginning of Cycle
Ovarian follicle: layer of cells surrounding oocyte (diploid).
Beginning of cycle: 1 begins maturing and oocyte (diploid) begins meiosis I producing 2 cells. One cell (haploid) receives most of cytoplasm and other cell dies.
Middle of cycle: Ovarian follicle burst; oocyte moves into one of two fallopian tubes, this is Ovulation.
Oocyte (haploid) undergoes meiosis II while in fallopian tube.
1 of 2 cells contains most of cytoplasm produces mature ovum, 2nd cell dies.

19. THE OVARIAN CYCLE
1 ovarian follicle matures changing to corpus luteum.
The hormone FSH is released stimulating development and growth of ovarian follicle; releasing more estrogen (Days ~1-13).
Increasing estrogen stimulates pituitary gland to secrete large amounts of LH & more FSH. This causes mature ovarian follicle to rupture releasing oocyte; known as ovulation (Day ~10-16).
LH promotes healing of ruptured ovarian follicle forming corpus luteum, which in turn secretes progesterone; stopping production of FSH and LH and stimulates thickening of uterine wall.

20. An unfertilized egg causes the corpus luteum to disintegrate which decreases progesterone production which causes endometrium (uterine lining) to detach from uterus and be expelled through menstruation.(Days 15-28). -body ready for another cycle.

21. THE MENSTRUAL CYCLE
Represents the periodic changes in the uterine endometrium.
Begins with 1st day of menstruation. (~Day 1-5)
The decreased production of progesterone causes endometrium to detach shed through menstruation. The endometrium and blood from ruptured blood vessels are discharged through the vagina.
Proliferation phase (~days 6-14): decreased release of progesterone allows for production of FSH & LH which increases release of estrogen stimulating the thickening of the endometrium. The endometrium begins to thicken again due to another developing ovarian follicle.
Secretory phase (~days 15-28) ends menstrual cycle; endometrium continues to thicken due to progesterone from corpus luteum .

23. The ovum has enough stored nutrients to survive about 12-24 hours
The ovum has enough stored nutrients to survive about hours. Spermatozoa can live from 1-5 days. Therefore pregnancy can occur within a 6 day period; five days before ovulation to one day after.
If ovum is fertilized corpus luteum continues secretion of progesterone until placenta is ready.
Fertilized ovum forms a zygote (diploid) attaching to wall of uterus (endometrium) and develops into an embryo.
If two eggs mature and are released fraternal twins may occur.
Ovulation begins at puberty and ends in a females mid to late 40s, menopause.
menopause￫ stage upon which women’s follicles have either ruptured or degenerated thus stopping the secretion of female hormones that stimulate the menstrual cycle. Therefore, menstruation stops. Side effects include: hot flashes, mood swings and bone loss.

24. Male Reproductive System
Two testes are located outside the body within the scrotum, a pouch of skin that keeps the testes at an optimal temperature for sperm development.
The scrotum is 3oC cooler than regular body temperature.

26. Spermatogenesis
During puberty pituitary gland secretes FSH, stimulating Spermatogenesis.
Is process of producing sperm cells through meiosis.
an increase in the production of testosterone stimulates the formation of spermatozoa (sperm).
Seminiferous tubules ➙ are inside each testicle, contain cells called spermatogonia; they are the site of sperm production.
~250 meters (850 feet) are packed into each testicle.
Spermatogonia (diploid cells) : cells lining walls of seminiferous tubules, they undergo meiosis to form spermatozoa (sperm). 1 spermatogonium produces 4 sperm cells.
Produce ~120 million sperm per day
The production of sperm occurs throughout most of the male lifespan.

28. The Path of Sperm:
Seminiferous tubules to epididymis ￫ site where sperm mature.
Then to the vas deferens ￫ help move sperm to Ampulla of vas deferens: holding site for sperm.
Sperm moves into Seminal duct then to the urethra.
Urethra: canal where sperm and urine are expelled.
In the urethra sperm are mixed with seminal fluids (whitish liquid) secreted by seminal vesicles, Cowper’s gland and prostate.
semen￫ fluid formed from sperm, secretions of the glands (prostate gland, Cowper’s gland and seminal vesicles) and vas deferens.
Semen helps to neutralize acid, give sperm energy and stimulate muscle contractions in the female reproductive tract.

29. The Path of Sperm continued
Penile erection: a result of sexual arousal causes blood to fill corpus cavernosum and corpus spongiosum (spongy tissue) of the penis allowing it to become erect.
Erection: increase in volume and rigidity of the penis.
Ejaculation ￫ contractions of the smooth muscles surrounding the urethra by which semen is forcefully expelled. ~ million sperm per ~3.5 mL of semen (per ejaculate).
~1% of ejaculate is sperm.
Sperm exit body through urethra, same opening as urine in the penis.
Penis: the sex organ that deposits sperm in the female reproductive system.
Andropause: decrease in hormone levels and sperm production. Doesn’t necessarily affect fertility.

30. Human reproduction
internal fertilization➙ fertilization of the egg by the sperm within the body of the female. The fertilization is dependant on the action of hormones, the nervous system, and the reproductive system.