1. REPRODUCTION AND HEREDITY
Chapter 18
REPRODUCTION AND HEREDITY

2. Endocrine System
The endocrine system regulates long- term changes in the body such as growth and development. It also controls many of your body’s daily activities.
Body’s use of energy from a meal
Its response to stress

3. Endocrine Glands
Endocrine gland: produces and releases chemical substances that signal changes in other parts of the body
Sweat glands release their chemicals into tiny tubes called ducts. The ducts carry the chemicals to the places where they will be used. Endocrine glands do not have ducts.

4. Hormones
A chemical substance produced by an endocrine gland is known as a hormone
A hormone travels to its target cells, where it turns on, turns off, speeds up, or slows down the activities of those cells.
Example: targets of the hormone adrenaline include cells in your heart, muscles, and brain.
Fight or flight response

5. Functions of Endocrine Glands
The endocrine glands include
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus gland
Adrenal glands
Pancreas
Reproductive glands

6. Hypothalamus
Hypothalamus: an endocrine gland located in the brain, actually part of both the nervous and the endocrines systems
Example: Nerve signals from the hypothalamus control body temperature and feelings of sleep and hunger, and hormones from the hypothalamus control the body’s water levels

7. Pituitary Gland
Releasing hormones from the hypothalamus signal the release of hormones from a pea-sized endocrine gland in the brain, called the pituitary gland.
Functions include: growth, reproductions, and metabolism
Metabolism: process by which you obtain energy from food

8. Other Endocrine Glands
Reproductive Glands:
Males: reproductive glands consist of two testes and in females, two ovaries
Puberty: period of sexual development during which a person becomes sexually mature and physically able to reproduce
Puberty starts when the hypothalamus signals the pituitary gland to begin producing two hormones
These hormones in turn signal the reproductive glands to produce sex hormones
Sex hormones activate several changes in your outward appearance

9. The Male Reproductive System
Structure and Function
Reproduction: the process by which organisms produce offspring
Reproductive cells are called sperm
The functions of the male reproductive system are to produce sex hormones, to produce and store sperm, and to deliver sperm to the female reproductive system

10. Male Reproductive System

11. Fertilization
A sperm cell may join with an egg in a process called fertilization
A fertilized egg can develop into a baby

12. Testes Testes: male reproductive glands
Two functions
Production of testosterone
production of sperm
Testosterone: affects the production of sperm and signals certain physical changes at puberty, such as growth of facial hair

13. Testes
Testes, also called testicles, hang outside the main body cavity, within a sac of skin called the scrotum
The temperature of the testes is a few degrees lower than the temperature inside the body
Sperm need this lower temperature to develop properly and survive

14. Testes
One or both of the testes may not descend into the scrotum before birth, a condition called undescended testis.
Sperm will not develop properly because the temperature is too high
This condition is also a risk factor for testicular cancer
Surgery is usually performed before age two to correct this condition

15. Penis
The penis is the external sexual organ through which sperm leave the body
The tip of the penis is covered with loose skin, called the foreskin
In some males the foreskin is removed shortly after birth
This procedure is called circumcision
Usually decided based on cultural or religious reasons

16. Sperm Production
Millions of sperm are produced in his testes each day.
Sperm production begins when the hypothalamus signals the pituitary gland to release two hormones
Luteinizing hormone: signal the tests to begin making testosterone
Follicle-stimulating hormone: signals the production of sperm

17. Pathway of Sperm
Sperm are produced in the testes. They mature and are stored in the epididymis
Sperm travel through the vas deferens to the seminal vesicles.
Seminal vesicles add a fluid that provides a source of energy for the active sperm
The prostate gland adds a fluid that protects the sperm
The bulbourethral glands add a fluid that protects sperm from acidic conditions in the urethra.

18. Pathway of Sperm and Release
Sperm cells mix with fluids produced by the prostate and two other glands.
The mixture of sperm cells and these fluids is called semen
Release of Sperm
The ejection of semen from the penis is called ejaculation.
Ejaculation occurs when muscles in the male reproductive system and at the base of the bladder contract, forcing semen through the urethra

19. Release of Sperm
Urethra: a tube that passes through the penis to the outside of the body
It carries urine as well but not at the same time
There is a valve within the urethra the prevents the fluids from mixing
Several million sperm cells are released during one ejaculation
Sperm stored in the male eventually degenerate, break down, and are disposed of

20. Erection
Ejaculation can only occur when the penis is in an erect state
An erection is a condition in which the penis becomes larger and stiffer as blood chambers in the penis become filled with blood
Most erections do not result in an ejaculation

21. Factors of an erection Sexual excitement Tight clothing
No apparent reason at all
Nocturnal Emissions: wet dream, an erection and ejaculation during sleep

22. Keeping Healthy
Caring for the male reproductive system involves cleanliness, sexual abstinence, protection from trauma, self-exams, and regular medical checkups.

23. Keeping Healthy Cleanliness: Thoroughly clean all external organs
Sexual abstinence: healthy choices can prevent such infections. The only way to eliminate your risk of sexually transmitted infections is to abstain or refrain from sexual activity

24. Keeping Healthy Protection from Trauma: protection and prevention
Self Exams: monitor your bodies for any signs of possible medical problems
Pain when urinating, unusual discharges, or sores on the genitals require medical attention

25. Medical Conditions Prostrate gland surrounds the urethra
In many older man, the prostate becomes enlarges or develops cancer
Starting at age 50, men are encouraged to get screened for prostate cancer
Prostate cancer is the second most common cause of cancer death of older men
Infertility: condition of being unable to reproduce.

26. Infertility 3 causes: Exposure to chemicals Having mumps after puberty
Having an undescended testis

27. Female Reproductive System

28. Female Reproductive System
The female reproductive system is called eggs or ova
The functions of the female reproductive system are to produce sex hormones, to produce eggs, and to provide a nourishing environment in which a fertilized egg can develop into a baby

29. Ovaries
Reproductive glands in which eggs are produced are called ovaries
Each ovary (2) is the size of an almond
Importance of the ovary:
They produce the female sex hormones estrogen and progesterone
Release mature egg cells

30. Estrogen and Progesterone
Estrogen: activate certain physical changes at puberty such as breast development and controls the maturation of eggs
Progesterone activates changes to a women’s reproductive systems before and during pregnancy
Ovulation: once puberty begins, one of the ovaries releases a ripened egg about once every month in a process

31. Fallopian Tubes
Fallopian Tubes: passageways that carry eggs away from the ovaries
Tiny hairlike extension called cilia line the fallopian tube and sweep the egg toward the uterus
Uterus: hollow, muscular pear-shaped organ
The narrow base of the uterus is called the cervix

32. Vagina
Vagina, or birth canal, is a hollow, muscular passage leading from the uterus to the outside of the body
Sperm enter a female’s body through the vagina
During childbirth, the baby passes out of the mother’s body through the vagina
The walls of the vagina are very elastic, which allows it to expand dramatically during childbirth

33. Menstrual Cycle
Females produce only one mature egg cell each month during a process called the menstrual cycle.
During the cycle, an ovary releases a mature egg. The egg travels to the uterus. If the egg is not fertilized the uterine lining is shed and a new cycle begins.
A cycle usually lasts 28 days

34. Menopause
Except during pregnancy, menstrual cycles occur each month from puberty until about the age of 45 to 55.
Menopause: the ovaries slow down their hormone production and no longer release mature eggs
The menstrual cycle stops

35. Stages of the Menstrual Cycle
Days 1-4: The uterine lining is shed during menstruation
Days 5-13: An egg matures in one of the ovaries, and the uterine lining thickens
Days 14-15: The ovary releases the mature egg during ovulation
Days 16-22: The egg travels through the fallopian tube to the uterus, and the uterine lining continues to thicken
Days 23-28: The unfertilized egg enters the uterus

36. Menstrual Discomfort
Many women experience abdominal cramps or other discomfort
If you are experiencing cramps, try
Engaging in moderate exercise
Take a warm bath
Apply a heating pad on the abdomen
Take aspirin or ibuprofen with doctor’s approval

37. Self-Exams and Medical Checkups
Women should do self exam on themselves of their own bodies
A yearly checkup of the reproductive system is recommended for all females who have reached puberty
An exam will include a pelvic exam and a pap smear
Pap smear: a sample of cells is taken from the cervix and examined under a microscope

38. Medical Checkups Starting at age 40, women should get a mammogram
A mammogram is an x-ray of the breast that can help detect breast cancer
Other detections:
Ovarian cyst: growths on the ovary
Endometriosis: condition in which tissue from the lining of the uterus grows outside the uterus in the pelvic cavity
Infertility: blocked fallopian tubes and problems with ovulation

39. Heredity
Heredity: passing on of biological traits from parent to child
Chromosomes: tiny structures found within cells that carry information about the characteristics you will inherit
Most of the cells in your body contain 23 pairs of chromosomes
Sex cells (sperm or eggs) contain 23 chromosomes
(23 from each parent)

40. Genes
A gene is a section of a chromosome that determines or affects a characteristic or trait
Hereditary information passes from one generation to the next through genes contained on the two sets of chromosomes that a person receives from their parents

41. Genetic Disorder
Genetic Disorders are caused by the inheritance of an abnormal gene or chromosome
For most diseases, your environment and your behavior affect your risk as much as or even more than your genes

42. Medical Advances
Genetic Testing: Analysis of a blood sample for the presence of abnormalities in specific genes
Gene therapy: scientists are currently researching a technique in which healthy copies of a gene are delivered to the cells of a person who has a defective copy of the gene