Study Guide

Study Guide

Sexually Transmitted Infections

Sexually transmitted infections (STIs) are diseases that spread through sexual contact. Bacterial STIs can be cured with antibiotics, but viral STIs cannot. Since some STIs have little or no symptoms, they often go untreated and can lead to serious consequences such as cancer and death. The only way to prevent STIs is to avoid sexual contact.

Fertilization to Old Age

Fertilization creates a zygote, which undergoes cell divisions and implants in the uterus. After implantation, it becomes an embryo and forms 3 cell layers, which differentiate and develop into different organs. At nine weeks, the embryo becomes a fetus, and the fetus continues to grow and takes nutrients from the placenta. During childbirth, uterus contractions push the baby out of the mother’s body.

Female Reproductive System

The female reproductive system consists of the female sex organs, the two most important of which are the uterus and the ovary. The female reproductive organ has many responsibilities that include the reception of sperm and support for a developing fetus during and post-birth. The female reproductive system develops before birth but doesn’t reach maturity until puberty.

Male Reproductive System

The male reproductive system, consisting of the penis, testes, and epididymes, is necessary for reproduction. The system forms before a child is born, but until hormones called testosterone are released during puberty (which occurs when a male is 12-18 years old), the male reproductive system remains immature. The secretion of testosterone after puberty allows males to produce sperm via spermatogenesis.

Environment & Health

There are many environmental factors that can affect human health, including pollution, carcinogens, and bioterrorism. These three, if not properly controlled, will have severe effects on human health. Air pollution can worsen lung diseases or cardiovascular issues, and carcinogens can cause cancer. Bioterrorism, if not caught, can lead to death, as in the case of the anthrax scare in 2001.

Immune System II: Immune System Diseases

Like any other system in the body, the immune system can have problems. Sometimes, the immune system can target the wrong types of cells, interpreting harmless substances as pathogens. Other times, damage can be done to the immune system itself, interfering with its ability to do its job. Such problems are called immune diseases. Some of these problems have cures and can be relieved. For others, investigation into effective cures is ongoing.

Excretory System

The body must get rid of the waste products of cellular activity. The process of removing these wastes is called excretion. The excretory system not only gets rids of wastes, but it also maintains homeostasis by regulating the contents of blood. The kidneys are the main organs of the excretory system. They regulate the chemical composition of blood and excrete the remaining waste as urine.

Digestive System

Everything that you eat is broken down by the digestive system. The process of digestion does two things: it gathers nutrients from the food you eat, and it produces waste. Foods need to be broken down mechanically and chemically into very small molecules. These nutrient molecules are absorbed through the wall of the small intestine and transferred around the body to provide a source of energy.

Respiratory System

The job of the respiratory system is the exchange of gases between the body and the outside air. This process, called respiration, actually consists of two parts. In the first part, oxygen in the air is drawn into the body and carbon dioxide is released from the body through the respiratory tract. In the second part, the circulatory system delivers oxygen to body cells and picks up carbon dioxide from the cells in return.

Immune System I: Lines of Defense and Lymphatic System

The immune system consists of three lines of defense to help protect bodies from invading pathogens, such as worms and germs. The first and second lines of defense are non-specific, so the processes are the same for all pathogens. The third line of defense is specific to the type of pathogen.

Body

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