Biology Essay Example

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The respiratory and circulatory systems are influenced by lifestyle choices. Smoking has negative effects on these systems, including increased blood pressure and heart rate, as well as reduced blood flow to the extremities. These findings come from Lesson 7.03: Digestive and Excretory Systems.

The digestive system is a series of steps and functions that start in the mouth, continue through the esophagus, and play a crucial role in the stomach where digestive fluids break down food. Ultimately, nutrients are absorbed in the intestines.

The excretory system is essential for removing waste from the human body. It accomplishes this by extracting waste through the kidneys, which produce urine. The bladder then collects and stores this urine until it's time to eliminate it.

The skeletal system comprises the bones of the body, providing support and protection to delicate areas like the skull and ribs. Additionally, the bones in the phemur and other leg bones enable us to stand and run.

The muscular system is crucial for various functions including movement, posture support, body temperature regulation, and blood circulation. It's worth mentioning that muscles connect to the skeletal framework through tendons, enabling muscle flexion and ultimately leading to skeleton movement.

The skin, which is the largest organ of the body, acts as its primary defense against pathogens by serving as the first line of defense. Being the initial point of contact with the outside world, it functions to shield what lies beneath through the epidermis. This layer acts as a barrier, preventing easy penetration of pathogens into the skin.

The main function of the male reproductive system is to store and transport sperm. The testes store

sperm necessary for fertilizing a woman's eggs and causing pregnancy. Other parts such as the prostate gland and urethra also help in moving sperm.

The female reproductive system is responsible for the structure and functions related to reproduction in women, while the male reproductive system plays a crucial role in men. Women possess ovaries which produce and release eggs, serving as the main aspect of their reproduction. Furthermore, during pregnancy, the uterus and cervix are involved in the development of the baby.

Fertilization is the process of sperm from the testes meeting eggs from the ovaries. This occurs when a man releases sperm during sexual intercourse and the sperm and egg unite in the woman's fallopian tubes.

The development after implantation is explained, with the embryo becoming a fetus after 8 weeks. In Lesson 7.06: Immune System, the body systems that protect against pathogens are identified. The skin acts as a barrier against pathogens and prevents easy entry into the body. Mucus helps prevent pathogens from entering the nose while breathing. The digestive system also aids in pathogen defense by eliminating them through acid presence.

The immune system cells improve blood flow to the affected area in order to fight against pathogens. Washing hands is an effective way to control pathogens because they often cannot enter through the skin. As a result, the main ways for pathogens to enter our bodies are through the mouth and eyes. By washing our hands, we can stop these pathogens from entering our bodies if we touch our eyes or mouth.

Vaccines are used in acquired immunity to expose individuals to pathogens artificially. This

exposure helps train the immune system to effectively combat the pathogens and develop specific defenses against them. As a result, subsequent exposure to the same pathogens is no longer a significant concern.