GED Class 5 Science Pt 1 2023 GED Test Audio Lessons, Audio GED Prep Project

Life Science: Anatomy and physiology



Nervous system



The nervous system is made up of the brain, the spinal cord, and the nerves. Electrical impulses are sent from the brain, travel down the spinal cord, and are sent out to the nerves. There are different kinds of nerves, those that control conscious motions and those that control unconscious processes. The nerves are what sense pain as a defense mechanism for your brain. They can sense a variety of sensations, such as hot and cold, pressure, and movement, all of which help the brain process information.



It is important to care for the nervous system, because once damaged, nerves cannot be repaired.



Skeletal and muscular system



The skeletal and muscular system work together in order to give the body shape and structure and to allow the body to move. The human body has over 200 bones, which are made up of a hard outer part and a softer inner part called marrow, which is responsible for red blood cell production and other functions of the immune system.



The points where bones connect and move against each other are called joints. There are various types of joints, from the hinge joint in the knee that just opens and closes to the ball and socket joints in the arms, which allow for a full rotating range of motion.



Ligaments are flexible bits of tissue that connect bones to other bones. Tendons are similar bits of tissue that connect bones to muscles.



There are several different kinds of muscles, including voluntary muscles and involuntary muscles.  Voluntary muscles are ones that are controlled directly by you thinking about them. They include in the muscles in your arms and legs that allow you to walk or to pick something up. Involuntary muscles are ones regulated by the brain that you do not have conscious control over. The heart is an example of this. Your heart keeps beating whether or not you think about it, and you cannot stop it by thinking about it either.



Respiratory system



The respiratory system is the system that takes in oxygen into the body and oxygenates the blood so that oxygen can travel throughout the body. It then takes in carbon dioxide and expels it from the body. The respiratory system consists of the lungs, the mouth, the throat, and the sinuses.



The lungs are full of tiny sacs called alveoli, which make the exchange of oxygenated blood and unoxygenated blood.



Circulatory system



The body’s circulatory system is responsible for carrying blood throughout the body. the blood is filled with oxygen in the heart, and is then pumped out into the body through blood vessels called arteries. Blood is pumped to the cells and is transferred to blood vessels called veins through tiny blood vessels called capillaries.



Veins then carry the unoxygenated blood back to the heart where it can pick up a new round of oxygen. You body performs this operation thousands of times a day without you having to think about it. In addition to carrying oxygen to cells, blood also transports nutrients to cells, takes away waste, and transport immune system cells to fight pathogens throughout the body.



If a blood vessel is broken, there are tiny cells in blood called platelets, which causes blood to clot together in order to plug the break.



Digestive system



The digestive system is responsible for processing the food that brought into the body. It separates nutrients and other useful materials from waste material. This process is called digestion.



Digestion begins in the mouth where glands create saliva, which starts to break down food. Food then passed down a muscular tube called the esophagus into the stomach. In the stomach, food is broken down by stomach acid and is then passed into the small intestine. Here,