1. Science Review Sheet Final Exam 2 nd Semester

2. As soon as the food enters your mouth, it begins it’s journey through your digestive system. No matter what you eat, your food goes through four steps- ingestion, digestion, absorption, and elimination. Food is ingested. Ingestion is the act of eating, or putting food in your mouth. Food is digested. Digestion is the mechanical and chemical breakdown of food into small particles and molecules that your body can absorb and use. Absorption occurs when the cells of the digestive system take in small molecules of digested food. Undigested food is eliminated. Elimination is the removal of undigested food and other wastes from your body. There are two types of digestion-mechanical and chemical. Mechanical digestion happens when you chew, mash, and grind food with your teeth and tongue. In chemical digestion, chemical reactions break down pieces of food into small molecules. After you swallow a bite of your food, it enters your esophagus. The esophagus is a muscular tube that connects the mouth to the stomach. Food moves through the esophagus and the rest of the digestive tract by waves of muscle contractions, called peristalsis. The stomach is a large hollow organ. Chemical digestion begins in the mouth and stomach. But most chemical digestion occurs in the small intestine. The small intestine is a long tube connected to the stomach. The folds of the small intestine are covered with fingerlike projections called villi. Notice also that each villus contains small blood vessels. The pancreas and the liver, shown in figure 7, produce substances that enter the small intestine and help with chemical digestion. The liver produces a substance called bile. Bile makes it easier to digest fats. The gallbladder stores bile until it is needed in the small intestine. The parts of food that are not absorbed in the small intestine move by peristalsis into the large intestine, also called the colon. Materials that pass through the large intestine are the waste products of digestion. The waste products become more solid as excess water is absorbed. Muscles in the rectum and anus control the release of this semisolid waste, called feces. The Digestive System

4. Breathing is the movement of air into and out of the lungs. Breathing enables your respiratory system to take in oxygen and to eliminate carbon dioxide. Every cell in your body needs oxygen for a series of chemical reactions called cellular respiration. During cellular respiration, oxygen and sugars react. This reaction releases energy a cell can use. Your respiratory system removes carbon dioxide and other waste gases from your body. If waste gases are not removed, cells cannot function. Air enters the body through the mouth and the nose. Cilia line the nose and most airways in the respiratory system. The cilia help prevent harmful particles from getting very far into your respiratory system. The trachea braches into two narrow tubes called bronchi that lead into the lungs. Lungs are the main organs of the respiratory system. Inside the lungs, the bronchi continue to branch into smaller and narrower tubes called bronchioles. In the lungs, the bronchioles end in microscopic sacs, or pouches called alveoli, where gas exchange occurs. During gas exchange, oxygen from the air you breathe moves into the blood, and carbon dioxide from your blood moves into the alveoli. Every time you breathe, your alveoli enable your body to take in billions of molecules of oxygen and get rid of billions of molecules of carbon dioxide. Below the lungs is a large muscle called the diaphragm that contracts and relaxes and moves air in and out of the lungs. The best way to maintain good respiratory health is to stay away from irritants and air pollution. The Respiratory System

6. The Skeletal System Your skeleton is part of your skeletal system and contains more than 200 bones. Your Skeleton is made of bones A bone is an organ composed of living tissue. Bones can move because they are attached to muscles. The skeletal system and the muscular system work together and move your body. There are two main types of bone tissue: compact and spongy. The insides of most bones contain a soft tissue called bone marrow. There are two types of bone marrow. Red bone marrow is the tissue where red blood cells are made. Yellow bone marrow stores fat and is found inside the longest part of long bones. Cartilage is a strong, flexible tissue that covers the ends of bones. Cartilage prevents the surfaces of bones from rubbing against each other and reduces friction. Before you were born, your skeleton was made mostly of cartilage. During your infancy and childhood, the cartilage was gradually replaced by bone. A joint is where two or more bones meet. Joints provide flexibility and enable the skeleton to move. Bones are connected to other bones by tissue called ligaments. Your Skeletal System contains two types of joints – immovable joints and movable joints. A break in a bone is called a fracture. Broken bones are able to repair themselves. One of the best ways to keep bones healthy is to exercise. A balanced diet also keeps bones healthy. Bones especially need calcium and vitamin D. Homeostasis requires that all body systems function properly together. Science Quiz Review Sheet Skeletal System and Muscular System

7. Your Skeleton has five major functions. It provides shape and support. It enables movement. It protects internal organs. It produces blood cells. It stores minerals and other materials.

8. The Muscular System Movement is an important function of the muscular system. But muscles are also important for protection, stability, and maintaining body temperature. Muscles also change chemical energy to thermal energy during exercise. Your body has three different types of muscles: skeletal, cardiac, and smooth. Each of these muscle tissues is specialized for a different function. The type of muscle that attaches to bones is skeletal muscle. Skeletal muscles are also called voluntary muscles, which are muscles that you can consciously control. Skeletal muscles work by pulling on bones. Because muscles cannot push bones, they must work in pairs. If you exercise, your muscle cells increase in size and the entire muscle becomes larger and stronger. Your heart is made up of cardiac muscles, which are found only in the heart. A cardiac muscle is a type of involuntary muscle, which is muscle you cannot consciously control. Smooth muscles are involuntary muscles named for their smooth appearance. Blood vessels and many organs, such as the stomach are lined with smooth muscles. Recall that a good diet keeps your bones healthy Your muscles benefit from a healthy diet, too. All muscles require energy to contract. This energy comes from the food you eat. Eating a diet full of nutrients such as protein, fiber, and potassium can help keep muscles strong. Tendons attach muscles to bones

9. Your Muscular System has four major functions. It enables movement It protects your organs It provides stability. It helps maintain body temperature

10. The Skin is the largest organ of your body. The epidermis is the outermost layer of skin and the only layer in direct contact with the outside environment. Below the epidermis is the dermis. The dermis is a thick layer of skin that gives skin strength, nourishment, and flexibility. The dermis contains sweat glands, blood vessels, nerves, hair follicles, and muscles. The innermost layer of skin insulates the body, acts as a protective padding, and stores energy. This layer is sometimes called the fatty layer or hypodermis. A bruise is an injury where blood vessels in the skin are broken, but the skin is not cut or opened. When you break one or more layers of skin, it is called a cut. Cuts often cut blood vessels, too. The released blood will usually thicken and form a scab over the cut. Some cuts are too large to heal naturally. If that happens stitches might be needed to close the cut while it heals. Have you ever injured your skin by contact with hot water or hot food? If so, then you had a burn. However, burns can also be caused by touching extremely cold objects, chemicals, radiation (such as sunlight), electricity, or friction (rubbing).

11. Functions of the Skin 1 st Function: Protection – Stops the body from drying out – Protects cells and tissue from damage – Skin is the first line of defense against dirt, bacteria, viruses, and other substances that might enter your body 2 nd Function: Sensory Response – Your skin has special cells called sensory receptors – These receptors detect temperature, texture, and pain 3 rd Function: Temperature Regulation 4 th Function: Production of Vitamin D 5 th Function: Elimination

12. Dictation: These are words you must memorize and then spell The Skeletal System The Muscular System The Skin The Digestive System The Respiratory System The Nervous System The Dermis Elimination Function Homeostasis Body Temperature Heart Lungs Small Intestine Bones Ligament Cartilage Veins Arteries Protection Voluntary Muscles Involuntary Muscle Skeletal Muscles Cardiac Muscles Smooth Muscles The Epidermis The Dermis The Hypodermis Bacteria Brain Spinal Cord Cut Burn Essential Sensory response Vitamin D Temperature Regulation