Human Body Systems

Unit Review Sheet

Facts and Definitions

Lesson 1: Our Bodies

• A body system is a collection of organs and other parts that work together to perform a specific task.
• The systems of the body are interdependent, meaning they work together and depend on one another.

Lesson 2: Cells, Tissues, and Organs

• The hierarchy or organization of the human body (from least to most complex) is cell —> tissue —> organ substructure —> organ —> system.
• The cell is the smallest structural unit in an organism.
• Tissue is composed of cells that perform a specific function.
• An organ is a structure composed of groups of tissues; organs perform specific tasks in the body.
• An organ typically has several substructures — units that perform specific functions within the organ.

Lesson 3: Musculoskeletal System

• The musculoskeletal system combines the skeletal system (bones) with the muscular system (muscles).
• An articulation (joint) occurs at the point where two bones meet.
• Synovial joints are the most common type of joint in the human body. They contain synovial fluid, which acts like an oily lubricant between the bones in the joint.
• Spongy bone reduces the overall weight of the bone and provides space for the marrow and blood vessels that supply nutrients to the bone.
• Compact bone provides strength to the bones.
• Skeletal muscle is the type of muscle you can control by flexing and relaxing.
• Cardiac muscle is responsible for the beating of your heart.
• Smooth muscle is found in the stomach, intestines, and the lining of the airways.
• Cardiac and smooth muscles are involuntary muscles — you have no conscious control over their activities.

Lesson 4: Cardiovascular System

• The cardiovascular system (also known as the circulatory system) is composed of the heart, blood vessels, and blood; it distributes blood, nutrients, and other substances throughout the body.

Lesson 5: Respiratory System

• The respiratory system is the way the body gets oxygen to every cell in the body, it protects the body from pollutants and allergens, and it removes some toxins, including carbon dioxide.
• Respiration at the body level involves taking in oxygen and eliminating carbon dioxide and other toxins. Cellular respiration uses this oxygen, if it is available, to create the energy needed to conduct all cell processes.
• Your lungs transfer oxygen to the blood by passing the air you breathe in through progressively smaller passages until they allow only single molecules through. These tiny passages end in microscopic air sacs called alveoli, where oxygen moves into the blood and carbon dioxide moves out.
• Smoking causes damage to the air passages, allowing mucous and pollutants to accumulate.

Lesson 6: Digestive System

• When you swallow, a flap called the epiglottis prevents the food from going down the trachea (windpipe) and into the respiratory system.
• In the stomach, food is mixed with chemicals and converted into a liquid called chyme.
• Most of foods' nutrients are absorbed in a long, thin tube called the small intestine.
• The primary organs in the digestive system include the mouth, esophagus, small intestine, large intestine, liver, pan, and gallbladder.

Lesson 7: Urinary System

• The primary functions of the urinary system are to filter wastes from the blood and to maintain balance in the volume and makeup of blood and other bodily fluids.
• The urinary system is also considered part of the excretory system, a collection of processes that rids the body of wastes and toxins.

Lesson 8: Endocrine System

• The endocrine system involves a series of glands, all of which produce hormones.
• Hormones are chemicals that control or affect various body functions.
• The hypothalamus is a portion of the brain that works closely with the pituitary gland to link together the nervous and endocrine systems. It also secretes hormones, most of which control the pituitary gland's production of certain hormones.
• The pituitary gland is called the master gland because it makes several important hormones, some of which influence the production of hormones in other glands.

Lesson 9: Reproductive System

• The reproduction system is the system of organs responsible for producing offspring. The reproductive systems of men and women are significantly different.
• In humans, the gametes (sex cells) are an egg from a female and a sperm from a male.
• Fertilization involves the egg and cell joining.

Lesson 10: Immune System

• The immune system is your body's way of defending against disease.
• An antigen is a harmful microbe attempting to infect the body.
• Macrophages are a type of white blood cell responsible for engulfing the antigens and transporting through lymph and blood vessels to the lymph nodes.
• Antibodies are created in the lymph nodes. They are proteins that are specific to one type of antigen. They disable the antigens making them susceptible to removal by macrophages.

Lesson 11: Nervous System

• The three major sections of the nervous system are the central nervous system (CNS), the peripheral nervous system (PNS), and the autonomic nervous system (ANS).
• The central nervous system (CNS) contains the brain and spinal cord and regulates thoughts, actions, and the body's automatic processes.
• The peripheral nervous system (PNS) contains the nerves that branch out from the brain and spinal cord to areas throughout the body and send signals to and from the CNS.
• Although it shares some sections of the CNS and PNS, the autonomic nervous system (ANS) also has its own nerves; all deal with involuntary body functions, meaning ones you don't consciously control.
• The primary parts of the nervous system are the brain, the spinal cord, and the vast network of nerves that extend to every part of your body.

Lesson 12: Balance in the Body

• Homeostasis is the process of ensuring internal balance in the body systems. It can also describe the state of being in balance or equilibrium.
• Thermoregulation is the process of maintaining a stable temperature.
• Feedback mechanisms are ways the body signals imbalances and the restoration of homeostasis.

Lesson 13: Human Growth and Development

• Genetics, lifestyle, and environment play important roles in a person's growth and development.

Final Project: Body Systems Presentation

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