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Physiology. Ms. Samuelian. Body Organization. The maintenance of a stable internal environment is called homeostasis If homeostasis is disrupted, cells suffer and sometimes die Many different “jobs” have to be done to maintain homeostasis
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Physiology Ms. Samuelian
Body Organization • The maintenance of a stable internal environment is called homeostasis • If homeostasis is disrupted, cells suffer and sometimes die • Many different “jobs” have to be done to maintain homeostasis • A group of similar cells working together forms a tissue • Two or more tissues working together form an organ • Organs working together make up an organ system
The Skeletal System • Bones, cartilage, and the special structures that connect them make up your skeletal system • Most bones start out as a soft, flexible tissue called cartilage • Cartilage contains mostly water, which gives it a rubbery texture • The place where two or more bones connect is called a joint
Skeletal Muscles • The muscles that move bones are called skeletal muscles • They help protect your inner organs • Skeletal muscles are attached to bones by tough tissues called tendons
Working in Pairs • Your skeletal muscles work in pairs to cause smooth, controlled movements • Many basic movements are the result of muscle pairs that cause bending and straightening
Did You Know? It takes 13 muscles to smile It takes 43 muscles to frown
The Cardiovascular System • The cardiovascular system transports materials to and from your cells • Blood supplies the cells of your body with oxygen • Blood is about 55% plasma and 45% red blood cells, white blood cells, and platelets • Plasma is the fluid part of the blood • Red blood cells supply your cells with oxygen • White blood cells defend the body against pathogens (bacteria, viruses, and other microscopic particles that can make you sick) • When you cut your skin, you bleed because your blood cells have been opened • As soon as bleeding occurs, platelets begin to lump together in the damaged area and form a plug that helps reduce blood loss
Circulatory System • The circulatory system consists of the heart, blood vessels, and blood • The heart pumps the blood through the blood vessels • Blood flows through the system in just one direction • Heart valves prevent blood from flowing backward
Heart • Your heart is a muscular organ about the size of your fist • The heart pumps oxygen-poor blood to the lungs and oxygen-rich blood to the body • Your heart has a left side and a right side separated by a wall • Each upper chamber is called an atrium • Each lower chamber is called a ventricle
Blood Vessels • Blood travels throughout your body through blood vessels • A blood vessel is a hollow tube that transports blood • There are three types of blood vessels: arteries, capillaries, and veins • Arteries are blood vessels that direct blood away from the heart • Capillaries are the smallest blood vessels in your body • Veins are blood vessels that direct the blood back to the heart
Blood Flows Under Pressure • The force exerted by blood on the inside walls of a blood vessel is called blood pressure
Did You Know? • Smoking is the leading cause of cardiovascular diseases and lung diseases
The Respiratory System“Out with the Bad Air; In with the Good!” • Your body needs a continuous supply of oxygen in order to obtain energy from the foods you eat • Respiration is the process by which a body obtains and uses oxygen and gets rid of carbon dioxide and water • Breathing is made possible by the respiratory system • The respiratory system consists of the lungs, throat, and passageways that lead to the lungs
Digestive System • Your digestive system breaks down the food you eat into nutrients that can be absorbed into your body
Excretory System • The excretory system filters wastes from the blood • Excretes the wastes from the body in urine
The Nervous System • What do the following events have in common: you hear a knock at the door, you write a book report, you feel your heart pounding after a run, you work a CAHSEE math problem, and you enjoy eating a sweet mango with chili powder. These events are all activities of your nervous system • The nervous system gathers and interprets information about the body’s internal and external environments and responds to that information • The nervous system keeps your organs working properly and allows you to speak, smell, taste, hear, see, move, think, and experience emotions
Bodies Need Antibodies • The immune system defends your body against pathogens, such as viruses or bacteria • Your immune system’s reaction to infection is called the immune response • Proteins on the surface of pathogens are called antigens • Antibodies stick to antigens to disable and help destroy the pathogens • Be nice to your immune system!
Antibodies • So, pathogens (the bad guy) are covered with proteins called antigens • Your B cells shift to “attack mode” when pathogens invade your body by releasing antibodies (the good guy) • Antibodies have two antigen-binding sites • Antibodies bind with the pathogen and as a consequence the pathogen can no longer harm the body
Immunity • When you’ve been exposed to a pathogen and you’ve produced antibodies to it, some of the B cells “remember” how to produce antibodies for that pathogen • So if the same pathogen enters the body a second time, antibodies will be ready for the attack and destroy the pathogens before it can multiply and cause disease •
Vaccination • Vaccinations protect you from specific diseases that can make you very sick, disable or even kill you • They boost your body's own defense system, which is also called the immune system • Vaccines create immunity that protects you from an infection without causing the suffering of the disease itself • Sometimes vaccines are called immunizations, needles or shots.
