Human Anatomy and Body Systems THE BODY SYSTEMS
Human Anatomy and Body Systems
THE BODY SYSTEMS Everyone is different. We have different skin colors, hair colors, body shapes and sizes — but we all look alike inside. If you could peek inside your own body, what would you see? Hundreds of bones, miles of blood vessels, and trillions of cells, all of which are constantly working together, doing all kinds of different things.
Levels of Organization Remember, the human body is organized in several levels, from the simplest to the most complex. . . Cells – the basic unit of life Tissues – clusters of cells performing a similar function Organs – made of tissues that perform one specific function Organ Systems – groups of organs that perform a specific purpose in the human body ***The purpose of the 11 organ systems is for the human body to maintain homeostasis.
The 11 Human Body Systems The 11 human body systems are as follows: -- nervous system -- integumentary system -- respiratory system -- digestive system -- excretory system -- skeletal system -- muscular system -- circulatory system -- endocrine system -- reproductive system -- lymphatic (immune) system
The Digestive System Purpose: to convert food particles into simpler micromolecules that can be absorbed into the bloodstream and used by the body Major Organs and their Functions: Mouth – to chew and grind up food -- saliva also begins the chemical breakdown Esophagus – pipe connecting mouth to stomach Stomach – secretes an extraordinarily strong acid (p. H = 2) that leads to breakdown of food -- once the food is broken down in the stomach and mixed with digestive juices, it is called chyme
Pancreas – produces the hormone insulin that regulates blood sugar levels -- also help neutralize stomach acid Liver – produces bile, which breaks down fats in foods Gallbladder – pouch-like organ that stores bile for future use Small Intestine – after digestion is complete, the chyme enters the small intestine where it is absorbed into the bloodstream -- the chyme is propelled along by folded surfaces called villi, on the intestine Large Intestine – removes water from the chyme and gets the waste ready for excretion
The Digestive System
INTERESTING FACTS… Food takes 3 days to complete its journey through the digestive system. An adult digestive system is about 30 feet long. An average person takes in about 4. 4 pounds of food and drink every day, consuming over 110, 000 pounds in a lifetime. Gravity and bands of muscles help food travel down the esophagus to the stomach, making it possible to eat lying down or even upside down. The stomach is lined with a slimy mucus and releases an acid called gastric juice to help dissolve food. Stomach noises are caused by food and air sloshing around. Water makes up about 70% of the body.
The Excretory System Purpose: to rid the body of wastes, including excess water and salts Major Organs and Their Functions Kidneys – the main organs of the excretory system -- waste-laden blood enters the kidney and the kidney filters out urea, excess water and other waste products, which eventually travel out of the kidney as urine -- eventually they travel through the ureter to the urinary bladder Rectum – solid (food) waste travels out of the body through the rectum
Skin – sweat glands remove excess water and salts from the body Lungs – expel the waste gas carbon dioxide The Excretory System
INTERESTING FACTS… Leftover waste in the large intestine is called fiber. Fiber sweeps the digestive system clean as it moves along. The large intestine contains millions of bacteria that feed on the leftovers in the bowel. Kidneys are located in the middle of the back. Each kidney contains up to a million tiny units called nephrons that filter all of the blood in the body. People with failing kidneys have their blood cleaned by a dialysis machine or have a new kidney transplanted.
The Respiratory System Purpose: to provide the body with a fresh supply of oxygen for cellular respiration and remove the waste product carbon dioxide Major Organs and Their Functions Nose – internal entry and exit point for air Pharynx – serves as a passage way for both air and food at the back of the throat Larynx – your “voicebox”, as air passes over your vocal chords, you speak Trachea – the “windpipe”, or what connects your pharynx to your lungs -- a piece of skin, called the epiglottis, covers the trachea when you swallow, preventing food from entering
Bronchi – the two large passageways that lead from the trachea to your lungs (one for each lung) -- the bronchi are further subdivided into bronchioles -- eventually, the further subdivisions lead to tiny air sacs called alveoli -- alveoli are in clusters, like grapes -- capillaries surrounding each alveolus is where the exchange of gases with the blood occurs The diaphragm is the muscle that causes you to breath -- hiccups are involuntary contractions of the diaphragm
Image of the Respiratory System
INTERESTING FACTS… The lungs fill up most of the chest cavity. The left lung is slightly smaller than the right lung, because it must allow enough space for the heart. Inside each lung is a network of thousands of tunnels called the bronchial tree which branch into bronchioles containing six million tiny bags (air sacs) called alveoli. The lungs take millions of O 2 molecules out of the air and put them into the blood to be delivered to the cells. Simultaneously, the lungs also take waste gases out of the blood. A smoker’s lungs are dark gray and full of dirt and tar.
The Circulatory System Purpose: to deliver oxygenated blood to the various cells and organ systems in your body so they can undergo cellular respiration Major Organs and Their Functions Heart – the major muscle of the circulatory system -- pumps blood through its four chambers (two ventricles and two atria) -- pumps deoxygenated blood into the lungs, where it gets oxygenated, returned to the heart, and then pumped out through the aorta to the rest of the body -- valve regulate the flow of blood between the chambers
Arteries – carry blood away from the heart and to the major organs of the body Veins – carry blood back to the heart away from the major organs of the body Capillaries – small blood vessels where gas exchange occurs Blood – the cells that flow through the circulatory system -- red blood cells contain hemoglobin, an iron-rich protein that carries oxygen -- white blood cells function in the immune system -- platelets help in blood clotting Spleen – helps to filter out toxins in the blood
Image of the Circulatory System
INTERESTING FACTS… The heart is a muscle about the size of a fist. Each blood cell takes around 20 seconds to make its deliveries and travel back to the heart. The heart works by contracting and relaxing. The heart has flapping valves that allow blood to flow in one direction. The flaps create a “lub-dup” sound. A heart attack is caused by a blood vessel blocked by a clot. The average person has about 5 liters of blood. The body can replace blood within a few weeks after loss. Platelets in the blood help it to clot, or stick together, to make scabs. The four blood types are A, B, AB, and O.
The Nervous System Purpose: to coordinate the body’s response to changes in its internal and external environment Major Organs and Their Functions Brain – control center of the body, where all processes are relayed through -- consists of cerebrum (controls though and senses) and cerebellum (controls motor functions) Spinal Cord – sends instructions from the brain to the rest of the body and vice versa -- any organism with a major nerve cord is classified as a chordate Nerves – conduct impulses to muscle cells throughout the body
Diagram of a Nerve Cell
INTERESTING FACTS… The left half of the brain controls the right half of the body and vice-versa. The human brain is more powerful and complicated than the world’s biggest computer. It can store millions of memories and do billions of calculations every day. The human body has over 100 billion neurons in all. The brain can receive over 100, 000 signals per second. Messages whiz through the nerves at up to 270 mph. Neurons reaching from the spinal cord to the toes are the longest cells in the human body, measuring up to 4 feet in length.
The Endocrine System Purpose: to control growth, development, metabolism and reproduction through the production and secretion of hormones Major Organs -- hypothalamus -- pituitary gland -- thyroid -- parathyroid -- adrenal glands -- pancreas -- testes -- ovaries
INTERESTING FACTS… Endocrine glands release hormones, chemicals that act as signals telling different parts of the body what to do. The body makes over 20 hormones, each with a different job to do. The blood carries hormones around the body until reaching the target organ, the body part needing it. Hormones can affect the way a person feels. As a person ages, the body makes less of some hormones.
The Skeletal System Purpose: to provide structure and support to the human body Bones are where new blood cells are generated (in the marrow), and require the mineral calcium for strength Major Bones of the Human Body -- femur (thigh bone) -- humerus (upper arm) -- radius and ulna (lower arm) -- cranium (skull) -- sternum (breastbone) -- clavicle (shoulder blade) -- fibula and tibia (calf) -- vertebrae (back) -- scalpula (shoulder) -- pelvic bone -- coccyx (tail bone) -- phalanges (fingers/toes)
INTERESTING FACTS… A baby is born with 270 bones while an adult body has 206 bones. The hands and feet contain half of the bones in the human body. Bones are made of the hard mineral calcium, living cells, blood vessels and nerves. Bones are made of several layers – periosteum, compact bone, and spongy bone. A joint is where two bones meet. Joints can be cartilagenous (spine), ball-and-socket (shoulders and hips), pivot (neck), gliding (wrists), and hinged (fingers, elbows, and knees).
The Muscular System Purpose: works with the skeletal and nervous system to produce movement, also helps to circulate blood through the human body -- muscle cells are fibrous -- muscle contractions can be voluntary or involuntary Major Muscles in the Human Body -- biceps -- triceps -- glutes -- hamstrings -- deltoids
INTERESTING FACTS… There are nearly 600 skeletal muscles that make up nearly half of the total body weight in the human. Muscles can only pull – they cannot push. Energy is stored in the muscles in a chemical called ATP. Lactic acid is released when the muscles are overworked and lack O 2, making the muscles hurt or ache. Muscles are attached to bones by tendons. The biggest muscles in the body are the gluteus maximus muscles (buttocks), but the muscle that can exert the most force is the masseter (jaw muscle).
The Immune System Purpose: to remove infectious diseases and other pathogens from the human body Major Organs and Their Functions Skin – also called the integumentary system, the skin is the body’s first line of defense White Blood Cells – recognize disease agents (antigens) and create antibodies to tag and remove these antigens -- phagocytes are the white blood cell type that actually eats and destroys these antigens Lymph Nodes – help restore fluid lost by the blood and return it to the circulatory system
INTERESTING FACTS… The immune system is constantly on guard to keep germs, bugs, and poisons out the body. The skin is the immune system’s first line of defense. There are germ-killing chemicals in saliva, tears, ear wax, and mucus. White blood cells destroy germs that enter through cuts. Sticky yellow pus is made of bodies of white blood cells that die in the battle against germs. An allergy is the immune system making a mistake. Some white blood cells make antibodies which can protect against bacteria, viruses, and poisons.
INTEGUMENTARY SYSTEM Major Structures skin, nails, hair Functions protects against injury, infection, and fluid loss; helps regulate body temperature
INTERESTING FACTS… Skin cells are made of a tough protein called keratin. About 40 million dead skin cells are lost each day. The average adult skin spread out would take up about 2. 2 square yards and would weigh around 15 pounds. The skin is waterproof. It keeps water out so the body is not a sponge and holds in moisture so it does not dry out. Skin expands to fit the body. Skin forms bumps when cold and releases sweat when hot. The skin repairs itself forming scabs and scars. Skin absorbs sunlight to make vitamin D. Too much sun can lead to sunburn and can even cause skin cancer.
REPRODUCTIVE SYSTEM Major Structures ovaries, uterus, and breasts (in females); testes and penis (in males) Functions produces gametes and offspring
INTERESTING FACTS… A person grows over 5 million times bigger changing from a single cell to a newborn human being. Humans grow for about 20 years, changing from a child to an adult. Male reproductive cells are called sperm, and female reproductive cells are called eggs. Sperm and eggs have only 23 chromosomes each. When joined together, sperm and egg make a whole cell called a fertilized egg which can grow into a baby.
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