The characteristics of connective tissue and the types of cells it contains vary, depending on where it is found in the body. Organs are the body's recognizable structures for example, the heart, lungs, liver, eyes, and stomach that perform specific functions. An organ is made of several types of tissue and therefore several types of cells Cells Often thought of as the smallest unit of a living organism, a cell is made up of many even smaller parts, each with its own function.
Human cells vary in size, but all are quite small. For example, the heart Biology of the Heart The heart and blood vessels constitute the cardiovascular circulatory system. The heart pumps the blood to the lungs so it can pick up oxygen and then pumps oxygen-rich blood to the body The eye Structure and Function of the Eyes The structures and functions of the eyes are complex.
Each eye constantly adjusts the amount of light it lets in, focuses on objects near and far, and produces continuous images that are instantly Even an organ as apparently simple as the gallbladder Gallbladder and Biliary Tract The gallbladder is a small, pear-shaped, muscular storage sac that holds bile and is interconnected to the liver by ducts known as the biliary tract.
See also Overview of the Liver and Gallbladder When two or more organs along with their associated structures work together they become component parts of a body system.
The brain is the control centre of the nervous system and is located within the skull. Its functions include muscle control and coordination, sensory reception and integration, speech production, memory storage, and the elaboration of thought and emotion.
The lungs are two sponge-like, cone-shaped structures that fill most of the chest cavity. Their essential function is to provide oxygen from inhaled air to the bloodstream and to exhale carbon dioxide.
The liver lies on the right side of the abdominal cavity beneath the diaphragm. Its main function is to process the contents of the blood to ensure composition remains the same. This process involves breaking down fats, producing urea, filtering harmful substances and maintaining a proper level of glucose in the blood.
The bladder is a muscular organ located in the pelvic cavity. It stretches to store urine and contracts to release urine. The kidneys are two bean-shaped organs located at the back of the abdominal cavity, one on each side of the spinal column. The heart is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions.
The stomach is a muscular, elastic, pear-shaped bag, lying crosswise in the abdominal cavity beneath the diaphragm. Its main purpose is digestion of food through production of gastric juices which break down, mix and churn the food into a thin liquid. The intestines are located between the stomach and the anus and are divided into two major sections: the small intestine and the large intestine. The function of the small intestine is to absorb most ingested food. The large intestine is responsible for absorption of water and excretion of solid waste material.
Explore the relationships between ideas about internal body organs in the Concept Development Maps Cell Functions. The lungs expand and contract as you breathe. The parts of the lungs involved in air intake are:. Your heart sits in the middle of your chest, to the left. The heart is a muscle at the center of your circulatory system.
The average adult heart is about the size of a fist: 5 inches long, 3. The heart pumps blood around your body through a system of blood vessels. The blood delivers oxygen to your brain and the rest of your body and then returns to pick up new oxygen through the lungs. You have two adrenal glands , one located on top of each kidney. Your pituitary gland controls your adrenal glands. The pituitary regulates your endocrine system. The spleen is located in the upper left of your abdomen, under your diaphragm and behind the top half of your stomach.
As part of your lymphatic system, the spleen filters your blood. It recycles red blood cells and sends out white blood cells lymphocytes to help fight infections.
You have two kidneys located below your rib cage. The kidneys are bean-shaped and about fist-sized. Your left kidney is typically a little larger than the right one. The kidneys filter out wastes and extra fluids from your body into urine.
Your kidneys help keep the salts and minerals in your blood in proper balance. The kidneys also make hormones that are important in controlling your blood pressure and producing red blood cells.
Your kidneys have an intricate filtering system. Each kidney has about 1 million filters, called nephrons. Each nephron has two parts: a renal corpuscle, which contains the glomerulus , and a tubule.
The glomerulus filters your blood. The tubule removes waste products and returns essential substances to your blood. One kidney can do the work of two. You can lead a normal life if you have only one healthy kidney. Your stomach is located in the upper, middle-left part of your abdomen. The stomach holds the solid foods and liquids you ingest and begins to break them down. Gastric acids and enzymes start the digestion process. After three to four hours , the stomach contents move on to be further digested.
The stomach muscle is lined with ridges called rugae that can expand and allow your stomach to hold more food and liquid. The pancreas is a 6- to inch-long gland that sits deep in the abdomen, below and behind the stomach. The top of the pancreas is nestled in the curve of your duodenum, part of your small intestine. Its function is to produce enzymes to help process food in the small intestine.
Its enzymes help digest fat, starch, and protein.
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