Chapter 3 The Remarkable Body The Body s Cells Cells the smallest units in which independent life can exist Enzyme any of a great number of working proteins that speed up a specific chemical reaction such as breaking the bonds of a nutrient without undergoing change themselves Fat cells cells that specialize in the storage of fat or form the fat tissue Inborn error of metabolism a genetic variation present from birth that may result in disease Phenylketonuria PKU an inborn error of metabolism that interferes with the body s handling of the amino acid phenylalanine with potentially serious consequences to the brain and nervous system in infancy and childhood Tissues systems of cells working together to perform specialized tasks Organs discrete structural units made of tissues that perform specific jobs muscles nerves blood bone heart liver brain Body system a group of related organs that work together to perform a function circulatory respiratory nervous systems The Body Fluids and the Cardiovascular System Blood the fluid of the cardiovascular system composed of water red and white blood cells nutrients oxygen etc Lymph the fluid that moves from the bloodstream into tissue spaces and then travels in its own vessels which eventually drain back into the bloodstream Arteries blood vessels that carry blood containing fresh oxygen supplies from the heart to the tissues Veins blood vessels that carry blood with the carbon dioxide it has collected from the tissues back to the heart Capillaries minute web like blood vessels that connect arteries to veins and permit transfer of materials between blood and tissues Plasma the cell free fluid part of blood and lymph Extracellular fluid fluid residing outside the cells that transports materials to and from the cells Intracellular fluid fluid residing inside the cells that provides the medium for cellular reactions Lungs the body s organs of gas exchange Blood circulating through the lungs releases its carbon dioxide and picks up fresh oxygen to carry to the tissues Intestine the body s long tubular organ of digestion and the site of nutrient absorption Liver a large lobed organ that lies just under the ribs It filters the blood removes and processes nutrients manufactures materials for export to other parts of the body and destroys toxins or stores them to keep them out of the circulatory system Kidneys a pair of organs that filter wastes from the blood make urine and releases it to the bladder for excretion from the body The Hormonal and Nervous Systems Hormones chemicals that are secreted by glands into the blood in response to conditions in the body that require regulation serving as messengers acting on other organs to maintain constant conditions Pancreas an organ with two main functions Endocrine function the making of hormones such as insulin which it releases directly into the blood Exocrine function the making of digestive enzymes which it releases through a duct into the small intestine to assist in digestion Insulin a hormone from the pancreas that helps glucose enter cells from the blood Glucagon a hormone from the pancreas that stimulates the liver to release Cortex the outermost layer of something ex The brain cortex where glucose into the bloodstream conscious thoughts take place Hypothalamus a part of the brain that senses a variety of conditions in the blood such as temperature glucose content salt content etc It signals other parts of the brain or body to adjust those conditions when necessary Fight or flight reaction the body s instinctive hormone and nerve mediated reaction to danger also known as stress response Neurotransmitters chemicals that are released at the end of a nerve cell when a nerve impulse arrives there They diffuse across the gap to the next cell and alter the membrane of that second cell to either inhibit or excite it Epinephrine the major hormone that elicits the stress response Norepinephrine a compound related to epinephrine that helps to elicit the stress response Metabolism the sum of all physical and chemical changes taking place in living cells includes all reactions by which the body obtains and spends the energy from food The Immune System Microbes bacteria viruses or other organisms invisible to the naked eye some of which cause diseases also called microorganisms Antigen a microbe or substance that is foreign to the body Immune system a system of tissues and organs that defend the body against antigens foreign materials that have penetrated the skin or body linings Lymphocytes white blood cells that participate in the immune response B cells and T cells Phagocytes white blood cells that can ingest and destroy antigens They are the first to defend body tissues against invaders It forms a pocket in its own outer membrane and engulfs the invader which it can attack with oxidizing chemicals digest or destroy the invader They leave a chemical trail behind so that other cells can find the infection faster The Digestive System T Cells lymphocytes that attack antigens T stands for the thymus gland of the neck where the T cells are stored and matured These cells read and remember the chemical messages that phagocytes use to identify invaders T cells seek out and destroy all invaders with the same identity defend against fungi viruses parasites etc B Cells lymphocytes that attack produce antibodies B cells respond rapidly to infections by releasing antibodies into the bloodstream they travel to the site of the infection and stick to the surface of the foreign particles killing or inactivating them Inflammation the immune systems response to cellular injury characterized by an increase in white blood cells redness heat pain and swelling The preference for sweet salty and fatty tastes seems to be inborn and can lead to overconsumption of foods that offer them The digestive tract is a flexible muscular tube that digests food and absorbs its nutrients and some non nutrients Digestive system the body system composed of organs that break down complex food particles into smaller absorbable products The digestive tract and alimentary canal are names for the tubular organs that extend from the mouth to the anus Digest to break molecules into smaller molecules a main function of the digestive tract with respect to food Absorb to take in as nutrients are taken into the intestinal cells after digestion the main function of the digestive tract with respect to nutrients The Mechanical Aspect of Digestion Peristalsis
View Full Document
Unlocking...