Sixth Grade Science 4th Quarter Vocab - Printable version

organ – a group of different tissues working together to perform a specific function.

system – made up of parts that work together for the benefit of the whole.  A group of organs that work together to perform a specific function. 

mucus – a slippery secretion that coats the inner walls of the digestive tract.  It helps food slide down and is also a form of protection.

sphincter – a ring of muscles at the beginning and end of the digestive tract.  Sphincters are located in between organs and make sure that food only goes in a one-way direction.

peristalsis – the wave-like motion of the digestive tract that moves food through.

mechanical digestion - the breaking apart of food by the action of teeth, tongue and muscles of the digestive tract

chemical digestion - the breaking down of food particles by the action of acids and enzymes in the digestive tract

bolus - chewed ball of food in the mouth

amylase- an enzyme in the mouth that breaks down starch into sugar

enzyme - a protein that speeds chemical reactions in digestion

esophagus - tube in the throat that leads from the mouth to the stomach

salivary glands - three pairs of glands around the mouth that produce saliva

pepsin - an enzyme in the stomach that breaks down proteins

gastric juice - a mixture of hydrochloric acid (HCl) and pepsin found in the stomach

protein - one of three basic food groups, needed for building tissues, found in meat, egg whites, nuts, beans and grains.  All enzymes are also proteins.

indicator - a substance that changes in some way when in the presence of another substance.  Ex.: benedict's solution turns red in the presence of sugar.

fiber - indigestible carbohydrates that stimulate peristalsis in the intestine, helping move food and waste through the digestive system

chyme - the pulpy mixture of food and gastric juices in the stomach

diffusion - the process in which molecules move from places where they are more concentrated to places where they are less concentrated

active transport - the process in which energy in a cell is used to move materials across or through a membrane

passive transport - the process in which molecules move through a membrane by diffusion, without using energy from the cell (passive transport is another name for diffusion when it occurs through a membrane)

duodenum - the first 25 centimeters of the small intestine, where most chemical digestion occurs

pancreas - a gland situated near the stomach that secretes digestive fluids into the small intestine to further digest carbohydrates and proteins

gall bladder - a gland which secretes bile into the duodenum to help digest fats

epiglottis -  a flap of tissue that covers the opening of the trachea when we swallow food, but which opens to allow air into the lungs when we breathe

trachea - the windpipe, a tube that leads from the throat to the lungs

bronchi - two branches of the trachea that lead to each of the lungs, then

alveoli -   tiny sacs in the lungs through which the exchange of oxygen and carbon dioxide takes place

diaphragm - a large flat muscle below the lungs that helps draw air into the lungs

bronchiole - small branches off of the bronchi that end in alveoli

artery - blood vessel that carries blood away from the heat

vein - blood vessel that carries blood back towards the heart

capillary - the smallest blood vessels, through which gases and nutrients diffuse

atrium - the "receiving" chamber of the heart where blood enters the heart.  There are two atria in the heart, the left atrium receives blood back from the lungs, the right atrium receives blood back from the rest of the body

ventricle -  the "pumping:" chamber of the heart.  There are two ventricles in the heart, the right ventricle pumps blood to the lungs, the left ventricle pumps blood to the rest of the body.

aorta -  the largest artery of the body, which carries blood from the left ventricle to the entire body

vena cava - the largest vein in the body, which collects oxygen-poor blood in the right atrium

valve - flaps of tissue in the heart and in veins that regulate the flow and direction of blood flow  in the body

blood cells - three types of living cells in human blood:  red blood cells carry oxygen, white blood cells fight infection, and platelets help in healing wounds

cellular respiration - a form of oxidation occurring in cells, in which food molecules combine with oxygen to release energy and give off waste

input/output -  the ingredients (inputs) and the products (outputs) of scientific processes