The nervous system coordinates rapid and precise responses to stimuli using action potentials. The endocrine system maintains homeostasis and long-term control using chemical signals. The endocrine system works in parallel with the nervous system to control growth and maturation along with homeostasis Hormones The endocrine system is a collection of glands that secrete chemical messages we call...

The Neuron Nervous tissue is composed of two main cell types: neurons and glial cells. Neurons transmit nerve messages. Glial cells are in direct contact \\ith neurons and often surround them The neuron is the functional unit of the nervous system. Humans ha\e about 100 billion neurons in their brain alone! While variable in size and shape, all neurons have three parts. Dendrites receive informa...

Digestive System single-celled organisms can directly take in nutrients from their outside environment. Multicellular animals, with most of their cells removed from contact directly with the outside environment, have developed specialized structures for obtaining and breaking down their' food. Animals depend on tV,lO processes: feeding and digestion. Animals are heterotrophs, they must absorb nu...

LYMPHATIC SYSTEM & IMMUNITY The lymphatic system is composed of lymph vessels, lymph nodes, and organs. The functions of this system include the absorbtion of excess fluid and its return to the blood stream, absorption of fat (in the villi of the small intestine) and the immune system function. Lymph vessels are closely associated with the circulatory system vessels. Larger lymph vessels are sim...

Types of Circulatory Systems Living things must be capable of transporting nutrients, wastes and gases to and form cells, Single-celled organisms use their cell surface as a point of exchange with the outside environment. Multicellular orgainsms have developed transport and circulatory systems to deliver oxygen and food to cells and remove carbon dioxide and metabolic wastes. Sponges are the simp...