Endocrine and Reproductive Systems Cell Membrane ReceptorsMany cell membranes have receptor molecules on their surface. These receptor sites play an important role in allowing cells and organs to communicate with one another. Hormonal Regulation Hormones provide a primary way for cells to communicate with each other. A hormone is a chemical messenger with a specific … [Read more...] about Endocrine and Reproductive Systems
Circulatory and Respiratory Systems
Circulatory and Respiratory Systems Circulatory System The circulatory system consists of the heart, blood, and blood vessels. There are three types of blood vessels: arteries, veins and capillaries.The heart is an organ made of cardiac muscle and it acts like a pump. The muscles of the heart contract and pump blood away from the heart (through the aorta) and to the … [Read more...] about Circulatory and Respiratory Systems
Human Body Systems Overview and Homeostasis
Human Body Systems Overview and Homeostasis Overview and Homeostasis Levels of Organization Living things have different levels of organization. The simplest level of organization is that of the cell. A group of cells with a similar function is called a tissue. Groups of tissues working together to perform a common function are called organs. An example of this would include … [Read more...] about Human Body Systems Overview and Homeostasis
Nervous System and Drugs
Nervous System and Drugs Nervous Regulation Nerve cells or neurons also allow cells to communicate with each other. Neuron communications are one way organism can detect and respond to stimuli at both the cellular and organism level. This detection and response to stimuli helps to maintain homeostasis in the cell or organism. Neurons may stimulate other nerve cells or muscle … [Read more...] about Nervous System and Drugs
Evolution: Variations
Evolution: Variations Variation Variations are differences between groups of organisms of one species. Mutation is one source of variation between different groups within a species. The variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions. Sources of VariationThe … [Read more...] about Evolution: Variations