When we are awake, we are constantly aware of sensory input from our external environment, and we consciously plan how to react to it. When we are asleep, the nervous system has a variety of mechanisms to dissociate cortical function…
After meticulous study of spinal reflexes, Charles Sherrington N10-2 deduced that neurons somehow communicate information, one to the next, by a mechanism that is fundamentally different from the way that they conduct signals along their axons. Sherrington had merged his…
Neurons receive, combine, transform, store, and send information Neurons have arguably the most complex job of any cell in the body. Consequently, they have an elaborate morphology and physiology. Each neuron is an intricate computing device. A single neuron may…
Extracellular fluid in the brain provides a highly regulated environment for central nervous system neurons Everything that surrounds individual neurons can be considered part of the neuronal microenvironment. Technically, therefore, the neuronal microenvironment includes the extracellular fluid (ECF), capillaries, glial…
The human brain is the most complex tissue in the body. It mediates behavior ranging from simple movements and sensory perception to learning, memory, and consciousness. It is the organ of the mind and accounts for the human capacity for…
The primary function of muscle is to generate force or movement in response to a physiological stimulus. The human body contains three fundamentally different types of muscle adapted to specialized functions. Skeletal muscle is responsible for the voluntary movement of…
The ionic gradients that cells maintain across their membranes provide a form of stored electrochemical energy that cells can use for electrical signaling. The combination of a resting membrane potential of −60 to −90 mV and a diverse array of voltage-gated…
Cellular communication in the nervous system is based on electrical and chemical signaling events that are mediated by ion channels. Certain types of cells, including neurons and myocytes, have a remarkable property called electrical excitability. In cells with this property,…
Physics is concerned with the fundamental nature of matter and energy, whereas the goal of medical physiology is to understand the workings of living tissue. Despite their different perspectives, physics and physiology share common historical roots in the early investigations…
The cells of the human body live in a carefully regulated fluid environment. The fluid inside the cells, the intracellular fluid (ICF), occupies what is called the intracellular compartment, and the fluid outside the cells, the extracellular fluid (ECF), occupies…