A nerve cell consists of a cell body, several short, branched extensions called dendrites that receive stimuli, and a long extension called an axon, which transmits signals to other nerve cells or muscle cells. Periodic signals A signal is periodic if it repeats itself exactly after some period of time. This is different from paracrine signaling, in which local concentrations of ligands can be very high. The sound produced by human being in conversation or photograph are converted into continuously varying electrical analog signal. In the digital format, signals are in the form of a string of bits, each bit being either ON or OFF (1 or 0). This means the signaling cell and the target cell can be the same or a similar cell (the prefix auto- means self, a reminder that the signaling cell sends a signal to itself). When the neurotransmitter binds the receptor on the surface of the postsynaptic cell, the electrochemical potential of the target cell changes, and the next electrical impulse is launched. signal analysis. Not all cells are affected by the same signals.

Small molecules, such as calcium ions (Ca2+), are able to move between cells, but large molecules like proteins and DNA cannot fit through the channels. The junction between nerve cells where signal transmission occurs is called a synapse. The main difference between the different categories of signaling is the distance that the signal travels through the organism to reach the target cell.

Communication of information involves use of signals, which are classified on the basis of their origin and nature.

In plants, plasmodesmata are ubiquitous, making the entire plant into a giant, communication network. Analog systems are less expensive than digital systems for the same application, but digital systems are more efficient, give better performance (less error and noise), and greater flexibility. (In the body, many endocrine cells are located in endocrine glands, such as the thyroid gland, the hypothalamus, and the pituitary gland.) Removing the signals will reestablish the concentration gradient for the signal, allowing them to quickly diffuse through the intracellular space if released again. 4) DO – Digital OutputSignal. While analog bandwidth measures the range of spectrum each signal occupies, digital bandwidth gives the quantity of information contained in a digital signal. When these impulses reach the end of the axon, the signal continues on to a dendrite of the next cell by the release of chemical ligands called neurotransmitters by the presynaptic cell (the cell emitting the signal). The bandwidth is about 10 kHz in amplitude modulated (AM) radio transmission and 15 kHz in frequency modulated (FM) transmission. Continuous time (analog) end discrete time (digital) signals; Coded and un-coded signals; Periodic and a-periodic signals; Energy and power signals; Deterministic and random signal Signal Types We can categorize signals by their properties, all of which will affect our analysis of these signals later. Figure 1. The small distance between nerve cells allows the signal to travel quickly; this enables an immediate response, such as, Take your hand off the stove! Communication systems can be either fundamentally analog, such as the amplitude modulation (AM) radio, or digital, such as computer networks. These signals are in discrete form. Signals from distant cells are called endocrine signals, and they originate from endocrine cells. (In the body, many endocrine cells are located in endocrine glands, such as the thyroid gland, the hypothalamus, and the pituitary gland.) An easy way to remember the distinction is by understanding the Latin origin of the prefixes: inter- means “between” (for example, intersecting lines are those that cross each other) and intra- means “inside” (like intravenous). Types of Signals: Analog and Digital. Paracrine signaling acts on nearby cells, endocrine signaling uses the circulatory system to transport ligands, and autocrine signaling acts on the signaling cell. These types of signals usually produce a slower response but have a longer-lasting effect.

The most crucial parameter in communication systems is the signal bandwidth, which refers to the frequency range in which the signal varies. Paracrine signals move by diffusion through the extracellular matrix. This is different from paracrine signaling, in which local concentrations of ligands can be very high.

Human speech has bandwidth of nearly 4 kHz. Signaling via gap junctions involves signaling molecules moving directly between adjacent cells. The distance between the presynaptic cell and the postsynaptic cell—called the synaptic gap—is very small and allows for rapid diffusion of the neurotransmitter.

Types of Signals. Did you have an idea for improving this content?

The bandwidth of a video signal is about 4.2 MHz and television broadcast channel has bandwidth of 6 MHz. The transfer of signaling molecules communicates the current state of the cell that is directly next to the target cell; this allows a group of cells to coordinate their response to a signal that only one of them may have received. 2) AO – AnalogOutputSignal. The distance between the presynaptic cell and the postsynaptic cell—called the synaptic gap—is very small and allows for rapid diffusion of the neurotransmitter. Communication between cells is called intercellular signaling, and communication within a cell is called intracellular signaling.