Biology and Sensation - AP Psychology

Nerve cells, or neurons, have a basic tree-like structure, which allows them to communicate with other nerve cells. Branch-like dendrites extend from the cell body (i.e. soma) and receive electrochemical signals from other cells. The long, thin axon endings—terminal buttons—extend from the other end of the soma. If the positively-charged signals received into the cell from the dendrites exceed the cell’s normally negative charge, then the axon allows the excess positive ions to travel down it to the terminal buttons, which in turn send neurotransmitters into the gap (i.e. synapse) between them and other cell’s dendrites. The myelin sheath does not itself relay signals, but rather is a natural lipid insulation on the axons of some cells.

Sodium and potassium are vital components associated with neural electrical transmissions. When it is at rest, a neuron is surrounded by a positive charge due to sodium and maintains an internally negative charge with potassium. When the neuron depolarizes, there is an influx of sodium into the cell. Upon repolarization, there is a potassium efflux where the neuron is restored to its original resting charges.

The correct answer is antagonist. An antagonist is any chemical that prevents a neurotransmitter from binding to its receptor site. Recall that a neurotransmitter is simply any chemical in the brain that enables the transmission of signals between neurons via synapses. Contrastingly, an agonist is any chemical that mimics the shape of a neurotransmitter well enough that it can bind to that neurotransmitter's receptor and stimulate the receptor just as if the neurotransmitter itself was binding to it. A so-called reuptake agent is not a real chemical classification, but the reuptake mechanism is an important aspect of neurotransmission. Reuptake refers to the process by which the presynaptic neuron reabsorbs its released neurotransmitter after the neurotransmitter has done its job by binding to the postsynaptic neuron.

Information enters the neuron through dendrites, the branch-like extensions which carry signals to the cell body (soma). When an action potential occurs, its signal will propagate down the axon of the cell, culminating in the release of neurotransmitters into the synapse from the terminal buttons. These neurotransmitters will cross the synaptic cleft in mere milliseconds, and bind to the receptor sites on the adjacent neuron's dendrites. This process leads to communication between neurons.

Neurons transmit electrical signals between one another, which allows for the communication of incoming stimuli from sensory receptors with the brain, communication of internal states of the body, communication between the brain and muscles to coordinate movement, and communication between the many cells of the brain to allow for the complex array of processes that form the basis for our everyday lives. Although neurons in the visual centers of the brain will indeed play a role in processing color information, at the level of the retina this information is derived from the the cones in photoreceptor cells, and subsequently communicated to the brain via the optic nerves. Neurons will communicate messages between the brain and glands of the body, but they themselves are not responsible for the production of enzymes. Neurons do not serve as energy stores for the body.

The myelin sheath coats the axon of a neuron and speeds up the transmission of messages. Myelin is a fatty coating that is unable to perpetuate the action potential signal. As a result, the signal jumps over the myelinated areas, bypassing much of the axon and speeding up transmission. This process is known as saltatory conduction.

The axon is the long, slender projection of a neuron that conducts electrical impulses away from the cell body. Dendrites are the branched projections of a neuron that recieve electrical stimulation from synapses and convey them to the cell body. The soma is the cell body of the neuron that contains the cell nucleus

Myelin is a white, fatty compound that surrounds the axons of white matter neurons. Its purpose is to increase the speed of an action potential.

At rest, there is a high concentration of sodium (Na+) outside the neuron and a high concentration of potassium (K+) inside the neuron. During an action potential, the gated channels for sodium open and, because there is such a difference in concentration, the sodium rushes into the axon. This makes the axon much more positive in charge. This positivity propagates along the axon until it reaches the end of the axon, where it triggers release of neurotransmitters into the synapse.

The depolarization of the neural axon during an action potential is driven by an influx of sodium ions, entering through voltage-gated sodium channels. Following this stage, voltage-gated potassium channels are stimulated, allowing potassium ions to exit the axon and causing hyperpolarization. The sodium-potassium pump then restores the ions to their original positions in preparation for the next action potential, known as repolarization.

Neurotransmitters are chemical substances that travel across synapses in the nervous system. Acetylcholine, dopamine, epinephrine, and GABA are all widely-studied neurotransmitters. Glucose, however, is a monosaccharide used for energy in the body. It serves no purpose as a neurotransmitter.

The corpus callosum is a large band of fibers that relays signals between the two hemispheres of the brain.

Located below the thalamus, the hypothalamus controls the pituitary gland and regulates biological needs, including homeostasis (body temperature), sexual drive, aggressive behavior, and hunger.

Top-down processing involves the impact of prior knowledge on sensation and perception. Many optical illusions are successful by capitalizing on our prior knowledge to influence our perception of an image.

Endorphins—released during exercise, sex, and excitement—work in relieving pain symptoms. Analgesics, painkillers, are developed to have similar neurological reactions with longer-lasting effects.

The zygote refers to a fertilized egg. At eight weeks, the baby becomes known as an embryo, and fetus refers to the stage of development between 8 weeks and birth.

Glial cells are located in the nervous system, and serve as support and protection for the neurons. Schwann cells, oligodendrocytes, astrocytes, and ependymal cells are all examples of neuroglia.

The brain and spinal cord together make up the Central Nervous System. The Peripheral Nervous System and all of its subdivisions are composed of the various neural pathways to and from the brain/spinal cord.

Glia, also known as glial cells, are non-neuronal cells that provide support and protection for neurons located in the central nervous system. Neurons are made up of dendrites, axons, and a cell body (which is covered by the myelin sheath).

The frontal lobe is responsible for the higher-level cognitive processes associated with executive functions. It contains the primary motor cortex and is involved in decision-making, as well as many other goal-directed behaviors.