Chapter 3 Flashcards
What is the nervous system?
The body’s electrochemical communication circuitry.
What are the characteristics of the nervous system?
Complexity, integration, adaptability, and electrochemical transmission.
What is the characteristic of complexity?
Billions of nerve cells carrying out a multitude of functions (breathing, reading, thinking, etc.).
What is the characteristic of integration?
The brain is able to make sense of tons of different types of information at all times.
What is the characteristic of adaptable?
The brain is able to adapt to new conditions in order to help us survive (plasticity is the term for this).
What is plasticity?
The brain’s physical capacity to change.
What is the characteristic of electrochemical transmission?
This is how the brain communicates with the rest of the body. It is a system of electrical signals that trigger the release of chemicals and electrical impulses to communicate with other cells. An impulse will travel down a nerve cell or neuron.
What are afferent nerves?
Also known as sensory nerves. Nerves that carry information about the external environment to the brain and spinal cord via sensory receptors. They communicate external conditions (the sight of a sunrise) and internal conditions (fatigue or hunger).
What are efferent nerves?
Also known as motor nerves. Nerves that carry information out of the brain and spinal cord to other areas of the body (muscles, glands, etc.)
What are the two primary divisions of the nervous system?
The central nervous system (CNS) and peripheral nervous system (RNS).
What is the central nervous system?
Made up of the brain and spinal cord. More than 99 percent of all nerve cells in our body are located in the CNS.
What is the peripheral nervous system?
The network of nerves that connects the brain and spinal cord to other parts of the body.
What are the two divisions within the peripheral nervous system?
The somatic nervous system and the autonomic nervous system.
What is the somatic nervous system?
Consists of sensory nerves, whose function is to convey information form the skin and muscles to the CNS about conditions such as pain and temperature, and motor nerves who function is to tell the muscles what to do.
What is the autonomic nervous system?
Take messages to and from the body’s internal organs, monitoring such processes as breathing, heart rate, and digestion.
What are the two divisions of the autonomic nervous system?
Sympathetic nervous system and parasympathetic nervous system.
What is the sympathetic nervous system?
Arouses the body to mobilize it for action.
What is the parasympathetic nervous system?
It calms the body.
What are the two types of cells in the nervous system?
Neurons and glial cells
What are neurons?
A nerve cell that handles information processing. The brain has 100 billion neurons and each neuron can make as many as 10,000 physical connections with other cells.
What are mirror neurons?
Nerve cells that are activated (in human and nonhuman primates) when an action is preformed and when observing the action being preformed. Remember that neurons are specialized and mainly preform one function. However, mirror neurons can seem to preform both functions which is interesting.
What are glial cells?
Also known as glia. They provide support, nutritional benefits, and other functions and keep neurons running smoothly. The are not specialized like neurons are. However, there are more glial cells in the nervous system than neurons (10 glial cells for every 1 neuron). Can be seen as the pit crew in the raceway of the nervous system.
What does every neuron have?
A cell body, dendrites, and an axon.
What is the cell body of a neruon?
The part of the neuron that contains the nucleus, which directs the manufacture of substances that the neuron needs for growth and maintenance.
What are the dendrites of the neuron?
Treelike fibers projecting from a neuron, receive information and orient it toward the neuron’s cell body. Most nerve cells have numerous dendrites, which increase their surface area, allowing each neuron to receive input from many other neurons.
What is the axon of the neuron?
The part that carries information away from the cell body toward other cells. They are extremely thin and can be very long with many branches. Some may extent more than 3 feet, all the way to the top of the brain to the base of the spinal cord.
What is the myelin sheath?
A layer of cells containing fat, encases and insulates most axons. Because of this, they speed up transmission of nerve impulses. The myelin sheath has developed as the nervous system as evolved because as the brain got larger, it became necessary for information to travel longer distances in the nervous system. Axons needed myelin sheaths to speed up the electrical impulses and convey information rapidly.
What is the nucleus in the cell body?
It directs the manufacture of substances the neuron needs for growth and maintenance.
What is resting potential?
The stable, negative charge of an inactive neuron.
What is action potential?
The brief wave of positive electrical charge that sweeps down the axon.
What is the all or nothing principle?
The principle that once the electrical impulse reaches a certain level of intensity (called the threshold) it fires and moves all the way down the axon without losing any intensity.
What are the four steps when a single neuron is activated and fired?
- Resting potential
- Depolarization
- Action potential
- Refractory period
What is the threshold of a impulse?
-55
What are synapse?
Tiny spaces between neurons. most synapses lie between the axon of one neuron and the dendrites or cell body of another neuron.
What is the synaptic gap?
The gap created by synapses. Before an impulse can cross the synaptic gap, it must be converted into a chemical signal.
What are terminal buttons?
Structures at the end of fibers of branches of the axon. Within the terminal button, very tiny synaptic vesicles (scars) store chemicals called neurotransmitters.
What are neurotransmitters?
Chemical substances that are stored in very tiny sacs within the terminal buttons and involved in transmitting information across the synaptic gap to the next neuron.
What happens to the rest of the neurotransmitter after delivering the message?
Some of it is used up in the production of energy, and some of it is reabsorbed by the axon that released it to await the next neural impulse.