Chapter 11 - Nervous System Flashcards
What is the Nervous system?
The nervous system is the human organ system that coordinates all of the body’s voluntary and involuntary actions by transmitting signals to and from different parts of the body.
Two divisions of nervous system?
The nervous system has two major divisions, called the central nervous system (CNS) and the peripheral nervous system (PNS). The CNSincludesthe brain and spinal cord, and the PNS consists mainly of nerves that connect the CNS with the rest of the body.
Divisions of the PNS
The PNS also has two major divisions: the somatic nervous system and the autonomic nervous system. The somatic system controls activities that are under voluntary control. The autonomic system controls activities that are not under voluntary control. The autonomic nervous system is further divided into the sympathetic division, which controls the fight-or-flight response; the parasympathetic division, which controls most routine involuntary responses; and the enteric division, which provides local control for digestive processes.
Nerve Impulses
Signals sent by the nervous system are electrical signals called nerve impulses. They are transmitted by special cells called neurons. Nerve impulses can travel to specific target cells very rapidly.
Divisions of Autonomic Nervous System:
The autonomic nervous system has three divisions: the sympathetic division, which controls the fight-or-flight response during emergencies; the parasympathetic division, which controls the routine “housekeeping” functions of the body at other times; and the enteric division, which provides local control of the digestive system.
Neurons
Neurons are one of two major types of nervous system cells. They are electrically excitable cells that transmit nerve impulses.
Glial Cells
Glial cells are the other major type of nervous system cells. There are many types of glial cells, and they have many specific functions. In general, glial cells function to support, protect, and nourish neurons.
Parts of a Neuron:
The main parts of a neuron include the cell body, dendrites, and axon. The cell body contains the nucleus. Dendrites receive nerve impulses from other cells, and the axon transmits nerve impulses to other cells at axon terminals. A synapse is a complex membrane junction at the end of an axon terminal that transmits signals to another cell.
Axons
Axons are often wrapped in an electrically-insulating myelin sheath, which is produced by glial cells. Electricalsignalsoccur at gaps in the myelin sheath, called nodes of Ranvier, which speeds the conduction of nerve impulses down the axon.
Neurogenesis
Neurogenesis, or the formation of new neurons by cell division, may occur in a mature human brain but only to a limited extent.
Tissues in the Brain and Nerves
The nervous tissue in the brain and spinal cord consists of gray matter, which contains mainly the cell bodies of neurons; and white matter, which contains mainly myelinated axons of neurons. Nerves of the peripheral nervous system consist of long bundles of myelinated axons that extend throughout the body.
Types of Neurons
There are hundreds of types of neurons in the human nervous system, but manycan be classified on the basis of the direction in which they carry nerve impulses. Sensory neurons carry nerve impulses away from the body and toward the central nervous system, motor neurons carry them away from the central nervous system and toward the body, and interneurons often carry them between sensory and motor neurons.
Interneurons
Interneuronscarry nerve impulses back and forth often between sensory and motor neurons within the spinal cord or brain.
The word glial comes from a Greek word meaning “____.”
glue
Types of Glial Cells
Different types of glial cells (neuroglia) are found in the central nervous system and peripheral nervous system. Ependymal cells, oligodendrocytes, astrocytes, and microglia are found in the CNS. Satellite cells and Schwann cells are found in the PNS.
Neurons, Glial cells, and intelligence
In the human brain, there are generally about equal numbers of neurons and glial cells. If you think intelligence depends on how many neurons you have, think again. Having a relatively large number of glial cells is actually associated with higher intelligence. When Einstein’s brain was analyzed, researchers discovered a significantly higher-than-normal ratio of glial cells to neurons in areas of the brain associated with mathematical processing and language. On an evolutionary scale as well, an increase in the ratio of glial cells to neurons is associated with greater intelligence in species.
What is a nerve impulse?
A nerve impulse is an electrical phenomenon that occurs because of a difference in electrical charge across the plasma membrane of a neuron.
What is the function of the Sodium Potassium Pump?
What is the gradient called?
The sodium-potassium pump maintains an electrical gradient across the plasma membrane of a neuron when it is not actively transmitting a nerve impulse. This gradient is called the resting potential of the neuron.
What is the action potential?
An action potential is a sudden reversal of the electrical gradient across the plasma membrane of a resting neuron. It begins when the neuron receives a chemical signal from another cell or some other type of stimulus. The action potential travels rapidly down the neuron’s axon as an electric current.
What is an action potential?
An action potential is a sudden reversal of the electrical gradient across the plasma membrane of a resting neuron. It begins when the neuron receives a chemical signal from another cell or some other type of stimulus. The action potential travels rapidly down the neuron’s axon as an electric current.
Neurotransmitters:
There are many different types of neurotransmitters. Their effects on the postsynaptic cell generally depend on the type of receptor they bind to. The effects may be excitatory, inhibitory, or modulatory in more complex ways. Both physical and mental disorders may occur if there are problems with neurotransmitters or their receptors.