Chapter 5 Flashcards
Myelin sheath
nerve conduction is determined by diameter of the nerve and the myelin sheath
multi layer lipid that insulates and protects the nerve fibers. Produced by cells called oligodendroglial cells in the cns
Neurons are similar to other cells in the body because:
Neurons are surrounded by a cell membrane.
Neurons have a nucleus that contains genes.
Neurons contain cytoplasm, mitochondria and other organelles.
Neurons carry out basic cellular processes such as protein synthesis and energy production.
neurons differ from other cells in the body because:
Neurons have specialize cell parts called dendrites and axons. Dendrites bring electrical signals to the cell body and axons take information away from the cell body.
Neurons communicate with each other through an electrochemical process.
Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters).
the nervous system contains two kinds of cells:
neurons are the cell type (primarily) responsible for communication and integration in the nervous system.
glia, which protect the neurons, but also modify their action.
Neurons (nerve cells) have three parts that carry out the functions of communication and integration:
dendrites, axons, and axon terminals.
Neurons have a fourth part the ____________, which carries out the basic life processes of neurons.
cell body or soma
synapse
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron. Some authors generalize this concept to include the communication from a neuron to any other cell type, such as to a motor cell
Neuron Types
bipolar (interneuron), unipolar sensory neuron, multipolar neuron (motoneuron), pyramidal cells
bipolar (interneuron)
A bipolar cell is a type of neuron which has two extensions. Bipolar cells are specialized sensory neurons for the transmission of special senses. As such, they are part of the sensory pathways for smell, sight, taste, hearing and vestibular functions.
unipolar sensory neuron
A unipolar neuron is a type of neuron in which only one protoplasmic process (neurite) extends from the cell body. Most neurons are multipolar, generating several dendrites and an axon and there are also many bipolar neurons.
multipolar neuron (motoneuron)
A multipolar neuron (or multipolar neurone) is a type of neuron that possesses a single axon and many dendrites (and dendritic branches), allowing for the integration of a great deal of information from other neurons. These processes are projections from the nerve cell body. Multipolar neurons constitute the majority of neurons in the central nervous system. They include motor neurons and interneurons and are found mostly in the cortex of the brain, the spinal cord, and also in the autonomic ganglia.
pyramidal cells
Pyramidal neurons (pyramidal cells) are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract.
Neuroglial cells
Located in the gray and white matter of the brain and support and protect the nerve cells. There are 40 to 50 times as many glial cells as nerve cells. They are small and do not participate in generation and transmission of nerve impulses. They maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems
Four types of Neuroglial Cells
Four types astrocytes, oligodendrocyte, ependymal and microglia
Astrocytes
Astrocytes (Astro from Greek astron = star and cyte from Greek “kyttaron” = cell), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. Astrocytes, function as connective tissue and provide skeletal support for the brain cells and their processes and contribute to the blood brain barrier and can degrade released neurotransmitters. (Fight or Flight- astrocytes help you degrade) Astrocytes will migrate to the site of a brain lesion (a stroke) (form a cavity to place ethe debris in).
Oligodendrocytes
Oligodendrocytes (from Greek, meaning cells with a few branches), or oligodendroglia, are a type of neuroglia. Their main functions are to provide support and insulation to axons in the central nervous system of some vertebrates, equivalent to the function performed by Schwann cells in the peripheral nervous system.
ependymal
Ependyma is the thin epithelial lining of the ventricular system of the brain and the central canal of the spinal cord, made up of ependymal cells. Ependyma is one of the four types of neuroglia in the central nervous system (CNS). It is involved in the production of cerebrospinal fluid (CSF), and is shown to serve as a reservoir for neuroregeneration.
microglia
Microglia are a type of neuroglia (glial cell) located throughout the brain and spinal cord.Microglia account for 10–15% of all cells found within the brain. As the resident macrophage cells, they act as the first and main form of active immune defense in the central nervous system (CNS).Microglia (and other neuroglia including astrocytes) are distributed in large non-overlapping regions throughout the CNS. Microglia are key cells in overall brain maintenance—they are constantly scavenging the CNS for plaques, damaged or unnecessary neurons and synapses, and infectious agents
Schwann
Glial cells of the PNS are called Schwann acting as connective tissue
Action potential
Excitability is a cells response to various stimuli
Conversion of this response into a nerve impulse is called an action potential
Stimuli include chemical or temperature changes, electrical pulses, and mechanical stimulation
Neuronal responses to brain injuries
Nerve cells in the brain are less capable fo regeneration
This restricts the recovery of sensorimotor functions and higher mental functions including language after lesions in the brain
Process of spontaneous recovery after trauma and vascular accidents
Axonal regeneration 10-18 days
