fox ch 7
Order by
41 terms
Terms | Definitions |
|---|---|
 What two systems are the nervous system divided into? | central nervous system (CNS) and the peripheral nervous system (PNS) |
| What does the CNS include? | the brain and the spinal cord |
| What does the PNS include? | the cranial nerves and the spinal nerves |
| What two types of cells is the nervous system composed of? | neurons and supporting cells |
| What are neurons? | the basic structural and functional units of the nervous system, which are specialized to respond to physical and chemical stimuli, conduct electrochemical impulses, and release chemical regulators; cannot divide by mitosis |
| What are supporting cells? | they aid the function of neurons and are about five times more abundant than neurons; called neuroglia or simply glial cells; can divide mitotically |
| What are three principal regions of a neuron? | 1) a cell body, 2) dendrites, 3) an axon |
| What is a cell body of a neuron? | the enlarged portion of the neuron that contains the nucleus; the "nutritional center" where macromolecules are produced; usually occur in clusters called ganglia |
| What is a dendrite? | thin, branched processes that extend from the cytoplasm of the cell body; from the Greek dendron = tree branch; transmits electrical impulses towards the cell body |
| What is an axon? | a longer process that conducts impulses away from the cell body |
| What is axoplasmic flow? | results from rhythmic waves of contraction that push the cytoplasm from the axon hillock to the nerve endings; slower |
| What is axonal transport? | employs microtubules and is more rapid and more selective; may occur away from the cell body called anterograde (kinesin proteins) or toward the cell body called retrograde transport (dyneins proteins) |
| What are the types of neurons? | 1) sensory, or afferent neurons, 2) motor, or efferent neurons, 3) association neurons, or interneurons |
| What is a sensory, or afferent neuron? | neuron that conducts impulses from sensory receptors into the CNS |
| What is a motor, or efferent neuron? | neuron that conduct impulses out of the CNS to effector organs (muscles and glands) |
| What is an association neuron, or interneuron? | neuron that is located entirely within the CNS and serve the associative, or integrative, functions of the nervous system |
| What are the two types of motor neurons? | 1) somatic motor neuron, 2) automatic motor neuron |
| What is a somatic motor neuron? | neuron responsible for both reflex and voluntary control of skeletal muscles |
| What is an automatic motor neuron? | neuron that innervate (send axons to) the involuntary effectors-smooth muscle, cardiac muscle, and glands; subdivided into sympathetic and para sympathetic |
| What are pseudounipolar neurons? | neurons that have a single short process that branches like a T to form a pair of longer processes |
| What are bipolar neurons? | neurons that have two processes, one at either end; this type is found in the retina of the eye |
| What are multipolar neurons? | the most common type, that have several dendrites and one axon extending from the cell body; motor neurons are an example |
| What are the two types of supporting cells in the PNS? | 1) Schwann cells and 2) satellite cells, or ganglionic gliocytes |
| What are Schwann cells? | supporting cells which form myelin sheaths around peripheral axons |
| What are satellite cells, or ganglionic gliocytes? | supporting cells which support neuron cell bodies within the ganglia of the PNS |
| What are the four types of supporting cells in the CNS? | 1) oligodendrocytes, 2) microglia, 3) astrocytes, 4) ependymal cells |
| What are oligodendrocytes? | supporting cells which form myelin sheaths around axons on the CNS |
| What are microglias? | supporting cells which migrate through the CNS and phagocytose foreign and degenerated material; hematopoietic (bone marrow) origin |
| What are astrocytes? | supporting cells which help to regulate the external environment of neurons in the CNS; the most common glial or supporting cells |
| What are ependymal cells? | suppoorting cells which line the ventricles (cavities) of the brain and the central canal of the spinal cord |
| What is the neurilemma or sheath of Schwann? | a continuous, living sheath of Schwann cells surrounding axons in the PNS; external to the myelin sheath |
| What is a myelin sheath? | the insulating covering of axons by successive wrappings of Schwann cells (PNS) or oligodendrocytes (PNS); internal to the neurilemma |
| What are the nodes of Ranvier? | the gaps in the myelin sheath that produce nerve impulses |
| What is white matter? | areas of the CNS that contain a high concentration of axons |
| What is gray matter? | areas of the CNS that contain high concentrations of cell bodies and dendrites, which lack myelin sheaths |
| What is the process of peripheral neuron regeneration? | the proximal portion may survive, but the distal portion will degenerate through phagocytosis. The myelin sheath provides a pathway and for the regeneration of an axon, and innervation is restored. |
| What are neurotrophins? | chemicals that promote fetal neuron growth; examples are nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), neurotrophin-3, neurotrophin-4/5 |
| What are the functions of astrocytes? | 1) take up K⁺ from the extracellular fluid, 2) take up some neurotransmitters released from the axon terminals of neurons, 3) the end-feet surrounding blood capillaries take up glucose from the blood, 4) appear to be needed for the formation of synapses in the CNS, 5) regulate neurogenesis in the adult brain, 6) induce the formation of the blood-brain barrier, 7) release transmitter chemicals that can stimulate or inhibit neurons |
| What is a blood-brain barrier? | the tight junctions between endothelial cells of the brain capillaries, that restricts the paracellular movement of molecules between epithelial cells, requiring the molecules to instead pass through the epithelial cells |
| What is the resting membrane potential? | a potential difference (voltage) across the membrane, in which the inside of the cell is negatively charged in comparison to the outside of the cell; Na⁺ is more highly concentrated in the extracellular fluid than inside the cell, whereas K⁺ is more highly concentrated within the cell |
| pg 170 | pg 170 |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.