nervous tissue Flashcards Preview

Spring 2013 / Anatomy 2 > nervous tissue > Flashcards

Flashcards in nervous tissue Deck (40):

a bundle of axons (plus associated connective tissue and blood vessels) located outside the brain and spinal cord is called_

a nerve


small masses of nervous tissue, consisting primarily of neuron cell bodies, that are located outside the brain and spinal cord are called_



what are the three major functions of the nervous system

1. sensory input: the nervous system uses its millions of sensory receptors to monitor changes occuring both inside and outside the body. The gathered information is called sensory input
2. integration: the nervous system processes and interprets sensory input and decides what should be done at each moment - a process called integration
3. motor output: the nervous system activates effector organs-the muscles and glands-to cause a response, called motor output


networks of neurons located in the walls of GI tract organs and help regulate digestive system activities is called_

enteric plexuses


structures that monitor changes in the internal and external environment are called_

sensory receptors


what are the two parts the nervous system is divided into

the CNS (central nervous system): consists of the brain and spinal cord
the PNS (peripheral nervous system): consists of nerves that extend from the brain to the spinal cord


spinal nerves carry impulses to and from the _

spinal cord


cranial nerves carry impulses to and from the _



what are the two functional subdivisions of the PNS

- sensory, or afferent division: consists of nnerve fibers that convey impulses to the central nervous system from sensory receptors located throughout the body
- motor, or efferent division: transmits impulses from the CNS to effector organs, which are the muscles and glands (they effect, or bring about a motor response)


what do somatic sensory fibers do?

convey impulses from the skin, skeletal muscles, and joints


what to visceral sensory fibers do?

transmit impulses from the visceral organs (within the ventral body cavity)


what are the two main parts of the motor (efferent) division

- somatic nervous system: composed of somatic motor nerve fibers that conduct impulses form CNS to skeletal muscles. VOLUNTARY NERVOUS SYSTEM (b.c. it allows us to consciously control our skeletal muscles)
- automonic nervous system (ANS): consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles, and glands. INVOLUNTARY NERVOUS SYSTEM (b.c. it regulates activities such as the pumping of our heart, or the movement of food through our digestive tracts.)


what are the two functional subdivisions of the ANS

- sympathetic division: generally supports exercise and emergency actions, ie: "fight-or-flight" responses
- parasympathetic division: generally promotes "rest and digest" activites


what is the enteric nervous system?

involuntary, ENS, "brain of the gut;" consists of neurons in the enteric plexuses that extend the entire length of the GI tract. The sensory neurons monitor changes in the GI tract and the motor neurons help regulate digestive system activites


what two types of cells make up the nervous system

- neurons: nerve cells that are excitable (respond to stimuli), and transmit electrical signals
- neuroglia: support, nourish, and protect the neurons and maintain the interstitial fluid that bathes neurons


when neurons respond to a stimulus and convert it into a nerve impulse, this is called a_

action potential


what are the three major parts of a neuron

- a cell body: contains the nucleus surrounded by cytoplasm that includes typical organelles
- dendrites: usually short, tapering, unmyelinated, and highly branched processes that emerge from the cell body
- axon: a long, thin, cylindrical process that may be myelinated and transmits nerve impulses away from the cell body


what is the name of the structure that joins the cell body to the axon

axon hillock


the axon and its collaterals end at where?

at the end of many fine processes called axon termina lbranches (arborizations)


nerve impulses are generated at the junction of the axon hillock and axon, which is called_

the trigger zone


most axons are surrounded by a _____ sheath. The purpse of myelin is _

to protect and electrically insulate fibers, and increase the transmission speed of nerve impulses


myelinated axons have gaps in the myelin sheath called _

nodes of ranvier


what is the name of the cells that produce the myelin sheaths around the PNS axons

schwann cells


what is the name of the cells that surround the cell bodies of neurons in the PNS ganglia, provide structural support, and regulate the exchange of materials between neuron cell bodies and the interstitial fluid?

satellite cells


regions of the brain and spinal cord containing dense collections of myelinated fibers are referred to as _____ _____

white matter


regions of the brain and spinal cord that contain mostly nerve cell bodies and nonmyelinated fibers is _____ _____

gray matter


in the spinal cord, _____ matter surrounds a butterfly-shaped core of _____ matter.

white, gray


in the brain, a thin layer of _____ matter covers the cerebrum and cerebellum. Masses of this _____ matter called _____.

gray, gray, nuclei


most nerves and all tracts (bundles of axons in the CNS) are composed of _____ matter



the junction between two neurons is called a _



at a synapse between neurons, the neuron sending the signal is called the _____ neuron, and the neuron receiving the message is called the _____ neuron.

presynaptic, postsynaptic


the synapse between a motor neuron and a muscle fiber is called a _

neuromuscular junction


the synpase between a neuron and a glandular cell is called a _

neuroglandular junction


in which kind of synapse do nerve impulses pass directly from the presynaptic neuron to the postsynaptic cell

in an electrical synapse


in a chemical synapse, the small gap between cells at a synapse is called the _

synaptic cleft


neurons are classified functionally or structurally. When classified structurally, what does this mean and what are the 3 subcategories?

the structural classification is based on the number of processes that extend from the cell body:
- multipolar neurons: usually have several dendrites and one axon; most neurons in the brain and spinal cord are of this type
- bipolar neurons: have one main dendrite and one axon; these are located in the retina, inner ear, and olfactory area of the brain
- unipolar or pseudounipolar neurons: sensory neurons have just one process extending from the cell body; this process branches to form a peripheral process (which is essentially an axon with dendritic branches at its distal end) and a central process (which has synaptic end bulbs at its distal end)


where can we find purkinje cells

in the cerebrum


where can we find pyramidal cells

in the cerebral cortex


what are the four types of neuroglia in the CNS?

1. astrocytes: star-shaped cells (with many processes) that perform several functions in support of neurons. They are the most numerous of the neuroglia. There are two types: protoplasmic (in gray matter) & fibrous (located in white matter)
2. oligodendrocytes: have few processes and produce a myelin sheath; each oligodendrocyte can myelinate parts of several axons
3. microglia: small, phagocytic neuroglia that protect the nervous system by engulfing microbes and removing debris of dead cells
4. ependymal cells: line the brain ventricles and the central canal of the spinal cord; they secrete and aid in the circulation of cerebrospinal fluid and they form the blood-cerebrospinal fluid barrier


brain tumors derived from glia are called_