The Nervous System – Flashcards

The central nervous system consists of a brain and spinal chord, this processes information. The peripheral nervous system consists of all neural tissue outside the CNS (spinal nerves, cranial nerves) which compose sensory input and motor output.

The PNS is divided into the afferent and efferent division. The afferent division brings sensory information to the CNS and the efferent division carries motor commands to muscles and glands. The afferent division begins at receptors (which may be a dendrite, specialized cell, or complex sense organ) and ends at the CNS. The efferent division starts in the CNS and ends at an effector (muscle cell, gland cell, or specialized cell). The efferent division includes the somatic nervous system and the autonomic nervous system. The autonomic nervous system is divided into the sympathetic and parasympathetic divisions.

Visceral neurons monitor other internal structures such as smooth muscle, cardiac muscle, glands, and respiratory and digestive organs. The somatic nervous system monitors skeletal muscles, joints and skin. These along with special sensory receptors make up the afferent division.

There are three types of sensory fibers. Interoceptors, exteroceptors, and proprioceptors. Exteroceptors provide information about the external environment in the form of touch , temperature, and pressure sensations and the more complex special senses of sight, smell, and hearing. Proprioceptors monitor position and movement of skeletal muscles and joints. Interoceptors monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems and provide sensations of deep pressure and pain as well as taste, another special sense.

There are two types. Skeletal muscle fibers and visceral effectors (smooth muscles, glands, cardiac muscles, adipose tissue)

An interneuron is generally situated between sensory and motor neurons. They are located entirely within the brain and spinal chord. They are responsible for the analysis of sensory input and the coordination of motor output. They can be classified as excitatory or inhibitory on the basis of their effects on the post synaptic membranes of other neurons.

The efferent division includes the somatic nervous system and the autonomic nervous system. The somatic nervous system controls skeletal muscle contractions. The autonomic nervous system regulates smooth muscle, cardiac muscle, and glandular activity.

The two divisions are the sympathetic nervous system and the parasympathetic system. These are involuntary systems that control the smooth muscle, cardiac muscle and glands.

Neurons are nerve cells that transfer and process information in the nervous system. Neurons have a cell body (soma) which contains the nucleus, mitochondria, ribosomes, and other organelles. The cell body has branching dendrites which are stimulated by environmental changes or the activities of other cells. From the cell body, the axon extends and conducts a nerve impulse (action potential) toward synaptic terminals. The axon ends in one or more synaptic terminals also called terminal boutons. These communicate with other cells.

The four types of neurons found in the CNS are oligodendrocytes, astrocytes, microglia, and ependymal cells. Oligodendrocytes myelinate the CNS axons and provide structural framework. Astrocytes maintain the blood brain barrier and provide structural support. They also regulate ion, nutrient and dissolved gas concentrations, absorb and recycle neurotransmitters; and form scar tissue after injuries. They plug blood vessels from leaking and prevents passive fluid transfer so that dont accidentally excite neurons. Microglia remove cell debris, wastes, and pathogens by phagocytosis they are part of the immune system. Ependymal cells line ventricles in the brain and the central canal of the spinal cord. They assist in producing, circulating and monitoring cerebrospinal fluid.

Satellite cells surround neuron cell bodies in ganglia; regulate O2 and CO2, nutrient, and neurotransmitter levels around neuron in ganglia. Schwann cells surround all axons in PNS and are responsible for myelination of peripheral axons as well as repair after injury. Also protect from interstitial fluids.

Anaxonic neurons are small and have more than two processes but axons cannot be distinguished from dendrites. They are found in the CNS and in special sense organs, and their functions are poorly understood. Bipolar neurons have two processes separated by a cell body. They have a number of fine dendrites that fuse to form a single dendrite. On the other side of the cell body there is a single axon. They play an important role in relaying sensory information concerning sight, smell and hearing. They are myelinated. The pseudounipolar neuron have a single elongate process with the cell body situated to one side. Sensory neurons of the peripheral nervous system are usually pseudounipolar and have myelinated axons. The multipolar neurons have more than two processes, with one axon and multiple dendrites. They are in the CNS as inter neurons and are often motor neurons.

Via an action potential, which is caused by permeability changes in the plasma membrane.

A synapse is a specialized site where a neuron communicates with another cell. This involves neurotransmitters traveling from terminal boutons on synaptic terminals. Three types are synapses with another neuron, neuromuscular synapses, and neuroglandular synapses.

Found in grey matter in the peripheral nervous system. They are collections of neuron cell bodies.

The are the white matter of the PNS, and are bundles of axons.

They are the gray matter on the surface of the brain in the CNS.

They are the gray matter in the CNS that are collections of neuron cell bodies in the interior of the CNS.

They are collections of neuron cell bodies in the CNS, each center has a specific processing function. Are gray matter of CNS.

They are bundles of CNS axons that share a common origin and destination. White matter.

white matter CNS. Several tracts that form an anatomically distinct mass.

Myelin is a layered phospholipid layer of schwann cells that ensheath axons. This increases the speed of a action potential being conducted. Nodes of ranvier are spaces between schwann cells. This occurs in the PNS. All cells in PNS have schwann cells to protect glial cells from interstitial fluids regardless of myelination status.

Presynaptic membrane with neuro transmitters inside vesicles found on synaptic knob/terminal bouton. Travel across synaptic cleft to protein receptors on postsynaptic membrane. Telodendria s a distal branch of a neuronal axon that can further branch into axon terminals.

Post: axons connecting ganglion with peripheral effectors. Pre: Axons connecting CNS to ganglion.

A specialized cell or cell process that monitors conditions in the body or external environment.

the area monitored by a single receptor. The larger the receptive field, the harder it is to localize a stimulus

Exteroreceptors provide information about the external enviornment. Proprioreceptors monitor the body's position. Interoreceptors monitor conditions inside of the body.

Nocireceptors respond to stimuli associated with tissue damage. These cause pain sensation. Thermoreceptors respond to change in temperature. Mechanoreceptors are stimulated or inhibited by physical distortion, contact, or pressure on their plasmalemmae. They are chemo, baro or tactile receptors.

When visceral pain sensations are often perceived as originating in more superficial regions that are innervated by the same spinal nerves. BRain freeze

Fine touch, pressure and vibration, deep pressure.

is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement.

Pacinian corupuscle and muscle spindles.

stretch receptors that monitor changes in the stretch of the walls of an organ and the pressure within that organ. Free nerve endings in the elastic tissue in the wall of a hollow organ.

detect changes in concentration of specific chemicals or compounds. Found in CNS, repsiratory, and cardiac.