Nervous Flashcards
Functions of the Nervous system
- Recieving sensory input
- Integrating Information
- Controlling muscles and glands
- Maintaining homeostasis
- Establishing and maintaining mental activity
consists of brain and spinal cord
Central Nervous system
consists of all nervous tissue outside the CNS (ganglia and nerves)
Peripheral Nervous System
PNS conducts PA from the sensory receptors of CNS
sensory division or afferent division
PNS conducts AP from the CNS to effector organs such as muscles and glands
Motor division or efferent division
Neurons that transmits AP from the periphery to the CNS
sensory neurons
Neurons that transmits AP from CNS toward the periphery
motor neurons
Transmits AP from CNS to skeletal muscles
Somatic Nervous System
Transmits AP from CNS to cardiac muscle, smooth muscle, and glands
Autonomic Nervous System
Unique subdivision of the PNS. Has both sensory and motor neurons contained wholly within the digestive tract
Enteric Nervous System or ENS
Recieve stimuli, conducts AP, and transmits signals to other neurons
Neurons or nerve cells
Single nucleus. The nucleus is the source of info. for gene expression
Cell body
Short, often highly branching cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips.
Dendrites
Single long cell process extending from the neuron cell body
Axon
Area where axon leaves the neuron cell body
Axon hillock
axon may remain unbranched or may branch to form
collateral axons
Many dendrites and a single axon
Multipolar neurons
2 process: 1dendrite and 1 axon. Located in some sensory organs
Bipolar Neurons
Single process extending from the cell body
Pseudo-unipolar neurons
Supportive cells of PNS and CNS. Far more numerous than neurons
Glial cells or neuroglia
major supporting cells in CNS. Stimulate the signaling activity of nearby neurons
Astrocytes
Astrocytes participate with the blood vessel endothelium to form permiability barrier
blood drain barrier
Line the fluid filled cavities within CNS. Produce cerebrospinal fluid
Ependymal Cells
Acts as immune cells of CNS, help protect the brain by removing bacteria and cell debris
Microglia
Provide insulating material that surround the axons in the CNS
Oligodendrocytes
Provide an insulating material that surround the axons in PNS
Schwann cells
Specialized layers that warp around the axons of some neurons
Myelin Sheaths
Axons with myelin sheaths
myelinated axons
Gaps in the myelin sheaths
nodes of Ranvier
Consists of groups of neuron cells bodies and their dendrites, where there is very little myelin
Gray matter
In CNS gray matter in the surface of the brain
cortex
clusters of gray matter located deeper in the brain
nuclei
In PNS , a cluster of neuron cell bodies
Ganglion
Consits of bundles of parallel axons with their myelin sheaths
White matter
White matter in CNS form _ , propagate AP from one area of the CNS to another
Nerve tracts or conduction pathways
opened by neurotransmitters or other chemicals
Chemically gated channels
opened by a change in membrane potential
Voltage gated channel
Muscle and nerve cells are _ , the resting membrane potential cjanges in response to a stimuli that activate gated ion channel
excitable cells
Na channels open very briefly and Na diffuses quickly into cell mambrane
Local current
AP is conducted along the entire axon cell membrane
Continuous conduction
AP jump from one node of Ranvier to the next along the length of axon
Saltatory Conduction
Junction where the axon of one neuron interacts with another neuron
Synapse
Chemical substances
neurotransmitters
If K or Cl channels are open , the inside of postsynaptic cell tend to become more negative
hyperpolarized
2 or more neurons synapse with the same neuron
converging pathway
the axon from one neuron divides and synapses with more than one other neuron
diverging pathway
Local potentials originate from different location on the postsynaptic neuron
Spatial Summation
Occurs when local potentials overlap in time
Temporal Summation
Nerves of PNS divides in 2 groups
12 pairs of cranial nerves and 31 pairs of spinal nerves
Communicate between the spinal cors and the body
Spinal nerves
Inferior end of the spinal cord and spinal nerves exiting there resemble a horses tail and called
cauda equina
White matter in each half of spinal cord a organized into 3 columns
dorsal, ventral, and lateral columsn
Consists of axons that conduct AP toward the brain
Ascending tracts