nervous system cells and communication Flashcards
describe the general functions of the nervous system
sensory, integration and motor
sensory function
receives information about the external and internal environments and communicates this information to the integrative system
integration function
process and distribute input signals and then distributes output signals to the motor region to initiate body responses
motor function
activates the effector organs/ cells to cause an appropriate action in response to the sensory information
what are the 2 divisions of the nervous system
CNS central nervous system (the brain and spinal cord) and PNS peripheral nervous system (nerves).
what are neurons
cells which communicate by receiving, transmitting and sending signals between each other
what is a dendrite (cell body and multipolar neurons) on a neuron
the receptive region. It receives and responds to incoming chemical signals
what is the axon on a neuron
the conducting region. it transmits electrical impulses (action potentials)
what is the axon terminals on a neuron
the secretory region. They secrete neurotransmitters that stimulate or inhibit other neurons or body cells
what is a multipolar neuron
They have 2 or more dendrites and a single axon extending from the cell body. Most common neuron type in the nervous system
what are unipolar neurons
dendrites are continuous with the axon and the cell body lies off to one side of the axon. most sensory neurons are unipolar neurons
what are anaxonic neurons
all cell processes extending from the cell body look alike (no distinct axon). located in brain and some special sense organs, but functions are poorly understood
bipolar neurons
have 2 distinct processes- a single dendrite with distal branches and a single axon- extending from the cell body. Rare, only found in some special sense organs
what is the neuroglia
cells which support and protect neurons in the CNS and PNS
astrocytes CNS
the most abundant in the CNS.
- regulate ECF concentrations and maintain the blood- brain barrier
ependymal cells CNS
form an epithelium called the ependyma which lines fluid- filled spaces in the brain and spinal cord. these cells produce, monitor and circulate cerebrospinal fluid
microglia CNS
move through nervous tissue and remove cellular debris, waste products and pathogens by phagocytosis
oligodendrocytes CNS
- provide structural framework by stabilising the position of neuronal axons
- produce myelin sheaths for neurons in the CNS
Schwann cells PNS
- form multi layered myelin sheaths around a segment of the axon in the PNS, just like oligodendrocytes in the CNS