Nervous Tissues Flashcards
What are the 3 parts of neurons
Dendrites, cell body, and axons
It receives messages from other neurons
Dendrites
Contains the genetic information determining cell function
Cell body
Conducts electrical impulses
Axons
Brain and spinal cord
CNS
Nerves or nerve fiber
PNS
It is a bundle of central axons
Nerve tract
Bundle of peripheral axons
Nerve fiber
It has myelinated axons
White matter
It has cell bodies and unmyelinated
Gray matter
Excitable cells that transmit electrixal signals
Neurons
Cells that surround and wrap neurons
-maintain homeostasis, form myelin and provide support for neurons
-non neuronal in CNS
- do not produce electrical impulse PNS
Neuroglia
It is around invidividual axon
Endoneurium
It is around individual fascicle
Perineurium
It is around entire nerve
Epineurium
It is afferent, arrives or bring stimuli
- info is transmitted from sensory receptor to CNS
Sensory neuron
It is efferent, exits or carry response
-info is from CNS to the effector cell
Motor neuron
It is found between sensory and motor which acts as mediator (bridge of communication)
Interneuron
It only has one axon
Unipolar
It has one axon and one dendrite
Bipolar
One axon but dendrites not coming from soma (cell body)
Pseudounipolar
Has many dendrites and one axon
Multipolar
What are the characteristics of ependymal cells
-Forms epithelial lining of ventricles (cavities) in the brain and central canal of spinal cord
- production and regulation of CSF
- apical surface covered of cilia that circulates CSF around CNS and has microvilli to absorb CSF
Produces myelin sheath
Oligodendrocyte
What is astrocytes
Specialized glial cells that outnumber neurons
-structural support insulating receptive surfaces, and buffer extracellular compartment
-during inflammation and injury they wall off damaged areas
Specialized macrophages that remove damaged neurons and infections
-maintain health of CNS
-professional innate phagocytes
Microglial cells
Surrounds neurons in PNS, support and protect
Satellite cells
Covers the neuron in myelin and alsi maintain nerve fibers PNS
Schwann cells
Why RMP is negative?
K+ positive leaks from inside that geneeate negative charge inside, so Na+ and K+ do not attain equilibrium
Steps of nerve conduction
- Neurons have resting membrane potential (-70 mV) > polarization
- Neurons are surrounded by high concentration of Na+
- The inside of neuron has some positively K+ ions and many charged ions (proteins and sulfates)
- Combination of Na+ environment outside and K+ positive inside = resting membrane potential
Also called as action potentials
- a self propagating wave of electrical disturbance
-electrochemical signal
Nerve impulses
Steps of nerve conduction: the action potential
- Dendrites are stimulated by axons of other neurons
- Na+ ions flow into the neuron by action of ion channels - membrane voltage positive = depolarization
- If the partial depolarization reaches -.65 mV (Ap threshold) the neurons fire
Na influx
Depolarization
K efflux
Repolarization
Na+ and K+ pump
Recharging
What are the effects of neurotransmitters?
- Excitatory neurotransmitters depolarize the postsynaptic cell membrane by stimulating the inflow of sodium ions
- Hyperpolarize the membraine by stimulating ion channels to allow K+ ions flow out, inhiniting neuron firing
Involved in memory and muscle activity
Acetylcholine (ACh)
Enhances mood, eating, sleep, and sexual behavior
Serotonin
An excitatory transmitter
Dopamine
Reduce pain and increase feeling of well being
Endorphins
