Neurophysiology Flashcards
What are the two categories of cells in the Nervous system?
- Neurons
2. Neuroglia
What is considered the major functional unit of the Nervous System?
Neuron
List the 7 parts of a Neuron
- Dendrite
- Cell body
- Axon
- Trigger zone
- Presynaptic Terminal
- Myelin Sheath
- Node of Ranvier
The information receiving area of the neural cell
Dendrite
The part of the neuron that contains organelles
Cell body/soma
The information carrying extension of the neural cell membrane
Axon
where the AP originates in a neural cell
Trigger zone/Axon Hillock
The end of the neuron that transmits information
Presynaptic Terminal
The part of the neuron that Enhances the speed of information transfer
Myelin Sheath
Gaps in the insulating myelin sheath are known as
Nodes of Ranvier
Which part of the Neuron passes messages away from the cell body to other neurons, muscles, or glands
Axon
Electrical signal that travels down the axon
Neural impulse
The periodical interruptions in the Myelin sheath
Nodes of Ranvier
The Myelin Sheath allows for _____ conduction of Impulse
Saltatory
What is Saltatory conduction
AP jumps from node to node which causes depolarization more rapidly
What is the conduction velocity in myelinated fibers proportional to?
Diameter of fiber
T/F larger axons have longer internodes and slower conduction velocities?
F faster conduction velocities
what is conduction proportional to in unmyelinated fibers?
Square root of the diameter
What are the 3 major types of neurons we discussed?
- Multipolar Neuron
- Bipolar Neuron
- Unipolar Neuron
What is the most prevalent type of neuron in the animal?
Multipolar
What makes multipolar neurons unique?
have 1 axon and numerous dendrites
What type of neuron are motor neurons
Multipolar Neurons
What do Motor neurons do?
send info from the brain/spinal cord to Muscles/Glands
What makes Bipolar Neurons unique»?
Have 2 processes, 1 axon and 1 dendrite
What is an example of a Bipolar neuron?
interneurons
What do interneurons do?
interconnect various neurons within the brain/spinal cord
Which type of neuron is used to link neurons together?
interneuron
What makes unipolar neurons unique?
Have a single stem process that bifurcates to form 2 progesses: peripheral and central
What are the 2 processes of unipolar neurons
- peripheral
2. central
Give an example of Unipolar Neurons
Sensory neurons
What is the function of sensory neurons.
send info. from receptors in sensory organs towards the brain/spinal cord
What are the 3 ways we can classify neurons based on their function?
- Motor or Efferent
- Interneurons or Association Neurons
- Sensory of Afferent
What is another name for Glial Cells
Neuroglia
T/F Neuroglia are smaller than neurons?
T
What is the function of Neuroglia?
Fill in the spaces in the NS not occupied by Neurons or blood vessels
T/F Neuroglia have the capability to produce AP?
F
List the 5 functions of Neuroglia:
- production of Myelin Sheath
- Modulate growth of developing or damaged neurons
- Buffer extracellular conc. of K+ and neurotransmitters
- Participate in the formation of contacts between neurons (synapses)
- Participate in some immune responses of NS
List the 4 types of Glial cells found in the CNS
- Microglial Cells
- Astrocytes
- Oligodendrocytes
- Ependymal Cells
What type of Glial cell is found in the PNS
Schwann Cells
This type of cell is found in the CNS and acts as macrophages to clear debris
Microglial cell
T/F Microglial cells play a role in developing the brain
T
How do Microglial cells help develop the brain?
By destroying the synapses that are unnecessary
Which type of cell helps to protect the brain from injury and infection?
Microglial cells
Connsists of 50% of the glial cell population in the CNS
Astrocytes
What is the function of Astrocytes?
Structural and metabolic support
List the 4 ways Astrocytes provide structural and metabolic support for the CNS
1 Forms outer and inner glial limiting memb. of CNS
- Release neurotrophic factors
- helps elongate axons and dendrites
- Participate in the repair process following tissue injury
Which ions do Astrocytes control the conc. of?
K; Na; Ca; Cl; HCO3
Glial cells that provide support to axons of neurons in the CNS
Oligodendrocytes
what is the reason the brain has white matter?
myelin sheath
Gray matter refers to areas with high populations of _____
Soma
Cells that cover the ventricles of the brain, central canal of CNS, and choroid plexus in the 4th ventricle of the medulla oblongata
Ependymal cells
T/F Ependymal cells are involved in creating CSF?
T
What is another name for Schwann Cells?
Neurolemmocytes
What is the function of Schwann Cells?
provide support to axons of PNS
What are the 2 subdivisions of the mammalian nervous system
Central and peripheral
Nervous system composed of the brain and spinal cord
Central
The CNS can be subdivided into 7 major regions:
- Spinal cord
- Medulla
- Pons
- Cerebellum
- Midbrain
- Diencephalon
- Telencephalon
What protects the CNS
The meninges and cerebrospinal fluid
What are the 3 protective layers of the CNS
- Pia Mater
- Arachnoid
- Dura Mater
What is the innermost meningeal layer, lying next to the CNS?
Pia Mater
The protective layer of the CNS that has a spiderweb like appearance, that traps CSF?
Arachnoid
The outermost protective meningeal layer of the CNS that is often fused with the inner surface of the skull
Dura Mater
What is CSF
Clear colorless fluid that provides micronutrients, carries away metabolic waste and is a shock absorber for CNS
Where is CSF found?
- Subarachnoid Space
- Central canal of spinal cord
- ventricular system of brain
T/F CSF is the major source of glucose for the brain.
F. Blood, have small amounts of glucose in CSF but not much
What is the function of the PNS
deliver sensory info to CNS and carries motor commands to peripheral tissues and systems
What is Endoneurium?
Connective tissue that surrounds the entire peripheral nerve fiber
What is the term for a bundle of nerve fibers?
Fascicle
What is the term for a bundle of fascicles?
Nerve
innervate parts of the head and connects directly to the brain
cranial nerves
innervates much of the body and connects to the spinal cord
Spinal Nerves
The nerves of the PNS can be subdivided into:
Motor and Sensory
What is the rER called in neural cells?
Nissel body
T/F mitochondria are found in both the soma and axons
T
The _____ integrate the incoming information and determine whether AP will be produced by the Neuron
Dendrites
What are dendritic spines?
protusions covering some dendrites that allows one dendrite to communicate with hundreds of axons
What are 2 ways neurons can be connected.
1 chemical synapses
2. electrical synapses
What are the most common type of synapses in neurological cells
Chemical
T/F chemical synapses are bidirectional
F. unidirectional
List the 4 Excitatory Neurotransmitters
- Acetylcholine
- Norepinephrine
- Epinephrine
- Glutamate
List the 5 Inhibatory neurotransmitters
- Acetylcholine
- Norepinephrine
- Epinephrine
- Serotonin
- Gamma-aminobutyric acid (GABA)
What are the 2 types of chemical synapses?
Excitatory or inhibitory
What are the two types of receptors for neurotransmitters
Ionotropic and metabotropic receptors
What are ionotropic receptors
neurotransmitter receptors that directly gate ion channels
What are the two types of ion channels
Cation and anion
channels opened by excitatory neurotransmitters
cation channels
Do cation channels induce depolarization or hyperpolarization
depolarization
channels opened by inhibitory neurotransmitters
Anion channels
Do Anion channels induce depolarization or hyperpolarization
Hyperpolarization
What are the 4 functions of G protein coupled receptors?
- open specific ion channels through the postsynaptic membrane
- Activate cAMP pathway
- Activate one or more intracellular enzymes
- Activate gene transcription
What are metabolic receptors?
Neurotransmitter receptor that act through second messenger systems
How is the cytoplasm of adjacent cells connected to one another?
Gap junctions
Are gap junctions Bidirectional or Unidirectional?
Bidirectional
What is the potential difference across the membrane of resting neurons?
-70mV
What are the 3 determinents of the memb. potential
- movement of ions toward a dynamic equilibrium
- differential permeability of the memb. to diffusion of ions
- Na:K pump
In order to initiate an action potential, graded potential must reach _________
Threshold potential
T/F the trigger zone is less sensitive to the depolarizing actions of the local current
F More sensitive
What is the minimum voltage change to trigger an AP
-55mV
What happens to the membrane potential during depolarization?
shifts toward more positive
excitatory neurotransmitters open cation channels
What are Excitatory Postsynaptic potentials? (EPSP)
Depolarizing graded potentials, they drive the MP toward the threshold
What Inhhappens to the membrane potential during hyperpolarization?
Shifts MP toward more negative
During hyperpolarization what do neurotransmitters do?
open anion channels
What are IPSP?
Inhibitory postsynaptic potential, hyperpolarizing graded potentials
what are the two types of summation
- Spatial Summation
2. Temporal Summation
What is spatial summation?
Graded potentials induced by different synapses summate in the postsynaptic neuron
simultaneous summaion of inhibitory IPSP and excitatory EPSP graded potentials also occur
What is temporal summation?
Successive discharges from a single presynaptic terminal summate in the post synaptic neuron
What is the Absolute Refractory period?
nearly the entire duration of the AP, Represents the time needed for the voltage gated sodium channels to revert from the inactivated state to the resting state
What is the Relative refractory period?
Time when voltage gated potassium channels are closed
