Chapter 11 Intro. Nervous System Flashcards
Nervous system
°Controls our perception and experience of the world.
° Directs voluntary movement.
° Seat of consciousness, personality learning, and memory.
° Regulate homeostasis.
2 divisions of the Nervous system
What are they?
°CNS - central nervous system
°PNS - peripheral nervous system
CNS are what parts of the body?
The brain and spinal cord
PNS are what parts of the body?
Consist of all nerves in the body
Cranial nerves and spinal nerves
Functions of the nervous system
(3 functions)
°Sensory function (PNS)
°Integrative functions (CNS)
°Motor functions
Sensory function (PNS)
°Sensory receptors gather info. about internal & external environment
°Afferent division carries info to CNS
Integrative functions (CNS)
Analyze and interpret incoming sensory info. and determines response
Motor functions
°action performed in response to integration
°efferent division carries info away from CNS
efferent division
(2 types of nervous systems)
carries info away from CNS
°Somatic nervous system
°Autonomic nervous system
Somatic nervous system
Carries info. to skeletal muscles
Autonomic nervous system (ANS)
Carries info. to smooth muscle, cardiac muscle, and glands
Afferent division
Carries info to CNS
Neurons
Excitable cells that are responsible for receiving and sending signals in the form of action potentials
Structure of neurons
°cell body
°dendrites
°axon
Structure of neurons
Cell body (soma) :
°nucleus
°cytoplasm with organelles
Structure of neurons
Dendrites:
Processes that receive info from other neurons, conduct impulse towards soma
Structure of neurons
Axon:
A processes that is a nerve fiber that conducts impulse away from soma
Processes
Cytoplasic extensions
Dendrites and axon
Structural neurons
(3 of them)
°Multipolar neurons
°Bipolar neurons
°Unipolar neurons
Structural neurons
Multipolar neurons:
(motor)
Single axon with multiple dendrites
Structural neurons
Bipolar neurons:
(Sensory)
One axon and one dendrite with the cell body between them.
Structural neurons
Unipolar neurons:
(Sensory)
Has only one fused axon that extends from the cell body and divides into 2 processes.
Functional neurons
(3 of them)
°Sensory
°Interneurons
°Motor
Functional neurons
Sensory neurons
(Afferent neurons)
Carries info towards CNS, they are Unipolar neurons and Bipolar neurons
Functional neurons
Interneurons
(Association neurons)
Relay info within CNS between sensory neurons and motor neurons, makes up most of the neurons in the body are Multipolar neurons
Functional neurons
Motor neurons
(Efferent neurons)
Carries info away from cell body in CNS to muscles and glands they are Multipolar neurons
CNS
Central nervous system
°Nuclei- cluster of neuron cell bodies
°tracts- bundle of axons
PNS
Peripheral nervous system
°ganglia- cluster of neuron cell bodies
°nerves- bundle of axons
Neuroglia
Supports and protects the neurons, maintains their environment and divides, and fills any spaces left by dead neurons
The 4 neuroglia of the CNS:
°Astrocytes
°Oligodendrocytes
°Microglia
°Ependymal cells
Neuroglia CNS
Astrocytes
Large star shaped cells
That transport nutrients and gases from blood vessels to neurons, creates the blood brain barrier (BBB)
Neuroglia CNS
Oligodendrocytes
Create myelin in the CNS
Neuroglia CNS
Microglia
When damaged turns into phagocytic cells
Neuroglia CNS
Ependymal cells
Ciliated cells that produce and distribute cerebral spinal fluid
The 2 neuroglia of the PNS:
°Schwann cells
°Satillite cells
Neuroglia PNS
Schwann cells
Creat myelin in PNS
Neuroglia PNS
Satellite cells
Supportive functions
Myelin
Made out of repeating layers of phospholipid plasma membrane, used for insulation of axon
Nodes of Ranvier
Spaces between the myelin sheath
White mater
Myelinated axons
Gray matter
Unmyelinated axon
Local potential
(Graded potential)
Travel short distance
Action potential
Travels the full length of an axon
Can cause maximum depolarization
It either happens or not doesn’t Doesn’t depend on strength, frequency, or length of stimulus like local potentials.
Ion channels
Ions pass through specific protein channels for diffusion
Resting Membrane potential
(RMP)
-70mV
Electrochemical gradient
Determines diffusion of ions across the plasma membrane
Electrical gradient
°Positive outside plasma membrane
°Negative inside plasma membrane
Chemical gradient
°Na+ (sodium) outside plasma membrane
°K+ (potassium) inside plasma membrane
Ion movements
(3 of them)
°Depolarization
°Repolarization
°Hyperpolarization
Ion movements
Depolarization
The movement of Na+ (sodium) across the plasma membrane into the cell. Membrane potential becomes more positive.
Ion movements
Repolarization
Movement of K+ (Potassium) across the plasma membrane out of the cell. Membrane potential becomes negative, returning to MRP.
Ion movements
Hyperpolarization
To much K+ (potassium) exits the cell, making the membrane potential more negative past the RMP
Refractory
Period of time after neuron has generated an action potential, when neuron cannot be stimulated to generate another action potential.
Conduction speed
Influenced by both axon diameter and presence or absence of myelination
2 types of conduction.
Saltatory conduction
Continuous conduction
Saltatory conduction
Myelinated axons Increase speed of conduction, exhibit jumping
Continuous conduction
Unmyelinated axon, slower
Neuronal synapse
Where a neuron meets its target cell.
Most synapse are…
Chemical
Postsynaptic potentials
Can be excitatory or inhibitory
Excitatory Postsynaptic Potentials
(EPSP)
Membrane potential moves closer to threshold.
Inhibitory Postsynaptic potentials
(IPSP)
Membrane potential moves further away from threshold.
Neutral integration
Process in which postsynaptic neuron integrates all incoming information into a single effect.
Neurotransmitters
(5 types)
°Ach
°adrenaline
°dopamine
°serotonin
°GABA
Neurotransmitters
Ach
Acetylecholine
Works at cholinergic synapse
(Excitability)
Neurotransmitters
Adrenaline
Works at adrenergic synapse
Neurotransmitters
Dopamine
Lack of it causes Parkinson disease
Neurotransmitters
Serotonin
Lack of it causes depression.
Neurotransmitters
GABA
An inhibitor
Lack of it leads to anxiety.
Neural circuits
Patterns of semantic connections between neural pools.
Diverging, circuits.
One neuron sends impulses to multiple post synaptic neurons.
Converging circuits.
Axon terminals from multiple neurons converge onto a single postsynaptic neuron
