Nervous System Flashcards
What are the two functions of the nervous system?
communication and regulation .
The nervous system is what % of your body weight?
2%
neurologist
has studied the nervous system extensively
action potentail
electrical activity
endocrine system
the other system and they communicate via chemical event, hormones
components of the nervous system
brain, spinal cord, nerves, sensory receptors
the nervous system is responsible for
sensory perceptions, mental activities, stimulating muscle movements, secretions of many glands
subdivisions of the nervous system
Central nervous system: CNS
Peripheral Nervous Syster: PNS
Brain and Spinal Cord
CNS
are continuous with each other at foramen magnum
Function of CNS
- processes incoming sensory information
- thoughts, emotions, memories
- stimulate muscle contration
- stimulate gland secretion
PNS
nervous tissue outside CNS
organs: nerves, ganglia, enteric plexuses, sensory receptors
subcategories of the PNS
Somatic nervous system: SNS
Autonomic nervous system: ANS
Nerves
bundles of axons
Ganglia
collections of nerve cell bodies outside CNS
- Act as relay stations
- Primarily associated with the autonomic nerves system
Enteric Plexus
Grouping of nerves in the the intestines
Helps to regulate digestion
Sensory Receptors
pick up information about change
- Located in the periphery
- Typically named by info they transmit
Mechanoreceptors
movement
Thermoreceptors
temperature
Baroreceptors
Blood
Chemoreceptors
chemical
Nociceptors
pain receptors
SNS
Skeletal muscle
ANS
Autonomism from learned informations
ANS subcatagories
sympathetic: fight or flight
Parasympathetic: rest and repose, non stress events
sensory function
Detect internal stimuli
Detect external stimuli
Information sent to CNS by cranial and spinal nerves (SNS)
Integrative function - CNS
Processing of sensory information
Formulating a response
Motor function
Elicitation of an appropriate motor response
Effector (muscle or gland)
Neuron
primary cell of the nervous system
Highly excitable
Receives and transmits action potential
parts of a nerve
cell body, dendrites, and axons
Cell body
metabolic activity takes place
Dendrites
bring info from another neuron into cell body
Axon
carries info out to the periphery, make up cranial and spinal nerves
Glial cell
Support and protect neurons
classification of neurons
by function or structure
function classifications
afferent, motor/ efferent/ interneurons
afferent
afferentwill always transmit the info from the periphery towards the CNS
motor/ efferent
take info from the CNS out to the periphery out to the effector. Carry a response
interneurons
within CNS from one neuron to another, the middle man
structural classifications
multipolar, bipolar and unipolar
multipolar
multiple dendrites, motor neurons, brain and spinal chord
- Most common
Bipolar
1 dendrite, 1 axon, eye, smell, and hearing
- Rarest
Unipolar
looks like axon and dendrite are fused. most sensory receptors, touch and taste
Atrocytes
- multi pointes star
- Connected to neuron and the blood vessel. Apart of blood brain barrier
- Remove waste products/ filter stuff from the blood
Oligodendrocytes
secrete a lipid protein substance called myelin.
Myelin wrap around cell bodies and protect them
Microglia
wandering cells, immune system function, they have the ability to phagocytize unwanted materials from getting into the neuron
Ependymal cells
line the ventricles in the brain and they secrete a protective fluid know as cerebro spinal fluid (CSF), blood barrier
CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
PNS
Schwann cells
Satelltie cells
Schwann cell
manufacture and secrete myelin
Satellite cells
manufacture and secrete myelin for cell bodies in the ganglia
is all nervous tissue myelinated?
no
myelinated axons
Myelin protects and insulates axons from one another
Myelinated neurons
White matter
Unmyelinated axons
grey, no lypo protein protection
- Lypo protein most important function is to regulate the way the action potential is transmitted along the axons
Nodes of Ranvier
There has to be places where they are exposed to the open environment
**Action potential for myelinated = faster ***
White matter = where info take place
Grey matter = where info is stored
Ganglion:
associated with autonomic portion
Nerve tissue
bundle of axons
- Classified via types of axons that comprise the nerves
Motor
transmit a response to periphery
Sensory
transmit info to CNS
Mixed
transmit sensory and nervous system
Grey and white matter
in spinal chord and brain
Brain
grey mater is the outside, store everything we learn
Spinal cord
grey matter in the center, transmits ingoing info into outgoing info
Myelin matter in brain
located in the center for speed
Myelin matter on spinal chord
how atp is transmitted
Center of brain
communication network
spinal muscle cannot…
store information
Polarized
charge, +
- Allows cell to be stimulated
Depolarize
action potential
Potential describes the difference in charge across the cell membrane
Difference in charge allows our neurons to do work
Work is by way of an action potential (electrical)
Graded potential
happens at a synapis, over a short distance, chemical not electrical
Ex: what happens at neuromuscular junction
- Purpose is to change the charge/ depolarize to allow action potential
Coulombs law
Likes repel and opposites attract
Potential
voltage
Current
is the flow of charge
- Dependent on voltage and resistance
Current, Voltage, Resistance
I
V
R
Ohm’s law
I = V/R
The human body is
electrically neutral
current
flow of ions across the cell membrane
voltage
difference in numbers of + and - ions
- separated by cellular plasma membrane (potential energy)
ion channels
- change resistance
- protein based structures
- ion channels are selective
resting membrane potential
-70 mV
passive leakage channels
- help maintain the resting membrane potential.
- They are always open
Gated channels
- closed until stimulated to open
- Two events can open this
1. Voltage change
2. Chemical/ ligand
Depolarization:
- sodium channels open
- Depolarization is a self limiting event
- Time
- Voltage
Repolarization
when sodium channels close and potassium channels open
After potential
(hyperpolarization) almost a rest period. Occurs when potassium channels stay open longer than needed to restore normalcy
All or none principle
it goes from start to finish
Refractory period
insures that the action potential flows in one direction by changing the sensitivity of where that action potential was
Absolute
no stimulus will create an action potential
Relative
the stimulus has to be stronger than threshold/ minimum
Factors that affect propagation
- Myelination
- Axon diameter
- Temperature
Myelination
- Myelinated axons are white
- Speeds up
Axon diameter
(large: fast, small: slow)
A - large
B - medium
C – small
Temperature
- Cold slows down the transmission of action potentials
- Heat increases the action potential flow
Myelinated axon
only areas exposed to environment is where action potential occurs
Saltatory conduction
the synapse
Junction between two cells Site where action potentials in one cell excite or inhibit another Components Presynaptic neuron Postsynaptic cell/neuron Types Axodendritic Axosomatic Axoaxonic Additional classification Electrical Chemical
Ap Propagation
AP propagation is quick & efficient
AP is always propagated to next cell
electrical synapses
- Found in cardiac muscle and many types of smooth muscle
- Most efficient but also the rarest
- Synapsis are always excititory
at the synapse
you can have an excitatory activity or an inhibitory activity
A graded potential will always
be created in the postsynaptic structure
The graded potential can create
an excitatory event
GABA
is the most common in the brain and is the one that a lot of anti anxiety medicine is designed to release
A lot of neurotransmitters
important in mental health
