Chapter 5 Flashcards
Parts of the nervous system
Central nervous system
Peripheral nervous system
Parts of peripheral nervous system
Motor
Sensory
Parts of peripheral motor system
Autonomic nervous system
Skeletal
Parts of sensory peripheral nervous system
Dorsal root ganglia
Cranial nerve ganglia
Parts of the autonomic nervous system
Sympathetic
Parasympathetic
Enteric
Draw out nervous system division map
Central nervous system
Brain and spinal cord
Peripheral nervous system
made of nerves, ganglia, sensory receptors and motor endings that are outside of brain and spinal cord
Mechanoreceptors
Measure pressure, flex and flexion
Chemoreceptors
Sensitive to chemicals in solution
Nocioreceptors
Sense pain, respond to pinch and chemicals released from damaged tissues. Detect harm
Afferent
Arriving at brain. Info collected by sensory system from in and out body moves toward the center and travels to brain
Integration processing of information
Decision making.
Nervous system processes and interprets sensory info and makes decisions about what you do at each moment
Efferent
Info leaving CNS. Goes back out through(somatic) motor division
Four things that can happen after information processing
- Skeletal motor response
- Cardiac muscle
- Smooth muscle
- Glands
Describe the travel of information through the nervous system
1.Information is sensed via receptors. Moves in afferent direction
- Information is processed by CNS during integration
- Info leaves in efferent direction and starts a motor response. One of 4 responses occurs
Soma
Body
Sympathetic
Fight or flight
Parasympathetic
Rest and digest
Both at tug of war
Autonomic tone
Dominance of sympathetic or parasympathetic nervous system
Function Of nervous system
Collects sensory info from inside and outside of the body and coordinate appropriate response
Thermo receptors
Respond to temperature changes
Why Is there a tug of war between sympathetic and parasympathetic?
Muscles and glands innervated by both systems. Helps maintain homeostasis
How many neurons in nervous system
100 billion
Enteric nervous system
Nervous system of GI tract. Supplies alimentary canal
Which nervous system can carry integration on its own separate from CNS
Enteric nervous system
Constantly communicates in microbiome of gut
Types of structures in peripheral nervous system
Spinal nerves
Ganglia
cranial nerves
Motor endings and receptors
Ganglia
Collection of cell bodies outside of CNS
Nuclei
Group of cell bodies inside of CNS
Why is the brain vascular?
The neurons are highly metabolically active
Neurons have a lot of which organelle
Mitochondria
What is the preferred energy source of neurons
Glucose
Gray matter is made of
Neuron cell bodies and unmyelinated axons
White matter is made of
Myelinated axons it is white because of cell membrane wrapping (myelin sheath)
Where does integration occur
Gray matter
What happens in Gray matter
Integration decision making and perception of senses
What happens in white matter?
Send signals to motor division
Highly efficient communication
Cortex
Outer layer of gray matter
Basal nuclei
Little bits of gray matter
Deep within white matter of cerebral hemispheres
Subcortical nuclei (under cortex)
Communicate with premotor cortex.
Nuclei
Clusters of neuron cell bodies in CNS
Basal nuclei function
Regulate movement
1.Starting and stopping
2.Repetitive motion (walking or riding bike)
- Inhibit antagonistic movement (stops unwanted or unnecessary movement)
How are white matter and gray matter arranged in the spinal cord
White is on the outside gray is on the inside
opposite of brain
Sulcus
Crease and brain furrow less deep than fissure
Gyrus
Is a raised area of the brain
What is the function of sulci and gyri
Increase the amount of gray matter on surface area. More area for integration of information
Fissure
Deep longitudinal depression between two hemispheres. Deepest inward folds on brain
Foramen magnum
Large opening and occipital bone brain stem goes through
Medulla oblongata
Inferiormost part of the brain stem
Brainstem parts
Midbrain, pons, medulla oblongata
Midbrain
Relay sensory and motor information between the spinal cord and the rest of the brain.
Superior colliculi of the midbrain
Help control the movement of eyes head and neck in response to unexpected stimuli like loud noise or flash
What is the brain stem called after it enters the vertebrae
Spinal cord
Direction of tracts of white matter in the spinal cord
Afferent and efferent
Meninges
Protective layers of CNS
Describe the meninges from superficial to deep
Dura mater
arachnoid Mater
Pia Mater
Dura mater
Thick fibrous outermost toughest
Inward folds help secure the brain to the skull
Tough mother in Latin
Two layer fibrous connective tissue
Arachnoid Mater
Spider mother, weblike
Trabeculae
Above subarachnoid space
Pia Mater
Tender mother
Delicate connective tissue, has many tiny blood vessels. Things tightly to brain like plastic wrap
Describe the functions of the meninges
1.Protect and cover CNS
2. Protect blood vessels and enclose venous sinuses
3. Contains cerebrospinal fluid
4. Form partitions in the skull
Periosteal layer of Dura mater
Attaches to inner surface of skull. Not found in spinal cord
Meningeal layer of Dura mater
True external covering of brain
Subarachnoid space
Spider like extension secure the arachnoid Mater to the Pia Mater.
Houses cerebrospinal fluid and largest blood vessels serving the brain
Nerves
Pns fibers of somatic and autonomic neurons
Arachnoid granulations
Protrude superiorly through the dura mater and into the superior sagittal sinus
Absorb CSF into venous blood of the sinus
Meningitis
Inflammation of meninges.
Serious threat to brain it may spread to the CNS
Encephalitis
Brain inflammation
How is meningitis diagnosed
Obtaining sample of CSF via lumbar tap
Cerebrospinal fluid
Forms liquid cushion
Prevents brain from crushing under its own weight
Nourishment, similar to blood plasma
Brain functions
- Perception and processing sensory stimuli
Execute voluntary motor responses and involuntary motor responses - Regulates homeostatic mechanisms
Spinal cord functions
1.Starts reflexes
2. Pathway from sensory and motor functions
Which parts of the spinal cord start reflexes
- From ventral horn & lateral horn
Ventral horn
Somatic
Lateral horn
Autonomic (gray matter)
Ganglia is found in
PNS
Ganglia
Collection of nerve cell bodies outside of CNS
Function of ganglia
Receive sensory information by dorsal root and cranial ganglia
-tells viscera to move via the autonomic nervous system
Where do you process visual information
Occipital lobe
What are functional MRIs used for
Study the central nervous system and get diagnostic info
Function of myelination
Speeds up communication
What is the speed of an unmyelinated signal
3 to 30 m per second
What is the speed of a myelinated signal
300 M per second
Oligodendrocyte
Creates the myelin sheath in the central nervous system
Has cell body off to the side
Neuroglia
Nerve glue.
Support and maintain neurons
Outnumber the neurons
Schwann cells
Myelinate axons in the peripheral nervous system
Nodes of Ranvier
Bit of exposed axon exposed to extracellular environment
Explain saltatory conduction
The action potential travels between gaps of myelination.
Moves more rapidly. Only nodes of Ranvier have to be depolarized
Dendrites
Branching listeners.
Neuron process that receives electrical signals and takes it to soma
Synapse
Space where dendrite and axon interact .
Where pre and post synaptic neurons almost touch
Presynaptic neuron
Sends impulse to synapse
Sends
Postsynaptic neuron
Takes electrical signal away from synapse
Receives
Explain how action potentials travel down neurons
- Impulse travels down axon to synaptic cleft
- Releases NT at the end
- Neurotransmitter binds to receptors of dendrites on postsynaptic neuron
Why are action potentials irreversible
The impulse travels in One direction
Describe the cell body of a neuron
Has normal cell components, lots of mitochondria, multiple nucleoli, endoplasmic reticulum has polyrbosomes
Polyribosome
Multiple ribosome. mRNA complex makes multiple copies of the same protein
Other names for polyrbosomes
Chromatophillic substance
Or Nissl bodies
Axon hillock
Where neuron narrows down to axon
What supports the axon from inside?
Neurofibrills
Where are neurotransmitters made?
Cell body. They travel to the synaptic knob
What goes down the axon?
Neurotransmitter,
Mitochondria,
Cell waste,
What happens to the things that are not needed at the end of the axon?
Goes back up
Electrical signal of an axon only moves in - direction(s)
One
Where does the electrical signal of a neuron start?
Axon hillock
Travels toward axon terminal into synaptic knobs
Unipolar neuron
One process comes from body
Bipolar neuron
Two processes extend from cell body
Multi-polar neuron
Multiple processes extend from cell body
1 axon many dendrites
Function of motor proteins
Move substances up and down the axon
Anterograde movement
Movement away from cell body
Retrograde movement
Move towards the cell body
Sensory neurons
Unipolar neurons
What happens in unipolar neurons during early development?
Axon and dendrites fuse
Dorsal root ganglia
Filled with bodies of unipolar sensory neurons in spinal cord
Collect sensory information from body and takes to the spinal cord and brain
Where can you find bipolar neurons?
Retina of the eye
90% of neurons in the central nervous system are
Multi-polar neurons one axon many dendrites
Which neurons can lack an axon?
Some vision neurons have no axon
What does the purkinje cell layer do?
Maps movements of the body and it’s found in the cerebral cortex
In cerebellum
Proprioception
Body’s ability to sense movement action and location
Tracts
Bundles of axons in the central nervous system.
Carries information (afferent) to brain
Nerve
Bundle of axons in the peripheral nervous system
Pyramidal cells found in
cerebral cortex
Cerebrum
Big part of brain
Cerebrum parts
Cerebral hemispheres
Cerebral cortex
White matter
Basal nuclei
Cerebellum
Proprioception
Most involved in producing smooth coordinates skeletal muscle activities
Where are olfactory receptors located?
Superior nasal cavity covered by mucous membranes
Olfactory neurons
Help smell things
Sensory neurons
Unipolar neurons that move electric impulses to the central nervous system
How many processes come out of a sensory neuron?
One
Relay neuron
Interneuron
Connect sensory neurons with motor neurons
What is the function of interneurons?
Move signal through the CNS pathways
Reflex
Automatic reaction to stimuli most simple neural pathway in the body
Only monosynaptic reflexes in the body
Stretch Reflexes
Monosynaptic reflex
involve a single synapse
Schwann cells
Individual cells from peripheral nervous system that make the myelin sheath
Why are they called oligodendrocytes?
They can myelinate multiple places on one axon or multiple axons
Myelin sheaths are made of
Lipids and proteins
What kind of information do Myelinsheaths conduct?
Sensory and motor information
Multiple sclerosis
Autoimmune
Immune system attacks myelin sheath
Erratic signals and poor signal strength
Guillain-Barre syndrome
Myelin sheath attacked in peripheral nervous system
Certain characteristics of myelin sheath in ____ let’s axons regrow
Peripheral nervous system
Large bundles of neurons including the axons and myelination
Nerve
Astrocytes
Shaped like star most abundant CNS neuroglia
Controls exchanges between blood capillaries and neurons
Directs connection in new synapses
Blood-brain barrier importance
Prevent certain substances from going into brain blood capillaries
Describe astrocytes
Apportion of their extensions connect to capillaries.
Filters substances out of capillary
How do astrocytes control the chemical environment?
Collect leaked potassium ions
Recapture and recycle neurotransmitters
True or false medications can cross the blood-brain barrier
True
Microglial cells in CNS
Macrophages
Live in brain
Phagocytize pathogens cellular debris and metabolic waste products
Epyndymal cells
Found in ventricles of brain.
Line cavities of brain and spinal cord.
Produce CSF.
Have cilia that helps circulate CSF
Parts of a neuron
Axon
Dendrites
Soma
Synaptic knobs
Why is it important to get rid of debris?
Debris can power bacteria
Ventricles
Space pockets in brain filled with cerebral spinal fluid and lined with epyndymal cells
Functions of cerebrospinal fluid
Move wastes, cushion and protect
What are the glial cells of the peripheral nervous system
Schwan cells and satellite cells
Satellite cells
Support cells body in the peripheral nervous system
What does myelination look like in extra fast communication?
Wraps around multiple times
Neurofibrils
In the middle of axon
Intermediate filaments that maintain shape
Neurolemma
Outer layer of schwann cell lets the PNS neuron repair and regrow
How are Schwann cells used for repair?
- Macrophages clean site of damage
- Neurolemma forms tunnel
- Neuron Targets reconnection of peripheral motor neuron with skeletal muscle.
Establishes reconnection between basement membrane and connective tissue below
What happens if a temperature is colder than the temperature you usually sense?
Will sense pain same if too hot
At rest the inside of a neuron is
Negative
Frey syndrome
Peripheral motor neurons reconnect incorrectly to the new target connect to sweat glands causes sweating instead of breaking down food through saliva
Which nervous system innervates the parotid gland?
parasympathetic
Explain how the nervous system works
- Sensory receptors in skin are activated
- Action potential (electrical charges)goes through the sensory axon
3.The inside of the axon goes from negative to positive (depolarization)
- The action potential goes through the dorsal root ganglion
Goes into spinal cord. Action potential travels through tract. - Sensory axon enters spinal cord and synapses with the brain.
Interneuron between sensory neuron to area in gray matter - Second neuron projects into thalamus
- Sensory pathway reaches the cerebral cortex. Decides what to do integration.
- Upper motor neuron execute’s motor command. Moves in efferent direction
- Connects with lower motor neuron. Makes contact with lower motor neuron in spinal cord.
- Lower motor neuron causes contraction of target skeletal muscle
Which cations are important for depolarization
Sodium and potassium
Ligand
Binds to receptor. chemical messenger
Which sensory information travels through the thalamus?
All except smell
What is the function of the thalamus?
Routes information to appropriate location
Neuromuscular junction
Innervated skeletal muscle
How do you make the inside of a cell positive?
Let sodium in
How do you make the inside of a cell negative?
Let potassium out through concentration. Gradient to reset
Extra and intracellular conditions for conduction of action potentials
External environment needs high concentration of sodium
Internal environment needs higher concentration of potassium than the outside
What is the neurotransmitter of skeletal muscles?
Acetylcholine
When does sodium start to enter the axon?
When the voltage is greater than the threshold value of negative 55 millivolts
When does the axon start to repolarize
When the voltage reaches positive 30 millivolts potassium starts to leave and sodium channels close
Is acetylcholine excitatory or inhibitory?
Can be both
Explain the function of ligandgated channels
1.When acetylcholine binds, the channel protein opens and things move down the concentration gradient.
2.Sodium rushes into cell calcium rushes into cell potassium leaves cell
Explain how mechanically gated channels work
- Channel protein is always hollow.
When appropriate signal is received. Channel opens
Open in response to a physical deformation of receptor. Such as touch and pressure
Give an example of a mechanically gated channel
Thermoreceptor
Voltage-gated channels
Sense changes in voltage cell interior. Goes from negative to less negative.
Channels open and let certain ions go down. Concentration gradients
Types of voltage-gated channels in neurons
Voltage gated sodium channels. Potassium channels
Which ion concentration is higher in extracellular fluid?
Sodium
Which ions concentration is higher in intracellular fluid?
Potassium
Leaky channel
Sodium lets down concentration gradient in predictable regular interval. Autonomic nervous system adjusts to control base level heart rste
Charge on inside of axon is more
Negative
Give an example of leaky channels
Sodium channels in cardiac conduction system
EPSP
Excitatory post synaptic potential
Tell cell to do something
sends excitatory signal
IPSP
Inhibitory postsynaptic potentials
Tells neuron don’t send signal
Where do signals add up
Axon hillock
How do EPSPs affect the charge
Make cell more positive
When do voltage-gated potassium channels open up?
After + 30 millivolts
What is hyperpolarization?
Potassium ions continue to leave cell
-becomes more negative than normal resting point
Normal resting point voltage of cells
-70 mV
What is the function of hyperpolarization
Keep signals from overlapping or going backward
Which channels are slower to close
Potassium channels
When do potassium channels open?
Positive 30 millivolts
How does the cell recover from hyperpolarization?
The sodium potassium pump restores concentration gradients
Approximate value of hyperpolarization
-92 mV
Explain how the sodium potassium pump moves
Three sodium out 2 potassium in
Why does the sodium potassium pump need energy?
Cause it moves against the concentration gradient.
Sodium goes back out where the concentration is higher. Potassium goes in to where it’s more concentrated
Explain voltage changes in neurons
- At rest -70mV
- Stimulus applied
- Depolarization ( voltage rises)
- +30 and repolarization (voltage falls)
- Hyperpolarization, and of AP
- Return to rest
What causes hyperpolarization of the cell?
Potassium channels that are slow to close
Why do decisions of action potentials happen at the axon hillock
Because all dendrites collect different charges and they taper at the axon hillock
Calcium has higher concentration in
Extracellular fluid
Exocytosis
Vesicles merge with plasma membrane to release content into extracellular space
What happens when the action potential reaches the synaptic knob?
- AP causes synaptic knob to make voltage gated calcium channels to open
- Calcium goes in.
- When calcium goes in and reaches a certain concentration. it tells vesicles with neurotransmitter to get released via exocytosis.
- Neurotransmitter is released into the synaptic cleft
- Neurotransmitter diffuses and binds to ligandgated channels. Often sodium channels. Sodium goes into next cell
Group C. Fibers
Nerve impulses move slowly because axons are nonmyelinated and small
No. Saltatory conduction
Group a fibers
Somatic sensory and motor fibers
Serve skin skeletal muscles and joints
Largest diameter thick myelin
Group B. Fibers
Lightly myelinated
Intermediate diameter
Transport impulses at average rate
Which system do B &C fibers serve?
Autonomic nervous system motor fibers serving visceral organs.
Visceral sensory fibers, smaller somatic sensory fibers, transmit sensory impulses from skin
What determines resting membrane potential
Distribution of sodium potassium, chlorine and plasma proteins
What can make the inside of a cell less negative
Influx of sodium or increase in extracellular potassium which reduces the amount of potassium leaving through leakage channels p
An influx of chlorine or a decrease in intracellular sodium can cause
Hyperpolarization
Absolute refractory period
Cannot respond to other stimulus sodium channels open and become an active as they open and then start to close
Relative refractory period
Cell can be stimulated with a stronger than normal stimulus
Sodium channels and resting state. Some potassium channels open resting potential reestablished
Leakage channels contribute to
Resting membrane potential
Describe the all or none phenomenon of action potentials
Action potential either occurs completely or does not happen if the threshold is not met
How is stimulus intensity coded?
Impulses per second.
Stronger stimuli generate action potentials more frequently than weaker stimuli.
Frequency not amplitude
Which substances are moved in anterograde movement
Mitochondria
Cytoskeletal elements
Membrane components used to renew axon plasma membrane
Enzymes needed to make neurotransmitters
Which substances are moved in retrograde movement?
Organelles returning to cell body to be recycled
Tell cell body about conditions at axon terminals delivers vesicles containing signal molecules
Which are the listeners of a neuron?
Cell body and dendrites
Which type of axonal transport allows certain viruses to circumvent the barrier created by astrocytes
Some viruses and bacterial toxins that damage neural tissues use retrograde axonal transport to reach cell body
Example of multipolar neurons
Motor neurons
Function of motor neurons
Carry impulses away from CNS to effector organs
A neuron with a distal peripheral process and a central process that extends to the central nervous system is most likely a
Sensory neuron
What does the distal peripheral process of a sensory neuron do?
Sensory receptor
What does the central process of a sensory neuron do?
Enter the central nervous system
Chiefly found in ganglia of PNS
Unipolar neurons
Most
Inter Neurons are confined within
CNS
What makes up 99% of neurons in the body?
Interneurons
Processes of interneurons
Multipolar
Process classification of sensory neurons
Unipolar
Parts of neurons
Dendrite soma axon and synapse
Collaterals
Multiple branches of axon’s target different structures
Collaterals emerge from
Myelinated nerve at myelin sheath gaps
Where do you find short distance signals called grated potentials that travel toward the cell body?
Dendrites
Graded potential
Localized changes in membrane potential. Usually in dendrites or soma
What is the secretary region of a neuron?
Axon terminal
Norepinephrine
Neurotransmitter used by post ganglionic neurons in sympathetic nervous system
Function of norepinephrine
Feels good
Enhanced by amphetamines
Removal from synapse blocked by tricyclic, antidepressants and cocaine
Function of serotonin
Inhibitory
Indirect action via second messengers
Sleep appetite, nausea, migraine, headaches regulating mood
Which neurotransmitter acts as a natural opiate and inhibits pain?
Endorphins reduce pain perception under stress
Drugs that block this neurotransmitter relieve anxiety and depression
Serotonin
Spatial summation
Multiple local potentials occur at different places on the same cell at the same time. Post synaptic neuron is stimulated
by many pre-synaptic neurons
Huge numbers of receptors by neurotransmitters and start EPSPs
Feel good. Neurotransmitter deficient in Parkinson’s disease
Dopamine
Involved in wakefulness appetite, control, learning and memory
Histamine
Grated potentials made at dendrites move through
Chemically gated ion channels
Differences between electrical and chemical synapses
Chemical: lake that two neuron shout across
Electrical: like doorway electrical synapses makes simple way of synchronizing brain activity
What kind of synapses are most abundant in the embryonic stage
Electrical synapses
Which circuit type is involved with precise mathematical calculations?
Parallel
Adenosine
Caffeine simultaneously blocking brain adenosine receptors.
Generally, inhibitory indirect action via second messengers
Serial processing
Whole system works in predictable All or nothing manner
Peptides with inhibitory opiate like actions
Endorphins
Neurons
Nervous system cell that generates and transmits electrical signals
Axon
Neuron process that carries action potentials away from body.
Impulse
Self propagating wave of depolarization
Neurotransmitters
Chemical messengers that help neurons communicate
Sensory receptors
Cell or part of cell specialized to respond to a stimulus
Somatic nervous system
Responsible for controlling voluntary movements and processing sensory information
Autonomic nervous system
Controls involuntary actions of the body
Synaptic cleft
Fluid filled space at a synapse
Sensory neurons
Sends sensory information from internal and external environment to CNS
Relationship between nuclei and interneurons
nuclei contain interneurons. modulate flow of information. interneurons within nuclei can have inhibitory or excitatory effects on the neurons they connect with.
Resting potential
-70 mV
Depolarization
Loss of state of polarity.
Loss of negative membrane potential
Repolarization
Return of the membrane potential to initial polarized state
Hyperpolarization
Membrane becomes more negative than resting membrane potential
Threshold potential
-55mV weakest stimulus capable of producing a response in an excitable tissue
Action potential
Brief electrical impulse that sends information
Acetylcholinesterase
Degrades acetylcholine and terminates it’s action at the neuromuscular junction and synapses
Neuromuscular junction
Synaptic connection between terminal end of a motor nerve and a muscle
Convergence
Lets neuron receive input from many neurons in a network
Divergence
One neuron can communicate with many other neurons in a network
Neuronal pools
groups of interconnected neurons in CNS that work together to carry out a specific function.
Explain the roles of K, Na, Cl and Ca in developing an action potential
- Potassium (K+): Potassium ions have a high concentration inside the cell compared to outside. This concentration gradient is maintained by the sodium-potassium pump. Potassium channels in the cell membrane allow K+ ions to flow out of the cell, making the interior of the cell more negative.
- Sodium (Na+): Sodium ions have a higher concentration outside the cell compared to inside. Sodium channels in the cell membrane allow Na+ ions to flow into the cell, making the interior more positive. This influx of positive charge depolarizes the cell.
- Chloride (Cl-): Chloride ions are also involved in establishing the resting membrane potential. Chloride channels allow Cl- ions to move across the cell membrane, helping to maintain the overall charge balance.
- Calcium (Ca2+): While calcium is not as directly involved in establishing the resting membrane potential as K+, Na+, and Cl-, it plays a crucial role in cell signaling and neurotransmitter release. Changes in intracellular Ca2+ levels can modulate the membrane potential and affect cellular communication.
Difference between neurons and neuroglia
Neurons are the primary functional units of the nervous system, responsible for transmitting electrical and chemical signals. Neuroglia, or glial cells, provide support and protection for neurons, as well as maintaining homeostasis in the nervous system.
