Nervous System Flashcards
(473 cards)
1
Q
Nervous Sys
A
Master controlling and communicating system of body
2
Q
How does nervous sys communicate?
A
Cells communicate via electrical and chemical signals,
3
Q
How are the those signals described?
A
Rapid and specific
4
Q
Primary cell of the nervous system
A
is the neuron
5
Q
Neurons are the key to what?
A
The key to neural transmission
6
Q
Sensory input –
A
info gathered by sensory receptors about internal and external changes (cold or hot)
7
Q
Integration-
A
processing and interpretation of sensory input and decides what actions are required
8
Q
Motor output-
A
activation of effector organs (muscles and glands) yields a response
9
Q
5 parts after stimulus but before response in simple reflect arc
A
- Receptor
- sensory neuron
- integration center
- motor neuron
- effector
10
Q
Central nervous system (CNS) parts and location
A
Brain and spinal cord of dorsal body cavity
11
Q
CNS job 3 parts
A
- Integration and control center
- Interprets sensory input and dictates motor output
- Motor output is based on reflexes, past experience, and/or current situation
12
Q
Peripheral nervous system (PNS) Location
A
The portion of the nervous system outside CNS
13
Q
PNS Consists mainly of
A
nerves that extend from brain and spinal cord
14
Q
Two types of nerves in PNS
A
Spinal and Cranial Nerves
15
Q
Spinal nerves
A
to and from spinal cord
16
Q
Cranial nerves
A
to and from brain
17
Q
PNS response simple term (common)
A
FIGHT OR FLIGHT
18
Q
Histology of nervous tissue
A
Highly cellular; little extracellular space
Tightly packed
19
Q
What are the 2 principal nervous cell types?
A
Neuroglia
Neurons (nerve cells )
20
Q
Neurons (nerve cells )
A
excitable cells that transmit electrical signals
21
Q
Neuroglia
A
small cells that surround and wrap delicate neurons: AKA glial cells, 6 types
22
Q
6 types of neuroglia
A
Astrocytes (CNS) Microglial cells (CNS) Ependymal cells (CNS) Oligodendrocytes (CNS) Satellite cells (PNS) Schwann cells (PNS)
23
Q
What neuroglia is most abundant?
A
Astrocytes (CNS)
24
Q
Astrocytes (CNS)
A
Most abundant, versatile, and highly branched glial cells with radiating processes that
25
What do astrocytes cling to?
Cling to neurons, synaptic endings, and capillaries
26
Astrocyte function
Functions include
Support and brace neurons and anchor them to their nutrient supply
Play role in exchanges between capillaries and neurons
Guide migration of young neurons
Control chemical environment around neurons and calcium concentration
Respond to nerve impulses and recycle neurotransmitters
Influence neuronal functioning
Participate in information processing in brain
27
Describe Microglial cells (CNS)
Small, ovoid cells with thorny processes that touch and monitor neurons
28
Microglial cells (CNS) monitor
Monitor the health of neurons then migrate toward injured neurons
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Microglial cells (CNS) transform
Can transform into a type of macrophage to phagocytize microorganisms and neuronal debris
30
Why are microglial cells vital?
Important because immune cells aren’t very permeable through the blood-brain barrier
31
Describe Ependymal Cells
Range in shape from squamous to columnar
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Ependymal Cells may be
ciliated
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Ependymal Cells line
Line the central cavities of the brain and spinal column
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Ependymal Cells form
Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells
35
Oligodendrocytes are
branched cells
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Oligodendrocytes processes
Processes wrap CNS nerve fibers, forming insulating myelin sheaths thicker nerve fibers
37
What gets damaged in MS?
Oligodendrocytes
38
Autoimmune disease is when
immune system attacks itself, they use chemo to stop immune response they don’t know why human body does this.
Different types of MS
39
Satellite cells Function
similar to astrocytes of CNS
40
Surround neuron cell bodies in PNS
Satellite cells
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Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers
Schwann cells (neurolemmocytes)
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Schwann cells (neurolemmocytes) Function
Similar function as oligodendrocytes
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Schwann Cells (neurolemmocytes) vital to what?
Vital to regeneration of damaged peripheral nerve fibers
44
Satellite cells anchor
neurons nerves need constant blood flow
45
Schwann cells have different
mylein sheath in some
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Nerve cell are
amitotic, they don’t divide
47
Neurons
Structural units of nervous system
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Neurons size and f(x)
Large, highly specialized cells that conduct impulses
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How long do neurons last?
Extreme longevity ( 100 yrs or more if healthy)
50
Neurons are Amitotic but?
with few exceptions (hippocampus: involved with memory and recall)
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Neuron high metabolic rate why?
High metabolic rate—requires continuous supply of oxygen and glucose
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All neurons have this?
All have a cell body and one or more processes
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Biosynthetic center of neuron does what?
Synthesizes proteins, membranes, and other chems
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Biosynthetic center of neuron has what?
```
Rough ER (chromatophillic substance or nissel bodie)
Most active and best developed in body
```
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Neuron cell body has?
Biosynthetic center of neuron
Spherical nucleus with nucleolus
Some contain pigments
In most, plasma membrane part of receptive region
Most neuron cell bodies in CNS
Nuclei – clusters of neuron cell bodies in CNS
Ganglia – lie along nerves in PNS (ganglion)
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Ganglia –
lie along nerves in PNS (ganglion
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Nuclei –
clusters of neuron cell bodies in CNS
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Nucleolus develops what?
ribosomes
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Chromatophilc-
stains easily
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Neuron Processes
Armlike processes extend from body
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Neuron Processes in CNS
Both neuron cell bodies and their processes
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Neuron Processes PNS
Chiefly neuron processes
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Tracts
Bundles of neuron processes in CNS
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Nerves
Bundles of neuron processes in PNS
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Two types of neuron processes
Dendrites (afferent**)
| Axon (efferent**)
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Dendrites In motor neurons how many?
100s of short, tapering, diffusely branched processes
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Receptive (input) region of neuron
Large surface area for information collection
Synapses with other neurons (bring info to dend)
Convey incoming messages toward cell body as graded potentials (short distance signals)
In many brain areas fine dendrites specialized
Collect information with dendritic spines
Appendages with bulbous or spiky ends
Dendrites
68
Receive info from sensory receptors or other neurons
Processes allow large surface cuz a lot of info
Graded potential = ap but shorte distance r, ap goes a meter about
Slightly mylienated, no schwann cells
Specialized due to information goes to specific motor movement ex) vision different from moving arm or leg
Dendrites
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Describe Axon Structure
One axon per cell arising from axon hillock
Cone-shaped area of cell body
In some neurons, the axon is short or absent (no msg)
In others, encompasses most of the length of neuron
Some 1 meter long
Long axons called nerve fibers
Occasional branches (axon collaterals)
Branches profusely at end (terminus)
Can be 10,000 terminal branches
Distal endings called axon terminals or terminal boutons
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Long axons are called ?
nerve fibers
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axon collaterals
Occasional branches
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Branches profusely at end
terminus
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distal endings are called what?
axon terminals or terminal boutons
| more common is axon terminals
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Axon absent are during
depol for other cells
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Nerve fibers are collections
of axons
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axon functional characteristics
Conducting region of neuron
Generates nerve impulses
Transmits them along axolemma (neuron cell membrane) to axon terminal
Secretory region (not where they are produced)
Neurotransmitters released into extracellular space
Either excite or inhibit neurons with which axons in close contact
Carries on many conversations with different neurons at same time (through electrical gradients)
Lacks rough ER and Golgi apparatus (don’t create protein)
Relies on cell body to renew proteins and membranes
Efficient transport mechisms for proteins and memrbanes
Quickly decay if cut or damaged (take a long time to regenerate)
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What is the conducting region of the neuron?
axon
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What part of neuron generates nerve impulses?
axon
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What part of neuron transmits nerve impulses along the axolemma (neuron cell membrane) to axon terminal?
axon
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What part of neuron is the secretory region of nerve impulses?
axon
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Neurotransmitters released into extracellular space
| and cause?
Either excite or inhibit neurons with which axons in close contact
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What carries on many conversations with different neurons at same time (through electrical gradients)?
axon
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What Lacks rough ER and Golgi apparatus (don’t create protein)?
axon
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What Relies on cell body to renew proteins and membranes
axon
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What Efficient transport mechisms for proteins and memrbanes?
axon
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What will Quickly decay if cut or damaged (take a long time to regenerate)?
axon
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Axons conduct info
away from the body
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The myelin sheath is comprised of
mylein
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Mylein
Whitish, protein-lipoid substance
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Segmented sheath around most long or large-diameter axons
Dendrites are always non-myelinated (they have shwann cells)
Myelinated fibers
Function of myelin
Protects and electrically insulates axon
Increases speed of nerve impulse transmission
Nonmyelinated fibers conduct impulses more slowly
Mylein sheath
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What is a Segmented sheath around most long or large-diameter axons?
mylein sheath
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Dendrites are always non-myelinated or myelinated?
Dendrites are always non-myelinated (they have shwann cells)
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2 functions of mylein
Protects and electrically insulates axon
| Increases speed of nerve impulse transmission
94
What fiber conducts nerve impulses more slowly?
nonmyleninated fibers
95
mylein sheath is similar to what in your afsc?
welding coat on electrode that insulates the weld
| jumps arc
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Myelination in the PNS
Formed by schwann cells
Wrap around axon in jelly roll fashion
One cell forms one segment of myelin sheath
Myelin sheath
Concentric layers of schwann cell plasma membrane around axon
Outer collar of perinuclear cytoplasm (formerly called neurilemma)
Peripheral bulge of schwann cell containing nucleus and most of cytoplasm
97
How is myelination formed in PNS?
Formed by schwann cells
Wrap around axon in jelly roll fashion
One cell forms one segment of myelin sheath
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What makes up myelin sheath in PNS?
Concentric layers of schwann cell plasma membrane around axon
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Outer collar of perinuclear cytoplasm (formerly called neurilemma) is made of what?
Peripheral bulge of schwann cell containing nucleus and most of cytoplasm
100
Process of Myelination in PNS 3 steps
1.) Schwann cell develops an axon
2.) The Schwann cell then rotates
around the axon, wrapping its
plasma membrane loosely around
it in successive layers.
```
3.)The Schwann cell cytoplasm is
forced from between the membranes.
The tight membrane wrappings
surrounding the axon form the myelin
sheath.
```
101
What gets damaged in ALS?
Myelination in PNS because Schwann cells get damaged and messes everything else up
102
Plasma membranes of myelinating cells have
less protein
103
Why do Plasma membranes of myelinating cells have
| less protein?
No channels or carriers (don’t conduct electrical impulse)
Good electrical insulator
Interlocking proteins bind adjacent myelin membranes
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Nodes of ranvier
(conduction of electrical impulse across the axon)
| like arc welding
105
2 aspects of nodes of ranvier
Myelin sheath gaps between adjacent schwann cells
| Sites where axon collaterals can emerge
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Nonmyelinated fibers are
Thin fibers not wrapped in myelin; surrounded by schwann cells but no coiling; one cell may surround 15 different fibers
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Myelin Sheaths in the CNS formed by
Formed by multiple, flat processes of oligodendrocytes, not whole cells
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Myelin Sheaths in the CNS wrap how many axons at once
60 axons at once
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Are nodes of ranvier present in Myelin Sheaths in the CNS formed by
Nodes of ranvier are present
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No outer collar of perinuclear cytoplasm in Myelin Sheaths in the CNS
No outer collar of perinuclear cytoplasm
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size of fibers and covered by what in Myelin Sheaths in the CNS
Thinnest fibers are unmyelinated
| Covered by long extensions of adjacent neuroglia
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White matter
Regions of brain and spinal cord with dense collections of myelinated fibers – usually fiber tracts
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Gray matter
Mostly neuron cell bodies and nonmyelinated fibers
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Function in gray matter
processing
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What matter has role in MS and axons ?
white matter
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Sensory Neurons
Transmit impulse from sensory receptors in skin/organs twd cns (integration)
Almost all are Unipolar
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Sensory Neurons are what kind of polar?
unipolar
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Where are the sensory neuron cell bodies located?
Cell bodies in ganglia in PNS
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Motor Neurons Carry impulsess
from CNS to effectors
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Motor Neurons are what polar?
Multipolar
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Where are cell bodies of motor neurons located?
Most cell bodies in CNS (except some autonomic neurons)
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Interneurons
(association neurons)
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Where are interneurons located?
Lie btw motor and sensory neurons
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What do interneurons do? Where?
Shuttle signals through CNS pathways where integration of information occurs; most are entirely within CNS
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What are 99% of body's neurons?
interneurons
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Where are interneurons confined?
Most confined in CNS
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Neurons are highly what (membrane potential)?
irritable
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Neurons respond to what > (membrane potential)?
Respond to adequate/threshold stimulus by generating an action potential (nerve impulse) along the axon length
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What is the impulse always in neurons regardless of what?
Impulse is always the same regardless of stimulus
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what is the resting membrane potential?
Potential difference across membrane of resting cell
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Numeric value for resting membrane potential and how come?
Approximately –70 mV in neurons (cytoplasmic side of membrane negatively charged relative to outside)
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What is the actual voltage difference numeric value in resting membrane potential?
Actual voltage difference varies from -40 mV to -90 mV
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What is membrane in resting potential termed?
Membrane termed polarized
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What is the resting membrane potential generated by? 2 things
Generated by:
Differences in ionic makeup of ICF and ECF
Differential permeability of the plasma membrane
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How is that generated by Differences in ionic makeup of ICF and ECF
Differential permeability of the plasma membrane? 2 things again
Higher K concentration inside the cell with protein anions creating a negative membrane charge
Large concentration of Na+ outside the cell making the outside environment more positive
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Differences in Plasma Membrane Permeability Characteristics in Nerve cell
Impermeable large anionic proteins
Slightly permeable to Na+ (through leakage channels)
25 times more permeable to K+ than sodium (more leakage channels)
Potassium diffuses out of cell down concentration gradient
Quite permeable to Cl–
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What happens with K+ during plasma membrane resting potential in nerve cell?
More potassium diffuses out than sodium diffuses in
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What does Na+ K+ Pump do in resting membrane potential of nerve cell?
Sodium-potassium pump stabilizes resting membrane potential
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How does sodium potassium pump work in resting memb potential in nerve cell?
Maintains concentration gradients for Na+ and K+
| 3 Na+ pumped out of cell; 2 K+ pumped in
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Membrane potential changes when
Concentrations of ions across membrane change
| Membrane permeability to ions changes
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Changes produce two types signals
Graded potentials
Action potentials
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Graded potentials
Incoming signals operating over short distances
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Action potentials
Long-distance signals of axons
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What do changes in membrane potential do in nerve cells?
Changes in membrane potential used as signals to receive, integrate, and send information
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Terms of change of membrane potential are relative to what potential?
Terms describing membrane potential changes relative to resting membrane potential
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What is occurring in depolarization of nerve cell membrane?
Decrease in membrane potential (toward zero and above)
Inside of membrane becomes less negative than resting membrane potential
Increases probability of producing a nerve impulse
Either graded or action potential
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depolarization increases the probablity of what? what are they called?
Increases probability of producing a nerve impulse
| Either graded or action potential
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Hyperpolarization what occurs?
An increase in membrane potential (away from zero)
Inside of cell becomes more negative than resting membrane potential)
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Hyperpolarization reduces probablity of ?
Reduces probability of producing a nerve impulse
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Hyperpolarization is the action of what kind of drugs?
Action of anti-anxiety medicine
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Why does hyperpolarization provide the reaction that it does?
No neural stimulus, keeps you relaxed since it reduces probability of producing a nerve impulse
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How long are grade potentials and why?
Short-lived, localized changes in membrane potential
Magnitude varies with stimulus strength
Stronger stimulus more voltage changes; farther current flows
153
Graded potential is what polarization wave?
Either depolarization or hyperpolarization
154
Graded potential are triggered by what?
Triggered by stimulus that opens gated ion channels
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GRADED POTENTIAL current flows and how?
Current flows but dissipates quickly and decays
Graded potentials are signals only over short distances
Positive ions move toward negative charges, therefore the charge flows in one direction
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Why does Membrane potential decays with distance?
Because current is
lost through the “leaky” plasma membrane, the voltage declines with
distance from the stimulus (the voltage is decremental).
Consequently, graded potentials are short-distance signals.
157
What is AP?
Brief reversal of membrane potential with a change in voltage of ~100 mV
158
How are AP different from GP?
Do not decay over distance as graded potentials do
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How does depolarization activate AP?
Depolarizing local currents open voltage-gated Na+ channels
Na+ influx causes more depolarization which opens more Na+ channels ICF less negative
160
What happens at threshold for depolarizaton to activate AP?
```
At threshold (–55 to –50 mV) positive feedback causes opening of all Na+ channels a reversal of membrane polarity to +30mV
Spike of action potential
```
161
Repolarizing phase what happens?
Na+ channel slow inactivation gates close
Membrane permeability to Na+ declines to resting state
Slow voltage-gated K+ channels open
K+ exits the cell and internal negativity is restored
162
What stops increasing during repolarization
AP spike stops rising
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What happens during hyper polarization?
Some K+ channels remain open, allowing excessive K+ efflux
This causes hyperpolarization of the membrane (slight dip below resting voltage)
Na+ channels begin to reset
164
What does hyperpolzartion do resting voltage?
This causes hyperpolarization of the membrane (slight dip below resting voltage)
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What is constantly leaving during hyper polarization?
K constnaly leaving cell causes hyperpolarization
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What happens with ions in Resting state?
No ions move through voltage-gated
| channels.
167
Depolarization is caused by what ion?
Na+ flowing into the cell
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Repolarization is caused by ion?
K+ flowing
| out of the cell.
169
Hyperpolarization is
| caused by
K+ continuing to
| leave the cell.
170
What do not all depolarization events yield?
Not all depolarization events produce APs
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What does an axon need to get triggered by?
For axon to "fire", depolarization must reach thresholdThat voltage at which the AP is triggered
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What happens at threshold during depolarization?
At threshold:
Membrane has been depolarized by 15 to 20 mV
Na+ permeability increases
Na influx exceeds K+ efflux
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What cycle begins after threshold?
The positive feedback cycle begins
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What kind of phenomenon is threshold?
All-or-None phenomenon
| An AP either happens completely, or it does not happen at all
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What is ALL or none phenomenon ?
All-or-None phenomenon
| An AP either happens completely, or it does not happen at all
176
propagation
increase in numbers
| spreading
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Propagation allows
AP to serve as a signaling device
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AP is a
signaling device
179
By propagation, what happens with ions?
Na+ influx causes local currents (electrical flow)
180
how does Na+ influx causes local currents (electrical flow)?
Local currents cause depolarization of adjacent membrane areas in direction away from AP origin (toward axon's terminals)
Local currents trigger an AP there: From positive to negative, one way propagation
This causes the AP to propagate AWAY from the AP origin
181
Since Na+ channels closer to AP origin are (propagation)
inactivated no new AP is generated there
182
Once initiated an AP is what and how so?
self-propagating
In nonmyelinated axons each successive segment of membrane depolarizes, then repolarizes
Propagation in myelinated axons differs
183
Absolute refractory period is?
When voltage-gated Na+ channels open neuron cannot respond to another stimulus
184
Absolute refractory period Ensures
that each AP is an all-or-none event
185
Absolute refractory period Enforces
one-way transmission of nerve impulses
186
Conduction velocities of neurons
vary widely
187
Rate of AP propagation depends on
Axon diameter
188
Degree of myelination
Continuous conduction in unmyelinated axons is slower than saltatory conduction in myelinated axons
189
Function/ role of myelin sheath
Myelin sheaths insulate and prevent leakage of charge
190
Fasted conduction
Saltatory conduction (possible only in myelinated axons) is about 30 times faster
191
Why is saltatory conduction the fastest?
| think about arc welding
Voltage-gated Na+ channels are located at myelin sheath gaps
APs generated only at gaps
Electrical signal appears to jump rapidly from gap to gap
192
In bare plasma membranes, voltage decays.
Without voltage-gated channels, as on a dendrite,
voltage decays because current leaks across the
membrane.
193
In nonmyelinated axons, conduction is slow
| continuous conduction
Voltage-gated Na+ and K+
channels regenerate the action potential at each point
along the axon, so voltage does not decay. Conduction
is slow because it takes time for ions and for gates of
channel proteins to move, and this must occur before
voltage can be regenerated.
194
In myelinated axons, conduction is fast (saltatory
| conduction).
Myelin keeps current in axons
(voltage doesn’t decay much). APs are generated only
in the myelin sheath gaps and appear to jump rapidly
from gap to gap.
195
Group A fibers
Large diameter, thickly myelinated somatic sensory and motor fibers of skin, skeletal muscles, joints
196
Group B fibers
Intermediate diameter, lightly myelinated fibers
197
Group C fibers
Smallest diameter, unmyelinated ANS fibers
198
Why does nervous system work?
Nervous system works because information flows from neuron to neuron
199
What are Neurons functionally connected by ?
synapses
200
Synapses are what? how?
Junctions that mediate information transfer From one neuron to another neuron Or from one neuron to an effector cell
201
Presynaptic neuron role
Sends the information
202
Postsynaptic neuron location
(in PNS may be a neuron, muscle cell, or gland cell)
203
Postsynaptic neuron function
Receives the information
204
Postsynaptic neuron and Presynaptic neuron can what?
Most function as both
205
Transmission crosses what?
synaptic cleft
206
Tranmission across the synaptic cleft is what kind of event?
Chemical event (as opposed to an electrical one)
207
Synaptic cleft depends on what?
Depends on release, diffusion, and receptor binding of neurotransmitters
208
Synaptic cleft Ensures
Ensures unidirectional communication between neurons
209
AP arrives at what during transmission across chem synapsis?
axon terminal of presynaptic neuron
210
Info transfer across synaspes causes what? and how?
Causes voltage-gated Ca2+ channels to open
| Ca2+ floods into cell
211
Synaptotagmin protein binds (info transfer chem synapse)
Ca2+ and promotes fusion of synaptic vesicles with axon membrane
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What occurs after synaptotagmin protein binding during info transfer chem synapse ? and higher what ?
Exocytosis of neurotransmitter into synaptic cleft occurs
| Higher impulse frequency --> more released
213
What diffuses across synapse during info chem transfer ?
Neurotransmitter diffuses across synapse
214
Neurotransmitter does what in chem transfer in synapse? how so?
Binds to receptors on postsynaptic neuron
| Often chemically-gated ion channels
215
What are opened when there are neurotransmitter transmitted across synapse chem? What does that cause?
Ion channels are opened
Causes an excitatory or inhibitory event (graded potential)
Neurotransmitter effects terminated
216
Neurotransmitters are considered to be what of the nervous system?
Language of nervous system
217
How many neurotransmitter have been id?
50 or more neurotransmitters have been identified
218
What are neurotransmitters made up of? this exerts what?
Most neurons make two or more neurotransmitters
Neurons can exert several influences
219
When are neurotransmitters usually released?
Usually released at different stimulation frequencies
220
Neurotransmitters are classified by what?
Classified by chemical structure and by function
221
Acetylcholine
(ACh)
222
What neurotransmitter was the first identified?
ACh
223
What neurotransmitter is the best understood?
ACh
224
ACh is released by what?
Released at neuromuscular junctions ,by some ANS neurons, by some CNS neurons
225
ACh is synthesized from what?
Synthesized from acetic acid and choline by the enzyme choline acetyltransferase
226
ACh is degraded by what?
Degraded by enzyme acetylcholinesterase (AChE)
227
ACh is released by ?
Released by all neurons that stimulate skeletal muscles
228
ACh excitatory by what muscle?
Excitatory: Skeletal muscle
229
ACh inhibitory by what tissue?
Inhibitory: Cardiac tissue
230
How are neurotransmitters classified by?
chem structure
231
4 Chem structure classifications of neurotransmitters
1. ) Biogenic Amines
2. ) Amino Acids
3. ) Peptides (Neuropiptides)
4. ) Gases and Lipids (gasotransmitters)
232
Biogenic Amines 2 groups that make them up
Catecholamines
| Indolamines
233
Catecholamines consist of ...?
Dopamine, norepinephrine (NE), and epinephrine
234
Catecholamines are synthesized from?
Synthesized from the amino acid tyrosine
235
Indolamines
Serotonin and histamine
236
What is serotonin synthesized from ?
Serotonin synthesized from amino acid tryptophan;
237
What is histamine synthesized?
histamine synthesized from amino acid histidine
238
Biogenic Amines are distributed in brain how?
Broadly distributed in brain
239
Biogenic amines play a role in what?
Play roles in emotional behaviors and biological clock
240
Some ANS motor neurons release (especially NE)
Biogenic amines
241
What type of chem functional enzyme has Imbalances associated with mental illness
Biogenic amines
242
What 4 amino acids are chemical structure neurotransmitters?
Glutamate
Aspartate
Glycine
GABA—gamma ()-aminobutyric acid
243
Neuropeptides consist of what 3 ?
Substance P
Endorphins
Gut-brain peptides
244
Substance P role
Mediator of pain signals
245
Endorphins kinds
Beta endorphin, dynorphin and enkephalins
246
Endorphins act as what?
Act as natural opiates; reduce pain perception
247
Example of endorphins
Runners high
248
Gut-brain peptides types
Somatostatin and cholecystokinin
249
Examples of gasotransmitters
Nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide gases (H2S)
250
Gasotransmitters bind with what?
Bind with G protein–coupled receptors in the brain
251
gasotransmitters are what soluble?
Lipid soluble
252
Gasotransmitters are synthesized how?
Synthesized on demand
253
NO (g) gasotransmitter is involved in ?
NO involved in learning and formation of new memories; brain damage in stroke patients, smooth muscle relaxation in intestine
254
H2S acts as how?
H2S acts directly on ion channels to alter function
255
Effects of Neurotransmitter (two things)
excitatory versus inhibitory
256
Neurotransmitter effect can be what?
Neurotransmitter effects can be excitatory (depolarizing) and/or inhibitory (hyperpolarizing)
257
How is neurotransmitter effected by?
Effect determined by receptor to which it binds
258
GABA and glycine usually are what neurotransmitter effect?
inhibitory
259
Glutamate usually are what neurotransmitter effect ?
excitatory
260
How do ACh an NE work?
Acetylcholine and NE bind to at least two receptor types with opposite effects
261
ACh works how for skel muscle?
ACh excitatory at neuromuscular junctions in skeletal muscle
262
ACh functions how for cardiac muscle?
ACh inhibitory in cardiac muscle
263
How do neurons function?
Neurons function in groups
264
The neuron groups contribute to what?
Groups contribute to broader neural functions
265
Where are there billion of neurons?
There are billions of neurons in CNS
266
Why are there billions of neurons?
Must be integration so the individual parts fuse to make a smoothly operating whole
267
CNS is made up?
brain and spinal cord
268
What are the 4 adult brain regions?
1) Cerebral hemispheres
2) Diencephalon
3) Brain stem (midbrain, pons, and medulla)
4) Cerebellum
269
Brain
Similar pattern
Additional areas of gray matter in brain
Cerebral hemispheres and cerebellum
Cortex disappears in brain stem
Ventricles: 4 ventricles
270
What are ventricles of brain filled with?
Filled with cerebrospinal fluid (CSF)
271
Ventricles in brain are connected how?
Connected to one another and to central canal of spinal cord
272
Lateral ventricleS and third ventricle connected by what?
Lateral ventricles third ventricle via interventricular foramen
273
Third and and fourth ventricle are connected via?
Third ventricle fourth ventricle via cerebral aqueduct
274
Cerebral Hemispheres are what?
Surface markings
275
What are the cerebral hemispheres are surface markings identified by?
```
Elevated ridges (gyri), shallow grooves (sulci), and deep grooves (fissures)
Longitudinal fissure
```
Transverse cerebral fissure
276
What are the 5 lobes of the cerebral hemispheres?
1) Frontal
2) Parietal
3) Temporal
4) Occipital
5) Insula
277
Central sulcus of cerebral hemispheres is what ?
Separates precentral gyrus of frontal lobe and postcentral gyrus of parietal lobe
278
Parieto-occipital sulcus Separates
occipital and parietal lobes
279
Lateral sulcus outlines the?
temporal lobes
280
Insula is what?
Fifth lobe of the cerebral hemisphere, buried within the lateral sulcus
281
Three basic regions of Cerebral Hemispheres
Cerebral cortex of gray matter superficially
White matter internally (communication)
Basal nuclei deep within white matter
282
Cerebral cortex
of gray matter superficially
283
White matter
internally (communication)
284
Basal nuclei deep
within white matter
285
Thin (2–4 mm) superficial layer of gray matter
40% mass of brain
Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding
Cerebral Cortex
286
What is the Thin (2–4 mm) superficial layer of gray matter
Cerebral cortex
287
What is 40% mass of brain?
Cerebral cortex
288
What part of the region of the cerebral hemisphere is the site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding?
Cerebral cortex
289
4 General Considerations of Cerebral Cortex
1) Three types of functional areas
1. ) Motor areas
2. ) Sensory areas
3. ) Association areas
2) Each hemisphere concerned with contralateral side of body
3) Lateralization (specialization)of cortical function in hemispheres
4) Conscious behavior involves entire cortex in some way
- No functional region of the brain acts alone
290
What is the Primary Motor Cortex located?
Located in the large pyramidal cells of precentral gyri
291
In Primary Motor Cortex there are Long axons that are called
pyramidal (corticospinal) tracts of spinal cord: Voluntary motor tracts
292
Function of Primary Motor Cortex
Allows conscious control of precise, skilled, skeletal muscle movements
293
In Primary Motor Cortex, Motor homunculi -
upside-down caricatures represent contralateral motor innervation of body regions
294
Premotor cortex does what?
Helps plan movements; staging area for skilled motor activities
295
Premotor cortex controls what?
Controls learned, repetitious, or patterned motor skills (typing, musical instrument) , and Controls voluntary actions that depend on sensory feedback
296
Premotor cortex coordinates what?
Coordinates simultaneous or sequential actions
297
Broca's Area location
Present in one hemisphere (usually the left)
298
Broca's area functions
Motor speech area that directs muscles of speech production
299
Broca's area active in?
Active in planning speech and voluntary motor activities
300
Frontal Eye Field Controls
Controls voluntary eye movements
301
What are the sensory areas of the cerebral cortex?
```
Conscious awareness of sensation
Occur in parietal, insular, temporal, and occipital lobes
�Primary somatosensory cortex
Somatosensory association cortex
Visual areas
Auditory areas
�Vestibular cortex
Olfactory cortex
Gustatory cortex
Visceral sensory area�
```
302
Anterior Association Area is aka what?
Prefrontal Cortex
303
What is the most common cortical region?
(Prefrontal Cortex) Anterior Association Area
304
(Prefrontal Cortex)Anterior Association Area is involved in what?
Involved with intellect, cognition, recall, and personality
305
What contains working memory needed for abstract ideas, judgment, reasoning, persistence, and planning ?
(Prefrontal Cortex)Anterior Association Area
306
Development depends on what in Prefrontal Cortex or Anterior Association Area?
feedback from social environment
307
Posterior Association Area is what region? and size?
Large region in temporal, parietal, and occipital lobes
308
What Plays role in recognizing patterns and faces and localizing us in space?
Posterior Association Area
309
What is Involved in understanding written and spoken language (Wernicke's area)?
Posterior Association Area
310
Limbic Association Area is part of what?
Part of limbic system
311
What Involves cingulate gyrus, parahippocampal gyrus, and hippocampus?
Limbic Association Area
312
What provides emotional impact that makes scene important and helps establish memories ?
Limbic Association Area
313
In Lateralization of Cortical Function what are almost identical?
hemispheres
314
Lateralization -
division of labor between hemispheres
315
What is lateralization also called?
Also called split-brain concept
316
Cerebral dominance -
hemisphere dominant for language (left hemisphere - 90% people), mathematics, and logic
317
Left hemisphere (Lateralization of Cortical Function)
tba
318
Right hemisphere (Lateralization of Cortical Function)
tba
319
How quickly do the hemispheres communicate and how they do this?
Hemispheres communicate almost instantaneously via fiber tracts and functional integration
320
Cerebral White Matter is what?
Myelinated fibers and tracts
321
Cerebral White Matter does what?
Communication between cerebral areas, and between cortex and lower CNS
322
What 3 fibers make up Cerebral white matter?
Association fibers
Commissural fibers
Projection fibers
323
Association fibers—
horizontal; connect different parts of same hemisphere
324
Commissural fibers—
horizontal; connect gray matter of two hemispheres
325
Projection fibers—
vertical; connect hemispheres with lower brain or spinal cord
326
what makes up the Basal nuclei/ganglia?
Subcortical nuclei
- Caudate nucleus
- Putamen
- Globus pallidus
327
Caudate nucleus + putamen =
striatum
328
Putamen + globus pallidus =
lentiform nucleus
329
What is basal nuclei/ganglia associated with?
Associated with subthalamic nuclei (diencephalon) and substantia nigra (midbrain)
330
Basal nuclei 5 functions
Functions thought to be
1 Influence muscle movements
2 Role in cognition and emotion
3 Regulate intensity of slow or stereotyped movements
4 Filter out incorrect/inappropriate responses
5 Inhibit antagonistic/unnecessary movements
331
What Influence muscle movements?
Basal Nuclei
332
What part of brain has role in cognition and emotion?
Basal Nuclei
333
What Regulate intensity of slow or stereotyped movements?
Basal Nuclei
334
what Filter out incorrect/inappropriate responses?
Basal nuclei
335
What Inhibit antagonistic/unnecessary movements?
basal nuclei
336
What Three paired structures make up the Diencephalon ?
Thalamus
Hypothalamus
Epithalamus
337
What Encloses third ventricle?
Diencephalon
338
What is Gateway to cerebral cortex?
Thalamus
339
What Sorts, edits, and relays ascending input?
Thalamus
340
The Thalamus sorts, edits, and relays ascending inputs that what??
Impulses from hypothalamus for regulation of emotion and visceral function
Impulses from cerebellum and basal nuclei to help direct motor cortices
Impulses for memory or sensory integration
341
What Mediates sensation, motor activities, cortical arousal, learning, and memory?
Thalamus
342
What Controls autonomic nervous system (e.g., blood pressure, rate and force of heartbeat, digestive tract motility, respiration, pupil size, etc.)?
Hypothalamus
343
What takes a part in the Physical responses/manifestations to emotions (limbic system)?
Hypothalamus
344
Example of the hypothalamus with Physical responses/manifestations to emotions (limbic system):
Perception of pleasure, fear, and rage, and in biological rhythms and drives (sex drive)
345
What Regulates body temperature – sweating/shivering?
Hypothalamus
346
What Regulates hunger and satiety in response to nutrient blood levels or hormones?
Hypothalamus
347
What Regulates water balance and thirst?
hypothalamus
348
What is example of how the hypothalamus Regulates water balance and thirst?
ADH from pituitary to increase water concentration
349
What Regulates sleep-wake cycles?
Hypothalamus
350
Suprachiasmatic nucleus
(biological clock)
351
What Controls endocrine system?
hypothalamus
352
How does hypothalamus control endocrine sys?
Produces releasing hormones
Controls hormone secretions of anterior pituitary gland (adenohyp)
Produces posterior pituitary (neurohypophosis) hormones
353
What are posterior pit hormones?
ADH
| Oxytocin
354
What are 3 regions of the brain stem?
Midbrain
Pons
Medulla oblongata
355
How is the brain stem different to spinal cord?
Similar structure to spinal cord but contains nuclei embedded in white matter
356
what Controls automatic behaviors necessary for survival
| ?
Brain stem
357
What Contains fiber tracts connecting higher and lower neural centers?
brain stem
358
The nuclei of brain stem are associated with what?
Nuclei associated with 10 of the 12 pairs of cranial nerves
359
What separates pons and cerebellum?
Fourth ventricle seperates pons and cerebellum
360
Fibers of pons do what?
Connect higher brain centers and spinal cord
| Relay impulses between motor cortex and cerebellum
361
Origin of cranial nerves are (pons) ?
V (trigeminal), VI (abducens), and VII (facial)
362
Pons nuclei 2 things about them
Some nuclei of reticular formation
| Nuclei help maintain normal rhythm of breathing
363
Medulla oblongata Joins?
spinal cord at foramen magnum
364
Medulla oblongata forms?
Forms part of ventral wall of fourth ventricle
365
Medulla oblongata contains?
Contains choroid plexus of fourth ventricle
366
Medulla oblongata pyramids have what?
Pyramids—contains two ventral longitudinal ridges formed by pyramidal tracts
367
MEdulla oblongata Decussation of the pyramids—
crossover of corticospinal tracts
368
Inferior olivary nuclei of medulla oblongata
—relay sensory information from muscles and joints to cerebellum
369
Cranial nerves VIII, IX, X, and XII are associated with what?
medulla
370
Vestibular nuclei (pons and medulla)—
mediate responses that maintain equilibrium
371
Several nuclei (e.g., nucleus cuneatus and nucleus gracilis) does what ?
relay sensory information to the somatosensory cortex
372
Functions of Medulla oblongata
```
Autonomic reflex center
Functions overlap with hypothalamus
Hypothalamus relays instructions via medulla
Cardiovascular center
Cardiac center
```
```
Vasomotor center
Respiratory centers
Generate respiratory rhythm
Control rate and depth of breathing (with pontine centers)
Additional centers: Regulate
Vomiting
Hiccuping
Coughing
Swallowing
Sneezing
```
373
11% of brain mass is what?
Cerebellum
374
What is Dorsal to pons and medulla?
cerebellum
375
What gets Input from cortex, brain stem and sensory receptors ?
cerebellum
376
What
| Allows smooth, coordinated movements?
cerebellum
377
Cerebellar hemispheres connected by?
vermis
378
Folia (of cerevellum) —
transversely oriented gyri
379
Each hemisphere of cerebellum has what?
three lobes
380
What are 3 lobes of each hemisphere of the cerebellum called?
Anterior, posterior, and flocculonodular
381
Arbor vitae— (cerebellum)
treelike pattern of cerebellar white matter
382
Cerebellum receives impulses from what ?
cerebral cortex of intent to initiate voluntary muscle contraction
383
Cerebellum signals are from?
Signals from proprioceptors and visual and equilibrium pathways continuously "inform" cerebellum of body's position and momentum
384
Cerebellar cortex calculates what?
the best way to smoothly coordinate muscle contraction
385
Last step of cerebellum processing?
"Blueprint" of coordinated movement sent to cerebral motor cortex and brain stem nuclei
386
2 Cognitive Functions of Cerebellum�
Role in thinking, language, and emotion
May compare actual with expected output and adjust accordingly
�
387
Limbic System is what part of the brain?
Emotional or affective brain
388
What 2 are two parts of limbic system?
Amygdaloid body
Cingulate gyrus
389
Amygdaloid body—
recognizes angry or fearful facial expressions, assesses danger, and elicits fear response
390
Cingulate gyrus—
role in expressing emotions via gestures, and resolves mental conflict
391
What Puts emotional responses to odors?
| Example: skunks smell bad
Limbic system
392
Where is Most output relayed via hypothalamus?
Limbic sys
393
What interacts with prefrontal lobes?
Limbic sys
394
What does the limbic sys interacts with prefrontal lobes do?
React emotionally to things we consciously understand to be happening
Consciously aware of emotional richness in our lives
395
Hippocampus and amygdaloid body play a role in what?
play a role in memory
396
What Sends impulses to cerebral cortex to keep it conscious and alert?
Reticular activating system (RAS)
397
This Filters out repetitive, familiar, or weak stimuli (~99% of all stimuli!)
Reticular activating system (RAS)
398
What has Strong impulses reach our consciousness?
RAS
399
What is Inhibited by sleep centers, alcohol, drugs?
RAS
400
A Severe injury of what results in permanent unconsciousness (coma)?
RAS
401
What RAS motor function?
Helps control coarse limb movements
| Reticular autonomic centers regulate visceral motor functions
402
What are centers in RAS for motor function?
Vasomotor centers
Cardiac center
Respiratory centers
403
Memory
Storage and retrieval of information
404
What are the 2 stages of memory?
Short-term memory
| Long-term memory
405
Short-term memory
(STM, or working memory)—temporary holding of information; limited to seven or eight pieces of information
406
Long-term memory has
limitless capacity (LTM)
407
Brain Structures Involved in Memory
Hippocampus and surrounding temporal lobes function in consolidation and access to memory
408
ACh from basal forebrain is necessary what?
for memory formation and retrieval
409
4 protections of BRain
1. )Bone (skull)
2. )Membranes (meninges)
3. )Watery cushion (cerebrospinal fluid)
4. ) Blood brain barrier
410
Membranes (meninges) cover and protect?
CNS
| Protect blood vessels and enclose venous sinuses
411
Membranes (meninges) contain
Contain cerebrospinal fluid (CSF)
412
Membranes (meninges) form
Form partitions in skull
413
How many layers do Membranes (meninges) have and what are they called?
Dura mater
Arachnoid mater
Pia mater
414
Meningitis
Inflammation of meninges
415
Dura Mater latin words
Tough Mother
416
What is the Strongest meninx?
Dura Mater
417
Dura Matter definition
Two layers of fibrous connective tissue (around brain) separate to form dural venous sinuses
418
Middle layer with weblike extensions is what?
Arachnoid Mater
419
What is Separated from dura mater by subdural space?
Arachnoid Mater
420
What has Subarachnoid space ?
Arachnoid Mater
421
Subarachnoid space contains
contains CSF and largest blood vessels of brain
422
Arachnoid villi of Arachnoid Mater protrude into superior sagittal sinus and permit . . .?
CSF reabsorption into the venous blood
423
Pia Mater latin
Gentle mother
424
What is Pia Matter?
Delicate vascularized connective tissue that clings tightly to brain
425
CSF is Synthesized by what?
choroid plexus in epithalamus
426
CSF composition
Watery solution formed from blood plasma
| Less protein and different ion concentrations than plasma
427
CSF has a constant what?
Constant volume
428
CSF provides? ow?
Gives buoyancy to CNS structures
Reduces weight by 97%
429
CSF function/ role
Protects CNS from blow and other trauma
| Nourishes the brain and carries chemical signals
430
Blood Brain Barrier helps?
Helps maintain stable environment for brain
431
Blood brain barrier separates what?
Separates neurons from some bloodborne substances
432
Cellular make up Blood brain barrier?
Continuous endothelium of capillary walls
| Tight junctions
433
What kind of barrier does the blood brain barrier have?
selective barrier
434
The selected barrier of blood brain barrier allows what by how?
Allows nutrients to move by facilitated diffusion
435
What does Blood Brain Barrier deny?
Metabolic wastes, proteins, toxins, most drugs, small nonessential amino acids, K+ denied
436
What substances are allowed through the blood brain barrier?
Allows any fat-soluble substances to pass, including alcohol, nicotine, and anesthetics
437
WHERE IS blood brain barrier absent?
Absent in some areas, e.g., vomiting center and hypothalamus, where necessary to monitor chemical composition of blood
438
Where does spinal cord begin?
Begins at the foramen magnum (C1)
439
Where does spinal cord end?
Ends at L1 or L2 vertebra
440
2 functions of the spinal cord?
Provides two-way communication to and from brain
| Contains spinal reflex centers
441
Protection of spinal cord has what three things?
Bone, meninges, and CSF
442
Epidural space of spinal cord
Cushion of fat and network of veins in space between vertebrae and spinal dura mater
443
Where is CSF in spinal cord?
CSF in subarachnoid space
444
Dural and arachnoid membranes extend to what?
sacrum, beyond end of cord at L1 or L2
445
Where is site of lumbar puncture or tap?
sacrum, beyond end of cord at L1 or L2
446
Spinal nerves of spinal cord is part of what ?
PNS
447
Spinal nerves have how many pairs?
31
448
Cervical and lumbosacral enlargements of spinal cord
Nerves serving upper and lower limbs emerge here
449
Cauda equina of gray matter
Collection of nerve roots at inferior end of vertebral canal
450
Dorsal horns of gray matter-
interneurons that receive somatic and visceral sensory input
451
Ventral horns of gray matter
some interneurons; somatic motor neurons; axons exit cord via ventral roots
452
Lateral horns of gray matter
sympathetic neurons
| (only in thoracic and superior lumbar regions) -
453
Dorsal roots of gray matter
– sensory input to cord (afferents)
454
Dorsal root (spinal) ganglia gray matter—
cell bodies of sensory neurons
455
Motor pathways involve two neurons:
Upper motor neurons
| Lower motor neurons
456
Upper motor neurons
Pyramidal cells in primary motor cortex
457
Lower motor neurons
Ventral horn motor neurons
| Innervate skeletal muscles
458
Peripheral Nervous Sys provides what?
Provides links from and to world outside body
459
What sys is All neural structures outside brain and spinal column?
PNS
460
What does PNS All neural structures outside brain and spinal column include?
Sensory receptors
Peripheral nerves and associated ganglia
Efferent motor endings
461
What are Specialized to respond to changes in environment (stimuli)?
Sensory Receptors
462
Activation of what results in graded potentials that trigger nerve impulses?
Sensory Receptors
463
Sensation (awareness of stimulus) and perception (interpretation of meaning of stimulus) occur in brain is what neural structure?
Sensory Receptors
464
Mechanoreceptors—
respond to touch, pressure, vibration, and stretch (tissue deformation)
465
Thermoreceptors—
sensitive to changes in temperature
466
Photoreceptors—
respond to light energy (e.g., retina)
467
Chemoreceptors—
respond to chemicals (e.g., smell, taste, changes in blood chemistry)
468
Nociceptors—
sensitive to pain-causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals)
469
What are 5 sensory receptors by stimulus type?
```
Mechanoreceptors
Thermoreceptors
Photoreceptors
Chemoreceptors
Nociceptors
```
470
Exteroceptors
Receptors in skin for touch, pressure, pain, and temperature
| Most special sense organs
471
Interoceptors (visceroceptors)
Sensitive to chemical changes, tissue stretch, and temperature changes
Sometimes cause discomfort, hunger, thirst, but usually unaware of their workings
472
Proprioceptors
Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
473
3 Sensory Receptor by location?
Proprioceptors
Interoceptors (visceroceptors)
Exteroceptors
