Intro to Neural Tissue/NS (Quiz 1) Flashcards
What are the organs of the nervous system?
-brain and spinal cord
-sensory receptors of sense organs like eyes and ears
-nerves connect NS with other systems
If a neuron does not depolarize to threshold then….
there is no AP
If a neuron does not release neurotransmitters then….
there is no continued propagation of info
Where and who a neuron communicates with determines our ___________, and controls how we process and coordinate the response
perception
What are the anatomical divisions of the nervous system?
1) CNS
2) PNS
What does the CNS consist of and what does it contain?
-consists of the spinal cord and brain
-contains neural tissue, connective tissue, and blood vessels
What are the functions of the CNS?
process and coordinate, more specifically:
-process sensory data from inside and outside of body
-coordinate motor commands and control activities of peripheral organs like skeletal muscles
-control and regulate high functions of the brain like intelligence, memory, learning, and emotion
sensory= info in
motor= info out
What makes up the PNS?
all neural tissue outside of the CNS
What is the main component of the PNS?
nerves
What are the functions of the PNS?
-deliver sensory info TO the CNS (afferent)
-carry motor commands TO peripheral tissues/systems from the CNS (efferent)
T/F: there are nerves in the brain
FALSE
What do nerves contain and what do they carry?
-contain bundles of axons (myelinated or unmyelinated) with connective tissues and blood vessels
-carry sensory info and motor commands in PNS through cranial and spinal nerves
Cranial nerves connect to….
brain (theres 12 pairs of cranial nerves)
Spinal nerves connect to….
spinal cord (theres 31 pairs and plexuses of spinal nerves)
Which axons are fast? Which are slow?
big axons= fast
smaller= slower
myelin also helps with speed
Bigger axons have more room for voltage gated sodium channels which helps with speed!
What are the characteristics of afferent neurons?
-info goes from the PNS to the CNS
-input goes to the brainstem or spinal cord
-it is sensory info about something
-info goes “in” or “to”
What are the characteristics of efferent neurons?
-info goes from CNS to PNS
-info leaves brain or spinal cord
-info goes from CNS to target tissue
-it is motor info to do something like contract or secrete
What does SAME mean (its a mnemonic)?
SA= sensory afferent
ME= motor efferent
Afferent and efferent transmission is used to describe….
bundles of axons in the PNS, known as nerves
T/F: peripheral nerves can contain axons of different classifications
true
What are the functional divisions of the afferent division of PNS?
receptors and effectors
What are receptors in regards to afferent division of PNS? What are the characteristics of receptors?
-1st part of neuron
-can detect changes or respond to stimuli
-its neurons and specialized cells or complex sensory organs like eyes and ears
What are effectors in regards to afferent division of PNS? What are the characteristics of effectors?
-they respond to efferent signals and have a response
-effectors are cells, organs, and glands
What are the efferent divisions of the PNS?
1) somatic NS (SNS)
2) autonomic NS (ANS)
Which NS controls skeletal muscle contractions, both voluntary and involuntary (reflex) muscle contractions, and is consciously aware of the contraction?
Somatic NS (SNS)
Which NS controls subconscious actions (involuntary) contractions of smooth muscle, cardiac muscle, and glandular secretions?
Autonomic NS (ANS)
Which NS divides into sympathetic and parasympathetic divisions?
Autonomic NS (ANS)
Which NS has dual innervation?
Autonomic NS (ANS has sympathetic and parasympathetic division)
The sympathetic division of the ANS has a _______________ effect
Stimulating
The parasympathetic division of the ANS has a ____________ effect
Relaxing
T/F: nervous tissue is only found in the nervous system
True
What are the cells of the NS?
Neurons and neuroglia
__________ are the basic functional units of the NS and have information processing and signaling roles
Neurons
Information transmitted throughout the body is a combination of action potentials- ___________ activity and neurotransmission via neurotransmitters- ____________ activity
electrical, chemical
What part of the neuron contains the nucleus and organelles, and is covered in dendrites?
soma/cell body
What is the name for RER in neurons?
Nissl substance (note: the function is still to make proteins, but in this case its specifically neurotransmitters)
What part of the neuron has dense/dark areas of RER and ribosomes and makes the neural tissue appear gray (gray matter)?
Nissl bodies/substance
What are dendrites? What are the characteristics?
-highly branched and have many dendritic spines
-they receive info from other neurons
-so more dendrites= more info
-they take up 80-90% of neuron SA
What are axons? What are the characteristics?
-long processes
-can be myelinated or unmyelinated
-axons carry electrical signals (APs) to target cell or next neuron
-axon structure is critical to function
What is axoplasm?
cytoplasm of axon, contains neurotubules, neurofibrils, enzymes, and organelles
What is axolemma?
-specialized cell membrane (has more channels than a regular plasma membrane)
-covers the axoplasm
T/F: APs are only sent in 1 direction, always away from the axon hillock
TRUE
Which part of the neuron decides on if there will be an AP or not?
axon hillock
What is the thickest section of the soma?
axon hillock
Which part of the neuron is where the soma becomes the axon and is attached to the initial segment?
axon hillock
Which part of the neuron is an important function for reaching threshold and the location of many voltage gated channels?
axon hillock
What is the area/junction called where a neuron communicates with another cell?
synapse
Which synaptic cell sends the message to another neuron?
presynaptic cell
Which synaptic cell receives the message from another neuron?
postsynaptic cell
What is the small gap called that separates the presynaptic membrane and the postsynaptic membrane?
synaptic cleft
T/F: APs can jump a synaptic cleft
FALSE, only the message will be sent, not the actual AP that is only generated at axon hillock
If there is a lot of receptors at the postsynaptic membrane then what is it called?
postsynaptic density
Branched axon terminals usually associate with and transmit a nerve impulse to another neuron’s cell body or soma or ___________. These are- axosomatic synapse and an axodendtritic synapse, respectively. Less frequently, an axon terminal forms a synapse with an axon terminal of another neuron, such as axoaxonic synapse functions to modulate synaptic activity in the other 2 types
dendritic spine
All 3 morphologic types of synapses (axosomatic, axodendritic, axoaxonic) have the features of all true synapses. What are the characteristics of true synapses?
-presynaptic axon terminal that releases neurotransmitters
-postsynaptic cell membrane with receptors
-synaptic cleft
Which synapse type is used as an interference mechanism?
axoaxonic synapses
Neurons at rest have a TRANSMEMBRANE potential. This means across the plasma membrane there is a charge difference. What is the normal/at rest charge?
-70mV (more neg on inside than outside of cell)
A concentration gradient of ions generates a voltage difference. This is known as….
an electrochemical gradient (the movement of ions changes the potential difference and the cell is no longer at rest)
What is the difference between Na+ and K+ at rest?
theres more Na+ on the outside and more K+ inside of neuron
What is it called once the membrane potential becomes more positive?
depolarization
What is it called when the membrane potential becomes more negative?
hyperpolarization
What is it called once the membrane potential goes back to resting state?
repolarization
A resting neuron has a transmembrane potential of -70mV. This is generated and maintained by a sodium potassium ATPase keeping sodium outside of the neuron. Opening sodium channels allows for sodium to move into the neuron causing ________________. APs are generated once a threshold across the neuron is reached. APs are the signals by which the brain receives, analyzes, and conveys info. This info is conveyed from a pre to postsynaptic neuron and neurotransmitters can open sodium channels that are excitatory, which will cause a localized ________ potential
depolarization, graded
Axon hillocks have sodium channels that open in response to voltage changes, which is where it reaches a _______ threshold and causes an AP
-60mV
At what membrane potential do sodium channels close?
-30mV
What is the second messenger used to tell vesicles to fuse to the presynaptic membrane and release neurotransmitters through exocytosis?
calcium
What are the 2 classes of neurotransmitters? What are the characteristics of each one, and what is the most common neurotransmitter for each one?
1) excitatory
-causes depolarization of postsynaptic membranes
-promotes action potentials
-most common neurotransmitter= glutamate
2) inhibitory
-causes hyperpolarization of postsynaptic membranes
-suppresses action potentials
-most common neurotransmitter= GABA
What are SSRIs?
selective serotonin reuptake inhibitor
-antidepressant used to inhibit the reuptake of serotonin
-there are reuptake pumps on presynaptic neuron and SSRIs inhibit this specific one (there are other reuptake pumps for other neurotransmitters)
What part of the neuron synthesizes and packages macromolecules?
soma
What part of the neuron is the site of most synaptic inputs?
dendrites
What part of the neuron conducts APs toward other neurons?
axon
What part of the neuron is a glial covering that speeds conduction?
myelin
What part of the neuron is where synaptic transmission occurs?
axon terminal/synaptic terminal
What is temporal summation?
one presynaptic neuron releases stimulus many times over a period of time (repeated)
What is spatial summation?
2 presynaptic neurons simultaneously sending stimuli to another neuron
What are the 3 functional classifications of neurons?
1) sensory (afferent)
2) motor (efferent)
3) interneurons (association neurons)
Sensory neurons are also known as ________ neurons
afferent (bc they go to CNS)
Motor neurons are also known as __________ neurons
efferent (bc they are leaving CNS)
Interneurons are also known as….
Association neurons within the CNS or projection neurons (usually within an ascending or descending tract)
ascending= belong to sensory pathway
descending= belong to motor pathway
Which receptors monitor internal organ systems and internal senses like taste, deep pressure, and pain?
interoceptors
Which receptors monitor external senses like touch, temp, pressure, and distance senses like sight, smell, and hearing?
exteroceptors
Which receptors monitor position and movement through joints, ligaments, tendons, and muscles?
proprioceptors
Which neurons are the “decision makers”?
interneurons
What are interneurons? Where are they located and what are their characteristics?
-mostly located in the brain, spinal cord, and autonomic ganglia
-between sensory and motor neurons
-coordination of motor activity
-involved in higher functions like memory, planning, and learning
-interneurons can have their processes confined to a single small area of the CNS or can have long axons reaching and connecting different areas like corticospinal neurons
-interneurons form 99% of our neurons and control and direct if, when, and where info goes
Sensory receptors are connected to the brain which then actively organizes __________, this can be stored as memory, elicit an emotional response or cause behavioral effects
perception
Synapses are within ______ matter. Neuronal projections and pathways determine function
gray
The _____ is divisible into gray and white matter
CNS
Gray matter is the location of the _____________________. Gray matter is where info is received or the axon begins. Gray matter is also located in the cortex of the cerebrum (on the surface) and cerebellum. This is where dorsal and ventral horns of the spinal cord and clusters of neurons called nuclei are in the rest of the CNS. Large areas of gray matter are also divided into nuclei within structures like the thalamus. Named nuclei have different functions, connections, and circuits
soma, nucleus, and dendrites
A nuclei is a cluster of neuronal cell bodies forming _____ matter in the CNS.
gray
What 4 terms mean gray matter?
-cortex
-nuclei/nucleus
-ganglia
-horns
What is white matter? What are the characteristics?
-areas of neural tissue where axons run
-as many axons have myelin around them (sheath) this gives the tissue a pale appearance due to the lipids
-axons travel in bundles
The bundles within the white matter have many different names. What are they?
test q
1) columns or funiculus (same thing)
2) tracts or fasciculus (same thing)
3) lemniscus
4) fiber
5) peduncle
all these mean bundle of axons or white matter!
What are peduncles?
structural bundle of axons (white matter) that is usually found in brainstem and helps hold structures together
T/F: smaller bundles are more direct in white matter
true
T/F: axon bundles of white matter have different origins and destinations but all transmit info
false, white matter has bundle of axons that all have a common origin and destination and transmit info
What is the most simple circuit in the NS?
reflex arc
define reflex
test q
-rapid automatic predictable responses to a stimulus
-somatic, autonomic, endocrine
-can involve the spinal cord (spinal reflexes) or brain (cranial reflexes)
-described by the complexity of the circuit (monosynaptic or polysynaptic)
What are the 7 components of the reflex arc?
test q- she said it’ll be a ranking question
1) stimulus
2) receptor
3) sensory neuron
4) integration center
5) motor neuron
6) effector
7) response
