Chapter 12 Flashcards
What is the study of the nervous system?
Neurobiology
What are the 3 steps of the nervous system carrying out a task?
Receive info and send this to the CNS, process info and determine a response, send instructions for response to effectors
2 major anatomical divisions of nervous system?
Central and peripheral
Divisions of PNS?
Afferent and efferent (sensory and motor)
Divisions of efferent/motor division?
Somatic and visceral
Divisions of visceral motor division?
Sympathetic and parasympathetic
Another name for the visceral division of the efferent/motor division of the PNS?
Autonomic nervous system/ANS
What is an effector?
A muscle or gland that carries out a response
Components of central nervous system?
Brain and spinal cord
3 fundamental properties of all nerve cells?
Excitability, conductivity, and secretion
3 general classes of neurons?
Sensory/afferent, interneurons, and motor/efferent
What do sensory neurons do?
Detect light, heat, pressure, chemicals, etc. And transmit this info to the CNS
What do interneurons do?
Receive signals from other neurons and process, and store or retrieve info. Determines how out body responds to stimuli.
What do motor neurons do?
Send signals to muscle and gland cells
Main components of a neuron?
Dendrites, soma, axon, and axon terminals
Components of the soma?
Nucleus, neurofibrils, neuroplasm, nissl bodies (rough ER and ribosomes), mitochondria, dendritic branches, golgi apparatus
Components of an axon?
Axon hillock, initial segment, axoplasm, axolemma (membrane), collaterals, varicosities (beads on axon), myelin sheath, nodes of Ranvier
What is at the end of an axon?
Terminal arborization (branches) ending in axon terminals
Shapes of neurons?
Multipolar, bipolar, unipolar, axaxonic
Axons and dendrites in a multipolar neuron?
One axon, multiple dendrites
Axons and dendrites of a bipolar neuron?
One axon, one dendrite
Axons and dendrites of a unipolar neuron?
It’s just a single process leading away from the soma
Axons and dendrites of an anaxonic neuron?
No axon, multiple dendrites. Local communication
What is anterograde transport?
Transport of materials away from the soma, down the axon
What is retrograde transport?
Transport of materials toward the soma, up the axon
What proteins do anterograde and retrograde transport use?
Anterograde: kinesin
Retrograde: dynein
Types of axonal transport?
Fast and slow
What is fast axonal transport?
Either anterograde or retrograde. Moves materials to axon or returns them to the soma and reports on conditions at the axon terminal.
What process can be exploited to bring pathogens into the nervous system?
Retrograde fast axonal transport
What is slow axonal transport?
Only anterograde. Stop-and-go. Supplies new materials for regenerating nerons
Most common type of neuron?
Multipolar
How many neuroglia are there compared to neurons?
10 neuroglia for every 1 neuron
Types of neuroglia in CNS?
Oligodendrocytes, ependymal cells, microglia, astrocytes
Neuroglia in PNS?
Schwann cells and satellite cells
What do oligodendrocytes do?
Form myelin sheaths in CNS which speed signal conduction
What do ependymal cells do?
Line cavities of brain and spinal cord, secrete and circulate cerebrospinal fluid
What do microglia do?
Wander through CNS looking for debris and damage to clean
What do astrocytes do?
A lot. Maintain blood brain barrier, form scar tissue (astrocytosis), form framework, regulate bloodflow and secrete nerve growth factors. And more
What do Schwann cells do?
Form myelin sheath in PNS, assist in regeneration of damaged fibers
What do satellite cells do?
Surround neurosomas in ganglia of PNS, providing insulation around neurosoma and regulating chemical environment of neurons
Buildup of myelin sheath?
Plasma membrane and glial cells. 20% protein, 80% lipid
How does the myelin sheath work in PNS?
The Schwann cell spirals outward up to 100 times
What is the neurilemma?
Outermost coil of myelin sheath in PNS
How does the myelin sheath work in the CNS?
Spirals inward. Anchored to multiple nerve fibers
What are nodes of Ranvier?
Gaps between segments of myelin sheath
What are internodes?
Myelin-covered segments from one gap to the next
What is the trigger zone?
The initial segment and axon hillock. Important for initiating nerve signals
What are brain tumors?
Masses of rapidly dividing cells arising from meninges, metastasis from tumors in other organs, and glial cells that are mitotically active in life
What is multiple sclerosis?
Disease of the myelin sheath where oligodendrocytes and myelin in CNS deteriorate and are replaced w/ hardened scar tissue
What is Tay-Sachs disease?
Hereditary disease in infants where there’s an accumulation of GM2 in myelin sheath, missing the enzyme to decompose
What are unmyelinated nerve fibers?
In the PNS, even unmyelinated nerve fibers can have a sheath, there’s just a gap
What affects the conduction speed of nerve fibers?
The fiber’s diameter and the presence or absence of myelin
Fastest kind of nerve fiber?
Large, myelinated
Requirements for nerve regeneration?
Neurosoma is intact, and some neurilemma remains. Only possible in PNS
What is nerve growth factor?
A protein secreted by a gland, muscle, or glial cells and picked up by axon terminals of neurons. Can indicate where damaged tissue is
What is electrophysiology?
Study of cellular mechanisms for producing electrical potential currents
What is electrical potential?
Difference in concentration of charged particles between 2 points
What is a current?
A flow of charged particles from 1 point to another
What is resting membrane potential?
Charge difference across plasma membrane. -70 mV
How are electrical currents made?
Flow of K+ and Na+ ions through gated channels in plasma membrane
3 types of channels?
Ligand-gated, voltage-gated, and mechanically-gated
What is the charge of ECF?
Negative
What is the charge of the ICF?
Positive
What is the plasma membrane most permeable to?
Potassium
What ion is inside the membrane?
K+ / potassium
What ion is outside the membrane?
Na+ / sodium
What does the sodium-potassium pump do?
Bring 3 Na+ out and 2 K+ into the cell
How much ATP does the sodium-potassium pump need?
70% of the nervous system’s requirements
What are leaks?
K+ wants to exit the cell and Na+ wants to enter bc of their concentration gradients leading them that way
What are local potentials?
Short-range change in voltage
4 characteristics of local potentials?
Graded, decremental (get weaker when they go further), reversible, and can be excitatory or inhibitory
Characteristics of action potentials?
All-or-none, nondecremental, and irreversible
What is the refractory period?
A period of resistance to stimulation
What is absolute refractory period?
No stimulus will trigger AP. Lasts while Na+ gates are open to inactivated
What is relative refractory period?
Only really strong stimulus will trigger AP. Lasts until hyperpolarization ends
What is continuous conduction?
In non-myelinated fibers, nerve signal is like a wave of dominos
What is saltatory conduction?
In myelinated fibers, signal jumps from node to node
What is a presynaptic cell?
A neuron that sends a signal
What is a postsynaptic cell?
A neuron that receives a signal
Types of presynaptic neurons?
Axodendritic, axosomatic, and axoaxonic
What are electrical synapses?
Neurons touch each other for quick transmission
What are chemical synapses?
Neurons send signals across a gap through neurotransmitters. Most common type of synapse
What are neurotransmitters?
Molecules that are released when a signal reaches a synaptic knob that binds to a receptor on another cell
Main categories of neurotransmitters?
Acetylcholine, amino acids, monoamines, neuropeptides, and purines
Types of synapses?
Excitatory cholingeric, inhibitory GABA-ergic, and excitatory adrenergic
What neurotransmitter does cholingeric use?
ACh
What neurotransmitter does GABA-ergic use?
GABA
What neurotransmitter does adrenergic use?
Norepinephrine
Slowest synapse type?
Adrenergic
How does stimulation end?
Presynaptic cell stops releasing neurotransmitter, ACh is broken down by AChE
What are neuromodulators?
Chemicals secreted by neurons that have long term effects on groups of neurons
What is summation?
Adding up postsynaptic potentials and responding to their net effect. In trigger zone
What is temporal summation?
1 synapse generates EPSPs in a compounding way
What is spatial summation?
EPSPs add up to threshold at axon hillock
What is presynaptic facilitation?
One neuron enhances effects of another
What is presynaptic inhibition?
One neuron suppresses effects of another
What is neural coding?
The way the nervous system converts information to a meaningful pattern of action potentials
What is the labeled line code?
Most important mechanism for transmitting information, nerve fiber specifically recognizes a certain stimulus type
What is recruitment?
Bringing additional neurons into play as the stimulus becomes stronger
What is a neural circuit?
Pathways among neurons
What is short-term memory?
Few seconds to a few hours
What is immediate memory?
Few seconds
What is long-term memory?
Up to a lifetime
What is explicit memory?
Events and facts you can put into words
What is implicit memory?
Reflexes or unconscious memories, like emotional or procedural memories
What is the frontal lobe responsible for?
Evaluating consequences, making judgments, forming plans
What is the parietal lobe responsible for?
Reading and speech
What is the temporal lobe responsible for?
Hearing and smell
What is the occipital lobe responsible for?
Vision
What is the cerebral cortex responsible for?
Processing info from sense organs and controlling body movement
What is the outer layer of the cerebrum?
Cerebral cortex. Gray matter
What is the inner layer of the cerebrum?
White matter
What is the limbic system responsible for?
Emotion, behavior, and memory
What does the thalamus do?
Receive information from sensory receptors and relay it to the proper region of the cerebrum
What does the hypothalamus do?
Recognize and analyze hunger, thirst, fatigue, anger, and body temperature. Coordinates nervous and endocrine systems
What does the cerebellum do?
Receive information about muscle and joint position and sensory inputs, and coordinate the actions of muscles
Regions of the brain stem?
Midbrain, pons, and medulla oblongata
What keeps the body functioning when unconscious?
Brainstem
