A&P 1-Chapter 12 Review

Which type of neuroglial cell engulfs cellular debris, waste products, and pathogens?

Microglia

What do neurons lack that most cells contain? What does this mean for the cell?

Most neurons lack centrioles and this means it cannot divide

What do nissl bodies do in response to injury?

Nissl bodies disperse, cell increases rate of protein synthesis

What is an example of flow of materials from the synaptic knob to the cell body?

Rabies is an example of flow of materials from the synaptic knob to the cell body.

Which carries impulses faster, continuous or saltatory?

Saltatory

Information about conditions inside and outside the body is known as _____________.

Sensory data

What are the 3 functional classifications of neurons?

Sensory neurons, motor neurons, and interneurons

Which controls skeletal muscle contractions?

Somatic nervous system (SNS)

What are the two divisions of the efferent division of the PNS?

Somatic nervous system (SNS) and Autonomic nervous system (ANS) (visceral motor system)

What is facilitation?

a neuron that is brought closer to the threshold

What is the all or none principle in relation to the neuron?

a stimulus either produces a typical action potential or does not produce one at all.

Describe the electrochemical gradient on Na.

a. Extracellular - high b. Intracellular - low c. Chemical gradient drives Na+ into cell d. Extracellular Na attracted to negative charge on inner surface

Describe the electrochemical gradient on K

a. Intracellular - high b. extracellular - low c. chemical gradient tends to drive out of cell d. electrical gradient opposes this movement because K+ attracted to - on inside and repelled by + outside

What does the peripheral nervous system consist of?

a. all the neural tissue outside the CNS b. carries sensory information to the CNS and carries motor commands to peripheral tissues and systems c. nerves - bundles of axons (nerve fibers) in the PNS; carries sensory information and motor commands d. cranial nerves - nerves connected to the brain e. spinal nerves - nerves connected to the spinal cord

Describe the events at a cholinergic synapse.

a. an action potential arrives and depolarizes the synaptic knob (normal stimulus for neurotransmitter release is depolarization of synaptic knob) b. Extracellular calcium ions enter the synaptic knob, triggering exocytosis of ACh (depolarization of synaptic knob opens voltage regulated Ca gates) c. ACh binds to receptors and depolarizes the postsynaptic membrane (primary response is increased permeability to Na) Depolarization is graded, if brought to threshold, an action potential will appear in the postsynaptic neuron d. ACh is removed by AChE - effects on the postsynaptic membrane are temporary

What are the 4 structural classifications of neurons?

a. anaxonic neuron b. bipolar neuron c. Unipolar neuron d. Multipolar neuron

Propagated changes in the transmembrane potential that, once initiated, affect and entire excitable membrane are known as _____________.

action potentials

Which brings sensory information to the CNS?

afferent division

What are the two functional divisions of the peripheral nervous system?

afferent division and efferent division

Sensory neurons are also known as ____________________.

afferent nuerons

The cells active and passive mechanisms do not ensure _____________________ .

an equal distribution of charges.

What is hyperplatization?

an increase in the negativity of the resting potential form -70mV to -80mV or more

Which are small and you cannot tell the axon from the dendrites?

anaxonic neuron

What is depolarization?

any shift from the resting potential - changes in potential from -70mV to smaller negative values

What do the ciliated ones in the brain assist in?

assist in circulation of CSF (cerebrospinal fluid - surrounds brain and spinal cord, provides protective cushion and transports dissolved gases, nutrients, and wastes)

Which is star shaped?

astrocytes

Which is the most numerous neuroglia?

astrocytes

What is the cell membrane covering the axoplasm?

axolemma

What is the long process from the cell body that is capable of propagating an electrical impulse?

axon

What are efferent fibers?

axons traveling away from CNS

What is the cytoplasm of the axon?

axoplasm

What are the functions of the CNS?

b. integrates, processes, and coordinates sensory data and motor commands c. higher functions (ex. - intelligence, memory, learning and emotion) d. sensory data - information about conditions inside/outside the body (ex. Body temp) e. motor commands - control or adjust activities of peripheral organs (ex. Control skeletal muscles when you walk)

What is the initial segment?

base of the axon

When does myelination begin and end?

begins late in development and not complete until early adolescence

Which has one dendrite, one axon, and a cell body inbetween?

bipolar neuron

What are nerves?

bundles of axons (nerve fibers) in the PNS; carries sensory information and motor commands

What are the functions of the PNS?

carries sensory information to the CNS and carries motor commands to peripheral tissues and systems

Where do motor neurons carry information?

carry info from CNS to peripheral effectors

What is the soma?

cell body of neuron

What effect does the electrical gradient have on the movement of K and Na?

cell membrane is more permeable to potassium than to sodium, so potassium leaves more readily than Na enters, this equals an interior net loss of positive charge, leaving an excess of negatively charge proteins

What is a neurotransmitter and where is it released from?

chemical messengers released by the presynaptic cell affect the postsynaptic cell (communication); packaged in synaptic vesicles

Which of the above is the most common type?

chemical synapses

What is the most wide spread synapse?

cholinergic synapse

At resting potential, most gate channels are __________.

closed

What are nissl bodies?

clusters of rough endoplasmic reticulum and ribosomes - synthesize proteins

What is a ganglion?

collection of neuron cell bodies in the PNS

What are motor commands?

control or adjust activities of peripheral organs (ex. Control skeletal muscles when you walk)

What is a membrane channel responsible for?

control the movement of ions across the cell membrane

The nerves connected to the brain are called ______________.

cranial nerves

What is perikaryon?

cytoplasm of neuron

What is Wallerian degeneration?

(PNS) schwann cells form hollow cord that follows path of neuron

What is an action potential?

- electrical impulse propagated across the surface of an axon and does not diminish as it moves away from its source

Describe the steps of a nerve impulse starting from depolarization of the initial segment to exciting the next neuron.

...

What is the threshold?

...

What is synaptic delay?

0.2-0.5 msec delay between arrival of action potential at synaptic knob and the effect on the post synaptic membrane, The fewer synapses involved, the shorter the total synaptic delay and the faster the response

What are the fine processes of dendritic branches?

dendritic spines

The effect of a neurotransmitter depends on what?

depends on the properties of the receptor, not on the nature of the neurotransmitter

Which carries motor commands to muscles and glands?

efferent division

Motor neurons are also known as _________________.

efferent neurons

What are synaptic terminals?

end of telodendria, part of synapse

What are the 4 types of neuroglia in the CNS?

ependymal cells, astrocytes, oligodendrocytes, microglia

Which are the epithelial cells that line the central canal of the spinal cord and ventricles of the brain?

epithelial cells

What does the sodium exchange pump do?

exchanges 3 intracellular sodium ions for 2 extracellular potassium, as resting potential it ejects sodium ions as soon as they come in, balances the passive forces of diffusion and the resting potential remains stable

What is an afferent fiber?

extend between sensory receptor and the spinal cord or brain

What do exteroceptors monitor?

external environment

What are telodendria?

fine extensions at the end of the axon or collaterals

What is the refractory period?

from the time an action potential begins until the normal resting potential has stabilized, the membrane will not respond normally to additional depolarizing stimuli

What is an excitatory postsynaptic potential?

graded depolarization caused by the arrival of a neurotransmitter at the postsynaptic membrane

What is an inhibitory postsynaptic potential?

graded hyperpolarization of the postsynaptic membrane

Changes if the transmembrane potential that cannot spread far form the area surrounding the site of stimulation is a _____________.

graded potentials

What is a post synaptic potential?

graded potentials that develop in the postsynaptic membrane in response to a neurotransmitter

What type of matter is dominated by unmyelinated fibers?

gray matter

What is the presynaptic cell?

has the synaptic terminal and sends a message

What will K and Na do in response to the chemical gradient passive force?

high concentration of K+ inside cell, tends to moveout through open K channels (concentration or chemical gradient) ii. high concentration of Na+ outside, so tend to come in

What are the two categories of neurotransmitters and what does each cause?

i. excitatory neurotransmitters - cause depolarization and promote the generation of action potentials ii. inhibitory neurotransmitter - cause hyperpolarization and suppress the generation of action potentials

What are the functions of Astrocytes?

i. maintaining the blood-brain barrier - isolates the CNS from general circulation ii. creating a three-dimensional framework for the CNS iii. repair damaged neural tissue iv. guiding neuron development v. controlling the interstitial environment

Why is there limited regeneration in the CNS?

i. more axons likely to be involved ii. astrocytes produce scar tissue that can prevent axon growth iii. astrocytes release chemicals that block the regrowth axon

What is synaptic fatigue?

if there is not enough ACh produced, the synapse remains inactive until ACh is replenished

Why does myelination improve coordination and control?

improves coordination and control by decreasing the time between the reception of a sensation and the initiation of an appropriate response

What functional type of neuron outnumbers all others?

interneurons

The areas of axon wrapped in myelin are known as ___________.

internodes

Where are interneurons located?

located within the brain and spinal cord

What is resistance?

measure of how much membrane restricts movement

What is myelin?

membranous wrapping of insulation, increases the speed at which an action potential travels along the axon

Which type is able to migrate through neural tissue?

microglia

Which type of neuroglial cells are least numerous and smallest?

microglia

What do interoceptors monitor?

monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems, taste, deep pressure and pain

What do proprioceptors monitor?

monitor the position and movement of skeletal muscles and joints

What is axoplasmic transport?

movement of materials (neurotransmitter, enzymes, and Lysosomes) between the cell body and the synaptic knob and vice versa. Materials flow in both directions.

Which has two or more dendrites and a single axon?

multipolar neuron

Which is the most common in the CNS?

multipolar neuron

What are voluntary contractions?

muscle contractions under your conscious control (ex. Writing and walking)

What are involuntary contractions?

muscle contractions under your subconscious control (ex. Put your hand on a hot stove) - reflex

What does axon diameter do to the propagation speed?

myelin increases speed

The inner surface has an excess of _____________ charges.

negative charges

What is involved in the cytoskeleton of a neuron?

neurofilaments, neurotubules, neurofibrils

What are the supporting cells of the nervous system called?

neuroglia

The basic functional unit of the nervous system is the _______________.

neuron

The areas in between internodes of oligodendrocytes are ______________.

nodes

What produces the myelin sheath in the CNS?

oligodendrocytes

What is a synaptic vesicle?

packages of neurotransmitters that are released by the presynaptic cell

What channels are always open?

passive or leak channels

What creates a current?

positive and negative attract, if nothing separates, move together and eliminate potential difference

The cytosol contains a high concentration of ___________.

potassium ions and negatively charged proteins

What are sensory receptors?

processes of specialized sensory neurons or cells monitored by sensory neurons

What is demyelination?

progressive destruction of myelin sheaths in both PNS and CNS, leads to loss of sensation and motor control

At each step, the message is repeated and the same events take place over and over, this is known as what?

propagation

What is the postsynaptic cell?

receives a message from the presynaptic cell

What are neuromodulators and what can they do?

released at the synapse with the main neurotransmitter, can alter rate of neurotransmitter release or change postsynaptic cell response

What is an interneurons responsible for?

responsible for distribution of sensory information and the coordination of motor activity

What is repolarization?

restoring normal resting potential after depolarization

What is a synaptic knob?

round synaptic terminal structure; contains mitochondria, portions of ER and neurotransmitter filled vesicles

What regulates the environment around the neurons?

satellite cells

What are the two neuroglia of the peripheral nervous system?

satellite cells and Schwann cells

What is responsible for myelination in the PNS?

schwann cells

The membrane of a neuron or axon is _______________________. What does this mean?

selectively permeable, means ions cannot freely cross, only through membrane channels

What is a receptor?

sensory structures that detect changes in the internal environment or respond to specific stimuli

What are collaterals?

side branches of an axon; enables communication with several cells

What are opioids and what do they do?

similar effects of opium and morphine, relief of pain, inhibit release of substance P that relays pain sensation

The extracellular fluid contains a high concentration of _______________.

sodium and chlorine ions

What do somatic motor neurons innervate? Visceral motor neurons?

somatic motor neurons innervate skeletal muscles and visceral motor neurons innervate all other peripheral effectors beside skeletal muscle

Which sensory neurons monitor the outside world?

somatic sensory neurons

The nerves connected to the spinal cord are called _______________.

spinal nerves

What is a graded potential?

stimulus produces temporary, localized change in the resting potential - graded potential - decreases with distance from stimulus

What are the two division of the Autonomic Nervous system?

sympathetic division and parasympathetic division

Where do neurons connect?

synapse

What is a neuromuscular junction?

synapse between a neuron and a muscle cell

What is a neuroglandular junction?

synapse between a neuron and a secretory (gland)cell

What is an effector?

target organs that respond to motor commands and do something

What is the difference between temporal and spatial summation?

temporal summation is the addition of stimuli occurring in rapid succession. Spatial summation involves multiple synapses that are active simultaneously.

What does the central nervous system consist of?

the brain and spinal cord

What is electrochemical gradient?

the sum of the chemical and electrical forces acting on that ion across the cell membrane

What is the axon hillock?

thickened region, connects the initial segment of the axon to the cell body

Where do sensory neurons deliver information?

to the CNS

What is resting potential?

transmembrane potential of a resting cell. All neural activities begin with a change in the resting potential of a neuron

What are some other neurotransmitters?

1. Norepinephrine - ANS, excitatory, depolarizing effect 2. Dopamine - CNS, either excitatory or inhibitory 3. Serotonin - CNS, may be responsible for many cases of severe chronic depression 4. Gamma aminobutyric acid or GABA - inhibitory

What are the 3 classes of gated channels? What does each respond to?

1. chemically regulated channels - open or close when they bind specific chemicals (Ach receptors) 2. voltage regulated channels - characteristic of excitable membrane - membrane capable of generating and conducting an action potential 3. mechanically regulated channels - open or close in response to physical distortion of the membrane surface

What are the 3 ways neurotransmitters and neuromodulators work?

1. compounds that have a direct effect on membrane potential - opening or closing membrane gated channels 2. compounds that have an indirect effect on membrane potential - have second messengers 3. lipid-soluble gases that exert their effects inside the cell

How do Astrocytes control the interstitial environment?

1. regulating the concentration of sodium ions, potassium ions, and carbon dioxide 2. providing a rapid transit system for the transport of nutrients, ions, and dissolved gases between capillaries and neurons 3. controlling the volume of blood flow through capillaries 4. absorbing and recycling some neurotransmitters 5. releasing chemicals that enhance or suppress communication across synaptic terminals

What is the resting potential? (number)

70mV

What does a cholinergic synapse release?

AcH

What are the 2 major divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Which part of the nervous system is responsible for higher functions such as intelligence, memory, learning, and emotion?

Central nervous system

What is the difference between continuous and saltatory propagation?

Continuous is an unmyelinated axon. In continuous propagation, i. action potential begins at the initial segment ii. the transmembrane potential becomes positive rather than negative iii. a local current then develops as sodium ions begin moving in the cytosol and the extracellular fluid - continuous propagation iv. each time a local current develops, the action potential moves forward, not backward because the previous segment is still in absolute refractory v. in continuous propagation, an action potential appears to move across the surface of a membrane in a series of tiny steps Saltatory propigation i. continuous propagation cannot occur along a myelinated axon, because myelin increase resistance to the flow of ions across the membrane ii. ions can readily cross the membrane only at nodes iii. when an action potential appears at the initial segment of a myelinated axon, the local current skips the internodes and depolarizes the node closest to the threshold iv. jumps from node to node - saltatory propagation v. carries impulses much more rapidly than continuous propagation vi. Myelination improves coordination and control by decreasing the time between the reception of a sensation and the initiation of an appropriate response

What are the processes of the cell body that receive information from other neurons?

Dendrites

Which controls smooth muscle, cardiac muscle, and glandular activity?

Autonomic nervous system (ANS)

What is the difference between chemical and electrical synapses?

Electrical Synapses a. located in the CNS and PNS b. extremely rare c. the presynaptic and postszynaptic membranes are locked together by gap junctions d. changes in the transmembrane potential of one cell will produce local currents that affect the other cell as if the two shared a common membrane Chemical Synapses a. cells are not directly coupled b. an arriving action potential may or may not release enough neurotransmitter to bring the postsynaptic neuron to threshold c. other factors may intervene and make the postsynaptic cell more or less sensitive to arriving stimuli d. most abundant type e. neurotransmitters

Describe type A,B, and C fibers.

Type A fiber - largest axon, myelinated, 300mph, urgent news Type B fiber - smaller, myelinated, 40 mph Type C fiber - unmyelinated, 2mph

Which has an axon and dendrite that are fused and the cell body lies off to one side?

Unipolar neuron

Which is most sensory neurons of the peripheral nervous system?

unipolar neuron

Which sensory neurons monitor the inside conditions?

visceral sensory neurons

What type of matter is dominated by myelinated fibers?

white matter