Ch. 35 - Pt. 1 Neuron Communication

What is the change in an organism’s environment?

What is the change in an organism’s environment?

stimulus

What system is where hormones are produced and circulated to trigger chemical reactions?

endocrine system

What system is where neurons send electrical signals to target cells to trigger reactions?

nervous system

What are the two divisions of the human nervous system?

central (CNS) and peripheral nervous system (PNS)

What part of the nervous system includes the brain and spinal cord; processes sensory information and initiates appropriate responses?

central nervous system (CNS)

What part of the nervous system contains cranial nerves and spinal nerves; gathers information from sensors and transmits to CNS and conducts decisions from CNS to effectors?

peripheral nervous system (PNS)

What are the three functions of the nervous system?

• receives sensory input (PNS)

• performs integration/decision making (CNS)

• generates motor output (PNS)

What are the two cells of the nervous system?

neurons and glial cells

What is a specialized cell that can receive and transmit electrical and chemical signals?

neurons

What part of the neuron consists of short highly branched processes specialized to receive stimuli?

dendrites

What part of the neuron contains a nucleus and organelles and is the bulk of the cytoplasm?

cell body

What is the electrically sensitive structure on the cell body of a neuron that integrates signals from multiple neuronal connections?

axon hillock

What part of the neuron is a long extension from the neuron cell body that conducts electrical signals away from the cell body to another neuron or to an effector organ; transmits the neuro signal?

axon

Where does the stimulus exit after traveling down the axon?

terminal branches/axon terminal

What fatty substance is produced by glia that insulates axons?

myelin

What are the three types of neurons?

• motor neurons

• sensory neurons

• interneurons

What type of neuron accepts nerve impulses from the CNS and transmits them to muscles or glands?

motor neurons

What type of neuron accepts impulses from sensory receptors and transmits them to the CNS?

sensory neurons

What conveys nerve impulses between various parts of the CNS and receives signals from neurons and transmits signals to other neurons?

interneurons

What supports, protects, and nourishes neurons?

glial cells

What are 4 glial cells in the CNS?

• oligodendrocytes

• astrocytes

• ependymal cells

• microglia

What type of glial cell forms myelin sheath around axons in the CNS?

oligodendrocytes

What type of glial cell provides nutrients and structural support in the CNS?

astrocytes

What type of glial cell produces cerebrospinal fluid that cushions and nourishes the neurons?

ependymal cells

What type of glial cell scavenges pathogens and dead cells?

microglia

What are 2 glial cells in the PNS?

• Schwann cells

• satellite cells

What type of glial cell forms the myelin sheath around axons in the PNS?

Schwann cells

What type of glial cell provides nutrients and structural support to neurons in the PNS?

satellite cells

What is the change in the membrane potential to a less negative value?

depolarization

What four ways do neurons maintain a negative resting membrane potential?

• selective permeability of the plasma membrane

• sodium-potassium pump

• passive ion channels

• large intracellular anions

What is the difference in electrical potential between the inside and outside of a cell?

membrane potential

What is the rapid change in the membrane’s electrical potential that allows a nerve cell to transmit signals; caused by the movement of ions into and out of the cell?

action potential

What is the resting potential of the neuron?

-70mV

• At the resting potential -70mV it is __ and gets hit with the stimulus that excites the cell

• When the cell hits -55mV (__ of __) it shoots up as it is __

• When you’re done with the action potential __ __ is hit

• __ happens to get it back to -70mV

• __ happens when the membrane potential reaches below -70mV

• After resting it raises back to -70mV

• polarized

• threshold of excitation; depolarized

• peak action

• repolarization

• hyperpolarization

• At rest the membrane is at resting membrane potential and all voltage-gated channels are __

• A large stimulus will bring the neuron to threshold -55mV causing voltage-gated __ channels to __

• At +30mV voltage-gated Na+ channels close and voltage-gated __ channels __ allowing the neuron to __

• closed

• Na+; open

• K+; open; repolarize

What is a electrical signal or series of action potentials that travel rapidly down the axon to the synaptic terminus in a positive feedback loop of local events?

nerve impulse

What includes the action potential traveling down the axon by jumping from one node to the next which increases speed and efficiency; only happens when there is myelin sheaths present?

saltatory conduction

What are gaps in myelin coverage along axons?

nodes of ranvier

What includes the action potential traveling down the axon; happens when there is no myelin sheaths present?

continuous condition

What is the junction between two neurons where neuronal signals are communicated?

synapse

What is the spherical structure that contains a neurotransmitter?

synaptic vesicles

What is the space between the presynaptic and postsynaptic membranes?

synaptic cleft

• When the action potential reaches the terminal branches it enters the __ neuron

• Voltage-gated __ channels open causing calcium to enter

• Calcium triggers the __ vesicles that are loaded with neurotransmitters to leave

• Neurotransmitters diffuse into the synaptic cleft and then bind to the __

• Binding of neurotransmitters cause the channels to open causing __ in a Na+ channel OR __ in a K+ channel

• Target cell can either be __ or __

• presynaptic

• Ca2+

• synaptic

• receptors

• depolarization; hyperpolarization

• excitatory; inhibitory

What part of the post-synaptic cell includes the depolarization of a postsynaptic membrane caused by neurotransmitter molecules released from a presynaptic cell?

excitatory postsynaptic potential (EPSP)

What part of the post-synaptic cell includes the hyperpolarization of a postsynaptic membrane caused by neurotransmitter molecules released from a presynaptic cell?

inhibitory postsynaptic potential (IPSP)