Nervous System
1. Neurons communicate with other neurons and stimulate both glands and muscles.
2. Match the following parts of the neuron and their function:
Dendrites input area, receives signals from other neuron conductive region; generates an action potential Soma (cell body) input area; main nutritional and metabolic area input area; receives signals from other neurons
Axon conductive region; generates an action potential
input area; main nutritional and metabolic area
3. Signals from other neurons are received at junctions called synapses, located primarily on the dendrites and cell bodies, the receptive and integrative regions of the neuron.
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4. The area where the axon emerges from the soma is called the axon hillox
This is also the area where the outgoing signal, called a/an action potential is generated.
5. An axon can branch, forming axon collaterals.
At the end, axons branch to form many axon terminals
6. What support cell type forms the myelin sheath? Schwann cells
Myelin is found around which part of the neuron? Axon
The tightly wound cell membrane around the axon forms the myelin sheath and acts as insulation.
7. The gaps between the Schwann cells, called the nodes of Ranvier are essential for the conduction of the action potential.
8. The most common central nervous system neuron, , is called a/an multipolar neuron.
9. Neurons have only one (only one or many) axon/axons.
Axons are frequently (never or frequently) branched.
Dendrites have many (only one or many) branch/branches.
Nervous System II: Anatomy Review
1. The somatic nervous system stimulates skeletal muscle.
The autonomic nervous system stimulates smooth muscle, cardiac muscle, and glands.
2. The autonomic nervous system (ANS) consists of two divisions, each innervating the effector organs. The sympathetic nervous system (SNS) generally speeds up everything except digestion. The parasympathetic nervous system (PNS) generally slows down everything but digestion.
Signals from the SNS cause the heart rate to accelerate, while signals from the PNS cause the heart rate to slow down.
Signals from the SNS cause smooth muscles of the intestine to relax contractions, while signals from the PNS cause these muscles to decrease contractions.
Signals from the SNS also cause the adrenal gland to secrete epinephrine and norepinephrine.
3. Neurons can excite or inhibit another neuron.
Exciting another neuron will increase the chances of a/an fire in the second neuron.
Inhibiting another neuron will make the chances of a/an action less likely.
4. Axons from one neuron can synapse with the dendrites or soma of another axon.
These synapses are called axodendritic (on dendrites) and axosomatic synapses (on soma). They carry input signals to the other neuron.
Axons from one neuron can synapse with the axon terminal of another neuron. These synapses are called axoaxonic and they regulate the amount of chemical transmitter released by the other neuron.
5. The electrical synapse:
Electrical current flows from one neuron to another through ions.
These synapses are always excitatory. (excitatory or inhibitory).
Advantages of the electrical synapses:
1. Fast signal conduction
2. synchronized activity for a group of neurons.
6. The chemical synapse:
Chemical synapses are not as fast as electrical but are the most common type of synapse.
A chemical, called a/an neurotransmitter, is released from the sending ? neuron and travels across the synaptic (a gap between the neurons) to the receiving neuron.
Advantages of the chemical synapse:
1. The signal can be either excitatory or inhibitory
2. The signal can be modified as it passes from one neuron to the next.
7. The neuron conducting the impulse toward the synapse is called the presynaptic neuron. The axon terminal contains membranous sacs filled with neurotransmitters.
An action potential in the axon terminal of the postsynaptic neuron causes the chemical transmitter neurotransmitter to be released. It diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane.
These receptors open ion channels. The movement of the charged particles causes an electrical signal called a/an synaptic potential.
