the nervous system anatomy

8. The most common central nervous system neuron, is called a/an _______________________ neuron.

multipolar, unipolar

1. Neurons communicate with other neurons and stimulate both ___________ and ______________.

muscles, glands

Voltage-gated potassium channels open at what voltage? __________ mV

+30

Since the neuron is permeable to Na+ as well as K+, the resting membrane potential is not equal to the equilibrium potential for K+, instead it is ___________ mV.

-70

Ion channels are regionally located and functionally unique. List all the areas on the neuron and the type of potential dependent on the following types of ion channels: Channels 1. Nongated 2. Chemically-gated 3. Voltage-gated Areas on the neuron Type of potential

1. Nongated- dendrites, cell body, axon- resting membrane potential 2. Chemically-gated (ligand) dendrites and cell body- synaptic potential (graded) 3. Voltage-gated- axons- action potential

Record the intracellular and extracellular concentrations of the following ions (mM/L): 1.Sodium (Na+) 2. Potassium (K+) 3.Chloride (Cl-)

1.Sodium (Na+) 15 and 150 2.Potassium (K+) 150 and 5 3. Chloride (Cl-) 10 and 125

2. Match the following parts of the neuron and their function: Dendrites Soma (cell body) Axon - conductive region; generates an action potential - input area; receives signals from other neurons - input area; main nutritional and metabolic area

2. Dendrites - input area; receives signals from other neurons Soma (cell body)- input area; main nutritional and metabolic area Axon -conductive region; generates an action potential

The presence of what ion inside the cell causes the synaptic vesicles to fuse with the membrane? ________

Ca++

What type of gated channels do these chemicals open? ________________

Chemically-gated

What structures in the cell membrane function as ion channels?

Integral proteins

Would sodium ions move into or out of the neuron through these channels? _______________

Into

What compensates for the movement (leakage) of Na+ and K+ ions? ______________

Na+ - K+ ATPase 3 Na+ in 2 K+ out

6. What support cell forms the myelin sheath? __________________ Myelin is found around which part of the neuron? ______________ The tightly wound cell membrane around the axon forms the myelin sheath and acts as ________________.

Schwann cells, axons, insulation

Place an "X" by the characteristics of voltage-gated sodium channels. ______ Always open ______ Found along the axon ______ Important for action potential ______ Opened and closed by gates ______ Found on the dendrites and cell bodies ______ Important for resting membrane potential

______ Always open ___X___ Found along the axon ______ Important for action potential ____X__ Opened and closed by gates ______ Found on the dendrites and cell bodies __X___ Important for resting membrane potential

a. The action potential changes the membrane potential from _______ mV (resting) to _______ mV and back again to the resting membrane potential. b. This results from a change in membrane permeability first to _______ then to _______ due to the opening of what type of ion channels? _____________________________________

a. -70, +30 b. Na+, K+, Voltage-gated

a. Conduction velocity along the axon is increased by what two characteristics? 1. ________________________________ 2. ________________________________ b. Conduction along a myelinated axon is called __________________________ conduction

a. 1. Increased diameter 2. Presence of myelin b. Saltatory

a. Where is the density of voltage-gated Na+ channels the greatest? __________________ b. What areas of the neuron generate signals that open these voltage-gated channels? __________________________________________ c. Opening of these channels causes the membrane to __________________ (voltage change

a. Axon hillock b. Dendrites, cell body c. Depolarize

Ion channels are selective for specific ions. What three characteristics of the ions are important for this selectivity?

a. Charge b. Size c. How much water the ion holds around it

a. Name the disease whose symptoms include loss of vision and increasing muscle weakness: __________________________ b. What does this disease destroy? ________________________________ c. How does this stop an action potential?

a. Multiple sclerosis b. Myelin sheaths of CNS axons c. Too few voltage-gated Na+ channels between the nodes of Ranvier

a. What is the name for the chemicals stored in the synaptic vesicles? ____________ b. What do these chemicals diffuse across? _________________________ c. Where do these chemicals bind to receptors? ______________________

a. Neurotransmitters b. Synaptic cleft c. Postsynaptic cell membrane

Name two channels (gated or nongated) through which chloride ions could pass into the cell through

a. Passive chloride b. Chemically-gated (GABA)

Name two ways these chemicals can be removed from the synaptic cleft. a. b. c.

a. Pumped back into presynaptic terminals b. Broken down by enzymes c. Diffusion

Acetylcholine (ACh) and GABA are neurotransmitters that open chemically-gated channels. What ions pass into the cell when these channels are activated? a. ACh: ________________________ ions b. GABA: ________________________ ions

a. Sodium b. Chloride

a. If the membrane reaches the trigger point, known as __________________, what electrical potential will be generated? __________________________________________ b. During the depolarization phase, voltage-gated __________ channels open and _______ enters the cell.

a. Threshold, Action potential b. Na+, Na+

a. The Japanese puffer fish contains a deadly toxin (tetrodotoxin). What type of channels does this toxin block? _______________________________ b. What potential would this toxin block? ___________________________ c. What specifically would cause death? ____________________________

a. Voltage-gated sodium b. Action c. Respiratory failure

Neurons can excite or inhibit another neuron. Exciting another neuron will increase the chances of a/an ___________________ in the second neuron. Inhibiting another neuron will make the chances of a/an __________________ less likely.

action potential, action potential

Axons from one neuron can synapse with the dendrites or soma of another axon. These synapses are called ______________________ (on dendrites) and _________________________ (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 ________________________, and they regulate the amount of ________________________ released by the other neuron.

axodendritic, axosomatic, axoaxonic, chemical transmitter (neurotransmitter)

4. The area where the axon emerges from the soma is called the ____________ ___________. This is also the area where the outgoing signal, called a/an _____________ _____________ is generated.

axon hillock, action potential

5. An axon can branch, forming axon ______________. At the end, axons branch to form many axon _________________.

collaterals, terminals

The electrical synapse: Electrical current flows from one neuron to another through _________________. These synapses are always (excitatory or inhibitory). Advantages of the electrical synapses: 1. _______ signal conduction 2. _____________ activity for a group of neurons

gap junctions, excitatory 1. Fast 2. Synchronized

The autonomic nervous system (ANS) consists 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 _________, while signals from the PNS cause the heart rate to ___________. Signals from the SNS cause smooth muscles of the intestine to _________ contractions, while signals from the PNS cause these muscles to _________ contractions. Signals from the SNS also cause the adrenal gland to _________ epinephrine and norepinephrine.

increase, decrease, decrease, increase, secrete

The chemical synapse: Chemical synapses are not as fast as electrical but are the most common type of synapse. A chemical, called a ______________________, is released from the sending neuron and travels across the ___________________(a gap between the neurons) to the receiving neuron. Advantages of the chemical synapse: 1. The signal can be either ____________ or ____________. 2. The signal can be ______________ as it passes from one neuron to the next.

neurotransmitter, synaptic cleft 1. excitatory, inhibitory 2. modified

7. The gaps between the Schwann cells, called the __________________________, are essential for the conduction of the action potential.

nodes of Ranvier

Channels can be classified as either gated or nongated channels. A sodium channel that is always open would be classified as a/an __________channel.

nongated

9. Neurons have (only one or many) axon/axons. Axons are (never or frequently) branched. Dendrites have (only one or many) branch/branches.

only one, frequently, many

The neuron conducting the impulse toward the synapse is called the __________________ neuron. The axon terminal contains ___________ ____________ filled with ______________________. An action potential in the axon terminal of the _____________neuron causes the chemical transmitter ____________________ to be released. It diffuses across the synaptic cleft and binds to receptors on the ________________ membrane. These receptors open __________________. The movement of the charged particles causes an electrical signal called a _______________________.

presynaptic, synaptic vesicles, neurotransmitter, presynaptic, neurotransmitter, postsynaptic, ion channels, synaptic or graded potential

The somatic nervous system stimulates ____________ muscle. The autonomic nervous system stimulates ___________ muscle, ____________ muscle, and ___________.

skeletal, cardiac, smooth, glands

3. Signals from other neurons are received at junctions called ________________, located primarily on the ________________ and __________________, the receptive and integrative region of the neuron.

synapses, dendrites, soma

What channels in the presynaptic neuron open up in response to an action potential? ________________________

voltage-gated Ca++