Neurotransmisson Avs 3l6f2

Neurotransmission Practice 1. The extensions of the neuron that receives messages from other neurons are the Dendrites 2. The extensions of a neuron that transmit information to other neurons are the axons; some of these extensions are insulated by a layer of fatty cells called the Myelin Sheath, which help speed the neuron’s impulses. 3. Identify the major parts of the neuron diagrammed below: a. Dendrites c. Axon b. Cell body d. Myelin Sheath

4. The neural impulse, or action potential is a brief electrical charge that travels down a(n) axon 5. The fluid interior of a resting axon carries mostly (positively/negatively) charged ions, while the fluid outside has mostly 6. 7. 8. 9.

10. 11. 12. 13.

14. 15. 16. 17. 18.

(positively/negatively) charged ions. This polarization, called the resting potential occurs because the cell membrane is selectively permeable. An action potential occurs when the first part of the axon opens its gates and (positively/negatively) charged ions rush in, causing that part of the neuron to be Depolarized During the resting pause following an action potential, called the refractory period the neuron pumps (positively, negatively) charged ions outside the cell. In order to trigger a neural impulse, excittory signals minus inhibitory signals must exceed a certain intensity, called the threshold Increasing a stimulus above this level (will/will not) increase the neural impulse’s intensity. This phenomenon is called an all or - none response. The strength of a stimulus (does/does not) affect the speed of an action potential. The junction between two neurons is called a synaptic The chemical messengers that convey information across the gaps between neurons are called neurotransmitters. These chemicals unlock tiny channels on receptor sites, allowing electrically charged atoms to enter the neuron. Neurotransmitters influence neurons either by exciting or developing their readiness to fire. Excess neurotransmitters are reabsorbed to the sending neuron in a process called reuptake Among the neurotransmitters that researchers have pinpointed is dopamine which influences movement, learning, attention, and emotions and seems to play a role in schizophrenia. The neurotransmitter, serotonin, affects mood, hunger, sleep, and arousal, while norepinephrine affects alertness and arousal. Finally, GABA is an inhibitory neurotransmitter implicated in eating and sleep disorders and is enhanced by alcohol consumption. A neurotransmitter that is important in muscle contraction is ACh The poison, curare produces paralysis by blocking the activity of this neurotransmitter. Naturally occurring opiatelike neurotransmitters that are present in the brain are called endorphines When the brain is flooded with drugs such as heroin or morphine it may stop producing these neurotransmitters. Drugs that produce their effects by mimicking neurotransmitters are called agonists Drugs that block the effects of neurotransmitters by occupying their receptor sites are called antagonists. The molecular shape of some drugs prevents them from ing through the blood brain barrier by which the brain filters out unwanted chemicals. The tremors of Parkinson’s disease are due to the death of neurons that produce the neurotransmitter Dopamine People with this condition can be helped to regain control over their muscles by taking L Dopa