Nervous System Flashcards
Which groups of living organisms have a nervous system?
Multicellular organisms
Which groups of living organisms have a nervous system?
Multicellular organisms
What can multicellular organisms with a nervous system do that those without cannot do
Orientation in space, more useful responses to the environment
What is role of neurotransmitters in the cell-to-cell communication
Transmits messages to other neurons and cells
What are some ways that the nervous and endocrine systems are similar to and different from each other
Endocrine: limited to chemical messages, slower
Nervous: chemical and electrical messages, always goes to the spinal cord or brain (central nervous system)
How does the “lock and key mechanism” we studied earlier in our enzyme unit apply to studying neurotransmitters and hormones
Neurotransmitters have specific receptors for hormones too
How might the same “lock and key mechanism” also apply when studying how certain drugs target specific cells in the brain
Receptors
What is the main function of the nervous system? Why do we have one?
To have a faster transmission of messages (electrical). To allow complex reactions to environment/stimulus.
Why is homeostasis crucial to the body?
To maintain life at comfortable levels
What is the myelin sheath? What is its function?
An insulation on the axon. It speeds up the movement of nerve impulses along the neuron
Steps in transmission of a nerve impulse
The nerve impulse reaches the axon tips where the neurotransmitter molecules are released. Receptors on the post-synaptic cell receive the neurotransmitter and this stimulus causes the membrane to become more permeable, the sodium floods in and the charges reverse. This continues down the axon tips until it is received by another neuron
Action potential
Nerve impulse. Reversal of polarity from a negative charge to a positive charge
How are nerve impulses inhibited? Of what advantage is this to the body?
If either negatively charged ions enter the post synaptic neuron or positively charged ions exit, action potential will be suppressed, thus inhibiting the nerve impulse. This is advantageous because there is more regulation. This is also a way to stop something (inhibit it) because it impairs the ability of the receptors.
Psychoactive drug
A drug that changes the activity of the central nervous system
Enkephalins
Drugs that block pain signals from going to the brain
How does cocaine addiction differ from heroin addiction?
Cocaine addiction occurs because it lowers the number of receptor proteins for dopamine. Heroin addiction does the opposite because more receptor proteins for enkephalins are made.
How does nicotine affect the nervous system
Nicotine mimics a neurotransmitter that controls a lot of the functions of the brain.
How does alcohol differ from other drugs in its effect on the nervous system
Alcohol is a depressant, so it decreases the activity of the nervous system.
Cocaine addiction
Cocaine attaches to dopamine receptors so more dopamine is left in the synaptic cleft, overstimulating the both neurons. This reduces the number of dopamine receptors in the post-synaptic cell.
Heroin Addiction
Heroin acts like opiates and attaches to the opiate receptors which blocks the release of inhibitory neurotransmitters and allows the release of dopamine creating a high
Why is addiction defined as a physiological response
Drugs attach to receptor proteins and block the neurotransmitters that are supposed to attach to those receptors. This overstimulates both neurons. Thus, less of the neurotransmitter receptors are produced, so the body cannot receive the proper amount of the neurotransmitter without the drug.
Neurons
Nerve cells that transmit info throughout the body
Nerve Impulses
Electrical Signals
Dendrites
Receive info from other cells
Axon
Long, membrane-covered extension of the cytoplasm that conducts nerve impulses
Axon terminals
Ends of the axon that release neurotransmitters
Myelin Sheath
A layer of insulation on the axon that allows the nerve impulse to move faster and is interrupted by node of Ranvier
nodes of Ranvier
Interruptions in the myelin sheath where the axon is exposed to surrounding fluid
Membrane Potential
Difference in electrical charge across the cell membrane (results from movement of ions in and out of the cell)
voltage-gated
ion channels that open or close based on the membrane potential
synapse
junction where a neuron meets another cell
synaptic cleft
gap between axon terminal/tip and receiving cell
presynaptic neuron
transmitting neuron
postsynaptic neuron
receiving cell
neurotransmitter
signal molecule produced by neurons, stored in vesicles and received by receptor proteins on postsynaptic cells where they either excite or inhibit the cell
chemical-gated ion channel
ion channels that open when a neurotransmitter binds to the receptor proteins on the postsynaptic cell
when positive ions go into the cell
action potential is produced (excitation)
when negative ions go into the cell or positive ions come out
action potential is suppressed (inhibition)
unused neurotransmitter
reabsorbed by presynaptic neuron or broken down by enzymes
small changes in membrane potential
affects membrane permeability to ions entering or leaving neurons
the nerve impulse causes neurotransmitters to be released by their vesicles
the neurotransmitters then bind to the receptor proteins on the post synaptic cell
drug
a chemical that alters body structure or biological functions`
addiction
physiological response caused by the use of a drug that laters the normal function of neurons and synapses
tolerance
increasing amounts of a drug is needed to reach the same feeling
