The hindbrain and midbrain of mammals are similar to those of other animals.
It functions in higher mental processes.
All mammals have neocortexes, but they are not the same.
Large variation has been observed in the number of crevices and folds, which can greatly increase the surface area and parts of the cortex are also enlarged and form very complex connections with other parts of the brain.
Increased brain capacity allowed mammals and especially humans to become more proficient at higher mental activities, such as manipulating the environment, complex learning, and anticipating the future, all of which have provided tremendous evolutionary advantages.
The more recently evolved parts of the brain can be identified.
Discuss the role of various neurotransmitters in the propagation of nerve impulses.
The nervous tissue is composed of two types of cells.
The nerve cells are the functional units of the nervous system.
They receive sensory information, send it to the brain, and conduct signals from the integration center to effector structures.
Depending on their function and location, the Neurons vary in appearance.
The "tree" are short, highly branched processes that receive signals from the sensory receptors and send them to the cell body.
The portion of the neuron that conveys information is called the axis.
Nerves can be formed by bundled xes.
Nerve fibers are often called axons.
Many axons are covered by a white layer.
There are a lot ofglia in the brain.
The Greek work for "glue" is what inspired the name for the cells.
Some researchers now say that some neuroglia cells are the "supervisors" of the neurons, because they play an important role in the formation of synapses.
There are several types of neuralgia in the central nervous system.
The brain has many different types of cells, the most important of which is the Astrocyte.
Microglia help remove debris.
The myelin sheath is made from tightly spiraled neuroglia.
The myelin sheath is formed in the central nervous system.
Schwann cells produce the fluid in the PNS.
Motor neurons cause muscle fibers to contract, and therefore they are said to innervate these structures.
Nerve impulses are taken from sensory receptors to the central nervous system.
A naked Page 691 nerve ending may be enough to build the sensoryreceptor into a complex organ, such as the eye or ear.
The process that extends from the cell body to the peripheral and central nervous system is called unipolar neurons.
"between" are only found within the central nervous system.
Nerve impulses are conveyed between different parts of the central nervous system.
Some messages are sent from one side of the brain to the other, while others are sent from one side of the brain to the other.
They form pathways in the brain that lead to higher mental functions.
The 1960s saw the development of experimental techniques to test this hypothesis.
The difference between the inside and outside of the axon is referred to as the difference between the inside and outside of the axon.
The axonalmembrane has action potential.
A resting potential of -70 mV is indicated by a voltmeter.
Outside the axon there is a majority of Na+ and inside there is a majority of K+.
Depolarization occurs when Na+ gates open and Na+ moves inside the axon.
Until a potential of +35 mV is reached, depolarization continues.
When gates open, K+ moves outside the axon.
The inside of the neuron is more negative than the outside when the axon is not conducting an impulse.
There is a correlation between the existence of this polarity and the ion distribution on either side of the axonal membrane.
There is a higher concentration of Na+) outside the axon and a higher concentration of K+) inside the axon.
The pump pumps three sodium ion out of the axon and two potassium ion into the axon.
The pump works because the ion diffuses toward areas of lesser concentration, because the membrane is somewhat permeable to them.
There are always more positive ion outside of the membranes than inside, and this accounts for some of the potential recorded by the voltmeter.
Large, negatively charged proteins are found in the axon cytoplasm.
The resting potential is -70 mV inside the cell.
As the nerve impulse occurs, there is a rapid change in polarity across a portion of the axon.
There are two types of gated ion channels that allow the passage of Na+ and K+.
The action potential is an all-or-none event.
The action potential begins if the threshold is reached.
The action potential goes up from -70 mV to +35 mV as the sodium ion moves to the inside of the axon.
The sodium channels close and the potassium channels open because of this reversal.
The potential drops from +35 mV to -70 mV when the axon is removed.
The action potential takes 2 mseconds.
Researchers find it useful to plot the voltage changes over time.
In myelinated axons, the gated ion channels that produce an action potential are located in the middle of the city.
The speeds have been recorded.
This speed is considerably greater than the rate of travel in nonmyelinated axons and allows what seems to be an instantaneous response.
When an action potential has moved on, the previous section undergoes a period in which the Na+ gates are unable to open.
The action potential can't move backwards and always moves down an axon toward its terminals.
The intensity of a signal traveling down a nerve fiber is determined by how many nerve impulses are generated.
Every axon has many fine endings, each tipped by a small swelling, called an axon terminal.
Each terminal is close to the dendrite of another neuron.
An action potential can begin.
A nerve impulse can't cross a cleft.
When nerve impulses reach an axon terminal, gated channels for calcium ion are opened.
The synaptic cleft is stimulated by the sudden rise in Ca2+.
They diffuse across the cleft to the postsynaptic area.
The response of the postsynaptic neuron can be either excitation or inhibition.
Fast-acting excitatory neurotransmitters use gated ion channels.
The metabolism of the postsynaptic cell is affected by other neurotransmitters.
More than 100 substances are known or suspected to be neurotransmitters.
Different tissues can be affected by many of these.
Depending on the location, it has either an excitatory or an inhibitory effect.
They are associated with the "runner's high" of exercisers because they also produce a feeling of tranquility.
Endorphins are produced by the brain when there is physical stress and emotional stress.
A neurotransmitter is removed from a cleft after it has been released.
The neurotransmitter can be inactivate by the postsynaptic membrane.
The short existence of neurotransmitters at a synapse prevents stimulation.
Drugs that affect the nervous system interfere with or potentiate the action of neurotransmitters.
Such drugs can interfere with the removal of a neurotransmitter from a synaptic cleft, mimic the action of a neurotransmitter, or enhance or block the release of a neurotransmitter.
Depression, a common mood disorder, may have an effect on the balance of the two neurotransmitters.
Prozac and other antidepressants prevent the reuptake of both serotonin and norepinephrine.
The effects of the two neurotransmitters in the brain that are involved in the emotional state can be prolonged by blocking reuptake.
Drugs that affect neurotransmitter activity are often abused for "recreational" purposes.
A number of dangerous drugs are described in the Biological Systems feature.
A single neuron has many dendrites and the cell body, and both can have connections with many other neurons.
It's not uncommon for one thousand to 10,000 synapses per single neuron.
A neuron is receiving a lot of excitatory and inhibitory signals.
An excitatory signal can cause the neuron to become less polarized or be closer to triggering an action potential.
The neuron becomes hyperpolarized, or farther from an action potential, as a result of an inhibitory signal.
The axon will transmit a nerve impulse if a neuron receives many excitatory signals.
The excitatory signals are being canceled out by the inhbitory signals.
Drug abuse can be seen when a person takes a drug at a dose level that increases the potential for a harmful outcome.
When more and more of the drug is needed to get the same effect, withdrawal symptoms occur when the user stops taking the drug.
This is also true for newborn babies of mothers who are addicted to drugs.
Alcohol is the most socially accepted form of drug use in the United States, even though it is illegal for people under the age of 21.
According to the survey, 39% of high school students drank some amount of alcohol, and 22% drank five or more drinks in one setting.
80% of young adults drink.
According to a U.S. government study, drinking in college contributes to an estimated 1,825 student deaths, 690,000 incidents of assault, and over 95,000 cases of sexual assault or date rape each year.
coma or death can occur if the blood level of alcohol becomes too high.
Several manufacturers began selling alcoholic energy drinks.
These drinks combine high levels of alcohol with caffeine and other ingredients.
Drug interactions can be complex, but the effects of caffeine can counteract some of the effects of alcohol, so that users feel able to drink more.
Most of these products were removed from the market after the FDA began sending warning letters to the manufacturers.
In 2012 about 23% of U.S. high school students and 7% of middle school students reported using tobacco products.
Nicotine is quickly delivered throughout the body when tobacco is smoked or chewed.
A feeling of stimulation is caused by the release of epinephrine from the adrenal glands.
Depression and fatigue can cause the user to seek more nicotine.
Nicotine stimulates the central nervous system to release dopamine, a neurotransmitter that promotes a temporary sense of pleasure.
70% of people who try smoking become addicted.
Smoking is associated with serious diseases of the cardiovascular and respiratory systems.
Only a small percentage of smokers are able to quit.
The NicVAX vaccine, which stimulates the production of antibodies that prevent nicotine from entering the brain, provided no advantage over a placebo in helping people give up smoking.
There are designer drugs that are made in laboratories.
meth or crank is a powerful drug in the central nervous system.
It can be snorted or smoked as crystal meth or ice.
The main ingredients in many cold and asthma medicines are pseudoephedrine and ephedrine.
Many states have passed laws making it harder to purchase these medications.
A former meth lab site is hazardous to humans and the environment because of the number of toxic chemicals used to prepare the drug.
More than 11 million people in the United States have used meth.
The most immediate effect of taking meth is a rush of euphoria, energy, and elevated mood.
In some individuals, a state of agitation leads to violent behavior.
amphetamine psychosis can be caused by chronic use and can be characterized by paranoia, hallucinations, and erratic behavior.
MDMA, also known as ecstasy, "X", and "molly", is a drug that is similar to methamphetamine.
It can interfere with the body's temperature regulation and have many of the same side effects as other stimulants.
The effects of smoking, snorting, or injecting these highly addictive substances are anything but relaxing.
Drug side effects after an initial euphoria include high fever, hallucinations, and extreme paranoia.
Horrifying stories about users committing violent acts on themselves or others have appeared in the news.
As recently as 2010, bath salts were legal and available from head shops, convenience stores, and online with innocuous-sounding brand names.
It's difficult to predict what chemicals might be found in bath salts, but it's safe to say that abusing these drugs often doesn't turn out well.
Drugs with sedative effects are known as date rape or predatory drugs.
During surgery on animals, ketamine can be used as an anesthesia.
Any of these drugs can be given to someone without their knowledge, and they can be vulnerable to sexual assault.
A rush of well-being lasts 5 to 30 minutes.
The crash period is characterized by fatigue, depression, and lack of interest.
Crack is the street name given to cocaine that is processed to a free base form for smoking.
Approximately 8 million Americans use crack.
The brain makes less dopamine with continued use of cocaine.
The user has an intense craving for the drug.
The brain of a cocaine user becomes less active over time.
The opium poppy plant is grown from Turkey to Southeast Asia and parts of Latin America.
Opiates are drugs derived from opium.
The number of heroin users in the United States has doubled in the last few years.
Drug addiction is common.
Heroin binding to the brain's cannabinoid receptors causes it to bind to the naturally occurring neurotransmitters that kill pain and produce feelings of tranquility.
Within a few minutes after heroin is injected, snorted, or smoked, a feeling of euphoria, along with the relief of any pain, occurs.
The body's production of endorphins decreases with repeated heroin use.
Heavy users can experience convulsions and death from respiratory arrest due to the use of shared needles.
Heroin addiction can be treated with synthetic opiate compounds that block heroin's effects.
methadone-related deaths are on the rise, and it can be addictive.
Marijuana can be smoked in a cigarette called a "joint," or in pipes or other paraphernalia.
Marijuana is the most popular illegal drug in the United States, with an estimated 65 million Americans having used it.
Some states have legalized its use for medical purposes, such as treating cancer, AIDS, or glaucoma, while two states have legalized its use for recreational purposes.
It has been found that the neurotransmitter anandamide is important for short term memory processing and may be related to feelings of contentment.
Long-term marijuana use can lead to brain impairment.
There has been an increase in awareness about a synthetic drug called K2 or spice.
K2 may be 100 times stronger than THC.
A mixture of other herbal products and smoked is sprayed with the chemical.
The amount of chemicals in K2 can vary greatly because there is no regulation of how they are produced.
There have been reports of serious medical problems and deaths in K2 users.
A form of heroin would have the desired effects with no side effects.
The sale of five chemicals used to make K2 was banned.
There are many neurons in a cell body.
The dendrite and cell body of the postsynaptic neuron hold the blue and red excitatory signals.
If the signals cause the potential to rise above the threshold, an action potential will occur.