fitness
Option E: Neurobiology and Behavior

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E5: The Human Brain
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Note: The lower part of the Brain Stem is also called the medulla oblongata. The main parts that should be looked at on the left figure are the brain stem, cerebellum, hypothalamus and the pituitary gland. The figure on the right shows the cerebral hemispheres.

Functions of each part:
Medulla Oblongata:
-Pathway for nerve impulses going from the body to the brain
-Controls involuntary functions/homeostatic activities such as respiration, vomiting, digesting, heart beat, arousal, sleep, and swallowing.
Cerebellum:
-Works to control voluntary yet unconcious movement, such as balance, movement, and muscle tone. Cerebellum damage can cause one to be uncoordinated and have trouble staying balanced.

Hypothalamus:
-This part works to maintain homeostasis. It is responsible for many functions, such as blood pressure regulation, thirst, heart rate, behavioral functions, wakefulness, energy levels, bladder & ovarian functions, and many more. In less words, it controls as well as organizes emotions, moods and feelings.

Pituary Gland:
-Produces and secretes hormones which are then transferred throughout the body. The hormones produced are important, and perform functions such as milk production in females after chilbirth, childhood growth, maintaining muscle mass & bone mass, fat distribution in the body, maintaining blood pressure & blood glucose levels, nervous system activity, and more.

Cerebral Hemispheres:
-The brain is divided into two halves (hemispheres), the right hemisphere and the left hemisphere. The right hemisphere controls the left side of the body, and the left hemisphere controls the right side of the body. These two hemispheres are able to communicate with eachother through nerve fibers.<

Animal experiments can be used to look at brain development and brain parts in specific functions. There was one experiment done by a neurosurgeon in Moscow to test the learning growth on the brain. He took new born puppies and kittens, and made two equal groups. He had a control group, which lived in normal conditions, and the experimental group, which was placed on a turntable, mimicking a "moving" world. After a few days, he'd "sacrifice" a kitten and puppy from each group and examine their brain. He found that the animals on the turtntable had greater growth in certain parts of their brain when compared to the animals in the normal living conditions. This experiment gives us the idea that other experiments on animals can be done to give us information on the brain. There are, however ethical issues. In this case, he actually sacrificed the animals, which is not ethical at all. When conducting experiments on animals, or any living organism for that matter, the animals safety should always be taken into consideration.

Brain lesions- There are different types of brain lesions. A brain lesion is an are of injury within the brain. By knowing which type of lesion is present, one can tell the type of injury the person suffered which caused them to have the lesion. For example, a cerebral infarction. Cerebral infarction means that a cluster of brain cells have died in a person, and this is usually caused by a stroke. Other types of lesions such as dementias and arteriovenous malformations can also tell us what a person has suffered and which part of their brain was affected.

FMRI (Functional Magnetic Resonance Imaging)- This is one of the more high tech ways to actually get a "map" of the brain, with the use of a magnetic field and radio frequency pulses. Through this, one can tell what a stroke, trauma, or other type of sickness has done to parts of the patient's brain. fMRI is able to keep track of the changes occuring in the brain, which means that this type of imaging can be used to track effects of conditions mentioned above. It can work as an important "follow up" type method.

The nervous system is divided in to two subparts: Parasympathetic and sympathetic. These two systems even eachother out to a certain extent; they work to do opposite tasks. In relation to heart rate, the sympathetic nervous system increases it, while parasympathetic slows it down. The sympathetic nervous system deals more with stress, which is why during stress the heart rate is accelerated. Functions of the parasympathetic nervous system include constricting the pupil, stimulating salivation, inhibiting the heart, stimulating digestive activity, contracting the bladder, and more. The sympathetic system does tasks such as dilating the pupil, inhibiting salivation, accelerating the heart, inhibiting digestive activity, relaxing the bladder, and more. These systems are important because they direct activities that we so automatically, like breathing.</b><br>
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The iris is the area around the pupil. It can vary in color, and adjusts size, allowing more or less light to pass through the pupil. The iris has a muscle called the sphincter muscle. This muscle is what constricts the pupil in bright light, and dilates it in dull/less light.

Blood Flow- Blood poor in oxygen goes through your right atrium, then into your right ventricle. From the right ventricle, the blood goes to your lungs, where it is replenished with oxygen, and then flows through your atrium, ventricle, and then to the rest of your body.

Pupil reflex- The pupil regulates the amount of light being absorbed by the eye. The pupil either expands, or gets smaller, depending on the intensity of the light. Greater intensity would result in the pupil becoming smaller (great light intensities could potentially harm the eye). Smaller amounts of instensity would mean that it's harder for the pupil to absorb the amount of light needed, and so the pupil expands, letting more light in.

The concept of brain death refers to parts of the brain being irreversibly harmed. In other words, the damage cannot be undone, and certain brain functions are now disabled. The brain works as a control room for the rest of the body, which is why tests on other parts of the body exist to help determine is someone has suffered brain death. One of these tests has to do with the pupil reflex. When someone has brain death, it also means that the pupil relfex is now nonexistant. Their pupils will no longer adjust to the amount of light going through the eye. A doctor can shine a bright light into the eye of the patient. If the pupil constricts, the brain is still in tact, and if there is no response, it is a sign that the person is brain dead.

Peripheral nerves extend to your skin, bones, muscles, joints ans internal organs from your spinal cord. These nerves have receptors at the end which respond to different sensations, such as pain, cold, warmth, etc.. Whenever these receptors detect someting potentially harmful, the nerve fibers relay the message to your spinal cord. Neurotransmitters (chemicals) are released into the spinal cord and sent to the brain. When in the brain, the signals travel to three different regions, which each do different things. In the somatosensory cortex, the signals are identified. It then goes to the limbic system which is where the person actually has the emotional feeling of the pain, and in the frontal cortex is where the pain is assigned a meaning.

Endorphins are a different type of neurostransmitter. They also send signals from the pain to the nervous system, but they actually work to reduce our perception in pain, the way other drugs would. As said before, when one feels pain, receptors pick up on it and send the message from the spinal cord to the brain. Endorphins actually interrupt this chain of messages, causing only some of the original messages to be transferred to the brain, resulting in a decrease of feelings of pain.<br>


E1: STIMULUS AND RESPONSE
E.1.1 Stimuli: change in the enviornment (internal or external) detected by a receptor. EX: a sound or an incresase in blood sugar
Response: change in an organism due to the stimuli
Reflex: a type of response that is rapid and unconscious EX blinking

E.1.2
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E.1.3
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- The central nervous system includes the brain and the spinal cord.<br>
- The spinal cord acts independently from the brain during reflex actions.<br>
- The reflex is an automatic response to specific stimuli.<br>
- The reflex response is a fast involuntary reaction which increases the chance of an animal avoiding damage and therefore increasing chances of survival.

E.1.4: Natural selection is the mechanism of evolution and requires three things:Variation in the phenotypes, A genetic basis to this variation, A change in the environment, If the organism is evolving then we might expect to observe a change in the frequency of heritable characteristics.

Example 1: European Blackcap migration patterns

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Sylvia atricapilla, Common name: Blackcap

Phenotypic variation is in the direction of migration (behaviour).

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The original behaviour is that the Blackcap migrates SOUTH from its summer breeding grounds in Germany to over winter in Spain.

The new behaviour in some of the Blackcap population (10%) in which they migrate to in a westerly direction to the UK.The hypothesis is that this behaviour has a genetic basis and that there is an increased fitness value of migration to the west.The researcher collected the un-hatched eggs from parent birds that had visited the UK in the previous winter.The un-hatched eggs are incubated away from the parents and have no contact with parent birds.Similarly un-hatched eggs from parent birds that over wintered in Spain &nbsp;the previous winter are collected, incubated and released as before.Birds of UK parentage flew west. Birds of Spanish parentage flew south.Conclusion: The direction of migration is genetically determined and the population is diverging due to behaviour (not speciation yet).Discussion: What is the advantage of flying west to the UK? Climate change will be less severe winters in the UK due to climate change. Birds going to the UK to winter do not having to traverse the Alps in their flight path.The UK is much closer meaning that birds returning to the breeding grounds begin pair bonding much earlier. They will reproduce and pass on this heritable trait of ‘West flying’ to their offspring.The ‘West flying’ behaviour will become more common.

Example 2: Prey preference in the Garter Snake of California
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Garter Snake Image

Coastal snakes diet includes amphibians and the Banana slug, Ariolimus californicua
Inland snakes diet main component frog, leach and fish (slug is absent)

Hypothesis:The difference in diet selection is behavioural and genetically inherited. Experiment: In an experiment pregnant snakes from the two regions have been collected. Inland and Coastal animals are isolated from each other.The hatchlings are offered Banana slug food over a 10 day period

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Conclusion:Costal Garter Snake eat more Banana slugs than Inland Garter snakes. Behaviour differences are genetically based. Two populations have diverged due to a difference in behaviour (not speciation, yet).

E.3.1
Innate behavior is something embedded in a person, without any influence from the outside world. It is genetically programmed in an organism. Innate behavior is in a person’s DNA, which means that it can be mutated, recombined, or be subject to natural selection. Examples of innate behavior are taxis, kinesis, reflex, and stereotyped behavior.
Learned behavior is a type of behavior stemmed from previous experience. Because of this, behavior usually changes as a response to an organism’s experience. It is a behavior that is acquired throughout the organism’s life as a result of trial and error or through mimicry of others’ behaviors. Examples of learned behaviors are habituation, imprinting behavior, insight behavior, classical conditioning, and operant conditioning.

E.3.2
Innate Behavior in Invertebrates:
Kinesis is the simplest method by which an invertebrate finds a place to live.
Barokinesis: increased movement because of changes in pressure, ie. Carcinus crab (swims towards the water as the pressure increases)
Hygrokinesis: increased movement due to changes in humididty, ie. some species of nematoda (move away from high humididty)
Photokinesis: increased movements due to changes in light, ie flatworms (their movements depend on the light intensity)

Taxis is a complex method of movement for invertebrates.
Phototaxis: an invertebrate moving toward (positive) or away (negative) from light, ie. Jellyfish
Geotaxis: an invertebrate’s movements depend on the gravitational force (positive or negative), ie. medusa and planaria
Rheotaxis: movement according to water flow, ie. anemone

E.3.4
The process of learning helps improve the chance of survival because it is crucial. An organism must learn to adapt to its environment’s changes. If it fails to adapt to its environment, better-suited animals are the ones who will survive. This is consistent with Darwin’s theory of survival of the fittest.

E.3.5
The first model of classical conditioning was made by Ivan Pavlov. Pavlov’s experiment had 4 components: unconditioned stimulus (meat), unconditioned response, conditioned stimulus (sound of the bell), and conditioned response. Both the conditional and unconditional responses were the dog salivating.

The dog has a tool measuring its saliva placed in his mouth. Pavlov rang a bell before he gave the dog meat. Then, he gave the meat to the dog. The dog, as an instinctive response to food, salivates. He repeated this step several times. After numerous repetitions, Pavlov rang the bell but didn’t give the meat. What he found was that the dog still salivated at the sound of the bell. This meant that the dog learned this behavior through the experience of having food after hearing a bell. The dog associated food with the sound of a bell, and as a response, he salivated.

E.3.6

Inheritance plays a part on birdsong development because the birds’ need to sing is instinctual. It is an innate behavior. Their capacity and ability to sing, though, is a learned behavior.

Learning is important to the development of birdsong in young birds. In order to mate with other birds, young male birds must learn a species-specific birdsong. There are two critical periods when a bird must learn their song. One is during the nestling stage, when the bird imprints the song memory in his nervous system. The second stage is during the birds’ sexual maturity. They’ll then begin singing the song imprinted on them. Sooner or later, he’ll match the imprinted song and sing it the way it was supposed to be sung.

E.6.1 Describe the social organization of honey bee colonies and one other non-human example
The social organization of honey bee colonies relies on the Queen bee because she determines the population. The queen bee leaves the hive to mate only once and start a new colony. The queen bee stores the sperm after mating and starts to determine the population by choosing to fertilize eggs or not which can either be male of female. She can determine whether to make more of one or the other. By not fertilizing eggs, she produces haploid males that are drones (OX). By fertilizing eggs, she produces a diploid female worker (XX) with a life span of five weeks. With the female she doesn’t have to worry about them turning into queen bees because of the chemical she secretes that prevent them to turn into a queen bee. After 5 years of a life of laying 1 egg per minute, she will die and the female eggs will turn into queen bees because the chemical will not be produced anymore. Those queen bees will go out and create other new colonies.
Another social non-human organization is that of a baboon. They organize themselves through hierarchies, but exist in troops which are groups. There is a dominant male baboon which is the alpha-male, and a dominant female which is the alpha-female. The females are usually all related because, unlike the males, they stay in the troops instead of moving in and out. The female receive their positions bases on their birth, the positions of their mothers. Unlike the females, the male baboons compete for dominance within the hierarchy because the higher he is, the more access to females he receives. Grooming signifies hierarchy and reciprocal grunts and cries do too. With relationships, the members are very cooperative. A sign to mate is when the male grooms the female.


E.6.2 Outline how natural selection may act at the level of the colony in the case of social organisms.

A man by the name of Richard Dawkins called a concept “The Selfish Gene”. This concept says that it isn’t the individual, but the gene of the individual that will survive in natural selection. For the bees, the females worker bees keep the hive cool not for themselves, but for its brothers and sisters that contain its gene. For the baboons, the young help the old to fight predators not to save themselves, but to save its troops that will contain a relative of some kind because the male will leave either way. It is all about their gene prospering in the next generations.


E.6.3 Discuss the evolution of altruistic behavior using two non-human examples.

Altruistic behavior is when one puts itself at risk or pay in some way to save another, for another individual to benefit. An example of this is when ground squirrels make an alarm call to the other squirrels when it sees a predator. By doing this is puts itself in danger, but the others benefit by returning to their burrows. Another example is when a mother elephant dies; a different female elephant will suckle the baby elephant.
E.6.4 Outline two examples of how foraging behavior optimizes food intake, including bluegill fish foraging for Daphnia.

Foraging behavior means to either maximize energy or to minimize time in consumption. Bluegill can either eat small or large Daphnia, but usually eat the large ones. When they have a limited amount of food, the bluegill will eat both, but conserves energy when there is abundance in food by eating the large ones only. Another example is of sheep, but they do the opposite. They find a better way not to be eaten. Bighorn sheep will graze on land most productive to minimize time in escaping by being in unobstructed views to escape.


E.6.5 Explain how mate selection can lead to exaggerated traits.

An exaggerated trait is the male peacock’s tail feathers, and this can be explained by mate selection which is a variant on natural selection. It was realized by Darwin that being selected over other potential mates results in reproductive success. One sex competes in being the most attractive to the other sex. The most attractive characteristics will be later inherited within the offspring and will be more attractive in the next generation. The process may keep on going causing more exaggerated traits.


E.6.6 State that animals show rhythmical variations in activity.

In activity, animals show rhythmical variations.


E.6.7 Outline two examples illustrating the adaptive value of rhythmical behavior patterns.

One example is when grizzly bears hibernate during the winter. Since there is nothing to feed on in the winter, they hibernate until they can find food in the spring, they adapt to the circumstances. Another example is rabbit fish. They only spawn on a new moon to reduce the cost of energy it takes to ensure the eggs and sperm meet. This occurs in the months of April, May

E.3.1

Innate behavior is something embedded in a person, without any influence from the outside world. It is genetically programmed in an organism. Innate behavior is in a person’s DNA, which means that it can be mutated, recombined, or be subject to natural selection. Examples of innate behavior are taxis, kinesis, reflex, and stereotyped behavior.

Learned behavior is a type of behavior stemmed from previous experience. Because of this, behavior usually changes as a response to an organism’s experience. It is a behavior that is acquired throughout the organism’s life as a result of trial and error or through mimicry of others’ behaviors. Examples of learned behaviors are habituation, imprinting behavior, insight behavior, classical conditioning, and operant conditioning.


E.3.2

Innate Behavior in Invertebrates:

Kinesis is the simplest method by which an invertebrate finds a place to live.

Barokinesis: increased movement because of changes in pressure, ie. Carcinus crab (swims towards the water as the pressure increases)

Hygrokinesis: increased movement due to changes in humididty, ie. some species of nematoda (move away from high humididty)

Photokinesis: increased movements due to changes in light, ie flatworms (their movements depend on the light intensity)

Taxis is a complex method of movement for invertebrates.

Phototaxis: an invertebrate moving toward (positive) or away (negative) from light, ie. Jellyfish

Geotaxis: an invertebrate’s movements depend on the gravitational force (positive or negative), ie. medusa and planaria

Rheotaxis: movement according to water flow, ie. anemone

E.3.4

The process of learning helps improve the chance of survival because it is crucial. An organism must learn to adapt to its environment’s changes. If it fails to adapt to its environment, better-suited animals are the ones who will survive. This is consistent with Darwin’s theory of survival of the fittest.

E.3.5

The first model of classical conditioning was made by Ivan Pavlov. Pavlov’s experiment had 4 components: unconditioned stimulus (meat), unconditioned response, conditioned stimulus (sound of the bell), and conditioned response. Both the conditional and unconditional responses were the dog salivating.

The dog has a tool measuring its saliva placed in his mouth. Pavlov rang a bell before he gave the dog meat. Then, he gave the meat to the dog. The dog, as an instinctive response to food, salivates. He repeated this step several times. After numerous repetitions, Pavlov rang the bell but didn’t give the meat. What he found was that the dog still salivated at the sound of the bell. This meant that the dog learned this behavior through the experience of having food after hearing a bell. The dog associated food with the sound of a bell, and as a response, he salivated.

E.3.6

Inheritance plays a part on birdsong development because the birds’ need to sing is instinctual. It is an innate behavior. Their capacity and ability to sing, though, is a learned behavior.

Learning is important to the development of birdsong in young birds. In order to mate with other birds, young male birds must learn a species-specific birdsong. There are two critical periods when a bird must learn their song. One is during the nestling stage, when the bird imprints the song memory in his nervous system. The second stage is during the birds’ sexual maturity. They’ll then begin singing the song imprinted on them. Sooner or later, he’ll match the imprinted song and sing it the way it was supposed to be sung.



E2: Perception of Stimuli


Mechanoreceptors: physical stimuli, initiates sensory neurons when effected by: touch, pressure, sound waves, stretching and motion

Chemoreceptors: sensory nerve cells sensitive to chemical substances

Thermoreceptors: nerve ending sensitive to heat

Photoreceptors: detect light enabling perception of sight


The Human Eye






Retina

Ganglion Cell
Bipolar Neurons

Rod Cells:
  • Photo receptors in the retina of the eye
  • Function best in dim light
  • Used in peripheral vision
  • Narrower than cone cells
  • Has three parts: inner segment, outer segment, and the synaptive terminal
  • Parts connected by cilium
  • Outer segment houses discs folded inward to allow for optimum light absorption
  • Little to nothing to do with color perception
  • Inner segment houses cell organelles including the nucleus
  • Fewer in number than cone cells
  • Light absorption materials located in rear of the eye
  • More sensitive than cone cells
Cone Cells:
  • Photoreceptors in the retina of the eye
  • Function best in bright lighting
  • Fewer in number than rod cells
  • Allow for color perception as well as the perception of rapid changes in field of vision(movement)
  • Three types of cone cells to see different colors and their variations
  • Same structure as rod cells with segments, organelle location, connections, and discs (these discs are folded for more pigment differentiation)
  • Shorter than rod cells
Edge Enhancement:
  • Filter in the eye to “sharpen” images
  • Focuses on boundary between parts of an image and increases the contrast between one part and the surroundings
  • Can be fooled by optical illusions such as the Herman Grid (white grid on a black background where the areas between intersections seem grey until you focus on a single intersection where the immediate grid “turns” white)

Contralateral Processing:
  • Field of vision split into left and right
  • Left field of vision is processed by right hemisphere of the brain, and the right is processed by the left hemisphere
  • Signals sent to their respective hemispheres by ganglion cells in the retina at the rear of the eye
  • Images are not separated by eye FIELD OF VISION DOES NOT MEAN EYE






Eardrum:
  • Also known as the tympanum and the myrnix
  • Its the membrane separating the external and middle ear
  • Transports sound from the air to the middle ear via a bone (malleus)
Bones:
  • Three of them: malleus, incus, and stapes
  • Attached to tympanic membrane that converts sound waves to vibrations in the bones
  • Stapes connects to the inner ear via the oval window
Oval Window:
  • A vestibular window where the sound/vibrations arrive amplified
  • Is the gateway to the inner ear

Round Window:
  • Separated from the middle ear by its membrane
  • Its filled with a fluid that causes the sensations of hearing
Cochlea:
  • Auditory part of the inner ear
  • Sensory organ of hearing
  • Vibrating liquid (from the round window) begins the process by bending hairs in your ear thus converting sound energy to electrical energy being sent to the brain causing “hearing”


E4: Neurotransmitters and Synapses

E.4.1 – State that some presynaptic neurons excite postsynaptic transmission and others inhibit postsynaptic transmission. - buy youtube likes

Some presynaptic neurons are designed to prevent (or inhibit) excitatory neurons from binding with the receptors on the postsynaptic membrane. This is known as postsynaptic inhibition or direct inhibition. A common example of an inhibitory neurotransmitter is GABA (Gamma Amino Butyric Acid) which leads to hyperpolarization. Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. Hyperpolarization is often caused by efflux of K+ through K+ channels, or influx of Cl– through Cl– channels. Some presynaptic neurons are designed to excite postsynaptic transmissions. The excitatory neurons often lead to depolarization, an electrical state in an excitable cell whereby the inside of the cell is made less negative relative to the outside than at the resting membrane potential. Depolarization is often caused by influx of cations, e.g. Na+ through Na+ channels, or by influx of Ca2+ through Ca2+ channels. - buy facebook likes


E.4.2 – Explain how decision-making in the CNS can result from the interaction between the activities of excitatory and inhibitory presynaptic neurons at synapses.

A neuron is on the receiving end of many excitatory and inhibitory stimuli. The neuron sums up the signals. If the sum of the signals is inhibitory then the axon does not fire. If the sum of the signals is excitatory, then the axon fires. This is the interaction that takes place between the activities of the excitatory and inhibitory neurons at the synapses. The summation of the messages is the way that decisions are made by the CNS.

E.4.3 – Explain how psychoactive drugs affect the brain and personality by either increasing or decreasing postsynaptic transmission.

Psychoactive drugs affect many different parts of our brains. They cause our brains to produce a degree of chemicals differing from the normal amount. Things like dopamine are produced much more than usual, making the brain change its thoughts and personality. Our personality can be affected by the chemicals changing in the brain, making it act in a completely different way. They do this in three ways.
1) Some act as neurotransmitters and bind to receptors for that neurotransmitter in postsynaptic membranes. They block the receptor, preventing the neurotransmitter from having its usual effect.
2) Some have the same effect of a neurotransmitter, but unlike the neurotransmitter, they are not broken down when they bind to the receptors, so the effect lasts much longer.
3) Some interfere with the breakdown of neurotransmitter in synapses and prolong the effect of the neurotransmitter.

E.4.4 – List three examples of excitatory and three examples of inhibitory psychoactive drugs.

Excitatory Psychoactive Drugs:
· Nicotine
·Cocaine
· Amphetamines

Inhibitory Psychoactive Drugs:
· Benzodiazepines
· Alcohol
· Tetrahydrocannabinol (THC)

E.4.5 – Explain the effects of THC and cocaine in terms of their action at synapses in the brain.

Cocaine will bind to dopamine transporters, which causes a flood of dopamine to the brain.
THC will mimic anandamide (which is released in response to pain), which then opens the flow of dopamine, releasing it to bind to the synaptic cleft. People with higher levels of dopamine tend to engage in more risky and thrill seeking behavior. Nerve cells release dopamine to communicate with the rest of the brain. These chemicals control sleep and pleasure. This could lead to addiction, which could be more readily passed on through genetics. The addict could also become a menace to society and could possibly overdose on drugs because they constantly try to achieve a greater high.

E.4.6 – Discuss the causes of addiction, including genetic predisposition, social factors and dopamine secretion.

Physical addiction occurs when the body stops producing neurotransmitting chemicals and starts relying on outside sources to initiate responses. Dopamine is one of the naturally occurring chemicals in the body that act as pain-killers and mood enhancers. Some psychoactive drugs act directly with dopamine secretion, varying moods and physical effects. The body’s need to secret dopamine at different times, while lacking the neurotransmitter to begin the process, messes with natural working order of the CNS. If a parent has been addicted to a substance, the child could possibly become addicted more readily. Peer pressure and other social factors, such as stress, can cause addiction because the person wants to achieve a greater high during stressed time periods and so they keep upping the dosage.