1. The Body and the Brain

2. The Nervous System  The nervous system regulates our internal functions.  The central nervous system consists of the brain and the spinal cord.  The peripheral nervous system is made up of nerve cells that send messages between the central nervous system and all the parts of the body.  Neurons - or nerve cells – run through our bodies and communicate with each other.  Neurons send and receive messages from other structures of the body, such as muscles and glands.  Each of us has over 100 billion neurons – mostly found in our brains.  Neurons look like trees.  Each neuron is made up of a cell body, a dendrite, and an axon.  The cell body looks like the top of the trunk. The cell body produces energy that fuels the activity of the cell.  The axons look like the root of a tree. They carry messages away from the center cell body.  The dendrites look like the branches of the tree. They receive information from other neurons and pass the message through the cell body.

4.  Some neurons are as small as an inch in length.  Others, like the neurons that run through our legs, can be several feet long.  Myelin is a white fatty substance that insulates and protects the axon.  The myelin casing also helps to speed up the transmission of the message.  The fibers at the end of the axon are called axon terminals.  Messages are sent from the axon terminals of one neuron to the dendrites of other neurons.  In order for the messages to be sent to each other, they must travel across the synapse – or the junction between the axon terminals of one neuron and the dendrites of another.  The coolest part about the synapse is the fact that new ones develop between neurons when we learn something new.

5.  Neurons travel in varying directions depending on the message.  For example, when you stub your toe, the sensory neurons carry information received by the senses to the central nervous system.  Motor neurons are the nerve cells that carry information from the CNS to the muscles and glands and influence their functions.  When you touch the hot stove, the sensory neurons tell the CNS that the stove is hot.  The motor neurons then travel from the CNS to tell the muscle to move the hand away from the stove.  Other motor neurons may stimulate the heart and make it beat faster because of the situation.

7.  A neurotransmitter is a chemical that is stored in sacs in the axon terminals.  There are several types of neurotransmitters.  When a person thinks about a friend, waves their hand, or yawn, neurotransmitters are involved.  Dopamine is a neurotransmitter that is involved primarily in motor behavior.  A deficiency in dopamine levels contributes to Parkinson’s Disease – which involves a loss of muscle control filled in with tremors and rigid movement.  An excess of dopamine contribute to schizophrenia.

8. The Central Nervous System  The spinal cord extends from the brain down the back, ending below the hips.  The spinal cord is a column of nerves and it is protected by the bones of the spine.  The spinal cord is also responsible for spinal reflexes.  A spinal reflex is an automatic response to something – like the hot stove/pull away situation.  Why do we blink when dust gets in our eyes? Why do some of us sneeze when we sniff pepper?

10.  The peripheral nervous system lies outside the central nervous system.  The somatic nervous system transmits sensory messages to the CNS.  The SNS allows us to experience the difference between hot and cold, pain and pleasure.  The autonomic nervous system regulates the body’s vital functions, such as heartbeat, breathing, digestion, and blood pressure.  The autonomic nervous system is interesting because is can be effected by emotion.

11.  The fight-or-flight response occurs because the sympathetic system is activated when a person is “going into action”.  This sympathetic system can disturb the ANS. Stress can cause digestion to falter, can increase and decrease the heartbeat in specific situations, and can elevate the blood pressure.  The parasympathetic system restores peace in the body.

12. ANS

14. THE BRAIN  The brain is divided into three sections: the Hindbrain, the Midbrain, and the Forebrain.  THE HINDBRAIN:  The medulla is involved in vital functions such as heart rate, blood pressure, and breathing.  The Pons is located in the front of the medulla and is involved in regulating body movement, attention, sleep, and alertness.  The cerebellum is responsible for balance and coordination. A person with an injured cerebellum might walk funny or fall over.

19.  THE MIDBRAIN:  The midbrain contains the parts of the brain that are involved in vision and hearing.  The reticular activating system is important for attention, sleep, and arousal.  Stimulation of this portion of the brai makes us alert and increases brain activity.  Some drugs, such as alcohol, reduce the activity of the RAS, which mean the alertness and reaction time will decrease.

21.  THE FOREBRAIN:  The forebrain contains four key areas.  The thalamus is a relay station for sensory stimulation.  The thalamus transmits sensory input such as pain or images captured by the eyes.  The hypothalamus (hypo – Greek prefix meaning “under”) is located under the thalamus.  The hypothalamus regulates body temperature, hunger, thirst, sexual behavior, caring for offspring, etc.  The hypothalamus is all about instinct, but humans, unlike animals, use cognitive thoughts – not just instinct.

24.  The limbic system is involved in learning and memory, emotion, hunger, sex, and aggression.  If a part of the limbic system is damaged, people can remember old memories, but cannot form new memories.  Damage can also lead people to act passively or aggressively without cause.  The cerebrum (Latin for brain) makes up 70% of the weight of the brain.  The cerebral cortex is the outer layer of the brain.  It is composed of two sides – the right and the left. Each side is called a hemisphere.  The information transmitted from one side is transmitted to the other side of the body.  The structure that connects the two hemispheres is the corpus callosum.

26. The Two Sides  The cerebral cortex is composed of two sides – or hemispheres.  Hemi – Greek for “half”  The left hemisphere controls the right side of your body.  The right hemisphere controls the left side of your body.  The corpus callosum aids in getting info from one side to the other.  For right-handed people, language originates on the left.  The language functions are usually associated with math and logic.  People who are supposedly logical are “left-brained”.  The right brain (non-language side) is more emotional, creative.  “Right-Brain” types are artistic and imaginative.  However, this “right/Left- brain” is mostly invalid and based on myth.

27. The Lobes  Each hemisphere has four parts, or lobes.  The frontal lobe is sometimes called the “executive center”  This is where we solve problems, make decisions, and store working memory.  Within the frontal lobe, Broca’s area controls facial muscles – so when people injure this area, they may speak slowly and simply.  The occipital lobe contains the primary visual area of the cortex.  When light strikes the eye, neurons in the occipital lobe fire, allowing us to see.  Damage to this lobe can cause people to recognize an object, but they could be unable to differentiate that object from a similar object.

29.  Skin sensations are felt through the parietal lobe.  Different neurons fire depending on the sensation – such as stubbing your toe, or getting stung by a bee.  The temporal lobe collects sounds picked up by the thalamus – and we hear sounds!  Association areas shape information into something meaningful, and each lobe has its own association area.

31. Let’s Review  2 parts of the nervous system –Central Nervous System –Peripheral Nervous System  3 sections of the brain –Hindbrain  Lower portion, vital functions, balance and coordination –Midbrain  Vision and hearing –Forebrain  Complex thought and emotions  4 association areas of the brain (make meaning of information, located in the cebral cortex) –Frontal, parietal, occipital, temporal

32. The Two Sides  The cerebral cortex is composed of two sides – or hemispheres.  Hemi – Greek for “half”  The left hemisphere controls the right side of your body.  The right hemisphere controls the left side of your body.  The corpus callosum aids in getting info from one side to the other.  For right-handed people, language originates on the left.  The language functions are usually associated with math and logic.  People who are supposedly logical are “left-brained”.  The right brain (non-language side) is more emotional, creative.  “Right-Brain” types are artistic and imaginative.  However, this “right/Left- brain” is mostly invalid and based on myth.

33. Right brain v. left brain  Even though there are some characteristics that are associated with each hemisphere, the corpus callosum allows the hemispheres to work together (rather than separately)  When the corpus callosum is damaged (or cut in surgery), the communication between hemispheres is altered, and that does effect some functions –If a patient holds an object in their left hand (projected to the right hemisphere, the “non- language” side, then the left brain might not be able to communicate and say what the object is  This situation demonstrates something called hemispheric specialization, which means certain functions are controlled by a certain side of the brain (AKA brain lateralization)

34. Testing the Brain  Accidents give researchers a window into the brain.  Examples, such as Phineas Gage, show psychologists and scientists how different parts of the brain respond to damage.  In 1969, Jose Delgado experimented with electrical stimulation on the brain.  He determined that when an implanted electrode in a bull’s brain, he could use electrical charges to stop a bull in the middle of a charge.  Basically, his thesis stated that electrical stimulation to various parts of the brain could change behavior.  An EEG – or electroencephalogram – is a device that records the electrical activity of the brain.  Electrodes attached to the skull pick up on the electrical charges – called brain waves – and patterns of these waves can be associated with sleep, thought, and relaxation.  A CAT – or computerized axial tomography – scan determines how dense brain tissue is by recording how much radiation is absorbed by an X-ray.  A MRI- magnetic resonance imaging- a person lies in a powerful magnetic field and radio wave cause the brain to give off energy- more powerful than a CAT scan  A PET – or Positron Emission Tomography – shows brain activity as it occurs so researchers can see which parts of the brain are stimulated when listening to music, performing math, or having a discussion with friends.

36. PET scan

37. CAT scan

38. MRI of brain on Meth

39. GLANDS  The endocrine system consists of glands that secrete substances called hormones into the bloodstream.  Hormones stimulate growth and reactions, such as changes in mood and activity levels.  Hormones are produced by several different glands.  The pituitary gland (just the size of a pea and situated under the hypothalamus), controls growth hormones, hormones (Oxytocin) that stimulate labor for pregnant women, and “mothering instincts”.  The thyroid gland produces thyroxin which affects the body’s metabolism.  Too little thyroxin leads to hypothyroid disorder – and these people can be overweight.  Too much thyroxin leads to hyperthyroid disorder, which can make people lose weight, become hyperactive, or sleepless.

41.  The adrenal glands are located above the kidneys and secrete cortical steroids.  Cortical steroids increase resistance to stress and promote muscle development.  The adrenal glands also release adrenaline… meant to help people in a stressful situation.  Nonadrenaline also steps in to help calm people during the stressful situation, whereas adrenaline prepares people for a fight. (Fight-or-Flight response)  The Testes produce testosterone and small amounts or estrogen and progesterone in males.  It is responsible for pushing boys through puberty so that they are ready to reproduce.  The ovaries produce estrogen and progesterone and small amounts of testosterone in women.  Again, the ovaries prepare women for puberty – which lead to reproduction and childbirth.  Really, sexual attraction is very chemical (or hormonal) because women have higher libido’s when they are ovulating because there is more estrogen in their body.

43. Heredity  Heredity is the transmission of characteristics from parents to offspring.  Heredity – while determining hair color, eye color and height – can also determine some psychological traits.  Shyness, leadership, aggressiveness, etc., can be linked to heredity.  However, for years, the debate has raged on about Nature vs. Nurture.  Does heredity really determine behavior?  Or is it purely based on upbringing?  As humans, we loath the nature idea because it states that everything is predetermined – meaning that we cannot become smarter or more athletic than our biology allows.  Psychologists argue that heredity cannot determine destiny because the environment DOES determine how a person develops.

44.  The best way to test this debate is by studying….?  Twins.  Identical twins share 100% of their genes.  Their DNA is identical, yet their fingerprints are different…  Fraternal twins, however, only share about 50% of their genes.  Therefore, identical twins are more likely to share traits – both positive and negative.  Identical twins, for example, are more likely to both develop autism than fraternal twins.  Beginning in 1979, Thomas Bouchard began studying twins that were being reared apart.  He found that twins who had never met one another – and had been “nurtured” differently – still shared unique mannerisms.  Researchers also study adopted children because they are removed from their biological families and can still share commonalities with their actual parents.  These studies can be controversial because it relies on twins, siblings, or children to remain apart – which is difficult to maintain ethically at times.