Biological Psychology. Unit Two AA Mr. Cline Marshall High School Psychology

Transcription

1 Biological Psychology Unit Two AA Mr. Cline Marshall High School Psychology

2 What are the biological factors that affect our behavior? In this unit we are going to take a look at biological psychology, which looks at the interplay between biological processes and mental states. When we think about making choices, we think about things happening in the mind: ideas that influence how we think. But, your brain, nerves and hormones also affect your behavior and how you feel. We can understand more about the human condition when we recognize how biology affects behavior. Your brain, nerves and hormones are responsible for your thoughts, feelings and actions. When you get hungry, remember your favorite place to eat, smell food cooking and take a big bite - biological processes are involved. Biopsychologists study the lines of communication between your brain, glands and muscles.

3 They look at the intersection between biology and psychology, between brain activity and mental states. Think of the brain as a computer, biopsychologists are the technicians who discover how the hardware affects how smoothly the software runs. An important contribution of biopsychology is finding biological causes of why we think, feel and act the way we do. Two biological systems that affect your behavior are your nervous system and your endocrine system. Your nervous system is an interconnected network of nerve cells (called neurons) that allow you to sense the things going on around you so you can react. Your brain tells you that you're hungry, but your nervous system tells your brain when you see food, and it even helps digest the food.

4 Your endocrine system, meanwhile, includes your hormone-producing glands and helps your body turn the food into energy. Biopsychologists and behavioral neuroscientists study the effects of biological processes like hunger, eating and digestion. Ideas, emotions and behavior are only the tip of the iceberg. Our understanding of biological causes of mental illnesses and genetic roots of disorders continues to grow. Biopsychologists have discovered genetic and biochemical triggers for eating disorders that cause us to rethink the idea that certain conditions are 'all in the head.' If you're not convinced, think about how your eating habits change when you're stressed out or sick. Behavioral neuroscientists also study neuroplasticity, or the brain's ability to reorganize in response to damage and new experiences.

5 You're probably familiar with the idea that when you lose the ability to use one of your senses, your other senses become stronger. There's actually a structural change in your brain that goes along with this shift in ability. If you became blind, parts of your brain that aren't responsible for your vision might grow larger to help compensate for your loss of sight. You would no longer be able to see food, but you'd be able to smell and taste it more than ever. Next time you think, feel or react, consider the roles that your brain, nerves, muscles and glands play. What are the parts of a neuron? Neurons are nerve cells that are constantly sending signals to your brain, muscles and glands.

6 You have over 100 billion neurons in your brain sending signals. The signals help the different parts of your body communicate with each other. Thanks to neurons, you're able to swat a mosquito if you feel it land on your arm or wave to a friend if you see her walking towards you. Neurons send chemical signals called neurotransmitters, and they work quickly to help you react to everything going on around you. Think of these neurons as little baseball players throwing balls to each other. The baseballs are the chemical signals called neurotransmitters. So, when you see a ball flying through the air towards you, sensory neurons send signals to your brain. This sets off a chain reaction of signals, which are fired off to motor neurons that cause your muscles to react so you can catch the ball.

7 Now, let's take a journey inside the human body to see what happens when we see, hear or touch something. Our neurons have dendrites, like catching arms, that receive signals. He also has a pitching arm that fires off signals. This pitching arm is called an axon. Like a pitcher's power sleeve, a myelin sheath covers the axon, or pitching arm, and boosts the speed at which a neuron can fire off signals. The terminal branches at the end of the axon make up the pitching hand. This is where neuron fires off signals.

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9 Here's how it works. When the signal comes in (think of it as a baseball), it excites the neuron into action. Positively charged sodium ions begin to enter the cell membrane. There are sodium ions in sports drinks, so think of this process as a neuron drinking a sports drink to increase electrolytes like sodium ions. A neural impulse, or electric current, travels from the dendrites (catching arms) through the axon (pitching arm) to the terminal branches (pitching hand) to be fired off to another neuron. This process is called the action potential. Then he winds up his pitch and...bam!...fires off the signal. The all-or-none law states that, once the neuron receives the signal, it has to fire it off. Like a pitcher who winds up and starts delivering the pitch, the neuron can't balk.

10 There's no stopping once the nerve impulse has been activated. But, if your neurons don't get the signal, they don't fire. So, you'll swat a mosquito only if you feel it land on your arm. Either you feel it and the neurons deliver the signals so you can react, or you don't. The signal (ball) flies over the synaptic gap (field) to another neuron (player) and the process repeats itself. The dendrite receives the chemical signal or neurotransmitter excites the neuron sodium ions enter the neuron and charge it an electric current travels through the axon and; the terminal branches fire off the signal over the synaptic gap to the next neuron

11 The synaptic gap is less than 1 millionth of an inch! In the brain, your neurons are packed together pretty tightly. But, in the outfield, some neurons have super long axons, or pitching arms. A single axon, like the one that starts at the base of your spine and extends to your big toe, can be over three feet long! But even with these super long neurons, the same process happens. When you run to catch a ball, the dendrites catch the neurotransmitters. The neurons get excited and sodium ions charge them. Electric currents travel through the axons all the way down your leg to the terminal branches in your toes to say pick up your feet! The terminal branches fire off neurotransmitters over the synaptic gaps to your other neurons.

12 And this process occurs over and over again until the signals get to where they need to be to trigger your muscles and glands into action. After the signal is fired, the neuron goes through a refractory period. What happens during this period is the neuron pumps out the sodium ions. Neurons sweat them all out and return to their normal state, or resting potential. The neuron s back to being mostly negatively charged...until the next time he catches a signal, which triggers him to play ball. So, the next time you catch a ball, think about all the sensory neurons firing signals inside to activate your motor neurons in your arms and legs. These nerve cells are responsible for your senses and reactions.

13 Neurons and neurotransmitters can be likened to billions of tiny baseball players engaged in a non-stop game of catch. Neurotransmitters are chemical signals that can affect such feelings as mood, hunger, anxiety and fear. In the human body, there are billions of little neurons, and they're not all the same. Some have short pitching arms and some have pitching arms up to three feet long! Some neurons throw neurotransmitters at the speed of one mph, and others throw fastballs up to 268 mph! Different neurons play different positions too. Your sensory neurons fire signals to your brain neurons, and your brain neurons in turn fire signals off to your motor neurons. Your nerves pass information about what you see and hear to your brain, which sends out signals to your muscles, so you can react.

14 So when you see a ball flying through the air towards you, your brain neurons send signals to your arms to reach out and catch the ball. The type of neurotransmitter that is fired depends on the function of the particular neuron firing it. On the receiving end, only certain types of neurons can receive these chemical signals. Neurons are team players, and each player has a position on the team. Because the neurons that are receiving the neurotransmitters have different functions, neurotransmitters affect different types of behavior. For example, your levels of the neurotransmitter serotonin regulate your appetite, sex drive, moods and ability to sleep. Low levels of serotonin may lead to anxiety or depression. Some anti-depressant drugs can help raise serotonin levels.

15 Other neurotransmitters control memory. Dopamine affects your ability to concentrate and learn. Dopamine levels also affect your ability to react and move. Dopamine deficiencies are found in patients with Parkinson's disease. Symptoms include shaking and the inability to walk. When you exercise, neurotransmitters called endorphins are fired from your gland neurons to your brain neurons and your spinal cord neurons to reduce pain and stress. So, neurons are the cells that pass the information, and neurotransmitters are the chemicals that carry that information. The details of how these function are the continuing work of neuroscientists today.