What is Behaviour?
- An example of a simple reflex response is woodlice moving away from light.
- Reflexes are always involuntary- they are automatic.
- Simple reflexes help animals to survive. Animals that only behave with simple reflexes cannot change their behavior, or learn from experience. This is a problem if the conditions around them change.
- Complex animals have reflex responses altered by experience and they make conscious decisions- they are more likely to survive when environment changes.
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Simple Reflexes in Humans
- The pupil reflex (bright light in eye, dilate pupil) stops bright light from damaging the sensitive cells at the back of the eye.
- Newborn reflexes are only present for a short time after the baby's birth. They are gradually replaced by behaviours learned from experience.
- In a few cases, they are missing or do not disappear at the right time- the baby's nervous system is not developing properly.
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Your Nervous System
- All reflexes and behaviors are coordinated by the nervous system.
- In a simple reflex, impulses are passed from one part of the nervous system to the next in a pathway called a reflex arc.
- Nerves make up the peripheral nervous system (they link brain and spinal cord to every other part).
- Neurons (like all cells) have a nucleus, cell membrane and cytoplasm but the cytoplasm is shaped into a long, thin extension- an axon.
- Axons carry electrical nerve impulses and must be insulated from each other with a fatty sheath wrapped on the outside. The fatty sheath increases the speed of the impulses.
- Receptors inside and outside the body detect stimuli. There are different types of receptors that detect a different type of stimulus.
- Effectors are either glands or muscles. When impulses arrive at these effectors they cause;
- 1. Glands to release chemicals (hormones, enzymes or sweat).
- 2. Muscles to contract and move part of the body
- Reflexes happen automatically to help you survive, but they can be modified by conscious control.
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- Neurons do not touch each other; when nerve impulses pass from one neuron to the next, they have to cross tiny gaps- synapses.
- How nerve impulses cross a synapse-
- 1. The impulses arrives at a synapse.
- 2. A chemical is released from the sensory neuron and diffuses. The molecule is the correct shape to fit into receptor molecules on the membrane of the motor neuron.
- 3. An impulse is stimulated in the motor neuron. The chemical is reabsorbed to be used again.
- The gap at a synapses is only about 20 nanometres wide- short time.
- Serotonin is a chemical released at a synapse that gives feelings of pleasure. Lack of serotonin is linked to depression.
- Prozac is an antidepressant drug that causes serotonin to build up at synapses by stopping it being reabsorbed.
- Ecstasy works in a similar way to Prozac, but it may destroy the synapses- causing anxiety and depression.
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- Scientists who study the brain are called neuroscientists- neurology is a fairly new science.
- Neurons carry electrical impulses around the body- they act as a simple brain, processing info from the receptors.
- All neurons in the brain carry 1+ specific functions.
- Consciousness is when you are awake and aware of your environment.
- The cerebral cortex deals with consciousness, intelligence, language and memory.
- Scientist study people whose brains are partially destroyed by injuries or diseases (strokes).
- fMRI scans can be used to show which parts of the brain are most active when a patients does different tasks, they have a greater flow of blood
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- Being able to learn behaviour is vital for survival when environment changes.
- Adding a stimulus that produces the same response as a reflex action is a type of learning called conditioning.
- Learning to link a new stimulus with a reflex action allows animals to change their behaviour- conditioned reflex.
- Conditioned reflexes help animals to survive.
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- Experience changes human behaviour- called learning.
- Neurons in your brain are connected to form complicated pathways. The 1st time a nerve impulse travels along a pathway between neurons, a connection is made. New experiences set up new pathways.
- If the experience is repeated or the stimulus is strong, more impulses follow the same nerve pathway; neuron connections are strengthened.
- Strengthened connections are easy for impulses to travel along- response is easier to make.
- Human babies develop nerve pathways quickly- still learn when old, but slower.
- Repetition helps you learn as it strengthens the pathways the brain uses to carry out a skill.
- Children learn language easily up to 8 years; brain easily makes neuron pathways in the language processing regions.
- A feral child does no learn to speak as they have not been exposed to language early enough in life.
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What is Memory?
- Memory is the ability to store and retrieve information.
- Short-term memory only store memories for about 30 seconds. Long-term memory is a long lasting or permanent store of memory.
- People with Alzheimer's suffer short-term memory loss, but can remember their childhoods. Some people can't remember their childhoods, but their short-term memory is normal.
- You can use a sensory memory store to store sound and visual info. for a short time.
- Explanations for how memory happens are called models of memory.
- The use of sensory, short-term and long-term memories at the same time is known as the multi-store model of memory.
- Short-term memory is now seen as an active "working memory". You can hold and process information that you are consciously thinking about.
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