B6

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  • Created by: Jess
  • Created on: 12-05-13 21:28
What is a stimulus?
A stimulus is a change in an organism's environment.
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Why do animals respond to a stimulus?
Animals respond to a stimulus because this increases their chances of survival
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Why controls an animal's response to a stimulus?
The Central Nervous System (CNS) processes the stimulus and coordinates a response that it sends to the rest of the body
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What is the CNS made up of?
The brain and spinal cord
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What is the peripheral nervous system made up of?
The peripheral nervous system consists of sensory neurons and motor neurons
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What are sensory neurons?
Sensory neurons are neurons that carry impulses from receptors to the CNS
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What is the job of motor neurons?
Motor neurons carry impulses from the CNS to the effectors
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What is the order of a responses to a stimuli?
Receptors --> Sensory neurons --> Relay neurons --> Spinal cord --> Brain --> Spinal cord --> Motor neurons --> Effectors
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How do impulses affect muscle cells in a response to a stimuli?
Muscle cells (effectors) contract, because the impulses travel down the motor neurons to the muscle cells, and the contraction brings about movement
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What are neurons?
Neurons are specially-adapted cells that carry an electrical signal when stimulated.
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What are you adaptations of an neuron?
1) They are elongated to make connections between different parts of the body 2) They have branched endings so that a single neuron can act on many other neurons of effectors
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What is benefit of having a fatty sheath surrounding an axon?
The fatty sheath: insulates the neuron fro neighbouring cells and increases the speed at which the nerve impulse is transmitted
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What are synapses?
Synapses are the gaps between adjacent neurons
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How are impulses transferred between neurons?
1)a nerve impulse reaches the synapse through the sensory neuron 2)the impulse triggers the release of neurotransmitters 3)neurotransmitters diffuse across the synapse&bind with receptor molecules on the membrane of the MN 4)a nerve impulse in sent
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What is a reflex action?
A reflex action is a fast, automatic, involuntary response to a stimulus
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What is the basic pathway for a reflex arc?
1)a receptor is stimulated 2)causing impulses along the sensory neuron to the spinal cord 3)the sensory neuron synapses with a relay neuron by-pass the brain 4)the relay neuron synapses with MN sending impulses to effectors 5)effectors respond
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What is the point of reflex responses?
to increase chances of survival e.g. finding food, sheltering from predators, finding a mate
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How can reflex responses be so fast?
Reflex responses are so fast as the response by-passes the brain, and the fixed pathway neurons in these actions allows the very rapid response as there isn't any processing of information by the brain
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What are 4 simple reflexes in babies?
1) Stepping reflex 2) grasping reflex 3) rooting reflex 4) sucking reflex
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Describe the stepping reflex
When a baby is held under its arms in an upright position, with feet on a firm surface, a baby will make walking movements with its legs
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What is the grasping reflex?
Grasping reflex is when a baby tightly grasps a fingers that is placed in its hand
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Describe the rooting reflex
The rooting reflex is when a baby turns its head and opens its mouth ready to feed, when its cheek is stroked
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What is the sucking reflex?
The sucking reflex is when a baby sucks on a finger/****** that is put in its mouth
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What is are examples of adult simple reflexes?
Pupil reflex. knee-jerk reflex, blinking when an object comes close to your face
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What is the pupil reflex?
In the pupil reflex your eye stops bright light from damaging the retina, as the iris controls the amount of light that enters your eyes and contracts various muscle fibres
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What is a conditioned reflex response?
A reflex response to a new stimulus can be learned by building an association between the stimulus that naturally triggers the primary stimulus & the new stimulus (secondary stimulus). The final response has no direct connection to the stimulus
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What is the point of a conditioned response?
Conditioned responses can increase the chances of survival
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How can you override or modify reflex actions?
In some situations your brain can override/modify a reflex action by sending a signal via a neuron to the motor neuron in the reflex
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What is an example of a reflex action being modified?
An example of modification is where you manage to keep a hot plate in your hand then the your body's natural reflex response to drop it
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How are neuron pathways formed?
1)each time you have a new experience a different neuron pathway is stimulated 2)each time the experience is repeated the pathway is strengthened 3)pathways that aren't used regularly are eventually deleted4)only pathways activated lots are preserved
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What happens as a neuron matures?
As a neuron matures it sends out multiple branches, increasing the number of synapses
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What is a PET scan?
A PET scan (position emission tomography) provides 3D images of the brain, which show neuron activity in parts of the brain
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What evidence is there that children can only learn some skills at particular stages at their lives?
Feral children, in the absence of any other humans the children don't ever gain the ability to talk. Learning language later in development is a harder, slower process
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What does the cerebral cortex area of the brain deal with?
The cerebral cortex deals with intelligence, memory, language and consciousness
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How many neurons does a human brain have?
The brain contains billions of neurons, giving humans a better chance of survival due to ability to arrive at complex conclusions quickly in different situations
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How do scientists map the brain sing physiological techniques?
damage to different parts of the brain can cause different problems e.g. speech loss, memory loss. Studying the effects of this has led to an understanding of which parts of the brain control different functions
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How are electronic techniques used to map the brain?
an EEG scan is a visual record of the electrical activity generated by neurons in the brain. Electrodes are placed on the scalp to pick up electrical signals. By stimulating the patient's receptors, the parts of the brain that respond can be mapped.
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What is memory?
Memory is the ability to store and retrieve information?
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What is short-term memory?
Short-term memory stores information for a limited period of time
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What is long-term memory?
Long-term memory stores an unlimited amount of information
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What is the multi-store memory model?
The multi-store model is where short-term memory can be rehearsed so that it enters the long-term storage
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What are the gaps in the multi-store model explanation of memory?
The multi-store model doesn't explain why some information doesn't need short-term rehearsal to go into long-term memory and why we forget isn't explained by the model either
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What are reasons that we forget things from the long-term memory?
Physical reasons such as neurons decaying e.g. in Alzheimer's disease and lack of retrieval, if we don't use the information for a long time, the pathway is lost, are reasons why we forget things from the long-term memory
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What makes you more likely to remember something?
repetition, strong stimulus associated with the memory e.g. colour/light/smell/sound; you can impose a pattern on the memory
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What can the effects of serotonin be?
Serotonin is a chemical transmitter used in the CNS that can have mood-enhancing effects i.e. is associated with feeling happy
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What does ecstasy do to the transporter sites in the transmitting neuron?
Ecstasy blocks the transporter sites causing serotonin to build up in the synapse. This causes serotonin concentration to build up in the brain, and the user to experience feeling of elation
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What type of changes to the body do nervous responses bring?
All nervous responses bring about fast but short lived responses.
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Why type of changes do hormones bring about in the body?
Hormones produced in glands e.g. insulin, adrenalin travel in the blood and so can move around all of the body. The response can last a lot longer in the body this way.
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Card 4

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