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How is the nervous system constructed for response compared to the endocrine system?
The nervous system involves an electrical impulse system that is constructed for much quicker responses.
What does a neuron consist of in its construction?
Includes a cell body that contains a nucleus and one or more nerve fibers. Fibers that transmit electrical information from one cell to another are called axons. Axons can range in size from less than a millimeter to over a meter long. Axons also differ in terms of diamter. This is important because the speed of the nervous impulse affects the speed at which animals respond behaviorally, and the thicker the diameter of an axon, the faster the nervous impulse travels along it.
From what part of the neuron does information leave?
The axon terminal.
What is a dendrite?
- Nerve cell fibers that receive electrical information from other cells.
- A neuron may have thousands of dendrites, forming what is called a dendritic tree.
What is the process of a stimulus resulting in a behavior due to nervous impulse?
Suppose the external stimuli is something touching the animal. In response to this stimulus, a wave of electrical activity sweeps down along the axons of sensory nerve cells that are in contact with the skin. For this process to begin, the stimulus must exceed the nerve cell's threshold. Once an impulse has reached the end of an axon, it must be transmitted to other neurons. This can be accomplished by an electrical impulse jumping across the synaptic gap between neurons or, more commonly, by the release of a neurotransmitter which are then absorbed by the membrane of the next neuron.
What is the threshold of a nerve cell?
A function of the amount of change in the voltage across a neuron's membrane.
What are the two ways that animals are able to use their nervous systems to gauge the strength fo a stimulus?
- 1.) The number of times that a neuron fires increases with the strength of the stimulus.
- 2.) The number of neurons that fire in response to a stimulus also increases as a function of stimulus strength.
What are the consistencies observed in evolutionary trends of the nervous system?
- 1.) Nerve cells that served specific functions-including functions linked to behavior-became clustered.
- 2.) Over evolutionary time, nervous systems became centralized, with longitudinal nerve cords becoming the major highway across which nervous impulses travel. The front end of the longitudinal nerve cord became dominant, leading to the evolution of the brain.
What is the purpose of the hippocampus?
An area of the cerebral cortex of the brain that is known to be important is spatial navigation.
What are the three types of neurons in invertabrates?
Sensory, inter, and motor.
What are phasic and tonic neurons and muscles?
- Phasic: fast and brief.
- Tonic: slow and sustained.
What are the sensory organs on a cockroach and how do they work?
The seta are lcoated on the cerci and they detect wind movements. Stimulus must be above the threshold, exites the giant interneuron, many sensory neurons on the giant interneuron, the GI synapses with a metathoracic ganglion, GI causes shut down of behaviors that are antagonistic to running, MTG synapse to leg motor neuron, MN AP cause muscle excitiation, MN's to the antagonistic muscles are inhibited, cockroach runs away from stimulus.
What are the steps of a chemical synapse?
AP reaches end of an axon, presynaptic neuron vesicles release neurotransmitter, absorbed by postsynaptic neuron, if sufficient, nueron fires.
What is the evolutionary history of the brain/nervous system?
- Nerve net (simple nervous system, no brain): Sea anemonea
- Segmented nerve trunk (bilaterally symmetric): Flatworm
- Ganglia (structures that resemble and function like a brain): Squid
- Brain (true brain and spinal chord): Frog
What is the evolution of the verterbrate nervous system/brain?
- Reduction of the midbrain
- Increase of the forebrain
- Cerebrum processing info
- Increase cerebellum
What are the differences between rods and cones in the eye?
- Rods are more sensitive to light.
- Cones tuned to particular wavelength: short, medium, long.
What is umwelt?
Each organism percieves differently.
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