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Bio Prac Sac 1
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32
Biology
11th Grade
03/02/2012

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Term
Another name for a nerve cell
Definition
Neuron
Term
What covers the axon
Definition
The myelin sheath
Term
What is the central nervous system
Definition
The spine and brain only. The peripheral nervous system is what branches off of that.
Term
The myelin sheath
Definition
A sheath that covers the axon and makes nerve impulses travel around them faster. They act as protection and insulation for an axon.
Term
Where do axons not have myelin sheath?
Definition
In the brain and other areas.
Term
Vesicles
Definition
Vesicles have a neuro transmitter that allows itself to go to the end of a neuron and cross a gap at the end of the neuron and carries onto to either a dendrite, muscle or a gland.
Term
Negative feedback
Definition
Something occuring in or on the body that is of a negative effect to our body. Negative feedback will make us carry out a response that will reduce the stimulus (thing wrong with our body)
Term
Positive Feedback
Definition
Lets us carry out a response to increase a stimulus.
Term
Is negative feedback essential to maintain homeostasis? T/F
Definition
True
Term
Reflex Reactions
Definition
Do not travel to the brain but just to the spinal cord and straight back. This is because it is quicker and more immediate to prevent damage. It is used to be quicker and protect your body.
Term
What is the function of a nerve cell?
Definition
To conduct a nerve impulse.
Term
Reflex Reactions
Definition
Do not travel to the brain but just to the spinal cord and straight back. This is because it is quicker and more immediate to prevent damage. It is used to be quicker and protect your body.
Term
Nerve cells cannot be replaced or repaired. T/F
Definition
True.
Term
If a direct nerve path is damaged...
Definition
then an alternative route may be sort out.
Term
Dendrites
Definition
Extensions of a neuron that receive messages from other cells / neurons.
Term
Nerve impulses travel..
Definition
Only in one direction from the dendrite end to the axon end.
Term
What are the two systems that send messages across our body.
Definition
Nervous System and the endocrine system
Term
Endocrine system
Definition
Transports messages through hormones that spread all across your body.
Term
Hormones
Definition
Are chemicals produced and taken through the blood stream and travel around the body.
Term
What is the problem with hormones and the advantage with nerves?
Definition
Hormones have to go all over the body rather than one specific point. Nervous system messages go to one specific point of the body and are therefore much quicker. Better if serious damage is happening to the body and immediate action needs to be taken.
Term
Which responses last longer. Hormone or nerves?
Definition
Hormone responses last longer than nervous system responses.
Term
What is the only very fast hormone
Definition
Adrenaline.
Term
What are the two main cells in the nervous system?
Definition
Neurons and neuroglia
Term
Neurons
Definition
The actual nerve cell that is the conducting cell that transmits impulses and is the structural unit of the nervous system.
Term
Neuroglia
Definition
Non conductive
And a support system for neurons
Term
What are the three types of nerves
Definition
Sensory (Afferent) that travel towards the central nervous system and convert stimuli into internal electrical impulses.

Motor (Efferent) are away from the CNS and can use muscle fibres to cause muscle contractions.

Interneurons are found between the sensory and motor neurons and most are found in the CNS.
Term
Three parts of a neuron
Definition
Cell body containing nucleus
Dendrites that project from the cell body and branch to receive signals from other neuorns and transmit impulses to the cell body
Axon
Term
Axon
Definition
One projects from each cell body and is elongated and takes messages away from the cell body in one direction only and connect to other neurons, muscles or glands.
Term
Internal environment includes
Definition
Tissue fluid
Term
Transmission of messages within the nervous system.

a) Relies on active transport of neurotransmitter

b) involves both electrical impulses and chemical messengers
Definition
b
Term
both systems nervous and endocrine
Definition
release chemical signals that act on tissues they control
Term
Why do hormone responses last longer?
Definition
Because hormones remain in the bloodstream for some time before being destroyed.
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