Neurones And Nervous Coordination Flashcards
What are the two main forms of coordination in animals as a whole
The nervous system and hormonal system
Describe how the nervous system uses nerve cells to pass electrical impulses along their length
They stimulate target cells by secreting chemicals, known as neurotransmitters, directly on to them.
This results in rapid communication between specific parts of the organism
The responses produced are often short lived and restricted to a localised region of the body.
Describe how the hormonal system works
It produces chemicals that are transported transported in the blood plasma to their target cells.
The target cells have specific receptors on their cell surface membranes and the change in the concentration of hormones stimulate them
This results in a slower, less specific of communication between parts of an organism
The responses are often long lasting and widespread
Compare the hormonal system and nervous system
H- communication is by chemicals called hormones
N- communication is by nervous impulses
H- transmission is by the blood system
N- transmission is by neurones
H- transmission is usually relatively slow
N- transmission is very rapid
H- hormones travel to all parts of the body, but only target cells respond
N- nerve impulses travel to specific parts of the body
H- response is widespread
N- response is localised
H- response is slow
N- response is rapid
H- response is often long lasting
N- response is short lived
H- effect may be permanent and irreversible
N- effect is usually temporary and reversible
What are neurones
Are specialised cells adapted to rapidly carrying electrochemical changes called nerve impulses from one part of the body to another
What is a mammalian motor neurone made of. And what are they.
A cell body - contains all usual organelles, including a nucleus and large amounts of RER. This is associated with the production of proteins and neurotransmitters
Dendrons- extensions of the cell body which subdivide into smaller branched Fibres, called dendrites, that carry nerve impulses towards the cell body
An axon - a single long fibre that carries nerve impulses away from the cell body
Schwann cells - surrounds the axon, protecting it and providing electrical insulation. They also carry out phagocytosis and play a part in nerve regeneration. Schwann cells wrap themselves around the axon many times, so that layers of their membranes build up around it
A myelin sheath- forms a covering to the axon and is made up of the membrane of the Schwann cells. They are rich in myelin (lipid)
Nodes of ranvier - constrictions between adjacent Schwann cells where there is no myelin sheath
How are sensory neurones classified to their function
They transmit nerve impulses from a receptor to an intermediate or Motor neurone. They have one dendron that is often very long. It carries the impulse toward the cell body and one axon that carries it away from the cell body
How are motor neurones classified according to their function
They transmit nerve impulses from an intermediate or relay neurone to an effector, such as a gland or muscle. Motor neurones have a long axon and many short dendrites
How and relay neurones classified according to their function
They transmit impulses between neurones e.g. sensory to motor neurones.
