Neurones and nervous coordination Flashcards
What are the 2 main forms of coordination in animals?
Nervous system
Hormonal system
Characteristics of the hormonal system
Use of chemicals called hormones
Blood
Slow response and transmission
Travels to all parts of body
Long lasting
Permanent and irreversible
Characteristics of nervous system
Nerve impulses
Neurones
Rapid response and transmission
Localised
Short lived
Temporary and reversible
What are neurones?
Specialised cells adapated to rapidly carry electrochemical charges from one part of the body to another
Structure of a neurone
Cell body
Dendrons/dendrites
Axon
Schwann cells
Myelin sheath
Nodes of Ranvier
What are dendrons
extensions of cell body that divide into dendrites, taking impulse TOWARDS cell body
What is the axon
Single long fibre that carries nerve impulses away from the body
What do schwann cells do?
Surround and protect axon and provide electrical insulation.
Wrap around axon
Also perform phagocytosis and help nerve regeneration
What is the myelin sheath?
The membrane of Schwan cells made of a lipid called myelin that covers the axon, acting as an electrical insulator
What are the nodes of Ranvier?
Constrictions between adjacent schwann cells where there is no myelin sheath.
How long are the nodes of Ranvier?
2-3 micrometres
Function of sensory neurones
Transmit nerve impulse from receptor to intermediate or motor neurone
Function of motor neurone
Transmit nerve impulse from intermediate neurone to an effector
Function of intermediate neurone
Transmit impulses between neurones
In the structure of a neurone, where does the impulse travel from and to?
Dendrites to axon
