Structure of the Nervous System Flashcards
What two parts does the nervous system consist of?
The Central Nervous System
The Peripheral Nervous System
What does the Central Nervous System consist of?
the brain and the spinal chord
What does the Peripheral Nervous System consist of?
Sensory and motor neurones
What is the role of the sensory neurone?
Carries the impulse from the receptor to the co-ordinator
Where are relay neurones found?
In the central nervous sytem
What do relay neurones do?
Receive impulses from sensory neurones and and send impulses to the motor neurones.
What is the role of the motor neurone
Carries the impulse from the co-ordinator to the effector organs
What are the two types of effectors?
Muscles and glands
How do muscles respond?
By contraction
How do glands respond?
By secreting hormones
What is the role of a dendrite?
Carries impulses towards the cell body
What is the role of the axon?
Transmits impulses away from the cell body
What are Schwann Cells?
Cells which surround neurones
What is the role of Schwann Cells?
To insulate neurones
Role of the myelin sheath
Acts as an electrical insulator and speeds up transmission along the axon.
How is the myelin sheath formed?
Schwann cells grow around the axons to form this multi-layered fatty sheath.
What are the Nodes of Ranvier?
Areas along the axon where the myelin sheath is missing
Do hydra have a Central Nervous Sytem?
No
What do hydra have instead of a CNS?
A nerve net
How many typesof nerve cells do hydra have?
1
Do hydra have myelinated or unmyelinated nerve cells?
Unmyelinated
Is the impulse transmission for hydra fast or slow?
Slow
