Nervous system Flashcards
What is the nervous system made up of
- Central nervous system
- Peripheral nervous system
What is the central nervous system
- Consists of brain and spinal cord
- Functions as a coordination centre that processes information
What is the myelin sheath
- Covers most long fibres
- Insulates nerve fibres
- Increases transmission speed of nerve impulses
What is a dendron
- Transmits nerve impulses towards neurone cell body
- End branches are called dendrites
What is an axon
- Transmits nerve impulses away from neurone cell body
- End branches are called axon terminals
What are the Nodes of Ranvier
Regions where myelin sheath is absent
What happens when nerve impulses reach the axon terminals
- Neurones are not physically attached to receiving cells
- There is a gap between a neurone and effector called the synapse
- Neurotransmitter is released into the synapse when nerve impulses reach the axon terminals
- Activity of receiving cells is altered
Describe the structure and function of the sensory neurone
- Circular cell body
- Long dendron, short axon
- Dendron and cell body outside CNS, axon inside CNS
Functions: Transmit nerve impulses from receptors to CNS
Describe the structure and function of the motor neurone
- Irregular cell body
- Long axon, dendrites
- Cell body and dendrites inside CNS, axon outside CNS
Functions: Transmit nerve impulses from relay neurone to effector
Describe the structure and function of the relay neurone
- Circular or irregular cell body
- Whole neurone inside CNS
Functions: Transmit nerve impulses from sensory neurone to motor neurone or to another relay neurone
Define a reflex
A reflex is any immediate response to a specific stimulus that occurs without any conscious effort
Define a simple reflex
Simple reflexes are built-in, unlearned responses, and they have protective functions
Define a reflex arc
A reflex arc is the shortest pathway by which impulses travel from the receptor to the effector
Define a conditioned reflex
Conditioned reflexes are acquired from past experiences of learning with a stimulus which was originally not effective in producing a response
What are the types of simple reflexes
Spinal reflex
- Spinal cord is reflex centre
Cranial reflex
- Brain is reflex centre