nervous system Flashcards
what is the basic structure of a neurone?
Dendron, cell body(which contains nucleus and cytoplasm) and axon
what are dendrons?
they are nerve fibres which send nerve impulses towards the cell body
what are axons?
they are nerve fibres which carry nerve impulses away from the cell body
transport of nerve impulse in the motor neurone
cell body in the motor neurone is irregular in shape. dendrites of the dendrons receives nerve impulses from other neurones and these nerve impulses are transmitted from node to node to the axon and to the axites where nerve impulses are transmitted to the effector
what is the myelin sheath?
it is a layer of fatty substances that shields and insulates the nerve fibre and it is surrounded by a membrane aka neurilemma
what is the node of Ranvier?
it is the region where myelin sheath is absent. it speeds up transmission by allowing nerve impulses to jump from node to node
what is the motor end plate?
the junction between the axite and the muscle fibre
what do sensory neurones do?
they transmit nerve impulses from sense organs to the central nervous system
what is the Axon Hillock?
it is the specialised part of the cell body that connects to the axon
what is the schwann cell?
it is myelin secreting cell
what is the synapse?
it is the junction between 2 neurones. nerve impulses from axon are transmitted to dendron by chemical means. nerve impulses are converted into neurotransmitters in the synapse
what are nerves?
nerves are a bundle of nerve fibres enclosed in a sheath of connective tissues
what is a nerve fibre?
it is a strand of cytoplasm extending out from the cell body
what do the brain and spinal cord consist of?
grey matter and white matter
what is the grey matter?
it composes of the cell bodies of the neurones and is located on the outer layers of the brain and central parts of the spinal cord
what is the white matter?
it composes of the nerve fibres of the neurone and is located in the central parts of the brain and outer parts of the spinal cord
what surrounds the spinal cord?
the spinal cord is encased within the vertebral column which serves as protection
what runs through the middle of the spinal cord?
a narrow canal containing cerebrospinal fluid
what do the spinal nerves divide into?
dorsal root containing only sensory neurone and ventral root only containing motor neruone. cell bodies of the sensory neurones are clustered together in the dorsal root ganglion. the grey matter in the spinal cord mainly contains cell bodies of the motor and relay neurones
how does the central nervous sytem process information?
information is gathered by receptors and is converted in electrical signals aka nerve impulses from the sensory neurone to the relay neruone in CNS. brain processes information based on the pattern of the nerve impulses and sends nerve impulses to the effector via the motor neurones for the intended action to be carried out
what is reflex action?
it is the immediate response to a specific stimulus without conscious control of the brain
what is the reflex arc?
it is the shortest pathway of nerve impulses from the receptor to the effector
types of reflex actions?
cranial reflex and spinal reflex
