nervous system Flashcards
roles of nervous system
-allows organism to detect changes in surrounding and respond to it
-allows organisms to process sensory information
-send nerve impulses to effector cells
how does the nervous system process information
-information is first gathered by the receptors
-information converted into nerve impulses
-nerve impulses that transmitted by cranial and spinal nerves to central nervous system
-brain processes information based on pattern of nerve impulses
-brain will send nerve impulses to effectors
-intended action is then carried out
function of dendrite and dendron
-dendrites receive nerve impulses from other neurons
-dendrons are nerve fibres that transmit nerve impulses towards cell body
what is myelin sheath
-layer of fatty substances that shield the nerve fibre, surrounded by thin membrane, neurilemma
what is nodes of ranvier
-regions where myelin sheath are absent, allow impulses to jump from node to node, speed up transmission
what is axon
-nerve fibres that carry nerve impulses away from cell body
what is motor end plate
-junction between dendrite and muscle fibres
-nerve impulses are transmitted across MEP by chemicals that stimulate the muscle
properties of cell body
-irregular in shape in motor neurone
-circular shape in sensory neurone
contains nucleus and cytoplasm
structure and function of relay neurone
-cell body with main relay fibre
-transmit nerve signals from sensory neurone to motor neurone
what is synapse
-junction between two neurones or between a neurone and effector
-impulses transmitted from axon to dendron
-nerve impulses are transmitted across synapse by chemical, neurotransmitters
how do synapse work
-presynaptic cell secretes neurotransmitters that crosses the synaptic cleft
-neurotransmitters crosses over to specific receptors on surface of receiving postsynaptic cell
function of sensory nerve fibres and motor nerve fibres
-SNF carry nerve impulses from sense organ
-MNF carry nerve impulses to effectors
-spinal nerves have both SNF and MNF
composition and location of grey and white matter
-grey matter consist of cell bodies and neurones, found in out layer of brain and central parts of spinal chord
-white matter consist of nerve fibres, found in central parts of brain, outer layer of spinal chord
properties of spinal chord
-31 pairs of nerves emerge at intervals along the length of spinal chord
-narrow central canal containing cerebrospinal fluid runs through middle of spinal chord
-each spinal nerve splits into two roots before it joins the spinal chord
properties of dorsal and ventral root
-DR joins the back part of the spinal chord, only contains sensory neurones
-VR joins front part of spinal cord, contains only motor neurones.
-cell bodies and dendrons of the motor neurone lie in the grey matter of the spinal chord
-axons of the motor neurone leaves the spinal chord and enter VR
what is dorsal root ganglion
-cell bodies of sensory neurones that are clustered together in a swelling
how are nerve fibres supplied to the rest of the body
-spinal nerves that contain nerve fibres from dorsal root and ventral root subdivides into branches
what is found in grey matter
-axons and cell bodies from relay neurones, dendrons of sensory neurones are found in dorsal root and spinal nerves
transmission of nerve impulses
-relay neurones that lay parallel to spinal chord, form synapse with motor and sensory neurone
-allow transmission of nerve impulses from sensory to motor neurone
-conduct nerve impulses from sensory neurone to brain
-conduct nerve impulses from brain to motor neurone
stimulus and response of cat purring on leg
-touch receptors in the leg are stimulated and sends nerve impulses through sensory neurones to the grey matter of spinal chord
-relay neurones conduct nerve impulses to the brain
-feeling of touch occurs when nerve impulses reach brain
-brain transmits nerve impulses through relay neurones of spinal chord to motor neurones
-motor neurones can cause muscle contraction
what is voluntary action
-action that involved the brain and the person can decide whether or not to act, since action is under control of will
what happens when your hand touches a hot object
-heat stimulates touch receptor in skin
-nerve impulses are produced and they travel along the sensory neurone to spinal chord
-in spinal chord, nerve impulses are transmitted across synapse to relay neurone, across another synapse to motor neurone. At the same time, nerve impulses trasmitted to brain
-upon receiving nerve impulses from relay neurone, motor neurones transmit nerve impulses to effector
-effector muscle contract, resulting in withdrawal of hand from hot object
what are reflex centres
-brain and spinal chord
recite a simple spinal reflex arc
-receptors in skin in the stimulus
-nerve impulses travel along sensory neurones to relay neurone
-relay neurone back along motor neurone to effector which is muscle
