Nervous System Flashcards
What is the function of the human nervous system?
The nervous system serves to co-ordinate and regulate bodily functions
What are the components of the human nervous system
Central nervous system (CNS): brain and spinal cord
Peripheral nervous system (PNS): cranial nerves from the brain, spinal nerves from the spinal cord
How does the nervous system function in response to a stimulus?
Receptors receive stimuli and generate nerve impulses
The nerve impulses travel along the sensory neurones from the receptors to the central nervous system
The central nervous system integrates sensory information from the receptors, so the brain and spinal cord will interpret information and initiate a response
A nerve impulse will be transmitted to the muscle along the motor neurone
The muscle effects an action and is called an effector
What is the nervous system made up of?
Neurones (nerve cells) and supporting cells
What are the three types of neurones and their functions?
Sensory neurones transmit nerve impulses from the receptors to the central nervous system
Relay neurones transmit nerve impulses from the sensory neurones to the motor neurones
Motor neurones transmit nerve impulses from the motor neurones to the effectors
What is a synapse and how are nerve impulses transmitted across them?
Synapses are small gaps between two neurones, or between a neurone and a muscle/gland
Nerve impulses are transmitted across the synapse by certain chemicals called neurotransmitters
What is each neurone made out of?
Axon: the portion of the neurone where nerve impulses are transmitted away from the cell body
Myelin sheath: surrounds the axon, protects and insulates the axon to enhance the transmission speed of nerve impulses
Schwann cells: supporting cells of the nervous system that wraps around axons forming the myelin sheath
Dendrite/dendron: portion of the neurone where nerve impulses travel towards the cell body
What are the gaps between the myelin sheath called?
Nodes of Ranvier
What are grey and white matter?
Grey matter: mainly the cell bodies of neurones, forms outer layer of brain and central parts of the spinal cord
White matter: consists of nerve fibres, forms central part of the brain and the outer layers of the spinal cord
What is each spinal nerve made of and what is the function of each root?
Dorsal nerve: contains only sensory neurones. Cell bodies of the sensory neurones are clustered together in a small swelling called the dorsal root of ganglion
Ventral nerve: only motor neurones. Cell bodes and dendrones of the motor neurones lie in the grey matter of the spinal cord
What does the spinal nerve contain?
Both dorsal and ventral nerves (sensory and motor neurone)
Mixed nerve, as the spinal nerve leaves the spinal cord, progressively subdivides into branches supplying nerve fibres to various parts of the body
Define reflex actions
Reflex actions are involuntary responses to a specific stimulus without any conscious control
What are the two types of reflex actions?
Spinal: when the spinal cord if the reflex centre
Cranial: when the brain is the reflex centre
What is the reflex arc?
The shortest pathway by which nerve impulses travel from the receptor to the effector in a reflex action
Receptor to sensory neurone to relay neurone to motor neurone to effector
What do the sensory, relay and motor neurones look like?
Sensory: axons with cell body
Relay: dendrites
Motor: dendrites and axons
