UNIT 2: (2.2a) Nervous Control Flashcards
Control and communication
what is stimuli?
internal and external changes
what does the nervous system consist of?
- brain
- spinal cord
- neurons
what does the central nervous system consist of?
- brain
- spinal cord
what role do neurons play in our nervous system?
connect the nervous system to all parts of our body. ensure information flows to and from CNS
why is information flow essential?
in multicellular organisms cells do not work independently and internal communication is required for survival of a multicellular organism
what are neurons?
nerve cells which carry information/ messages along neurons as electrical impulses
what are sensory neurons?
pass information/messages in the form of electrical impulses from receptors in sense organs to the CNS
what are inter neurons?
operate within the CNS
what are motor neurons?
pass information/messages in the form of electrical impulses from the CNS to muscles or glands ( effectors) enabling a response to occur
how are messages sent between neurons?
- tiny gap between neurons called a synapse.
- messages in the form of electrical impulses are transferred between neurons by chemicals at synapses
- chemical diffuses between the gap and makes the next neuron transmit an electrical impulse
what is the first stage in a response to stimuli?
receptors in our sense organs detect changes in the environment (stimuli)
what is the second stage in a response to stimuli?
an electrical impulse is then sent to the CNS via sensory neuron
what is the third stage ina response to stimuli?
information arrives at the CNS and is processed
what is the fourth stage in a response to stimuli?
if the body needs to perform a physical activity the CNS sends a message to a muscle or a gland via motor neuron
what is the fifth stage ina response to stimuli?
the motor neuron then makes the effector respond e.g muscle may contract or a gland releases a hormone
what is a reflex action?
rapid, involuntary response that protects the body from harm
what is the first stage in the reflex action?
receptors in the skin detect pain
what is the second stage in the reflex action?
the pain acts as a stimulus for the reflex action
what is the third stage in the reflex action?
an impulse travels from the receptor along the sensory neuron to the spinal cord
what is the fourth stage in the reflex action?
an inter neuron connects the sensory neuron to the motor neuron (reflex arc)
what is the fifth stage in the reflex action?
an impulse leaves the spinal cord in the motor neuron and travels to the muscle
what is the sixth stage in the reflex action?
the muscle responds by contracting and the hand is removed from danger
what are examples of a reflex arc?
- blinking
- pupil of the eye dilating in response to no light
- knee jerk reaction
why are reflexes faster than normal response?
the brain is ‘by-passed’ as no conscious decision is required
