The Nervous System Flashcards
What is a stimulus?
A detectable change in the external or internal environment of an organism, for example light or pressure
What is a receptor?
Something that detects a stimulus and converts this to electrical energy to send the information as an electrical impulse to the CNS via neurones, for example photoreceptors and thermoreceptors
What is an effector?
Receives electrical impulses from the CNS and brings about a response eg muscles and glands
What is a sensory neurone?
A neurone that brings neurones from the sense organs or receptors into the CNS
What is a motor neurone?
A neurone that carries impulses from the CNS to the effector organs
What is a relay neurone?
A neurone that receives impulses from certain neurones and passes them on to other appropriate neurones, found in the spinal cord
What does the axon do?
It is an extension of the cytoplasm that transmits impulses away from the cell body to the axon endings
What are dendrites?
They are thin extensions of cytoplasm that receive impulses from other nerve cells and transmit impulses towards the cell body
What is a cell body?
Contains the nucleus and groups of ribosomes in the cytoplasm that synthesise neurotransmitters
What is a synaptic end bulb?
The swelling at the end of the axon where the neurotransmitter is stored
What are Schwann cells?
They surround peripheral neurones in vertebrates and grow around the axon to form a multi-layered myelin sheath
What are nodes of Ranvier?
Intervals in the myelin sheath between adjacent Schwann cells
