Neurons and the Nervous Systems Flashcards
Neurons and Mitosis
Neurons are the smallest living parts of the nervous system.
They cannot be replaced by mitosis (amitotic).
Parts of a Neuron
Dendrite: Receives the stimulus and picks up information.
Cell Body: Nourishes the cell and produces the nerve impulse.
Axon: Conducts impulses.
Myelin: Acts as insulation and aids in conduction.
Nerve Endings: Substances that stimulate the dendrites of the next neuron, muscle, or gland.
Communication at a Synapse x
An electrical impulse stimulates the release of neurotransmitters in the nerve endings.
Neurotransmitters stimulate the dendrites of the next neuron.
The synapse is the contact zone where signals are transferred between neurons.
Communication occurs through chemical, electrical, and chemical processes.
Propagation of Nerve Impulses
Nerve impulses always travel in one direction.
The impulse travels from the cell body through the axon to the dendrites of the next neuron.
Central Nervous System (structures involved)
Encephalon (cerebrum, cerebellum, and brain stem)
Spinal Cord
Peripheral nervous system
All of the nerves in the body - 12 pairs of cranial nerve and 31 pairs of spinal nerves
What is a nerve?
A nerve is a bundle of axons
Types of nerves
Sensory, motor, and mixed nerves
Structures involved in Voluntary actions
The brain
The spinal cord
Motor nerves
Muscles
Structures involved in Involuntary Actions (Reflex)
Sensory organs
Sensory nerves
Spinal cord
Motor nerves
Muscles
Components of a Reflex Arc (e.g., hand removal from a hot surface)
Processor: Detects a stimulus (HEAT).
Sensory nerve brings the stimulus to the spinal cord.
Spinal cord processes this information.
Spinal cord sends out a nerve impulse via the motor nerves to the affected area.
The muscle in the area reacts and contracts, raising the hand.
Advantage of Reflex Reaction
Reflex reactions protect the body from potential harm.
