Important Vocabulary (highlighted in the handout): Stimulus, neurons, dendrites, neurotransmitters, axon, myelin, action potential, graded potential, transmembrane potential, neuroglia, cerebrum, spinal cord
What is the central nervous system? It’s a system which consists of the nerves in the brain and spinal cord. This system only makes up about 3% of a human’s body weight but serves a vital function, gathering information about and reacting to its environment and any stimulus.
Don’t Shoot the Messenger
Much of the CNS is made up of neurons, or nerve cells. Each neuron has a cell body, which includes a soma with a nucleus, a nucleolus, a cytoplasm called the perikaryon (which make up the CNS’ grey matter), and dendrites, wide branching extensions which make up about 80-90% of the neuron’s total surface area (dendrites are also known as white matter). These dendrites are like antennae which receive signals from other cells …show more content…
Their size ranges from 1 mm to 1 m, and each axon synapses with 1 000 to over 10 000 neurons. Each axon has a cytoplasm called an axoplasm, which contains neurofibrils, neurotubules, small vesicles, lysosomes, and mitochondria. It cannot create proteins because it has no rough endoplasmic reticulum, and a plasma axolemma (cell membrane) of neuroglia or interstitial fluid surrounds the entire axon to protect it. In a multipolar neuron, the axons’s base is attached to the soma at a thickened cone-shaped region called the axon hillock. Nerve impulses occur between the axon hillock and initial segment where action potentials begin (an area called the “trigger zone”). Sometimes axons have side branches called collaterals, which usually branch off at a 90 ° angle and allow a neuron to communicate with many cells at once. Each axon branch ends in a thin extension series called telodendria, which ends at the synaptic terminals. Me Oh
What is the central nervous system? It’s a system which consists of the nerves in the brain and spinal cord. This system only makes up about 3% of a human’s body weight but serves a vital function, gathering information about and reacting to its environment and any stimulus.
Don’t Shoot the Messenger
Much of the CNS is made up of neurons, or nerve cells. Each neuron has a cell body, which includes a soma with a nucleus, a nucleolus, a cytoplasm called the perikaryon (which make up the CNS’ grey matter), and dendrites, wide branching extensions which make up about 80-90% of the neuron’s total surface area (dendrites are also known as white matter). These dendrites are like antennae which receive signals from other cells …show more content…
Their size ranges from 1 mm to 1 m, and each axon synapses with 1 000 to over 10 000 neurons. Each axon has a cytoplasm called an axoplasm, which contains neurofibrils, neurotubules, small vesicles, lysosomes, and mitochondria. It cannot create proteins because it has no rough endoplasmic reticulum, and a plasma axolemma (cell membrane) of neuroglia or interstitial fluid surrounds the entire axon to protect it. In a multipolar neuron, the axons’s base is attached to the soma at a thickened cone-shaped region called the axon hillock. Nerve impulses occur between the axon hillock and initial segment where action potentials begin (an area called the “trigger zone”). Sometimes axons have side branches called collaterals, which usually branch off at a 90 ° angle and allow a neuron to communicate with many cells at once. Each axon branch ends in a thin extension series called telodendria, which ends at the synaptic terminals. Me Oh