Nervous System Flashcards
What is the nervous systems function?
The Nervous system allows us to sense and respond to conditions inside and outside the body.
What germ layer does the nervous system develop from?
The nervous system develops from the ectoderm
What does the CNS consist of?
The Central Nervous System consists of the brain and spinal cord.
What does the PNS consist of?
The Peripheral Nervous System consists of cranial nerves, spinal nerves, and associated ganglia.
What is a cranial nerve and how many are there?
A cranial nerve connects the brain to organs mainly in the upper head / body.
There are 12 pairs of cranial nerves.
What are the spinal nerves and how many are there?
The spinal nerves connect the spinal cord to parts of the body below the head.
There are 31 pairs of spinal nerves.
What are the two subdivisions of the PNS?
The Peripheral nervous system consists of two subdivisions:
- Somatic Nervous System: Voluntary. Will carry impulses to skeletal muscles, tendons, and skin
- Autonomic Nervous System: Involuntary. Impulses are carried to cardiac muscle, smooth muscle, or glands.
What are the three subdivisions of the autonomic nervous system?
The three subdivisions of the autonomic nervous system are:
- sympathetic: Fight or Flight, energy generation. (increased heart rate, tense muscles, blood vessels constrict, all digestion stops)
- parasympathetic: Rest and Digest, calmness. (decreased heart rate, dilated blood vessels, digestion)
- Enteric: controls the secretory and motile functions of the digestive tract
What is a motor neuron?
Also known as efferent, a motor neuron relays signals from the brain or spinal cord to muscle or gland cells.
What is a sensory neuron?
Also known as afferent, a sensory neuron relays signals from the internal and external environment to the CNS.
What is the Pneumonic for Motor and Sensory neurons?
SAME
Sensory - afferent
Motor - efferent
What is a ganglion?
A ganglion is a mass of neuron cell bodies usually found outside the CNS
What is a Neuron composed of?
A neuron is the basic unit of nervous tissue, it is a nerve cell including cell body (soma), axon, and dendrites
What is the difference between an axon and a dendrite?
An axon conducts neural impulses away from the cell body (soma)
A dendrite conduct neural impulses toward the cell body (soma)
How many neurons are in the body?
There are over 100 billion neurons in the body.
How do neurons reproduce?
- THEY DON’T!
- They are so specialized that they are incapable of reproducing themselves.
- Replacing old neurons with new neurons would literally “erase” our memory away, thus there is no mitosis in these cells.
- There ability for regeneration is very poor.
Describe the nucleus and organelles of the neuron
The neuron has the following organelles:
- Nissl bodies ( A specialized neural cell organelle that is essentially a large complex of rough ER and ribosomes)
- mitochondria
- ribosomes
- golgi apparatus
- lysosomes
- The nucleus is large
What are nissl bodies?
Nissl bodies are specialized organelles in the neuron that are composed of large branching Rough ER and ribosomes.
Describe the brains relationship to glycogen
- Glycogen is stored in the brain, but not at the same levels as the liver or skeletal muscle.
- Glycogen is stored in specialized non-neuronal cells called astrocytes.
What are glial cells?
Glial cells surround neurons and provide support and protection for them. Glial cells represent the most abundant cell in the CNS. They include:
- Astrocytes
- Oligodendrocytes
- Schwann Cells
- Microglia
- Satellite cells,
- Ependymal cells
What is an Axon?
- An axon is an extension of a neuron that carries nerve impulses away from the cell body (soma) to target cells such as the nerve, muscle, or gland cells.
- No neuron has more than a single axon.
What is a Dendrite?
A dendrites are highly branched neuronal extensions that bring nerve impulses toward the cell body (soma)
Where are mitochondria located in the neuron?
Mitochondria are found scattered all over the cytoplasm of the cell body, axon, and dendrites, but it is most abundant at the axon terminals
What are axon terminals?
Axon terminals are the end of the axon where neurotransmitters get released into the synapse