The Nervous System Flashcards
2 types of nervous system cells
Neurons and glial cells
Neurons
Specialized cells in the nervous system that control behavior, convey sensory information, and signal movement. Their main function is communicate, and they communicate with other neurons and glial cells using neurotransmitters
Glial cells
Support the function of neurons
4 major components of neurons
A soma, dendrites, axon, axon terminal
Soma of neuron
The cell body that contains the nucleus (and DNA). Components in the soma support a neuron’s basic physiological processes. Also contains the mitochondria and the endoplasmic reticulum (ribosomes)
Dendrites
Neurons have many dendrites that branch off of the soma. Dendritic spines grow along the dendritic branches. The dendritic spines and the membranes of dendrites contain proteins called receptors that are activated by neurotransmitters
Axons
Release neurotransmitters for signaling with other neurons. There is usually only one axon that is opposite from the dendrites. The axon begins at the axon hillock. The axon is like a wire that transmits an electrical signal
Axon hillock
The part of the soma where the axon begins
Axon terminal
The axon ends with multiple branches called axon collaterals, which contain the axon terminals. They are also called presynaptic terminals. They contain vesicles of neurotransmitters
Postsynaptic terminal
A part of a dendrite that contains receptors for neurotransmitters
Synaptic cleft
The small space between the axon terminal and the postsynaptic terminal
Synapse
The components that make up the connection between neurons- the axon terminal, postsynaptic terminal, and synaptic cleft
Myelin
Fatty material that acts as insulation for the axon and speeds up action potentials through saltatory conduction
Node of Ranvier
Exposed portion of axon, allows the cell to interact with the extracellular fluid
The language of the brain is
Electrochemical
Interneuron
A neuron with the soma and axon found in the same structure. They transmit signals between sensory and motor neurons and are typically located in the brain and spinal cord
Sensory neurons
Convey sensory information via axons to the central nervous system. They are considered afferent neurons because their axons are going to another structure
Motor neurons
Convey motor information via axons from the central nervous system. They are considered efferent neurons because their axons are coming from a structure
3 types of glial cells
- Oligodendrocytes
- Astrocytes
- Microglial cells
Central nervous system
brain and spinal cord. Sensory activities, memory, and emotions
Peripheral nervous system
connects the CNS with the rest of the body. There are multiple divisions
Broadly, what is the main function of neurons?
Communicating messages
Node of Ranvier
Gaps between the myelin on the axon, where the axon is exposed to extracellular space. The nodes contain sodium channels that can open in response to an action potential and rejuvenate the action potential as it travels down the axon. The action potential slows down at these nodes and speeds up to get through the myelinated sections of the axons
Saltatory conduction
How the action potential travels down the axon. Action potentials slow down as they reach the nodes of Ranvier and speed up as the reach the myelinated sections. This makes it look like the action potential is jumping from node to node. Think of “saltar” in Spanish
Astrocytes
Glial cells that form the blood brain barrier, respond to injury, and regulate neurotransmission. They support neuronal function by acting at synapses during neurotransmission
Oligodendrocytes
Glial cells that form myelin by extending their membranes around axons (in the CNS only). They also hold cells in place. Oligodendrocytes migrate to a certain region of the brain in the juvenile stage but do not migrate after that
Schwann cells
Produce myelin in the peripheral nervous system
Myelin
An insulating layer that surrounds the axons of neurons intermittently. It is mostly composed of lipids. It helps prevents current from leaking out through the axonal membrane, which also prevents the action potential from decaying as it travels down the axon. Myelinated axons conduct action potentials more quickly and efficiently
Microglia
A type of glial cell. Removes cellular waste through phagocytosis. A major part of the immune system in the CNS. There are 2 types- M1 and M2
Multiple sclerosis
Symptoms include motor dysregulation, paralysis, and other symptoms- all result from the degeneration of myelin sheaths
How do astrocytes form the blood brain barrier?
They force endothelial cells to fit tightly together
Endothelial cells
A single layers of cells that lines all blood vessels and lymphatic vessels. It allows your blood and tissues to interact
M1 microglial cells
Release chemicals that promote inflammation. Inflammation is a protective response, but it can damage the blood brain barrier if long term. Inflammation may weaken the blood brain barrier and allow in cells that damage neurons
M2 microglial cells
Release chemicals that reduce inflammation and promote growth and development of cells
What is the broad function of glial cells?
To support the function of neurons. They are one of 2 types of cells found in the brain and outnumber neurons in some regions
Anterior
The front portion of the brain
Posterior
The back portion of the brain
Ventral
The bottom of the brain, which faces toward the stomach- different from inferior because it’s more toward the front
Dorsal
The top of the brain- different from superior because it’s more toward the back