2.1 The Cells of the Nervous System Flashcards
Neurons
Receive information and transmit it to other cells
Nervous system consists of which kind of cells?
Two: neurons and glia
Estimated numbers of neurons in humans
100 billion
Membrane (or plasma menbrane)
The surface of a cell. It’s structure separates the inside of the cell from the outside enviroment.
Nucleus
The structure that contains the chromosomes (DNA; hereditary controll)
Mitochondrion (mitochondria)
The structure that preformes metabolic activities, providing the energy that the cell requires for all other activities
Ribosomes
The sites at which the cell synthesize new protein molecules that provide building materials for the cell
Endoplasmic reticulum
A network of thin tubes that transport newly synthesized proteins and other substances to other locations
Motor neuron
Has its cell body (soma) in the spinal cord. It recives excitation (arousal, sensation) from other neurons throught its dendrites and conduts impulses along its axon to a muscle.
Sensory neuron
Neuron that is highly sensetive to a particular type of stimulation, such as light, sound or touch
Dendritic spines
The short outgrowths that receive incoming information. That information apparently plays a key role in learning and memory
Soma ( or cell body)
Contains the nucleus, ribosomes, and mitochondria. Most metabolic work of the neuron occurs here
Axon
Is the neuron’s information sender, conveying an impulse toward other neurons or an organ or muscle
Myelin sheath
An insulating material that covers vertebrate axons
Nodes of Ranvier
Also known as myelin sheath gaps, are the gaps formed between the myelin sheaths and can generate electrical activity
Presynaptic terminal (or end bulb or bouton/button)
Axons many branches each of which swells at its tip. This is the point from which the axon releases chemicals from one neuron and the next
Afferent axon (afferent starts with “a” as in admit)
Brings information into a structure
Every sensory neuron is this to the rest of the nervous system
Efferent axon (efferent starts with “e” as in exit)
Carries information away from a structure
Every motor neuron is this from the nervous system
Interneuron or intrinsic neuron
A nerve cell found within the CNS that acts as a link between sensory neurons and motor neurons
Glia
Type of cell in the nervous system that, in contrast to neurons, does not conduct impulses over long distances.
The brain has several types with different functions
E.g. Astrocytes, microglia and radial glia
Astrocytes
Is star-shaped glia and wrap around the presynaptic terminals (button) of a group of functionally related axons. It
- sends messages
- remove waste material created when neurons die
- controll the amount of blood flow to each brain area
- dilate the bloodvessels to bring more nutrients into the area of heightend activity in some brain areas
Microglia
Cells that remove waste materials such as viruses, fungi, and other microorganisms.
They function like part of the immune system
Oligodendrocytes (OL-i-go-DEN-dro-cytes)
In the brain and spinal cord
Specialized type of glia that build the myelin sheaths that surround and insulate certain vertebrate axons (same as the Schwann cells)
Schwann cells
In the periphery of the body
Specialized type of glia that build the myelin sheaths that surround and insulate certain vertebrate axons (like the oligodendrocyte)
Radial glia
Guide the migration of neurons and their axons and dendrites during embryonic development. When embryological development finishes most radial glia differentiate into neurons
Blood-brain barrier
The vertebrate brain does not replace damaged neurons (unlike skin cells and blood cells), so to minimize the risk of irreparable brain damage, the body builds a wall along the sides of the brain’s blood vessels. This wall keeps out most viruses, bacteria, and harmful chemicals
Active transport
The brain uses a protein-mediated process that expends energy to pump chemicals from the blood into the brain. These chemicals include things like
- glucose (the brain’s mail fuel)
- amino acids (the building blocks of proteins)
- purines
- choline
- few vitamins
- iron
- certain hormones
Glucose
A sugar
Vertebrate neurons depend almost entirely on this
Thiamine
Vitamin B1 that the body needs to use glucose
Dendrites
Branching fibers that get narrower near their ends. It receives information from other neurons
