Cells of the Nervous System Flashcards
Central Nervous System (CNS)
- comprised of the brain and spinal cord
- All encased with bone- all protected with bone like a helmet
- These are so well protected because if you damage the brain or spinal cord they won’t grow back
(no regrowth possible if you sever a nerve, could get brain plasticity. Where other areas of the brain take over and do the function) - encased within the skull and spinal column.
Peripheral Nervous System (PNS)
- comprised of nerve tissue located outside of the brain and spinal cord.
- Regrowth can happen in this system(nerves can grow back if they are severed)
Soma
the cell body of a neuron which contains the nucleus (contains the DNA which controls the function of the neuron,nucleolous)
Dendrite
A branched treelike structure attached to the soma of a neuron; receives information from the terminal button of other neurons.(way they get info from other neurons tissue, sensory connections)
Axon hillock
Site of summation for incoming information(info in forms of changes in electrical charge, if enough excitation happens then an action potential is propaganded)
Axon
The long, thin cylindrical structure that conveys information from the soma of a neuron to its terminal button
Terminal button
The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.(allow connections with neighboring neurons and send info to that neuron)
Synapse
A junction between the terminal button of an axon and the membrane of another neuron.
What is the basic structure of a neuron?
soma dendrite axon hillock axon terminal button synapse
What are the basic components of a neuron?
Input, integration(axon hillock), conduction, output (may release neurotransmitters or flex muscle or connect to blood vessels and capillaries)
Terminal Buttons
end point of axons – transform electrical signal from the axon into a chemical signal sent across the synaptic cleft.
Neurotransmitter
A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron
Bipolar neurons
a neuron with one axon and one dendrite attached to its soma(sensory)
Multipolar neurons
A neuron with one axon and many dendrites. Most common in CNS.
Unipolar neurons
A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system.
Somatosensory (touch, pain)
How can neurons be classified?
shape: bipolar,multipolar and unipolar
size- large and small
function
Describe Classification of Neuron by size
Large- pyramidal
Small- granular
Sensory neuron
transmits sensory information to the central nervous system.(press on your skin and a signal is sent to you brain that your being touched)
Motor neuron
controls the contraction of a muscle or the secretion of a gland.
if your being touched and you don’t like your being touched you can move your arm away)
Interneuron
located entirely within the central nervous system.
Connecting everything, allow for the free flow of info from one neuron to the next
Can connect a sensory and motor neuron
i
- in your ear you have a cochlea which is filled with liquid and little cilia which vibrate depending on the noise your hearing and those get sent to a neuron in the brain
Action potential
electrical signal down the axon
Membrane
A structure consisting primarily of lipid (fat-like) molecules that makes up the outer boundary of a cell.
Cytoplasm
The viscous, semi-liquid substance inside the cell- Goop
Nucleus
Contains all of the genetic material that the neuron needs to function (chromosomes).
Mitochondria
Double membrane. Contain their own DNA and replicate independently of cells. Converts nutrients into ATP.
Adenosine triphosphate (ATP)
The cell’s primary energy source.
Describe how mitochondria arose
Mitochondria represent formerly free-living bacteria that were taken inside another cell around 1.5 billion years ago.(symbiotic relationship)
double membrane and their own DNA
you inherit your mitochondrial DNA from your mother.
Endoplasmic reticulum
storage reservoir and channel for transporting chemicals through the cytoplasm appears in two forms…
Rough ER
Produces proteins that are either transported out of the cell (attached) or distributed around cytoplasm (free-floating).
Smooth ER
lipids produced here.
Golgi apparatus
Generates and secretes neurochemicals (exocytosis). Wrapping and packing.
Lysosome
An organelle surrounded by membrane; contains enzymes that break down waste products.(like recycling plants)
Cytoskeleton
Matrix of protein strands that give the neuron its shape.
Microtubule
A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within the cell.
Axoplasmic transport
An active process by which substances are propelled along microtubules that run the length of the axon.
Anterograde
In a direction along an axon from the cell body to the terminal buttons. Fast (500 mm/day)
Retrograde
In a direction along an axon from the terminal buttons(end feet) toward the cell body. Slower (half as fast)
Retaking up neurotransmitter which is recycled
kinesin
Kinesin molecules “walk” like an inchworm down a microtubule, carrying their cargo from the soma to the terminal buttons.
Moves things down from the cell body to the end foot
Neurons
(grey matter) – electro-chemical transfer of information from one region to another.
Glia
(white matter) = Greek for glue; outnumber neurons 10:1, supporting cast.
What are the functions of gila?
- modify chemical milieu.
- guide neurons to final site during development.
- remove dead neurons after damage.
- Phagocytosis
- serve some nutritive needs for neurons
-maintain the blood – brain barrier.
Phagocytosis
eat up invaders or other tissue that’s not supposed to be there and get them out.
astrocytes
type of glia
surround neurons and contact blood vessels via end-feet.
allow transmission of ions across vascular wall and forms blood-brain barrier.
provides physical support.
provide nourishment.
maintain chemical milieu(makeup) surrounding neurons.
What do astrocytes supply neurons with?
supply neurons with glucose obtained from capillaries.
glucose is processed within the astrocyte to produce lactate which is then released into the extracellular fluid surrounding the neuron.
the lactate is taken up by the neuron for use by mitochondria to produce atp
Camillo Golgi-figured this out
Oligodendrocytes
type of glia
produce myelin, the fatty sheath that covers the axon – can myelinate multiple axons in Central Nervous System.
Can produce up to 50 segments of myelin.
- Not all axons are myelienated- depends on their role and the distance the signal must travel
Schwann cells
type of glia
involved in production of myelin in peripheral nervous system – only myelinates a single nerve.
also digest dead axons and provide process for regrowth.
What is myelin?
Myelin acts as insulation- axon is like electrical cable which has insulation around it so the signal doesn’t degrade too much until it gets to the source, one thing myelin does is insulate signal to allow for electrical signal to travel more efficiently
Myelination speeds up the conduction of the neural signal
The fat in myelin makes “white-matter” white.
Nodes of Ranvier
gaps in the myelin sheath
unmyelinated areas of axon
myelin sheath (tubular) is not continuous along the axon (sections of ≈ 1-2µm)
fibre tract
– when a group of cells send their signal to one specific place this is known as a…
(e.g. the biggest fiber tract is corpus callosum).
What is the Blood-Brain Barrier ?
Regulates the chemicals that can enter the CNS from the blood. Prevents many low-life forms, such as toxins, that make it into the blood stream from infecting the brain.- things can get by
Helps the CNS maintain the proper composition of fluids inside and outside the neurons.
selectively permeable – some things can get through.
the chemical milieu inside and outside the neuron is delicate – the blood brain barrier protects the balance of chemicals.
not uniform throughout-– area postrema
area postrema
maintains a weak blood-brain barrier which allows for the detection of toxins in the blood stream and triggers vomiting response
How can the BBB be broken down?
hypertension (high blood pressure): high blood pressure opens the BBB
The increased pressure is opening up the gaps more
development: the BBB is not fully formed at birth.
hyperosmolarity: a high concentration of a substance in the blood
microwaves & radiation
infection: exposure to infectious agents
trauma, ischemia, inflammation, pressure: injury to the brain
Microglia
damaged neural tissue is invaded by microglia which then remove dead cells
protect the brain from invading micro-organisms
1 ) ________ neurons gather information from the environment related to light, odors, and contact with objects.
A) Sensory
B) Motor
C) Inter-
D) Relay inter-
E) Local inter-
A
The ________ is defined as comprised of the brain and spinal cord.
A) peripheral nervous system
B) central nervous system
C) enteric nervous system
D) human nervous system
E) local circuit system
B
3) The ________neuron is the most common nerve cell type in the central nervous system.
A) apolar
B) multiglial
C) unipolar
D) bipolar
E) multipolar
E
4 ) Nerve damage that impaired the ability to sense temperature and touch might be expected to
involve which type of nerve cell?
A) bipolar neurons
B) multipolar neurons
C) unipolar neurons
D) apolar neurons
E) B and D are correct.
C
5 ) Which of the following is NOT a function of the glial cells?
A) provision of nutrition to the brain
B) removal of physical debris from the brain
C) physical support of neurons
D) insulation of nerve cells from each other
E) the conduction of action potentials
E
6 ) Which of the following cells are important for the supply of energy for neurons?
A) Schwann cells
B) phagocytes
C) dendrocytes
D) astrocytes
E) nanotubules
D
Input zone
(dendrites, cell body, nucleus)
Integration zone
(axon hillock)
Conduction zone
(axon)
Output zone
axon terminals)
Describe how information flows down a neuron
- connections from other axons (terminal buttons of neuron connecting with the dendrites of another neuron)
Send information down the cell body through the dendrites
At the cell body things summate at axon hillock
If powerful enough then continuing of info flowing down to end feet where neurotransmitters can be released and communication with a neighboring neuron happens
What are the 4 main types of glial cells?
- astrocytes
- oligodendrocytes
- Schwann cells
- microglia
