Neurons And Glia

Question 1

Neurons

Answer 1

Primary processor of neural information.
* sense changes in the environment
* communicate changes to other neurons
* command the body’s responses to these sensations.

(The chips of the choc chip cookie)

Question 2

Glia (glia cells)

Answer 2

• insulates, supports and nourishes neighboring neurons.
• electrical and chemical functionality

(The dough of the choc chip cookie)

Question 3

Nervous System Components

Answer 3

Neurons - primary processors of neural signals
Nueroglia - support the electrical and chemical functions of neurons
Vascular endothelium - involved in the blood supply to brain tissue

Question 4

Nissl Stain

Answer 4

Stain created by dyes that can stain the nuclei of all cells as well as clumps (nissl bodies) of material surrounding the nuclei of neurons. Realized each region of brain performs a different function.

It distinguishes between neurons and glia and allows study of its cytoarchitecture

(Franz Nissl 1900s)

Question 5

Nissl Bodies

Answer 5

Are aggregation of rough ER

• Staining high concentrations of rRNA
• Under pathological conditions Nissl bodies dissolve or disappear (chromatolysis)

Question 6

Golgi Stain

Answer 6

Stain by soaking brain tissue in a silver chromate solution makes small % of neurons darkly colored in their entirety.

Camillo Golgi (~1873)

Question 7

What did the Golgi Stain show?

Answer 7

Makes a small % of neurons darkly colored in their entirety.
Revealed that the neuronal cell body (region of neuron around the nucleus shown with Nissl stain)

Question 8

Who was Santiago Ramon y cajal?

Answer 8

Histologist/artist used Golgi’s method to come to an opposite conclusion and supported the Neuron doctrine.

Question 9

What theory did Golgi support and what was it?

Answer 9

Reticular theory

Neurites of different cells are fused together to form a continuous reticulum, or network, similar to the arteries and veins of the circulatory system.

Question 10

What theory did Cajal support?

Answer 10

Neuron doctrine: nervous system made up of discrete, individual cells called neuron and communicate with each other across gaps (synapses)

Neurites of different neurons are not continuous with each other and communicate by contact and not continuity.

Question 11

What are the main parts of the prototypical neuron?

Answer 11

The soma (cell body), the dendrites, and the axon, and the axon terminal.

Question 12

The inside of the neuron is separated from the outside by the _____.

Answer 12

Neuronal membrane

Which lies like a circus tent on an intricate scaffolding, giving each part of the cell its special 3D appearance.

Question 13

Cystosol

Answer 13

The Watery fluid inside the cell which is salty, potassium rich solution.

Question 14

Organelles

Answer 14

Membrane enclosed structures within the soma

Question 15

Cytoplasm

Answer 15

Contents within a cell membrane (e.g., organelles, excluding the nucleus)

Question 16

The nucleus

Answer 16

Centrally located ball looking thingy.

Question 17

Chromosomes

Answer 17

Located within the nucleus and contain the genetic material DNA (deoxyribonucleic acid). The DNA in each of your neurons is the same and same as the neurons in the cell of your liver, kidney and other organs.

Question 18

Proteins

Answer 18

Molecules that exist in a wide variety of shapes and sizes, perform many different functions, and bestow upon neurons virtually all f their unique characteristics.

Question 19

Protein synthesis

Answer 19

The assembly of protein molecules, occurs in the cytoplasm

Question 20

Messenger Ribonucleic Acid (mRNA)

Answer 20

Since DNA never leaves the nucleus, an intermediary long molecule mRNA must carry the genetic message to the sites of the protein synthesis in the cytoplasm.

Consists of 4 different nucleic acids strung together in various sequence to form a chain.

Question 21

Amino Acids

Answer 21

The building blocks of proteins. there are 20 different kinds of amino acids.

Question 22

Ribosomes

Answer 22

Protein synthesis occurs at these dense globular structures in the cytoplasm

Question 23

Rough Endoplasmic Reticulum (rough ER)

Answer 23

In neurons, many ribosomes are attached to attack of membrane called rough ER. Rough ER abounds in neurons, far more than glia or most other non-neural cells

Question 24

Free ribosomes

Answer 24

Rough ER is a major site protein synthesis in neurons, but not all ribosomes are attached to rough ER. Many are freely floating and are called ** free ribosomes**

Question 25

Smooth ER

Answer 25

Look like rough ER without the ribosomes. Is heterogenous and performs different functions in different locations. Some smooth ER is continuous with rough ER and is believed to be a site where the proteins that jut out from the membrane are carefully folded, giving them a 3D structure.

Question 26

Golgi Apparatus

Answer 26

The stack of membrane-enclosed disks in the soma that lies farthest from the nucleus. One important functions: sorting of certain proteins that are destined for delivery to different parts of the neuron, such as the axon and dendrites.

Question 27

Mitochondrion

Answer 27

A very abundant, sausage shaped organelle in the soma. The site of cellular respiration. - inhale - Peruvian acid - exhale - 17 ATP

Question 28

ATP adenosine triphosphate

Answer 28

The cell’s energy source/ energy currency of cell. The chemical energy stored in ATP fuels most of the biochemical reactions of the neuron .

Question 29

The cytoskeleton

Answer 29

The scaffolding of the neuron membrane. The bones of the cytoskeleton are the microtubules, microfilament and neurofilaments. Cytoskeleton is not static, and the elements of the cytoskeleton are dynamically regulated, and are in continuous motion.

Question 30

Microtubules

Answer 30

Big (d=20nm) and run longitude and down Neurites, and appear as a straight, thick walled hollow pipe. Strands consist of the protein tubulin . The wall of the pipe is composed, smaller strands that are braided like rope around the hollow core and consist of the protein tubulin. (Pearl wrap)

Question 31

Tubulin

Answer 31

A single tubulin molecule is small and globular; the strand consists of tubulin stuck together like pearls on a string | green tube

Question 32

Microtubule-Associated Proteins (MAPs)

Answer 32

Regulation of microtubule assembly and function. MAPs anchor the microtubules to one another and to other parts of the neuron

Question 33

Dissociated tau proteins are seen in neurodegenerative diseases.

Answer 33

True

Question 34

Microfilaments

Answer 34

Braids of two thin strands that are polymers of the protein actin. (d=5nm) Run longitudinally down the core of the neurites like microtubules and are closely associated with the membrane. **Cell shape influence and Anchored** to membrane by attachments with a mesh-work of fibrous proteins that line the inside of the membrane like a spider wen. | red 2 braid

Question 35

Actin

Answer 35

Actin is one of the most abundant proteins in cells of all types, including neurons, and are believed to play a role in changing cell shape. Actin microfilaments are constantly undergoing assembly and disassembly, and this process is regulated by signals in the neuron.

Question 36

neurofilaments

Answer 36

(d = 10 nm) Structurally resemles bones and ligaments. Each strand of rope consists of individual long protein molecules, making neurofilmaments **mechanically very strong**

Question 37

The Axon

Answer 37

A structure found only in neurons and highly specialized for the transfer of information over distances in the nervous system.

Question 38

Axon Hillock

Answer 38

The axon begins with the axon hillock, which tapers away from the soma to form the initial segment of the axon proper. There is no protein synthesis in axon because no rough ER, so all proteins in axon must originate in the soma

Question 39

Features That Distinguish Between the Axon and the Soma

Answer 39

1. No rough ER extends into the axon, and there are few, if any, free ribosomes in mature axons. 2. The protein composition different 3. Structural differences = functional differences 4. No ER = no protein synthesis so all protein must originate from soma.

Question 40

Axon Collaterals

Answer 40

Axons often branch, and these branches can travel long distances to communicate with different parts of the nervous system.

Question 41

Recurrent Collaterals

Answer 41

Occasionally, an axon collateral returns to communicate with the same cell that gave rise to the axon or with the dendrites of neighboring cells. These axons branches are called recurrent collaterals

Question 42

The Parts of an Axon

Answer 42

All axons have a beginning(**the axon hillock**), a middle(**the axon proper**), and an end. The end is called the **axons terminal** or **terminal bouton**(French for "button"),

Question 43

Axon Terminal

Answer 43

The terminal is a site where the axon comes in contact with other neurons (or other cells) and passes information on to them.

Question 44

The point of contact between the axon and another neuron (or other cell) is called:

Answer 44

synapse

Question 45

Terminal Arbor

Answer 45

Sometimes axons have many short **branches at their ends**, and each branch forms a synapse on dendrites or cells bodies in the same region.

Question 46

The cytoplasm of the axon terminal differs from that of the axon in several ways...

Answer 46

1. Microtubules do not extend into the terminal. 2. The terminal contains numerous small bubbles of membrane, called **synaptic vesicles**. 3. The inside surface of the membrane that faces the synapse has a particularly lot covering of **proteins**. 4. The axon terminal cytoplasm has **numerous mitochondria**, indicating a high energy demand.

Question 47

Two sides of synapses

Answer 47

presynaptic (axon terminal) and postsynaptic (dendrite or soma of another neuron). These names indicate the usual direction of information flow from "pre" to "post".

Question 48

synaptic cleft

Answer 48

space between presynaptic and postsynaptic membranes

Question 49

Synaptic Transmission

Answer 49

The transfer of information at the synapse from one neuron to another

Question 50

Neurotransmitter

Answer 50

Neurotransmitter is a chemical signal, is stored in and released from the synaptic vesicles within the terminal. At most synapses, information in the form of **electrical impulses** traveling down the axon is converted in the terminal into a **chemical signal** that crosses the synaptic cleft. On the postsynaptic membrane, this chemical signal is converted again into an electrical one.

Question 51

Axoplasmic Transport

Answer 51

The movement of material down the axon from the soma.

Question 52

Anterograde Transport

Answer 52

Material is enclosed within vesicles, which then "walk down" the microtubules of the axon. The "legs" are provided by a protein called kinesin, and the process is fueled by ATP. Kinesin moves material only from the soma to the terminal.

Question 53

Retrograde Transport

Answer 53

Movement of materials up the axon from the terminal to the soma. Is believed to provide signals to the soma about changes in the metabolic needs of the axon terminal. The "legs" for retrograde transport are provided by the protein dynein.

Question 54

Dendritic Tree

Answer 54

The dendrites of a single neuron are collectively called a dendritic tree. Each branch of the tree is called a dendritic branch.

Question 55

Dendrite Functions

Answer 55

Because dendrites function as the antennae of the neuron, they are covered with thousands of synapses

Question 56

The dendritic membrane under the synapse (the postsynaptic membrane) has many specialized protein molecules called ________ that detect the neurotransmitters in the synaptic cleft

Answer 56

receptors

Question 57

Dendritic Spines

Answer 57

The dendrites of some neurons are covered with specialized structures called dendritic spines that receive some types of synaptic input. (the know shaped thingy)

Question 58

Dendritic Spine Function

Answer 58

They believed to isolate various chemical reactions that are triggered by some types of synaptic activation. Spine structure is sensitive to the type and amount of synaptic activity.

Question 59

Dendrite Cytosplasm

Answer 59

The cytoplasm of dendrites most resemble that of axons. It is filled with cytosckeletal elements and mitochondria. Difference is that polyribosomes can be observed in dendrites, often right under spines, so there is protein synthesis.

Question 60

Classification of Neuronal Structure Based on Number of Neurites

Answer 60

A neuron with a single neurite is said to be **unipolar**. If there are two neurites, the cell is **bipolar**, and if there are three or more, the cell is **multipolar**. Most neurons in the brain are multipolar.

Question 61

Classification of neurons based on structure

Answer 61

* number of neurites * dendrites * connections * axon length

Question 62

Classification of Neurons Based on Dendritic Tree Structure

Answer 62

two broad classes of dendritic tree: stellate cells (star shaped) and pyramidal cells (pyramid shaped)

Question 63

Primary Sensory Neurons

Answer 63

Information is delivered to the nervous system by neurons that have neurites in the **sensory surfaces** of the body, such as the skin and the retina of the eye.

Question 64

motor neurons

Answer 64

Neurons that have axons that form synapses with the muscles and command movements

Question 65

Interneurons

Answer 65

Neurons in the nervous system that form connections with other neurons

Question 66

**Golgi Type I **Neurons or Projection Neurons

Answer 66

Neurons that have long axons that extend from one part of the brain to the other. Pyramidal cells usually have long axons that extend to other parts of the brain and are therefore Golgi Type I neurons

Question 67

**Golgi Type II **Neurons or Local Circuit Neurons

Answer 67

Neurons that have short axons that do not extend beyond the vicinity of the cell body. Stellate cells have axons that never extend beyond the cerebral cortex and are therefore Golgi Type II neurons

Question 68

Green Fluorescent (GEP)

Answer 68

When illuminated with the appropriate wavelength of light, the GEP fluoresces bright green, allowing visualizaion of the neuron in which it is expressed

Question 69

Astrocytes

Answer 69

The most numerous glia in the brain. These cells fill most of the spaces between neurons. An essential role of astroyctes is regulating the chemical content of this extracellular space.

Question 70

Functions of Astrocytes

Answer 70

* Found primarily in gray matter * Closely associated with neuronal cell bodies, dendrites and synapses * Help maintain ionic balance of extracellular fluids * Take-up and process neurotransmitters from synaptic clefts * Assist in the formation of new synapses and circuits * Contribute to the formation of the *blood brain barrier* and brain ependymal (ventricular) barrier * Contribute to the formation of scars following injury

Question 71

BBB

Answer 71

Selective permeability barrier that protects the brain from potentially harmful substances in the bloodstream while allowing essential nutrients to pass through.

Question 72

Disease associated with astrocytes // bbb

Answer 72

Parkinson’s & Huntington’s Disease Amyotrophic Lateral Sclerosis (ALS)

Question 73

Myelinating glias that provide layers of membrane that insulate axon are

Answer 73

oligodendroglial and Schwann cells (membrane is called myelin)

Question 74

Ogligodendroglial

Answer 74

Only in the **central nervous system** (brain and spinal cord) One ogligodendroglial cell contributes myelin to **several** axons.

Question 75

Schwann cell

Answer 75

Only in the **peripheral nervous system** (parts outside the skull and vertebral column). One Schwann cell myelinates only a **single** awon

Question 76

node of Ranvier

Answer 76

A short length where the axonal membrane is exposed because the myelin sheath is interrupted periodically

Question 77

Ependymal Cells

Answer 77

Special cells that line fluid-filled ventricles within the brain and play a role in directing cell migration during brain development

Question 78

Microglia

Answer 78

A class of cells that function as phagocytes to remove the debris left by dead or degenerating neurons and glia

Question 79

Microglial cells

Answer 79

glial cell in the central nervous system (CNS) that function as the brain’s immune cells. They play a crucial role in maintaining brain health by monitoring the environment, responding to injury, and defending against pathogens.

Question 80

Microglial Cells and Disease:

Answer 80

Alzheimer’s Disease Schizophrenia, Autism, depression

Question 81

Oligodendrocytes

Answer 81

glial cell in the central nervous system (CNS) that play a crucial role in supporting neurons by producing myelin, the insulating sheath that wraps around axons to enhance signal transmission.

Question 82

Oligodendrocytes and Disease:

Answer 82

Multiple sclerosis Schizophrenia, Bipolar Disorder