Chapter 3: What are the functional units of the Nervous system? (Non mcq questions).

Question 1

What do cells do?

Answer 1

Make proteins. They use the proteins they produce to play a dynamic role in orchestrating our behavior

Question 2

How did the first anatomists highlight individual cells in the nervous system?

Answer 2

To make it firm, they soaked it in formaldehyde, which removes the water from the tissue. The firmed-up tissue was then sliced in thin sheets that could be placed under a microscope for viewing. Scientists continue to develop ways of visualizing cells so that an individual cell or its parts stand out from the dense background of surrounding cells. Visualization is aided by using dyes that either color an individual cell completely, color some of the cells’ components, or, as described in Research Focus 3-2, “Brainbow: Rainbow Neurons,” color the cell only when it is engaged in a particular activity.

Question 3

What does Brainbow allow?

Answer 3

By visualizing living brain tissue in a dish, brainbow provides a method of examining changes in neural circuits with the passage of time.

Question 4

What is Cajal Neuron theory?

Answer 4

Neurons are the functional units of the Nervous system

Question 5

What does an Axon do?

Answer 5

The main “root” of a Neuron is the single axon (Greek for “axle”) that carries messages to other neurons

Question 6

What does a Dendrite do? How many does a Neuron have?

Answer 6

A neuron’s branching extensions, or dendrites (from Greek for “tree”), collect information from other cells.

dendrite Branching extension of a neuron’s cell membrane that greatly increases the surface area of the cell and collects information from other cells. Neurons may have 1-20 dendrites.

Dendrites in turn may have, many, branches and the spines on the branches may number in the thousands. Dendrites collect information from other cells and these spines are the point of contacts with other neurons.

The extent of a cells branches corresponds to its information processing capacity.

Question 7

What is the Soma?

Answer 7

The cell body (soma) core region of the cell containing the nucleus and other organelles for making proteins. Where the information in processed.

Question 8

What do Neurons do?

Answer 8

As the information-processing units of the nervous system, neurons acquire information from sensory receptors, pass the information on to other neurons, and make muscles move to produce behaviors. They encode memories and produce our thoughts and emotions. At the same time, they regulate body processes such as breathing, heartbeat, and body temperature, to which we seldom give a thought.

Question 9

What can a group of Neurons be likened to?

Answer 9

A crowd cheering.he loss of a neuron or two is no more noticeable than the loss of one or two voices from a cheering crowd. It is the crowd that produces the overall sound, not each person. In much the same way, although neuroscientists say that neurons are the information-processing units of the brain, they really mean that large teams of neurons serve this function.

Question 10

What are the two important properties of Neurons?

Answer 10

Their plasticity and longevity.

Question 11

What is an axon hillock, an axon collateral and teleodendria?

Answer 11

Juncture of soma and axon where the action potential begins.

Axon collateral: Branch of an Axon.

teleodendria: Smaller branches or end branch of an axon.

Question 12

What is the Dendritic spine?

Answer 12

Protrusion from a dendrite that greatly increases the dendrite’s surface area and is the usual point of dendritic contact with the axons of other cells.

Question 13

What is the Terminal Button?

Answer 13

Knob at the tip of an axon that conveys information to other neurons. Does not usually touch another cell but “almost connects”.

Question 14

What is a Synapse?

Answer 14

“The almost connection” between cells. It’s the junction between one cell and another that enables information transfer between neurons.

Question 15

What does a shape of a Neuron mean?

Answer 15

The shape of a neuron influences how it collects and channels information.

Question 16

What are sensory Neurons designed to do?

Answer 16

They bring information from sensory receptors into the spinal cord and brain.

Sensory neurons are the simplest neurons structurally. A bipolar neuron found in the retina of the eye, for example, has a single short dendrite on one side of its cell body and a single short axon on the other side. Bipolar neurons transmit afferent (incoming) sensory information from the retina’s light receptors to the neurons that carry information into the visual centers of the brain.

A sensory neuron that is a bit more complicated is the somatosensory neuron, which brings sensory information from the body into the spinal cord. Structurally, the somatosensory dendrite connects directly to its axon, so the cell body sits to one side of this long pathway.

Question 17

What do Interneurons do?

Answer 17

Association neuron interposed between a sensory neuron and a motor neuron; thus, in mammals, interneurons constitute most of the neurons of the brain.

Also called association cells because they link up sensory and motor neurons, interneurons branch extensively, the better to collect information from many sources. A major difference between animals with small brains and animals with large brains is that large-brained animals have more interneurons. A specific interneuron, the stellate (star-shaped) cell, is characteristically small, with many dendrites extending around the cell body. Its axon is difficult to see in the maze of dendrites.

Question 18

What is a pyramidal cell?

Answer 18

Distinctive interneuron found in the cerebral cortex. Carries information from the cortex to the rest of the brain and spinal cord.

Question 19

What is a Purkinje cell?

Answer 19

A distinctive neuron found in the Cerebellum. It carries information from the cerebellum to the brain and spinal cord.

Question 20

What are Motor Neurons?

Answer 20

Neuron that carries information from the brain and spinal cord to make muscles contract.

To collect information from many sources, motor neurons have extensive networks of dendrites, large cell bodies, and long axons that connect to muscles. Motor neurons are located in the lower brainstem and spinal cord. All efferent (outgoing) neural information must pass through them to reach the muscles.

Question 21

Neurons with large cell bodies have (1) and neurons with small small cell bodies have (2).

Answer 21

(1) Long extensions. (2) short extensions. Long extentsions carry information to distant parts of the nervous system and short extensions are engaged in local processing. Eg the dendritic tips of some somomatosensory neurons are located in the big toe and their axons are in the base of your brain.

Pyramidal cells and motor neurons are examples of long extensions.

Question 22

How do Neurons communicate?

Answer 22

Excitation and inhibition.Neurons “excite” (turn them on) or “inhibit” (turn them off) other neurons. “Yes” signals are excitatory and “no” signals are inhibitory.

Each neuron receives thousands of excitatory and inhibitory signals every second.

The neuron’s response to all those inputs is democratic: it sums them. A neuron is spurred into action only if its excitatory inputs exceed its inhibitory inputs. If the reverse is true and inhibitory inputs exceed excitatory inputs, the neuron does not activate.

Question 23

What do Glial cells do?

Answer 23

Glial cells (from the Greek word for “glue”) are often described as the support cells of the nervous system.

Nervous-system cells that provides insulation, nutrients, and support and that aids in repairing neurons and eliminating waste products.There are 5 types of them.

Although they do not transmit information themselves, they help neurons carry out this task, binding them together (some do act as glue) and providing support, nutrients, and protection, among other functions

Question 24

What do Ependymal cells do?

Answer 24

makes and secretes cerebrospinal fluid; found on the walls of the ventricles in the brain.

Question 25

What do Astrocyte cells do?

Answer 25

• Keep Neurons healthy.
• Form Blood brain barrier.
• Enhance brain activity.

Star-shaped glial cell that provides structural support to neurons in the central nervous system and transports substances between neurons and blood vessels. They secrete chemicals that keep neurons and heal them if injured.

They play a role cotributing to the partion of blood vessels and the brain: the blood-brain barrier

Yet another important function of astrocytes is to enhance brain activity. When you engage in any behavior, whether it’s reading or running, the neural network responsible for that behavior requires more fuel in the form of oxygen and glucose. In response to the activity in the network, the blood vessels that supply the network expand, allowing greater oxygen- and glucose-carrying blood flow. But what triggers the blood vessels to dilate? This is where the astrocytes come in. They receive signals from the neurons that they pass on to the blood vessels, stimulating them to expand and so provide more fuel.

Question 26

What does Cerebrospinal fluid do?

Answer 26

Cerebrospinal fluid serves several purposes. It acts as a shock absorber when the brain is jarred, it provides a medium through which waste products are eliminated, it assists the brain in maintaining a constant temperature, and it is a source of nutrients for parts of the brain located adjacent to the ventricle

Question 27

What is hydrocephalus?

Answer 27

Happens in babies. Happens when CSF flow is blocked. Causes swelling and eventual mental retardation or death. Shunts allow the CSF to be drained.

Question 28

What is a Tumor? What are the symptoms? Their incidence rate?

Answer 28

A tumor is a mass of new tissue that undergoes uncontrolled growth and is independent of surrounding structures.

The incidence of brain tumors in the united states is about 20 per 100,000 according to the central Brain tumor registry of the united states (2011).

Brain tumors do not grow from neurons but rather from glia or other supporting cells. the rate of growth depends on the type of cell affected.

Symptoms:the earliest symptoms usually result from increased pressure on surrounding brain structures and can include headaches, vomiting, mental dullness, changes in sensory and motor abilities, and seizures .

many symptoms depend on the precise location of the tumor. the three major types of brain tumors are classified according to how they originate

Question 29

What are the three types of Tumours and symptoms?

Answer 29

1: Gliomas arise from glial cells, are slow growing, not often malignant, and relatively easy to treat if they arise from astrocytes. in contrast, gliomas that arise from the precursor blast or germinal cells that grow into glial cells are much more often malignant, grow more quickly, and often recur after treatment.
2: Meningiomas, the type of tumor that r. J. had, attach to the meninges and so grow entirely outside the brain. These tumors are usually well encapsulated, and if they are located in places that are accessible, recovery after surgery is good.
3: Metastatic tumor becomes established by a transfer of tumor cells from one region of the body to another (which is what the term metastasis means). typically, metastatic tumors are present in multiple locations, making treatment difficult. symptoms of the underlying condition often first appear when the tumor cells reach the brain.

Question 30

How do you treat a Tumor?

Answer 30

1. Treatment for a brain tumor is usually surgery, which also is one of the main means of diagnosing the type of tumor.
   2: radiotherapy (treatment with X-rays) is more useful for destroying brain tumor cells.

chemotherapy, although common for treating tumors in other parts of the body, is less successful in the treatment of brain tumors because getting the chemicals across the blood–brain barrier is difficult.

Question 31

What is the blood brain barrier?

Answer 31

A protective partition between blood vessels and the brain.

Astrocytes attach to the blood-vessel cells, causing them to bind tightly together. These tight junctions prevent an array of substances, including many toxins, from entering the brain through the blood-vessel walls. The molecules (smallest units) of these substances are too large to pass between the blood-vessel cells unless the blood–brain barrier is somehow compromised.

But the downside to the blood–brain barrier is that many useful drugs, including antibiotics such as penicillin, cannot pass through it to the brain either. As a result, brain infections are very difficult to treat. Scientists can bypass the blood-brain barrier and introduce drugs into the brain by inserting small tubes that allow the delivery of a drug directly to a targeted brain region.

Question 32

What do Microglia do? What is Phagocystosis?

Answer 32

Glial cells that originate in the blood, aid in cell repair, and scavenge debris in the nervous system.

Microglia monitor the health of brain tissue and play the role of its immune system. They identify and attack foreign tissue. When brain cells are damaged, microglia invade the area to provide growth factors that aid in repair. There are several different kinds of microglia, and microglia take different shapes depending upon the role they are performing.

Several different types of them.
Microglia engulf any foreign tissue and dead brain cells, an immune process called phagocytosis.

When full they take on a distinctive appearance. The stuffed and no-longer-functioning microglia can be detected as dark bodies in and near regions of the brain that have been damaged

Alot of research done on them.

Question 33

What do Oligodendroliga and Schwann cells do?

Answer 33

Oligodendroglia:Glial cells in the central nervous system that myelinate axons

schwann cell Glial cell in the peripheral nervous system that myelinates sensory and motor axons.

Question 34

What is Multiple Sclerosis? It’s symptoms?

Answer 34

Nervous-system disorder that results from the loss of myelin (glial-cell covering) around neurons.

If myelin is damaged, a neuron may be unable to send any messages over its axons. In multiple sclerosis (MS), the myelin formed by oligodendroglia is damaged, and the functions of the neurons whose axons it encases are disrupted.

ms is caused by a loss of myelin (see illustration), both on pathways bringing sensory information to the brain and on pathways taking commands to muscles. this loss of myelin occurs in patches, and scarring is frequently left in the affected areas. eventually, a hard scar, or plaque, forms at the site of myelin loss. (ms is called a “sclerosis” from the Greek word meaning “hardness.”) Associated with the loss of myelin is impairment of neuron function, causing characteristic ms symptoms of sensory loss and difficulty in moving.

Fatigue, pain, and depression are common related symptoms. Bladder dysfunction, constipation, and sexual dysfunction all complicate the condition. multiple sclerosis greatly affects a person’s emotional, social, and vocational functioning.

Symptoms are difficult to diagnose. May be related to vitamin D imbalance and genetic susceptibility.

Question 35

What is Myelin?

Answer 35

Glial coating that surrounds axons in the central and peripheral nervous systems; prevents adjacent neurons from shortcircuiting.

Myelin speeds up the flow of information along a neuron. Neurons that are heavily myelinated send information much faster than neurons having little or no myelin. Neurons that send messages over long distances quickly, including sensory and motor neurons, are heavily myelinated.

If myelin is damaged, a neuron may be unable to send any messages over its axons. In multiple sclerosis (MS), the myelin formed by oligodendroglia is damaged, and the functions of the neurons whose axons it encases are disrupted.

Question 36

What is paralysis? What is it’s relation to axons?

Answer 36

The Cessation of both movement and sensation is paralysis. Happens when motor and sensory axons are severed. In a period of weeks to months after motor and sensory axons are severed, movement and sensation will return. The human body can repair this kind of nerve damage, so the paralysis is not permanent.

Both microglia and Schwann cells play a part in repairing damage to the peripheral nervous system. Microglia remove all the debris left by the dying axon. Meanwhile, the Schwann cells that provided the axon’s myelin shrink and then divide, forming numerous smaller glial cells along the path the axon formerly took. The neuron then sends out axon sprouts that search for the path made by the Schwann cells and follow it.

If damage happens in CNS, such as the spinal cord is cut, the regrowth and repair of axons does not happen.

Question 37

Why can’t the Central Nervous system heal itself?

Answer 37

Neuronal growth doesn’t happen as much because neurons are focused on one type of behavior.

When the CNS is damaged, as happens, for example, when the spinal cord is cut, regrowth and repair do not occur, even though the distance that damaged fibers must bridge is short. That recovery should take place in the peripheral nervous system but not in the central nervous system is both a puzzle and a challenge to treating people with brain and spinal-cord injuries.

In nonmammalian vertebrates (fish, amphibians, and reptiles) and in birds CNS neurons can regrow. Regrowth in mammals may be lacking in part because, as mammalian neuronal circuits mature, they become exquisitely tuned to mediate individualized behavior and so are protected from the proliferation of new cells or the regrowth of existing cells. In the CNS, the oligodendrocytes themselves play a role in inhibiting neuron regrowth

Question 38

the five types of glial cells are (1), (2), (3) ,(4) and (5)their functions include(1), (2) (3), (4) and (5) neurons.

Answer 38

(1) Ependymal Cells
(2) Astrocyte.
(3) Microglia.
(4) Oligodendroglia.
(5) Schwann cells

(1) Nourishing, (2) removing waste, (3) insulating), (4) supporting and (5) repairing.

Question 39

The two classes of Nervous system cells are (1) and (2)

Answer 39

Neurons and Glia

Question 40

neurons, the information-conducting units of the nervous system, either(1) or (2) one another through their connecting synapses.

Answer 40

(1) excite or (2) inhibit

Question 41

What is the main obstacle to producing a robot with all the behavioral abilities displayed by a mammal?

Answer 41

The main obstacle is duplicating the complexity of the mammalian brain and its ability to change (plasticity).

Question 42

How do you view a Neuron?

Answer 42

Electron microscope.

Question 43

What determines the characteristics and functions of a Neuron?

Answer 43

It’s proteins.

Question 44

The constituent parts of the cell include the (1),(2) ,(3) ,(4) ,(5) and (6).

Answer 44

(1) Cell Membrane
(2) Nucleus
(3) Endoplasmic reticulum
(4) Golgi bodies
(5) Microtubules
(6) Exocytosis

Question 45

the product of the cell is (1) which serve many functions that include acting at the cell membrane as (2), (3) and (4) to allow substances to cross the membrane.

Answer 45

(1) Proteins.
(2) Channels
(3) Gates
(4) Pumps

Question 46

once proteins are formed in the (1) they are wrapped in membranes by (2) and transported by (3) to their designated sites in the neuron, to its membrane, or for export from the cell by (4).

Answer 46

(1) Endoplasmic Reticulum
(2) Golgi Bodies
(3) Microtubules
(4) Exocytosis

Question 47

The basic sequence of events in building a protein is that (1) makes (2) makes (3)

Answer 47

(1) DNA
(2) RNA
(3) Protein

Question 48

What is Mendelian Genetics?

Answer 48

The study of how genes influence our traits.

Question 49

What are Autosomes?

Answer 49

The first 1-22 pair of Chromosones which determine most of our phyiscal attributes and behaviour.

Question 50

What are Alleles?

Answer 50

Alternative form of a gene; a gene pair contains two alleles. Each cell contains two copies of every gene, one inherited from your and one from your mother. These two copes of a gene are called Alleles.

They are homozygous alleles( two identical alles for a trait) and heterozygous alleles (two different alleles for a trait). IF both are homo, they encode the same protein, if hetero they encode different proteins.

If hetero, three possible outside of protein encoding (1) only the allele from the mother may be expressed, (2) only the allele from the father, (3), both alleles are expressed simulataneously.

Question 51

What is a dominant allele and a recessive allele?

Answer 51

A member of a gene pair that is routinely expressed as a trait is called a dominant allele; a routinely unexpressed allele is recessive. Alleles can vary considerably in their dominance. In complete dominance, only the allele’s own trait is expressed in the phenotype. In incomplete dominance, the expression of the allele’s own trait is only partial. In codominance, both the allele’s own trait and that of the other allele in the gene pair are expressed completely. Each gene makes an independent contribution to the offspring’s inheritance, even though the contribution may not always be visible in the offspring’s phenotype. When paired with a dominant allele, a recessive allele is often not expressed. Still, it can be passed on to future generations and influence their phenotypes when not masked by the influence of some dominant trait.

Question 52

What is a Mutation?

Answer 52

Allteration of an allele that yields a different version of its protein.

The mechanism for reproducing genes and passing them on to offspring is fallible. Errors can arise in the nucleotide sequence when reproductive cells make gene copies. The altered alleles are mutations.

A mutation may be as small as a change in a single nucleotide base. Because the average gene has more than 1200 nucleotide bases, an enormous number of mutations can potentially occur on a single gene. For example, the BRCA1 (breast cancer) gene, found on chromosome 17, is a caretaker gene that contributes to preventing breast cancer, but more than 1000 different mutations have already been found on this gene. Thus, in principle, there are more than 1000 different ways in which to inherit a predisposition to breast cancer from just this gene.

Question 53

What is Tay-Sachs Disease?

Answer 53

Caused by a dysfunctional protein that acts as an enzyme know as HEX A (hexosaminnidase A) that fails to break down a class of lipids (fats) in the brain.

Symptoms usually appear a few months after birth and rarely at later ages. The baby begins to suffer seizures, blindness, and degenerating motor and mental abilities. Inevitably, the child dies within a few years. Tay-Sachs mutations appear with high frequency among certain ethnic groups, including Jews of European origin and French Canadians, but the mutation in different populations is different.

Question 54

What is Huntington’s Disease?

Answer 54

Huntington’s disease hereditary disease characterized by chorea (ceaseless, involuntary, jerky movements) and progressive dementia, ending in death.

huntington’s disease is devastating, characterized by memory impairment, abnormal uncontrollable movements, and marked changes in personality, eventually leading to virtually total loss of normal behavioral, emotional, and intellectual functioning. fortunately, it is rare, with an incidence of only 5 to 10 victims in 100,000 people. it is most common in people of european ancestry. the symptoms of huntington’s disease result from the degeneration of neurons in the basal ganglia and cortex. those symptoms can appear at any age but typically start in midlife.

Question 55

What is Down syndrome?

Answer 55

Down syndrome is a chromosomal abnormality resulting in mental retardation and other abnormalities usually caused by an extra chromosone 21.

In humans, one condition due to a change in chromosome number is Down syndrome, which affects approximately 1 in 700 children. Down syndrome is usually the result of an extra copy of chromosome 21. One parent (usually the mother) passes on two of these chromosomes to the child, rather than the normal single chromosome. Combining

Question 56

What is Transgenic?

Answer 56

Transgenic technology enables scientists to introduce genes into an embryo or remove genes from it.

Question 57

What is Knock in and know out technology?

Answer 57

knock-in technology, a number of genes or a single gene from one species is added to the genome of another species and is passed along and expressed in subsequent generations of transgenic animals.

Knockout technology is used to inactivate a gene so that a line of mice fails to express it (Eisener-Dorman et al., 2008). The line of mice can then be examined to determine whether the targeted gene is responsible for a human disorder and to examine possible therapies for the disorder. It is potentially possible to knock out genes that are related to certain kinds of memory, such as emotional memory, social memory, or spatial memory. Such technology would provide a useful way of investigating the neural basis of memory.

Question 58

What are Chimeric animals?

Answer 58

Chimeric animals are composites formed when an embryo of one species receives cells from a different species. The resulting animal has cells with genes from both parent species and behaviors that are a product of those gene combinations.

Question 59

What distinguishes Mendelian Genetics from Epigenetics?

Answer 59

MEndelian genetics concentrates on inheritance patterns - on which genes parents pass to their offspring and offspiring pass to suceeding generations.

Epigenetics is the study of how the environment and experience can affect the inherited genome.

Question 60

(1) is the oldest form of genetic manipulation. Genetic engineering techniques manipulate or alter the genome of an animal. (2)produces an animal that is genetically identical with to a parent or sibling; (3) contain new, altered, or inactivated genes.

Answer 60

(1) Selective Breeding
(2) Cloning
(3) Transgenic

Question 61

Each of our (1) chromosome pairs contains thousands of genes, and each gene contains the code for one (2) .

Answer 61

(1) 23

(2) proteins

Question 62

The genes that we receive from our mothers and fathers may include slightly different (1) of particular genes, which will be expressed in slightly different (2) .

Answer 62

(1) alleles

(2) proteins

Question 63

Abnormalities in a gene, caused by a(n) (1) , can result in an abnormally formed protein that, in turn, results in the abnormal cell function. Chromosome abnormality can result in the abnormal function of many genes. (2) for example, is caused by an extra copy of chromosome 21.

Answer 63

(1) Mutation
(2) Down syndrome
(3) Trisomy