2.1.1 Cells Of The Nervous System 2

Question 1

An ____ axon brings information into a structure; an ____ axon carries information away from a structure.

Answer 1

afferent : efferent

Question 2

If a cells dendrites are entirely contained within a single structure, the cell is an ____ or intrinsic neuron of that structure.

Answer 2

interneuron

Question 3

____ (or neuroglia), the other major components of the nervous system, do not transmit information over long distances is neurons do, although they perform many other functions.

Answer 3

Glia

Question 4

The brain has several types of glia with different functions. The star-shaped ____ wrap around the presynaptic terminals of a group of functionally related axons.

Answer 4

astrocytes

Question 5

By taking up ____ released by axons and then releasing them back to other axons, an astrocyte helps synchronise the activity of the axons, enabling them to send messages in waves.

Answer 5

ions

Question 6

Astrocytes also remove ____ material created when neurons die and control the amount of blood flow to each brain area.

Answer 6

waste

Question 7

____, very small cells, also remove waste material as well as viruses, fungi, and other microorganisms.

Answer 7

Microglia

Question 8

____ in the brain and spinal-cord and Schwann cells in the periphery of the body are specialised glia that build the myelin sheaths that surround and insulate certain vertebrate axons.

Answer 8

Oligodendrocytes

Question 9

____ ____ guide migration of neurons and their axons and dendrites during embryonic development.

Answer 9

Radial glia

Question 10

The mechanism that excludes most chemicals from the vertebrate brain is known as the ____-____ barrier.

Answer 10

blood-brain

Question 11

The blood-brain barrier depends on the ____ cells that form the walls of the capillaries.

Answer 11

endothelial

Question 12

Outside the brain, such cells are separated by small gaps, but in the brain, they are joined so ____ that virtually nothing passes between them.

Answer 12

tightly

Question 13

The barrier keeps out useful chemicals as well as harmful ones. Those useful chemicals include all ____ and ____ ____, the building blocks for proteins. For the brain to function, it needs special mechanisms to get these chemical across the blood-brain barrier.

Answer 13

fuel and amino acids

Question 14

Mechanism one. Small uncharged molecules, including ____ and ____ ____, cross freely. Water crosses through special protein channels in the wall of the endothelial cells.

Answer 14

oxygen and carbon dioxide

Question 15

Mechanism two. Molecules that dissolve in the ____ of the membrane also cross passively. Examples include vitamins A and D and all the drugs that affect the brain.

Answer 15

fats

Question 16

For a few other chemicals, the brain uses ____ ____, a protein mediated process that expends energy to pump chemicals from the blood into the brain.

Answer 16

active transport

Question 17

Chemicals actively transported into the brain include ____ (the brains main fuel), ____ ____ (the building blocks of proteins), purines, choline, a few vitamins, iron, and certain hormones.

Answer 17

glucose, amino acids

Question 18

The blood-brain barrier is ____ to ____. In people Alzheimer’s disease or similar conditions, the endothelial cells lining the brains blood vessels shrink, and harmful chemicals enter the brain.

Answer 18

essential to health

Question 19

However, the barrier also poses difficulty in medicine because it keeps out many ____.

Answer 19

medications

Question 20

Most cells used a variety of carbohydrates and fats for nutrition, but vertebrate neurons depended almost entirely on ____, a sugar.

Answer 20

glucose

Question 21

Because the metabolic pathway that uses glucose requires oxygen, neurons need a steady supply of ____.

Answer 21

oxygen

Question 22

Although neurons require glucose, glucose shortage is rarely a problem. The liver makes glucose from many kinds of carbohydrates and amino acids, as well is from ____, a breakdown product from fats.

Answer 22

glycerol

Question 23

The only likely problem is an inability to use glucose. To use glucose, the body needs vitamin B1, ____.

Answer 23

thiamine

Question 24

Prolonged thiamine deficiency, common in chronic alcoholism, leads to death of neurons and a condition called ____ ____, marked by severe memory impairments.

Answer 24

Korsakoff’s syndrome