Chapter 2 pt. 1

Question 1

What are the components of the nervous system?

Answer 1

• neurons
• glial cells
• synapses
• resulting circuits of precisely arranged and connected cells
• cerebrospinal fluid

Behavior arises from coordination of these cells, even if there are few

Question 2

Roundworm NS

Answer 2

• 302 neurons
• sensory (recieve input), inter, and motor (move body) neurons
• head receptors recieve input, goes through interneurons, and travel to the motor neurons to help the body move

Question 3

Sea Slug (Aplysia Californica) NS

Answer 3

• 18,000 neurons
• sensory, motor, and inter neurons
• tail and siphon skin recieve info, transmit to interneurons, and send to motor neurons
• neurons are arranged in circuits… when neurons are connected into circuits, you get behavior

Question 4

Rat NS

Answer 4

• 50 million neurons
• NS w many parts (eyes, nose, tail, etc.) controlled by different areas of their brain
• Brain and spinal cord
• peripheral nerves
• sympathetic NS
• parasympathetic NS
• enteric NS

more neurons=more complex circuits= more complex functions

Question 5

Human NS

Answer 5

• more neurons and more discrete brain regions that control every aspect of our lives
• more complex circuits
• capable of abilities no other species is

Question 6

Similarities among nervous systems

Answer 6

• neurons are the building block of the nervous system and the element of processing information
• cells are connected into circuits via synapses in all species
• certain aspects of the NS are shared across all species (ex. peripheral ganglia) and especially in closely related species (ex. brain and spinal cord in mammals)

Question 7

What is cerebrospinal fluid and what does it do?

Answer 7

• Cerebrospinal fluid is salty water (contains lots of ions)
• Helps enable signal conduction (provides a medium for the exchange of materials like nutrients between blood vessels and brain tissue)
• Protects the brain (acts as a shock absorber and protects the brain from minor blows and sudden movements)

Question 8

What are the different types of cells of the nervous system?

Answer 8

• neurons
• glia
• cells making up the microvascular system of the brain that provide nutrition and protect the brain

Question 9

What did Camillo Golgi do?

Answer 9

• Won the nobel prize in 1906 for developing a staining technique to stain neurons in the entirety (axons and dendrites)
• Golgi technique revealed a variety of neuronal morphologies
• Gave clear descriptions of cerebellum, hippocampus, spinal cord, and olfactory bulb for the first time

Question 10

Ramon Y Cajal

Answer 10

• discovered dendritic spines
• identified axonal growth cone (showed us that neurons grow from one end of the brain to another, grow and progress ot wherever they need to be)

Question 11

Multipolar Neuron

Answer 11

• Many dendrites projecting out of cell body
• Defined integration zone w/ long axon

Question 12

Bipolar neuron

Answer 12

• 1 dendrite coming out of cell body that then branches out
• Especially common in sensory systems

Question 13

Unipolar Neurons

Answer 13

• Have no dendrites, just dendrite-like branches
• transmit touch info from body to spinal cord

Question 14

What are dendritic spines?

Answer 14

• Small protrusions/outgrowths coming out of dendrite that form synapses, increasing surface area thus increasing ability of the neuron to make more synapses
• Both number and structure may be rapidly altered by experience, such as training or exposure to sensory stimuli
• Some change from minute to minute while others may be stable for a lifetime

Question 15

Dentrites

Answer 15

• Input zone where information comes in (recieving end)
• Dendrites from 1 neuron can recieve info via synapses from other neurons

Question 16

Axon Hillock

Answer 16

• Integration zone between dendrite and axon (aka axon initial segment)
• Main componenet that determines what happens next with all incoming information
• Is the initial conductno zone… info is electrically transmitted and the axon hillcock comes up with a net resul of electrical impulses and will decide to fire or not based on how much is recieved

Question 17

Axon

Answer 17

• Conduction zone, takes info from axon hillcock and sends it forward through electrical conduction (On the outside)
• On the inside: important substances for the axon and terminals structure+function (ex. neurotransmitters) are conveyed after being manufactured in the cell body under the control of the neurons’ genes
• Molecules are loaded into transport vesicles (hollow spheres with leg-like motor proteins on outer surface)
• When activated the motor proteins walk the vesicles along microtubles in the axon

neurofilaments help structure of axon, microtubules help transport vesicles go from one end to another, motor proteins enable movement of the transport vesicles

Question 18

Anterograde vs. Retrograde Transport

Answer 18

• Antergrade brings newly formed neurotransmitters that need to be inserted in the membrane (From dendrite to axon terminals)
• Retrograde transport brings broken down neurotransmitters that need to be fixed or replenished from terminals to cell body

Question 19

Axon terminal

Answer 19

• where info from neuron leaves
• presynaptic neuron sends neurotransmitters to post-synaptic neurons (via dendritic spine or dendrite’s spine)
• Pre and postsynapic neurons are differentiated based on visable mitochondria in the presynaptic neuron

Question 20

Cell body

Answer 20

• mitochondria- produce the energy neurons need to function
• nucleus- contains the genetic info and instructions that tell the neuron what it needs to produce
• ribosomes- translate the genetic instructions into proteins

Question 21

Synaptic cleft

Answer 21

the tiny gap between the pre and postsynaptic neurons where neurotransmitters are dumped and then attck to the post synaptic celll during this chemical transfer of information

Question 22

List the different types of glial cells

Answer 22

• astrocytes
• oilgodendrocytes
• Schwann cells
• microglial cells

Question 23

Astrocytes

Answer 23

• star-shaped, non-polar glial cells that help form tight junctions with blood vesicles that regulates local blood flow to provide more supplies to neurons when they are active
• Take nutrients from blood vessels and transfers them to the neurons, is a protection mechanism
• Help form the blood brain barrier by sitting between capillaries and neurons
• Support the metabolic and biochemical needs of neurons to allow a circuit to actually function
• Directly regulate synaptic signaling (triparite synapse).. astrocytes come through and cover the synapse so neurotransmitters don’t spill over. Then breaks down the spillage and uses it for other things
• React to brain injury (repair and scarring) by alerting the immune response in the brain

Question 24

Microglia

Answer 24

• True immune response cells found in the brain
• Astrocyte will activate the microglia when something foreign is detected
• Microglia can become so large that it will encapsulate a foreign object and degrade it (phagocytosis), and then return to its original cell
• Are remarkable active, migrate to sites of injury/disease to remove debris from injured or dead cells

* swelling is a physical enlargement of microglia

Question 25

Oligodendrocytes and Schwann cells

Answer 25

• Olig. encapsulate and insulate multiple segments of multiple neurons (form myelin sheath in the CNS)
• Schwann cells myelinate cells in the Peripheral NS, one cell completely wraps itslef around a segment of an axon

Question 26

Nodes of ranvier

Answer 26

• Small uninsulated patches of axonal membrane that remain exposed
• this allows the generation of a fast electrical impuse along the axon (without them the impulse would be very slow due to mylenation)