Nervous System

Question 1

Neurons

Answer 1

Nerve cells specialised for communication with each other. They have long extensions that help them respond to stimulation from other neurons and communicate with them (dendrites)

Question 2

Neuronal/cell membrane

Answer 2

Separates the inside from the outside of the cell, encases the entire neuron
Made up of two layers of fat molecules called the lipid bilayer with embedded proteins to help it perform its functions

Question 3

Cell body (soma)

Answer 3

Central region of the neuron that manufactures new cell components, consisting of small and large molecules.
It is the main site where proteins are synthesised and it provides continuous renewal of cell components.
It is where the cells metabolic processes take place

Question 4

Dendrites

Answer 4

Extensions for receiving information from other neurons. These receiving parts gradually taper from the cell body region, much as a branch on a tree narrows as it extends outwards

Question 5

Axon (nerve fibre)

Answer 5

Portion of the neuron that send signals/nerve impulses. These long tail-like extensions are usually very thin near the cell body. This narrowness creates an area that is easily activated by incoming signals

Question 6

Synaptic vesicles

Answer 6

Membranes that store various neurotransmitters that are released at the synapse

Question 7

Axon terminal

Answer 7

Knoblike structure at the far end of the axon.

Question 8

Neurotransmitters

Answer 8

Chemical messengers specialised for communication and released at the synapse

Question 9

Synapse

Answer 9

Space between two connecting neurons through which messages are transmitted

Question 10

Synaptic cleft

Answer 10

Space between two connecting neurons where neurotransmitters are released

Question 11

Glial cells (definition)

Answer 11

Support cells in the nervous system that play a role in the formation of myelin and the blood–brain barrier, respond to injury and remove debris.
The most abundant of glial cells are astrocytes.

Question 12

Node (of Ranvier)

Answer 12

Gap in the myelin sheath of an axon, which helps the conduction of nerve impulses.

Question 13

Astrocytes

Answer 13

A type of glial cell in the CNS. The most abundant. A single astrocyte interacts with as many as 300 000–1 000 000 neurons.
Astrocytes communicate closely with neurons, increase the reliability of their transmission, control blood flow in the brain, and play a vital role in the development of the embryo.
We can find astrocytes in abundant supply in the blood–brain barrier, a protective shield that insulates the brain from infection by bacteria and other intruders.

Question 14

Oligodendrocyte

Answer 14

Glial cell in the CNS concerned with production of myelin that promotes new connections among nerve cells and releases chemicals to aid in healing

Question 15

Myelin sheath

Answer 15

Glial cell-wrappers around axons that act as insulators of the neuron’s signal. This sheath contains numerous gaps all the way along the axon called nodes, which help the neuron conduct electricity more efficiently

Question 16

Resting potential

Answer 16

Electrical charge difference (–60 millivolts) across the neuronal membrane, when the neuron is not being stimulated or inhibited

Question 17

Action potential

Answer 17

When a neuron is at rest, there are positive and negative ions on both sides of the membrane. During an action potential, positive ions rush in and then out of the axon. This process occurs along the axon until the axon terminal releases a neurotransmitter
Qualities of action potential:
1. All or nothing. Similar to the firing of a gun; when we pull the gun’s trigger, it either fires with maximum power or it does not fire at all.
2. Regenerative, meaning that, once started, the process is self-perpetuating; the action potential continues all the way down to the axon terminal.
3. The mechanism of action potentials differs from that of graded potentials. During an action potential, a positive charge flows rapidly into the axon and then rapidly flows out, bringing the membrane potential slightly below its original resting value

Question 18

Threshold

Answer 18

Membrane potential necessary to trigger an action potential

Question 19

Absolute refractory period

Answer 19

Time during which another action potential is impossible; limits maximal firing rate

Question 20

Receptor sites

Answer 20

Locations that uniquely recognise a neurotransmitter

Question 21

Reuptake

Answer 21

Means of recycling neurotransmitters

Question 22

Graded potential

Answer 22

Postsynaptic potentials that can be excitatory or inhibitory, depending on whether positively or negatively charged particles flow across the neuronal membrane and in which direction they flow

Question 23

Function of nervous system

Answer 23

Information processing (taking in information, processing it to determine significance and acting on it)

Question 24

Explain what happens during a reflex action (e.g. touching a hot surface)

Answer 24

1. Sensory receptors in the fingers respond
2. Afferent (sensory) nerve fibres carry the message to the spinal cord
3. Synapse passes message to interneuron in the spinal cord, which relay the message to efferent nerve fibres
4. Efferent (motor) nerve fibres send a message to the muscles located in the hand

Question 25

Afferent neurons

Answer 25

Sensory neurons that carry nerve impulses from sensory stimuli towards the central nervous system and brain

Question 26

Efferent neurons

Answer 26

Motor neurons that carry neural impulses away from the central nervous system and towards muscles to cause movement

Question 27

3 steps in neurotransmission

Answer 27

1. Release of the neurotransmitter from the axon terminal into the synaptic cleft 2. Binding of the neurotransmitter to its receptor site 3. Halting neurotransmission by either the chemical breakdown of the neurotransmitter or by reuptake of the neurotransmitter back into the axon terminal—a process by which the synaptic vesicle engulfs the neurotransmitter

Question 28

Glutamate (function)

Answer 28

Main excitatory neurotransmitter in the nervous system; participates in the relay of sensory information and learning

Question 29

Gamma-aminobutyric acid (GABA) (function)

Answer 29

Main inhibitory neurotransmitter in the nervous system. Alcohol and anxiety drugs increase GABA activity.

Question 30

Acetylcholine (function)

Answer 30

``` Muscle contraction (PNS) Cortical arousal (CNS) ```

Question 31

Noradrenaline (function)

Answer 31

Cortical arousal

Question 32

Dopamine (function)

Answer 32

Motor function and reward

Question 33

Serotonin (function)

Answer 33

Corticol arousal

Question 34

Endorphins (function)

Answer 34

Neuropeptide associated with pain reduction

Question 35

Anandamide (function)

Answer 35

Pain reduction, increase in appetite (Associated with THC)

Question 36

The network of neurons in the brain changes over the course of development in four primary ways

Answer 36

1. Growth of dentrites and axons 2. Formation of new synapses (syptanogenesis) 3. Death of certain neurons and retraction of axons that make connections that are not useful (pruning) 4. Insulation of axons with a myelin sheath (myelination)

Question 37

Potentiation

Answer 37

The increase in strength of nerve impulses along pathways which have been used previously, either short-term or long-term

Question 38

Neurogenesis

Answer 38

Creation of new neurons in the adult brain

Question 39

Two ways that stems cells could be used to of treat neuro- degenerative disease

Answer 39

1. Researchers can implant stem cells directly into the host’s nervous system and induce them to grow and replace damaged cells. 2. Researchers can genetically engineer stem cells so that the cells can administer gene therapy; that is, provide the patient with replacement genes

Question 40

Central nervous system

Answer 40

The part of the nervous system comprising the brain and spinal cord that controls mind and behaviour

Question 41

Peripheral nervous system

Answer 41

Nerves in the body that extend outside the brain and spinal cord

Question 42

6 sections/systems of the CNS

Answer 42

1. Cortex (frontal, parietal, temporal and occipital lobes) 2. Basal ganglia 3. Limbic system (Thalamus, hypothalamus, amygdala, hippocampus) 4. Cerebellum 5. Brain stem (midbrain, pons, medulla) 6. Spinal cord

Question 43

Somatic nervous system

Answer 43

Part of the peripheral nervous system carrying messages from the CNS through the body to control movement

Question 44

Autonomic nervous system

Answer 44

Part of the peripheral nervous system controlling the involuntary actions of our internal organs and glands, which (along with the limbic system) participates in emotion

Question 45

Sympathetic division

Answer 45

Part of the autonomic nervous system engaged during a crisis, or after actions requiring fight or flight - Synapse onto second stage neurons at a significant distance from target organs

Question 46

Parasympathetic division

Answer 46

Part of the autonomic nervous system that controls rest and digestion - Synapse onto second-stage neurons near the target organ

Question 47

- Cranial nerves (definition) - How many pairs? - Longest pair?

Answer 47

- Part of the peripheral nervous system that project from the brain. They are mostly sensory nerves. - 12 pairs of cranial nerves - Vagus nerve

Question 48

Vagus nerve

Answer 48

Cranial nerve that transmits motor and sensory information traveling to and from the gut

Question 49

What are Meninges? | Name them

Answer 49

Set of three protective membranes - Dura Mater meninx (tough, fibrous layer) - Arachnoid meninx (more delicate, spider-like structure) - Pia Mater meninx (delicate fibrous layer that adheres to surface of CNS)

Question 50

Cerebrospinal fluid (function) Produced by? Found in?

Answer 50

- Protects the CNS by cushioning the brain - Choroid plexus - Central canal, four cerebral ventricles & subarachnoid space

Question 51

Choroid Plexus (defintion/function)

Answer 51

Network of capillaries that project from the pia mater into the ventricles of the brain. Produces cerebrospinal fluid

Question 52

``` Cerebral ventricles (definition) Name them ```

Answer 52

Set of 4 interconnected cavities within the brain Lateral ventricles (2) Third ventricle Fourth ventricle

Question 53

Hydrocephalus

Answer 53

Buildup of cerebrospinal fluid in the ventricles. May result from obstruction in the cerebral aqueduct

Question 54

Blood-brain barrier

Answer 54

Cell walls of the cerebral blood vessel are wedged closely together, forming a "blood-brain barrier" to keep unwanted molecules, pathogens and toxins in the blood. Certain large molecules like glucose are allowed to pass through. (cell walls of regular blood vessels are more loosely packed)

Question 55

Nucleus

Answer 55

Contains genetic information (DNA). Spherical structure that acts like the brain of the cell

Question 56

Axon Hillcock

Answer 56

Cone-shaped region connecting the cell body and axon

Question 57

``` Lipid Bilayer (definition) Embedded protein functions? ```

Answer 57

- 2 layers of fat molecules found in the cell/neuronal membrane - Channel proteins provide a passage for certain molecules to pass through the membrane & signal proteins send a signal to the inside of a neuron when a certain molecule binds to the outside

Question 58

Ribosomes

Answer 58

Small structures located on the end of endoplasmic reticulum that are involved in synthesising proteins

Question 59

Endoplasmic reticulum

Answer 59

Structure made from folded membranes. Sections with ribosomes attached (rough sections) are involved in synthesising proteins. Sections without ribosomes attached (smooth sections) are involved in synthesising fats.

Question 60

Cytoplasm

Answer 60

Thick, clear fluid inside the cell

Question 61

Microtubules

Answer 61

Tubular structure involved in transporting cellular materials throughout the neuron

Question 62

Golgi complex

Answer 62

Made up of membranes in the shape of flattened, stacked pouches, the golgi complex packages molecules to be used later or to be sent out of the cell.

Question 63

Mitochondria

Answer 63

Generates large quantities of energy through an aerobic process

Question 64

4 classifications of neurons

Answer 64

- Multipolar interneuron (short or absent axon & single brain area. Role in integrating neuronal activity) - Bipolar neuron (2 projections from the cell body) - Unipolar neuron (1 projection from the cell body) - Multipolar neuron (more than 2 projections rom the cell body)

Question 65

Clusters of cells & axons in the CNS are called? | Clusters of cells & axons in the PHN are called?

Answer 65

- Nuclei & Tracts | - Ganglia & Nerves

Question 66

Microglia

Answer 66

Type of glial cell in the CNS. The smallest glial cells, they protect against injury and disease by engulfing cells and cellular debris, multiplying and promoting an inflammatory response

Question 67

Schwann cells

Answer 67

Type of glial cell in the PNS. Similar function to oligodendrocytes in myelinating axons to increase speed and efficiency of signals.

Question 68

What are Gray matter and White matter composed of?

Answer 68

- Gray matter is composed largely of cell bodies and unmyelinated interneurons - White matter is composed largely of myelinated axons. (It is the myelin that gives the white matter its glossy white sheen.)

Question 69

Dorsal and ventral horns

Answer 69

Located in the spinal cord, the two dorsal arms of the spinal gray matter are called the dorsal horns, and the two ventral arms are called the ventral horns

Question 70

Spinal nerves How many? Where do they connect to spine?

Answer 70

Pairs of spinal nerves are attached to the spinal cord— one on the left and one on the right—at 31 different levels of the spine. Each of these 62 spinal nerves divides as it nears the cord, and its axons are joined to the cord via one of two roots: the dorsal root or the ventral root.

Question 71

Dorsal root neurons

Answer 71

All dorsal root axons, whether somatic or autonomic, are sensory (afferent) unipolar neurons with their cell bodies grouped together just outside the cord to form the dorsal root ganglia. Many of their synaptic terminals are in the dorsal horns of the spinal gray matter

Question 72

Ventral root neurons

Answer 72

The neurons of the ventral root are motor (efferent) multipolar neurons with their cell bodies in the ventral horns. Those that are part of the somatic nervous system project to skeletal muscles; those that are part of the autonomic nervous system project to ganglia, where they synapse on neurons that in turn project to internal organs (heart, stomach, liver, etc.).

Question 73

Reticular formation

Answer 73

Complex network of about 100 tiny nuclei that occupies the central core of the brain stem from the posterior boundary of the myelencephalon to the anterior boundary of the midbrain.