The Nervous System

Question 1

Definition of homeostasis?

Answer 1

Maintaining a stable internal environment within the body

Question 2

Examples of how homeostasis helps the body?

Answer 2

Negative feedback loops, water regulation, temperature control

Question 3

Which parts of the body are part of the central nervous system?

Answer 3

Brain, spinal cord and relay neurones

Question 4

What makes up the Peripheral Nervous System?

Answer 4

The Somatic and Autonomic Nervous Systems

Question 5

The difference between somatic and autonomic?

Answer 5

Somatic is voluntary (muscles and skin) and the autonomic is involuntary (organs)

Question 6

What is the autonomic nervous system made of?

Answer 6

The sympathetic and parasympathetic nervous systems

Question 7

The Sympathetic Nervous System?

Answer 7

Activated in times of stress, your ‘fight or flight’ instincts

Question 8

The Parasympathetic Nervous System?

Answer 8

Controls your body in times of rest

Question 9

The neurotransmitters used in sympathetic and parasympathetic?

Answer 9

Sympathetic = Noradrenaline (Na)
Parasympathetic = Acetylcholine (ACh)

Question 10

Peristalsis?

Answer 10

Involuntary muscle movement involved in digestion in small intestine

Question 11

Name the parts of a motor neuron?

Answer 11

Cell body, Dendrites, Axon, Axon terminals, Nodes of Ranvier, Schwann cells and myelin sheath

Question 12

What is a node of Ranvier?

Answer 12

The small gap between the Schwann cells

Question 14

Where does depolarization occur in the neuron?

Answer 14

The Nodes of Ranvier

Question 15

The name for when a neuron has Schwann cells and a myelin sheath?

Answer 15

Myelinated axons

Question 16

The name for when the electrical impulse skips a node?

Answer 16

Saltatory conduction

Question 17

What physical difference is there between motor and relay neurons?

Answer 17

Relay neurons have a shorter axon and a larger cell body

Question 17

What is the Pacinian corpuscle?

Answer 17

A specific sensory receptor that detects mechanical pressure

Question 18

Definition of a transducer?

Answer 18

Something that converts a stimulus into action potential / nerve impulse

Question 18

Differences that a sensory neuron has?

Answer 18

Has a dendron at the top instead of an axon near the dendrites, cell body is down the side and smaller as well

Question 18

Reflex arc, what is it?

Answer 18

A genetic survival mechanism

Question 18

Where is the Pacinian corpuscle normally?

Answer 18

In fingers, joints and feet

Question 19

Type of neurons found in the spinal cord?

Answer 19

Sensory and motor neurons

Question 20

How does the Pacinian corpuscle help the neuron?

Answer 20

Helps convert mechanical pressure into a nervous impulse

Question 21

The 4 main types of sensory receptor?

Answer 21

Mechanoreceptor (pressure and movement), chemoreceptor (chemicals), thermoreceptor, photoreceptor (light)

Question 21

What are dendrons responsible for?

Answer 21

Passing the electrical impulse towards the cell body

Question 21

What is a myelinated axon?

Answer 21

A plasma membrane made up of many phospholipid bilayers, transmits impulses faster

Question 22

Features of sensory neurons?

Answer 22

Specific to stimulus, act as transducers (convert stimulus into impulse)

Question 22

Normally what is an effector?

Answer 22

A muscle or gland

Question 23

Structure of the Pacinian corpuscle?

Answer 23

End of sensory neuron found within center, surrounded by layers of connective tissue, each layer separated by gel

Question 24

What happens when the sodium ion channels change shape in the membrane?

Answer 24

Their permeability will change, when too narrow for sodium the neuron has resting potential, when stretched it then has action potential

Question 24

Potential difference across membrane when at resting potential?

Answer 24

-70mV

Question 25

Potential difference across membrane when at action potential?

Answer 25

Around 40mV

Question 26

Charge inside axon during resting potential?

Answer 26

Axon = Negative Tissue fluid = Positive

Question 27

How do the charges change once wave of depolarization has occurred?

Answer 27

The axon becomes positively charged and the tissue fluid is negatively charged now

Question 27

How do K+ ions leak out the axon?

Answer 27

Facilitated diffusion

Question 27

When pressure is applied to the Pacinian corpuscle what happens?

Answer 27

It will change shape and stretch the sodium ion channels allowing more sodium ions to pass through

Question 27

Once sodium ion channels have been stretched what happens now the sodium concentration has increased?

Answer 27

The influx of sodium ions changes the potential of the membrane, it becomes depolarized

Question 27

The ratio for Na+ to K+ pumped in and out?

Answer 27

For every 3 Na+ ion there is 2 K+ ions

Question 27

During resting potential where is there a higher concentration of sodium ions?

Answer 27

Outside in the tissue fluid

Question 27

What actively pumps the Na+ and K+ ions in and out of the neuron?

Answer 27

ATPase by active transport

Question 27

When can a stimulus set up an action potential?

Answer 27

Only when its above a threshold level

Question 27

What happens when stimulus is under the threshold?

Answer 27

Gated channels remain closed, no depolarization which means no action potential

Question 27

What is the net result of ions in resting potential?

Answer 27

More sodium ions outside axon than K+ ions inside

Question 28

Which gates are open during depolarization?

Answer 28

Sodium gates are open allowing them to move into the axon and change the charge to positive

Question 29

Which gates are open during repolarization?

Answer 29

Potassium gates open and move out through facilitated diffusion down a conc gradient

Question 30

What is the refractory period?

Answer 30

After repolarization, Na+ and K+ ions remain closed so membrane can't be depolarized, no impulse can pass

Question 31

How long is the refractory period?

Answer 31

0.5ms

Question 32

What is the importance of the refractory period?

Answer 32

Makes each action potential distinct, keeps it travelling one way

Question 33

How many mV is the threshold for an action potential?

Answer 33

-55mV