Neurons communicate quickly

Question 1

What does the nervous system do?

Answer 1

Coordinates all our voluntary and involuntary actions

Question 2

In a neuron what are the dendrites?

Answer 2

Short extensions that receive and carry nerve impulses/ messages/ signals from other cells

Question 3

In a neuron what is an axon?

Answer 3

A single, long extension of the cell body. The axon carries nerve impulses away from the cell body. The length varies greatly. Closer to the brain they can reach up to a few mm and from the spinal cord to the foot they can be up to a m to a foot.

Question 4

What is the myelin sheath?

Answer 4

A fatty material that most axons are covered by. These axons are called the myelinated axons, while some axons dont have it these axons are called the unmyelinated axons.

Question 5

Where is the myelin sheath formed?

Answer 5

Outside the brain and spinal cord, this sheath is formed by the Schwann cells, those produced and wrap around an axon

Question 6

What does a myelin sheath do?

Answer 6

Speeds up the action potential, by the nerve impulse jumping from one node of Ranvier to another node of Ranvier (The intervals in the

Question 7

What is a synapse?

Answer 7

Occurs where the axon terminal of one neuron joins with a dendrite or cell body of another.

Question 8

At the synapses how are messages carried between the neurons?

Answer 8

The neurons dont actually touch at the synapses, there is a tiny gap, so messages are carried between them through the movement of chemicals called neurotransmitters.

Question 9

What are the three types of neurons?

Answer 9

sensory/ motor/ and Interneurons

Question 10

What are sensory neurons?

Answer 10

Afferent or receptor neurons carry messages from the receptor in the sense organs, or in the skin, tot he central nervous system.

Question 11

What are motor neurons?

Answer 11

Efferent or effector neurons, which carry messages from the central nervous system to the effects, the muscles and glands.

Question 12

What are interneuron?

Answer 12

Links between the sensory and motor neurons.

Question 13

What are the 4 structural types of neurons?

Answer 13

Multipolar
Unipolar
Bipolar
Pseudo unipolar

Question 14

What is a multipolar neurons?

Answer 14

1 axon, multiple dendrites, extending from the cell body. Majority of interneurons in brain and spinal cord, as well as motor neurons that carry messages to skeletal muscles

Question 15

What is bipolar neuron?

Answer 15

1 axon, 1 dendrite, occurs in the eyes, ears and nose, where they will take impulses from the sense receptors to other cells.

Question 16

What are unipolar neurons?

Answer 16

1 axon. Not found in humans or any other vertebrates, they carry messages between neurons, and are found mainly insects.

Question 17

What are pseudo unipolar neurons?

Answer 17

1 axon, 2 extensions, have both attributes of unipolar and bipolar neurons. They carry messages to the spinal cord and are found in the spinal cord.

Question 18

What is the conduction of a nerve impulse?

Answer 18

A nerve impulse is an electrochemical change that travels along a nerve fiber. It involves a charge in electrical voltage, and it is bought about by changes in chemicals (Specifically the concentration of ions inside and outside the cell membrane of the neuron)

Question 19

What is electrical charge and potential difference?

Answer 19

Electrical charges can be pos or neg.
When pos and neg charges come together , energy is released.
If a group of neg and a group of pos charges are separated they have the potential to come together and released energy.
The potential, between two places can be measured, in either V or mV

Question 20

Potential different across a cell membrane?

Answer 20

Chemical substances dissolve in water, they break up into electrically charged particles called ions.
This process can happen to substances dissolved in the fluid around or inside the cell (Intracellular or extracellular fluid)

Question 21

What does the extracellular fluid contain?

Answer 21

High concentration of sodium chloride, most of the charged particles are positive sodium ions and negative chloride ions.

Question 22

What does the intracellular fluid contain?

Answer 22

Low concentration of sodium chloride ions. The main positive ions are potassium, and the negative ions come from a variety of organic substances made by the cell.

Question 23

What do differences in the concentration of ions mean?

Answer 23

There is a potential between the inside and the outside of the cell membrane

Question 24

What is the membrane potential?

Answer 24

Occurs in all body cells, but is particularly large in nerve cells and muscle cells. The membrane potential of unstimulated nerve cells, known as resting potential, this is about -70mV

Question 25

Which channels are open all the time?

Answer 25

Leakage channels

Question 26

What channels are only open when the nerve is stimulated?

Answer 26

Voltage-gated channels

Question 27

What is the sodium-potassium pump?

Answer 27

Sodium and potassium ions move across the cell membrane through a carrier protein known as the sodium-potassium pump. The pump moves two potassium ions into the cell every three sodium ions are removed.

Question 28

What is an action potential?

Answer 28

The stimulus to a neuron is sufficient, the signal will be passed along the neuron.

Question 29

In an action potential how does a signal travel down a neuron?

Answer 29

The opening and closing of the voltage-gated channels, which causes the rapid depolarisation and repolarisation of the membrane.

Question 30

How long does an action potential last?

Answer 30

aprox 1 millisecond.

Question 31

What is depolarisation and how does it occur?

Answer 31

The sudden increase in membrane potential. Occurs if the level of stimulation exceeds 15 mV, or the threshold.