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Biology Year 2 > C13 - Neurones & the Nervous Impulse > Flashcards

C13 - Neurones & the Nervous Impulse Flashcards

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1
Q

What is a Neurone

A

A nerve cell

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2
Q

What type of cells are NEURONEs?

A

NEURONES are specialist NERVE CELLS,

adapted to rapidly carry nervous impulses

from one part of the body to the other…

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3
Q

What are the 3 types of neurones?

A
  1. Sensory neurones
  2. Motor neurones
  3. Relay neurones
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4
Q

What does a SENSORY NEURONE do?

A

A SENSORY NEURONE

Carries impulses… from the sense receptors or organs into the CNS

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5
Q

What does a MOTOR NEURONE do?

A

A MOTOR NEURONE

Carries impulses from the CNS to the effector organs

e.g. Muscles + gland

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6
Q

What does a RELAY NEURONE do?

A

A RELAY NEURONE

Acts as a connector or association…

It receives impulses from sensory neurones or other relay neurones and transmits them to motor neurones or other relay neurones

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7
Q

ADDITIONAL SLIDE

What is does the CELL BODY/CENTRON contain?

A
  • Contains a NUCLEUS and a GRANULAR CYTOPLASM
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8
Q

Additional Slide

What is the composition of the cytoplasm?

A

The cytoplasm is

  • Granular & contains many ribosomes
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9
Q

What does the Nucleus contain?

A
  • DNA
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10
Q

What do nissl granules do

What is the FUNCTION of NISSI GRANULES?

A
  • Cytoplasmic granules comprising ribosomes grouped on RER
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11
Q

What does a dendrite do

What is the FUNCTION of a DENDRITE?

A

A dendrite is a thin fibre…

Which carries impulses towards the cell body.

A cell body may have several dendrites

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12
Q

What does an axon do

What is the FUNCTION of an AXON?

A

An Axon is a thin fibre…

Carrying impulses away from the cell body.

A cell body can only have one axon

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13
Q

What do Schwann cells do

What is the FUNCTION of a SCHWANN CELL?

A

A SCHWANN CELL…

Surrounds and support nerve fibres .

In vertebrate embryos, SCHWANN CELLS wrap around the developing axons many times and withdraw their cytoplasm, leaving a multi-layered phospholipid myelin sheath.

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14
Q

What does the MYELIN sheath do?

What is the FUNCTION of a MYELIN SHEATH?

A

A MYELIN SHEATH is an…

electrical insulator and speeds up the transmissions of impulses

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15
Q

What do the nodes of ranvier do

What is the FUNCTION of the NODES od RANVIER?

A

The NODES OF RANVIER are…

1 micrometre gaps in myelin sheath, where adjacent schwann cells meet and where the axon membrane is exposed.

They allow impulses to be transmitted rapidly down the Neurone.

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16
Q

What does the synaptic end bulb do

What is the FUNCTION of the SYNAPTIC END BULB

A

A SYNAPTIC END BULB

is the swelling at the end of axon, in which the nuerotransmiter is created.

17
Q

What is the role of the axon ending

What is the FUNCTION of the AXON ending/Terminal?

A

The AXON ending/Terminal

Secretes the nuerotransmitter which transmits impulse to adjacent neurone.

18
Q

Additional Card

Jamie you need to know how to draw a Motor Neurone…

A
19
Q

THE NERVOUS IMPULSE SECTION STARTS HERE…

A
20
Q

What does RESTING POTENTIAL mean?

A

The RESTING POTENTIAL is the potential difference across the membrane of a cell when no nervous impulse is being conducted.

Additional point.

A neurone is an excitable cell, which means it can change its resting potential.

Most other cells are not excitable and cannot change their resting potential.

21
Q

what is the standard potential difference across a cell membrane?

A

70 mV

22
Q

Is the membrane more positive or negative on the inside?

A

more negative

23
Q

So what is the rest potential

A

-70 mV

24
Q

What is the resting potential a result of

A

the negative ions of large proteins, of organic acids such as pyruvate and of organic phosphates e.g. ATP ^-4 in the cytoplasm and from the uneven distribution of inorganic ions

25
Q

what is a trait from within the cells

A

the inside of a cell has both a higher concentration of potassium ions and a lower concentration of Na+ ions than the outside.

26
Q

what is the result of the inside of the having a higher concentration of K+ ions and a lower concentration of Na+ than the outside

A

The K+ ions would tend to diffuse out and the NA+ ions would tend to diffuse in.

Some of the channels that allow the K+ ions to diffuse out are open, whilst most of the channels that allow the na+ ions to move in are closed.

This makes the axon membrane 100 X more permeable to K + ions which therefor diffuse out faster than the NA+ ions are able to diffuse back in

27
Q

What is the role of the sodium-potassium pump

A

It pumps K + ions back into the cell and Na + ions back out They are transmembrane proteins with ATPase activity that transport K + and Na+ ions across the membrane, against a concentration gradient by active transport they maintain the concentration and an uneven distribution of ions across the membrane

28
Q

Why is a cell described as polarised?

Reworked card.

A

A membrane is described as polarised when there is a potential difference accross the cell membrane

i.e. The membrane is -ve on the inside of the cell (owing to the -ve ions found on the large protiens of organic acids e.g. pyruvate and organic phosphates) and postive on the outside of the cell

29
Q

Why is their a potential difference across the cell membrane I.e. Polarised.

The answer to this question has two parts:

Part 1

The sodium- potassium exchange pumps

Push K+ ions back into the cell and NA+ ions back out.

The Sodium -potassium exchange pumps are transmembrane proteins, with ATPase activity that transport K+ and NA+ ions across the membrane against a concentration gradient by active transport

A

The inside of the cell has

  • A higher concentration of K+ ions
  • A lower concentration of NA+ ions

Therefore K+ ions more likely to diffuse out & NA+ ions more likely to diffuse in.

The channels which allow K+ ions to diffuse out tend to be open and the channels which allow NA+ ions to diffuse in. tend to be closed

This makes the axon cell membrane 100x more permeable to K+ ions than to NA+ ions.

The sodium- potassium exchange pumps Push K+ ions back into the cell and NA+ ions back out.

The Sodium -potassium exchange pumps are transmembrane proteins, with ATPase activity that transport K+ and NA+ ions across the membrane against a concentration gradient by active transport

30
Q

Study point 1

A

Microelectrodes inserted into resting axons, measuring the electrical potential, have shown that the inside of the membrane has a negative electrical charge compared with the outside

31
Q

study point 2

A

Approximately 3 Na + ions are pumped out and 2K+ ions are pumped in for every ATP molecule that is hydrolysed

32
Q

Study point 3

A

In establishing the resting potential, ions move in two different ways they diffuse through membrane channels and are actively transported by sodium-potassium pumps

33
Q

What does the distribution of ions look like at resting potential.

A

Biology Year 2 (37 decks)

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