COM S7

Question 1

gather information about the structure of neurones and nerves

Answer 1

• Nerve = bundle of axons (neuronal fibres) bound together like wires in a cable
• Neurone = nerve cell
• Axons and dendrites  bundled together = nerves
• Three types of neurones include:
– Sensory neurones  receive and carry messages to brain and spinal cord (CNS)
– Motor neurones  carry messages from CNS to effectors (muscles and glands)
– Connector neurones  carry messages between sensory neurones and motor neurones, usually in CNS

Question 2

Dendrites, function?

Answer 2

Receives signal from previous neuron and conducts impulse to cell body

Question 3

Cell body, function?

Answer 3

Largest part  contains nucleus, cytoplasm, Golgi body, endoplasmic reticulum and mitochondria

Question 4

Axon, Function?

Answer 4

Extension that conducts impulses away from the cell body to another neurone or tissue

Question 5

Myelin sheath, function?

Answer 5

Insulates axon  electrical signal transported quicker along neuron

Question 6

Schwann cell, function?

Answer 6

Make up myelin sheath

Question 7

Node of Ranvier, function?

Answer 7

Gaps between Schwann cells  affects rate of impulse

Question 8

Axon terminal, function?

Answer 8

Line up next to dendrites of next neuron, or target cells  signal leaves neuron

Question 9

Synapse, function?

Answer 9

Gap between axon terminals of one cell and dendrites of next

Question 10

Identify neurones as nerve cells that are the transmitters of signals by electro-chemical changes in their membranes

Answer 10

• Neurone = nerve cell  transmits impulse from one part of neuron to another
• Nerve impulse = change in voltage
• Impulse transmitted as wave of electrical charges that travel along cell membrane of neurone
• Electrical changes caused as sodium ions move into neurons  called electrochemical impulse
• After signal transmitted  potassium ions move outside cell  restore original charge of neurone
• Electrical change: moving from dendrite to axon terminal
• Chemical change: moving from axon terminal to dendrite

Question 11

Membrane resting potential = ?

Answer 11

Membrane resting potential = -70mV
•	Without electrical impulse going through = normal 
•	Difference in charge (voltage) between intracellular and extracellular parts of cell
•	Potassium can pass in and out freely 
•	Sodium gate closed at -70mW  sodium particles cannot get in from extracellular
•	Intracellular = more negative charge 
 Negative protein 
 Negative phosphate 
 Positive potassium 
•	Extracellular = less negative charge 
 Negative chlorine 
 Positive sodium

Question 12

Action potential = ?

Answer 12

Action Potential = -55mV
• Membrane resting potential changes to -55mV
• Allows sodium gate to open  sodium particles enter intracellular
• Positive particles repel each other  new positive sodium ions start being pushed along axon

Question 13

Action potential and propagation?

Answer 13

• Propagation: as positive charge moves through neurone  Chain reaction throughout axon from sodium ion gate to sodium ion gate
• Myelin sheath  makes sure positive particles cant leave  transmission efficiency
• As sodium enters cell, eventually reaches +50mV  sodium gates close and potassium gates open  VOLTAGE FALLS

Question 14

Action potential and hyperpolarisation and the refractory period?

Answer 14

• Hyperpolarisation: potassium channels close

* Refractory period: charges return to normal position (-70mV) by sodium/potassium pump  action potential not possible

Question 15

Define the term ‘threshold’

Answer 15

• Threshold = level of stimulation required to change a resting potential into an action potential

Question 16

correlated with ‘threshold’ explain why not all stimuli generate an action potential

Answer 16

• When neurone fires = ‘all or nothing’ response  level of stimulation either reaches the threshold and action potential is generated OR it is below threshold and nothing happens
• Action potential occurs at dendrites  triggers many potentials along axon as ion channels open
• Stimulus moves in one direction 
• If stimulus very strong  rate of propagation increases
• When action potential reaches axon terminals  neurotransmitter released into dendrites of next neurone, binds with receptor molecules  stimulates a new action potential

Question 17

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound

Answer 17

• Left hemisphere: controls right side of body (and vise versa)
• Two halves communicate through bundles of nerve fibres that make up the corpus callosum
Frontal lobe, Temporal lobe, Parietal lobe, occipital lobe.

Question 18

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound (Frontal Lobe)

Answer 18

contains the Broca’s area - SOUND
 Controls muscles of speech and articulation of sound
 In left side of brain

Question 19

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound (Temporal Lobe)

Answer 19

SOUND
 Hearing, memory processing & integration of sensory information (hearing & vision)
 Includes Wernicke’s area – controls interpretation of language

Question 20

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound (Parietal Lobe)

Answer 20

LIGHT

 Interpreting writing & used when reading

Question 21

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound (Occipital Lobe)

Answer 21

LIGHT

 Receives and interprets visual information from retinas

Question 22

Give an aim.
examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perception

Answer 22

To distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perception

Question 23

Give a method.
examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perception

Answer 23

1. Cut sheep brain in half to reveal two hemispheres
2. Locate the:
   Cerebrum, Cerebellum, Medulla Oblongata,

Question 24

Cerebrum? when found in the practical?

Answer 24

 Highly folded
 White matter inner layer – grey matter outer layer
 Controls conscious thinking, including messages from sensory receptors
 Sending messages to receptor organs

Question 25

Cerebellum? when found in the practical?

Answer 25

 Small folds on surface
 Behind brain stem
 Coordinates posture, movement & balance

Question 26

Medulla Oblongata? when found in the practical?

Answer 26

Grey matter inner layer – white matter outer layer
 Upper extension of spinal cord
 Hindbrain
 Controls basic functioning e.g. breathing

Question 27

Give a risk assessment for the brain practical.

Answer 27

• Take special care when using scalpels  very sharp
 Don’t leave close to edge of bench
 Dispose carefully in sharps container
• Wear gloves
• Clean dissecting equipment with warm soapy water
• Dispose of animal material carefully
• Wash hands thoroughly

Question 28

Quick summary on Speech, Sight and Sound in the brain.

Answer 28

Speech: Broca’s area (Frontal lobe)
Sight: Occipital lobe
[Light  eye  optic nerve  occipital lobe]
Sound: Wernicke’s area (Temporal lobe)
[Sound wave  auditory canal  cochlea  auditory nerve  temporal lobe]

Question 29

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour

Answer 29

Behaviour: animals are active in response to signals from their surroundings
• Requires:
 Detection of stimuli by sensory receptors
 Transmission of information through nervous system
 Correct interpretation of signals by brain to coordinate behaviour
• Depends on complexity of nervous system & genetic inheritance

Question 30

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour (innate aspects)

Answer 30

Inherited genetically through organisation of nervous system

 Occurs automatically in response to stimulus

Question 31

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour (learnt aspects)

Answer 31

 Result of experience
 Requires nervous system where info can be stored and retrieved
 Response specific to circumstances
• Environmental conditions will always influence behaviour
 Stable: behaviours are inherited and predictable
 Unstable: behaviours based on learning and unpredictable

Question 32

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour (insight learning)

Answer 32

problem solved as a result of thinking about it
o Requires complex brain, ability to process a lot of information and coordinate a response
o Only humans and some birds can do this

Question 33

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour (humans)

Answer 33

 Complex nervous system  we can learn and communicate effectively
 Importance of correct brain interpretation  coordinate behaviour basis of our everyday lives
 Eyes, ears, muscles, feet – all have sensory receptors to determine position of body
 Normal day functions such as walking – we need coordination between receptors and brain

Question 34

When things go wrong with correct interpretation of sensory signals by the brain for the coordination of animal behaviour?

Answer 34

• The importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour is highlighted when something goes wrong.
conditions such as multiple sclerosis, cerebral palsy and neurofinromatosis arise.

Question 35

Multiple Sclerosis and the effect on interpretation of signals?

Answer 35

 Autoimmune attack on myelin sheath of nerve cells
 Myelin sheaths in CNS destroyed  become hard substances called scleroses
 Impulses not functional and don’t work  no insulation = no conduction of impulse through axon

Question 36

Cerebral Palsy and the effect on interpretation of signals?

Answer 36

 Neuromuscular damage  muscles lack coordination due to brain cell damage
 Brain cells  unable to transmit messages to muscles
 Muscles cannot be controlled

Question 37

Neurofibromatosis and the effect on interpretation of signals?

Answer 37

 Genetic disorder  causes tumours to grow along nerves
 NF1: learning difficulties – CNS – not being able to walk
 NF2: hearing loss – CNS