Nervous system

• Neurotransmitter released in the pns

  Acetylcholine
• Neurotransmitter released by sns

  Noradrenaline
• parasynthetic nervous system

  the division of the autonomic nervous system that calms the body, conserving its energy
• sympathetic nervous system


  the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
• What is the pituitary gland?

  An endocrine gland, it produces hormones in response to certain stimuli
• What is the medulla?

  -Controls heartbeat

  -Breathing

  -Force of heartbeat

  -Controls the diameter of the blood vessels
• Explain the purposes of the Hypothalamus


  -Monitors and controls body temperature, sugars, amino acids and ions

  -Plays an important role in osmoregulation
• What is the hippocampus

  formation and retrieval of memories
• What is the functions of the cerebrum

  -coordinates the body's voluntary actions

  -Opposite hemispheres responsible for the opposite half of the body.
• Analyse and explain the conduction velocity in the myelinated and the unmyelinated axons


  -Increase in diameter increases conduction velocity in both axon types

  -More surface area for ion movement an therefore depolarisation

  -Conduction velocity is greater in the unmyelinated axon compared to the myelinated axon

  -Myelinated axons have a smaller diameter than unmyelinated

  -Greater efficiency of myelinated neurones compared to unmyelinated axons

  -Impulse jumps from node to node/saltory conduction

  -The myelin insulates

  -Insulation is discontinuous at nodes of Ranvier

  -Depolarisation only at nodes
• Analyse the data to explain the effect of tetrodotoxin on the neurone

  -Neurone at resting potential

  -Voltage gate sodium ion channels blocked

  -No movement of sodium ions into the neurone

  -Therefore prevents depolarisation
• Explain why a person with Alzhimer's disease may show a change in behaviour

  -Less cerebral cortex

  -So individual has inability to do everyday tasks

  -Smaller hippocampus

  -Loss of memory/unable to preform everyday tasks
• Describe the events that would lead to the release of acetylcholine at a synapse

  -Action potential arrives at pre-synaptic knob

  -Calcium channels open and calcium ions diffuse in

  -Vesicles move into the membrane

  -Vesicles fuse with the membrane and release acetylcholine
• Comment on how the tetrodotoxin affects the potential difference of a neurone when prey is paralysed


  -Change in potential difference in tetrodotoxin is smaller

  -No action potential

  -Voltage gated sodium channels do not open

  -Sodium ions cannot pass through the membrane

  -No nerve impulse to muscles
• Explain how age might affect the structure of a neurone and the speed of transmission of an impulse

  -Slows transmission/Impulse

  -Because of reduces schwann cells/myelin sheath

  -Affects saltory conduction

  -Affects action potential
• Explain why the speed of the nerve impulses in a non-myelinated neurone is slower than impulses in a myelinated neurone

  -No saltory conduction

  -The impulse cannot jump from node to node

  -Less/No nodes of ranvier

  -Sodium channels have to stimulate current flow along each section of membrane
• Compare and contrast the effect of diameter on the speed of an impulse in a myelinated and in a non myelinated neurone

  -Myelinated line has a linear correlation, meaning that there is a steeper rate in speed on nerve impulse-They have the same speed at 0.1μm-Non-myelinated neurones have a slower increase than the myelinated. -They both have positive correlation
• Describe and explain the sequence of events that occurs after the synapse, after a neurotransmitter has been released

  -Diffuses across gap-Binds to receptors on post-synaptic membrane-Gated channels open/Sodium travels through the post synaptic membrane-Causing depolarisation-If sufficient is present, an action potential is set up in post synaptic membrane-This allows integration in the post synaptic cell-There is one way flow of information-Neurotransmitter broken down by enzyme-so that it does not get prolonged action potential in post synaptic membrane-Reabsorbed through pre-synaptic membrane
• Describe the process by which acetylcholine is released from a synapse

  -An action potential arrives at synaptic knob-Causes the calcium ion channels to open, causing an influx of calcium ions diffusing across the neurone-Synaptic vesicles fuses within the terminal membrane -This allows acetylcholine to be released into the synaptic cleft-vesicles move towards the presynaptic membrane.
• Eugenol can be used to reduce pain Suggest an explanation of how this drug affects the movement of the sodium ions and reduces pain

  -Higher concentration of NA+ outside -Sodium ions move in causing depolarisation-Eugenol affects Na+ gates -Reduces influx of Na+ -Depolarisation is less likely to occur -No impulse transmitted along the neurone-No transmission to the next neurone -Pain not being sensed as impulse stopped before entering CNS
• Describe the effect of eugenol on the percentage inhibition of sodium ion movement

  -As concentration increases the percentage inhibition decreases

  -Non linear correlation

  -(Mention data in the table)
• What direction does the nerve impulse move in the axon of a motor neurone

  Down. (Always from cell body to motor end plate)
• What is the extension bit on a dendron?

  Dendrite

  
• Explain how a resting potential is maintained in a neurone

  -Sodium potassium pumps pump out 3Na+ ions for every 2K+ ions that enter the cell using ATP-Sodium move out the cell whereas the potassium move in-Potassium ions move out through potassium ion channels- Sodium ions do not move in-Outside is more positive than the inside-Most potassium ion channels stay open when not stimulated
• Describe the differences in the structure of a myenlinated sensory neurone and a mylinated motor neurone

  MYELINATED SENSORY NEURONE:- Longer dendron- Shorter axon- No motor end pate- Cell body towards the middle

  MYELINATED MOTOR NEURON:- Shorter dendron- Longer axon- Has motor end plate- Cell body at the end
• Where is the medulla oblongata located?

  brain stem - between pons and spinal cord

  
• Which region of the brain only controls the breathing and heart rate

  Medulla oblongata
• Explain why the person had problems moving their right arm

  -There is damage to their left cerebellum-Movement is no longer automatic
• State the part of the brain that a person used to think about moving their right arm

  Left cerebrum
• Functions of cerebellum

  -Controls and balances posture

  -Coordinated the precise, voluntary movements involved in walking, hand manipulations, speech and writing
• compare and contrast the PNS to the CNS

  PNS: -Divided into stomatic and automatic -Parasympathetic and sympathic -Sensory input and motor input

  CNS: -No somatic, no automatic -Carries out processing information

  BOTH: -Both have nerve cells -Both have synapses