Topic 2b: Control (CNS, Brain, Reflexes) - PAPER ONE Flashcards
Name the parts of the brain and their functions
Cerebrum: Responsible for Intelligence, language, memory and vision
Cerebellum: Responsible for muscle coordination and balance
Medulla Oblongata: Controls unconscious activities such as breathing and heart rate
Why is it difficult to treat problems in the central nervous system?
1) Hard to repair damage to the nervous system
2) Some parts of the nervous system are not easy to access
3) Treatment for problems may lead to permanent damage
What methods alternative to surgery can be used to investigate brain function?
- CT Scans
- PET Scans
Explain the use of CT Scans
- Uses X-rays to produce an image of the brain
- Shows the main structures of the brain, but not their functions
Explain the use of PET Scans
- Use radioactive chemicals to show which parts of the brain are active
- Very detailed, show structure and function of the brain
- Useful for studying disorders that change the brain’s activity
What parts is the human nervous system divided into?
Central nervous system - brain and spinal cord
Peripheral nervous system - sensory and motor neurons
What are sensory receptors?
Groups of cells that detect a change in your environment
Explain what happens when the CNS coordinates a response
1) Stimulus is detected by receptors. When receptors are stimulated, they produce electrical impulses
2) Impulses travel along sensory neurons to the CNS
3) CNS coordinates the response, impulses travel through CNS along relay neurons
4) CNS sends information to effector (muscle or gland) along a motor neuron - the effector responds accordingly (muscle may contract)
Explain the roles of the Neuron’s cell body extensions
- They have a cell body with extensions that connect to other neurons
- Dendrites/Dendrons carry nerve impulses towards the cell body
- Axons carry nerve impulses away from the cell body
- Some axons surrounded by myelin sheath acting as an electrical insulator, speeding up the electrical impulse
Is it better for Neurons to be long or short? - why?
- Longer neurons speed up the impulse
- Connecting neurons together slows the impulse down
Describe the structure of a Sensory Neuron
Dendron transmits electrical impulse from receptor cells to cell body,
One short axon transmits electrical impulses from cell body to the CNS
Describe the structure of a Motor Neuron
Short dendrites transmit electrical impulses from CNS to cell body,
One long axon transmits electrical impulses from the cell body to the effector cells
Describe the structure of a Relay Neuron
Short dendrites transmit electrical impulses from sensory neurons to cell body,
Axon transmits impulses from cell body to motor neurons
What’s a synapse?
A gap between two neurons
Explain the process that occurs at the synapse
- An electrical impulse stimulates the release of chemicals called neurotransmitters
- They diffuse across the synapse/gap
- Neurotransmitters then stimulate an electrical impulse in the next neuron
What happens to the speed of an electrical impulse at the synapse? - why?
Slightly slows down because diffusion of the neurotransmitters across the gap takes time
Explain the reflex arc
1) Stimulus is detected by Receptor Cells
2) Electrical impulses travel along sensory neuron to relay neurons in the CNS
3) Impulses then travel along motor neuron to the effector (muscle/gland)
What’s a reflex?
An automatic, rapid response to a stimulus
Where do the neurons in reflex arcs go through?
Spinal cord or an unconscious part of the brain
Explain what would happen to someone’s reactions when the action of some neurotransmitters are inhibited
- Reactions would be slowed down
- Because there is reduced neurotransmission across the synapse
Explain why painkillers reduce the pain felt
by a person (painkillers prevent neurotransmitters binding to receptors)
- Painkillers prevent neurotransmitters binding to receptors in the next neuron
- So, an electrical impulse is not triggered in the neuron and therefore the signal is not received by the central nervous system
- And the person does not feel pain
