Topic 11 Nervous System Flashcards
he nervous system enables humans to react to their ——–
and coordinate their ————-
surroundings
behaviour
Explain how the structure of the nervous system structure as well ot is adapted to its functions summarised :
Adaptations
reflex arc doesn’t travel to brain so quicker
Information from receptors passes along cells (neurones) as electrical impulses to the central nervous system (CNS).
The CNS is the brain and spinal cord.
The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones.
Stimulus - Receptor - Coordinator - Effector - Response
Explain how structures in a reflex arc relate to their function:
- When you touch an object a receptor in your skin is stimulated. An electrical impulse from a receptor passes along a sensory neurons to the CNS- in this case the spinal cord
- When an impulse from the sensory neurone arrives at synapse with a relay neurone, a chemical is released. The chemical diffuses across the synapse to the relay neurone where it sets off a new electrical impulse that travels along the relay neurone
- When the impulse reaches the synapse between the relay neurone and a motor neurone returning to the arm, another chemical is released. Again, the chemical diffuses across the synapse and starts a new electrical impulse travelling down the motor neurone to the effector
- When the impulse reaches the effector organm it is stimulated to respond.
why reflex actions are important quick bullets:
Automatic ( they do not involve the conscious part of the brain)
Rapid; protect from harm
Method for carrying out an investigation into the effect of a factor on human reaction time.
Each person has three practice goes before the 5 readings are taken.
Person one places their dominant arm (e.g. right arm) on the table with their hand over the edge
Person one opens their thumb and forefinger so they are 3cm apart
Person two holds a metre ruler so 0 cm is level with the top of their thumb
Person two drops the ruler and person one catches it
Record the distance the ruler fell at the top of the thumb
Repeat 5 times and calculate a mean distance
Convert to reaction time using the conversion table below
Person 1 and 2 now swap round and repeat the experiment.
Independent variable
Dependent variable
Person
Distance the ruler fell
Control variables
Distance between thumb and finger
Which hand they are catching the ruler with (dominant or non-dominant)
How much they had practised before the experiment
What the person had eaten or drunk before the experiment (e.g. caffeinated drink)
Noise levels in the room
How tired the person is
What is someone’s dominant arm/hand?
How else could you measure reaction time?
The hand/arm they use for most tasks
Use a reaction time test online.
Describe the main sources of error
The ruler may not held so 0 is at the top of the thumb
Ruler might not be read accurately to the top of the thumb
Describe how to improve the accuracy of the experiment
Repeat more times and calculate a mean
Suggest an uncontrolled variable
How tired the person was / what the person ate or drank before the experiment
Describe how to improve the validity of the experiment
Repeat on a number of different days
Give the people taking part the same food / drink before the experiment
Describe how you could change the experiment to investigate something different
Keep the person/people the same but change whether they use the dominant or non-dominant hand
Keep the person/people the same but change how much they practise before the experiment starts.
Keep the person/people the same but change the noise level (e.g. by using headphones and music)
Keep the person/people the same but change what they have eat / drink
Keep the person/people the same but change how tired they are (by doing in the morning / at the end of the day)
Consider your answer to the question above
Describe how you could change the experiment to investigate something different
and describe how you would you ensure a valid investigation that would give a valid conclusion that wasn’t just about one person
Carry out the experiment on a large group of people / have a large sample size
Explain the brain in the context of the nervous system
the brain controls complex behaviour. It is made of billions of interconnected neurones and has different regions that carry out different functions
Name the 1st, 3rd and 4th label ignore the 2nd
1st- cerebral cortex
3rd- cerebellum
4th- Medulla
cerebral cortex function
consciousness, intelligence, memory & language
cerebellum function
coordination of muscular activity
medulla function
unconscious activities such as heartbeat & breathing
Explain some of the difficulties of investigating brain function and treating brain damage and disease.
the brain is incredibly complex and delicate- the investigation of brain function and any treatment of brain damage or disease is difficult. It also carries risks, such as physical damage to the brain or increased problems with brain function (e.g difficulty with speech).
Describe how neuroscientists have been able to map the regions of the brain to particular functions by:
studying patients with brain damage
electrically stimulating different parts of the brain
using MRI scanning techniques
studying patients with brain damage- If a small part of the brain has been damaged the effect this has on the patient can tell you a lot about what damaged part of the brain does. E.g if an area at the back of the brain was damaged by a stroke and the patient went blind, you know that that area has something to do with vision
Electrically stimulating the brain- The brain can be stimulated electrically by pushing a tiny electrode into the tissue and giving it a small zap of electricity y observing what stimulating different parts of the brain does, it’s possible to get an idea of what those parts do. E.g when a certain part of the brain known as the motor area is stimulated it causes muscle contraction and movement.
MRI Scans- A magnetic resonance imaging (MRI) produces a very detailed picture of the brain’s structures. Scientists use it to find out what areas of the brain are active when people are doing things like listening to music or trying to recall a memory.
Evaluate the benefits and risks of procedures carried out on the brain and nervous system.
Benefits:
Treatment of Conditions: Procedures such as deep brain stimulation or neurosurgery can treat various neurological disorders, including Parkinson’s disease, epilepsy, and severe depression, improving patients’ quality of life.
Diagnostic Insights: Techniques like MRI and CT scans provide detailed images of the brain, allowing for accurate diagnosis of conditions such as tumors, strokes, or multiple sclerosis.
Research Advancements: Brain surgeries and studies contribute to our understanding of brain functions and neurological diseases, leading to the development of new treatments and therapies.
Risks:
Surgical Risks: Any brain surgery carries risks such as infection, bleeding, or damage to surrounding brain tissue, which can lead to complications like seizures or cognitive impairments.
Anesthesia Risks: Procedures often require anesthesia, which can have side effects and poses risks, especially in patients with pre-existing health conditions.
Psychological Effects: Procedures affecting the brain can lead to changes in personality, mood, or cognitive function, impacting the patient’s mental health and social interactions
Retina relating structure to function
contains receptor cells that are sensitive to light intensity and colour
Optic nerve:
relating structure to function
carries impulses from the retina to the brain
Sclera:
relating structure to function
tough outer layer that has a transparent region at the front called the cornea
Iris:
relating structure to function
muscular - controls the size of the pupil and the amount of light reaching the retina
Ciliary muscles and suspensory ligaments:
relating structure to function
can change the shape of the lens to focus light onto the retina
Describe the process of accommodation.
Changing the shape of the lens to focus on near or distant objects
When the eye encounters a near object what happens:
- The ciliary muscles contract
2. The suspensory ligaments loosen
3. The lens becomes thicker and refracts light rays more strongly
When the eye encounters a distant object what happens:
- The ciliary muscles relax
2. The suspensory ligaments are pulled tight
3. The lens is pulled thin and only slightly refracts light rays
New eye technologies:
now include hard and soft contact lenses, laser surgery to change the shape of the cornea, and a replacement lens in the eye
relay neurone which is found in the
central nervous system.
Look at the diagram. What part of the eye is identified by label 1?
sclera
Explain simple and relfex arc pathways + how they differ
Simple Reflex Arc
A direct pathway involving few neurons (sensory neuron and motor neuron, sometimes one interneuron).
Complex Reflex Arc
An intricate pathway involving multiple interneurons, allowing for more elaborate responses.
Key Differences
Number of Neurons: Simple reflex arcs have fewer neurons; complex reflex arcs have multiple.
Processing Level: Simple arcs are fast and automatic; complex arcs involve more processing and coordination.
What type of lens can be used to correct short sight?
concave
What type of lens can be used to correct long sight?
convex
vitreous body fills
the space in the eye
In myopia light rays converge
in front of the retina
In hyperopia light rays converge
behind the retina
What is the name given to the reflex that changes the shape of the lens in the eye
accommodation reflex
. When focusing on distant objects, the shape of the lens in the eye is
Because since the source is far away
long and thin
Since the source is far away, the rays will be nearly parallel so require less bending to focus on the retina.
Which part of the eye changes shape to increase or decrease the amount of light that enters into the eye?
iris
