Topic 8 Grey Matter Flashcards
1
Q
What is the largest part of the brain?
A
The cerebrum
The cerebrum is involved in vision, learning, thinking, emotions, and movement.
2
Q
What are the two halves of the cerebrum called?
A
Cerebral hemispheres
The cerebrum is divided into the right and left cerebral hemispheres.
3
Q
What is the thin outer layer of the cerebrum called?
A
Cerebral cortex
The cortex has a large surface area and is highly folded to fit into the skull.
4
Q
What functions does the cerebrum control?
A
- Vision
- Learning
- Thinking
- Emotions
- Movement
Different parts of the cerebrum are involved in different functions.
5
Q
Where is the hypothalamus located?
A
Just beneath the middle part of the brain
The hypothalamus plays a critical role in homeostasis.
6
Q
What is one key function of the hypothalamus?
A
Thermoregulation
The hypothalamus maintains body temperature at the normal level.
7
Q
What does the hypothalamus produce that affects the pituitary gland?
A
Hormones
The pituitary gland is located just below the hypothalamus.
8
Q
Where is the medulla oblongata located?
A
At the base of the brain, at the top of the spinal cord
The medulla oblongata is critical for automatic control of vital functions.
9
Q
What vital functions does the medulla oblongata control?
A
- Breathing rate
- Heart rate
These functions are essential for survival.
10
Q
What type of imaging technique uses radiation to visualize the brain?
A
Computed Tomography (CT)
CT scans show dense structures in the brain as light areas.
11
Q
What can CT scans help diagnose?
A
Medical conditions related to the brain
They can reveal damaged brain structures.
12
Q
What imaging technique produces detailed images without radiation?
A
Magnetic Resonance Imaging (MRI)
MRI scans provide high-resolution images of the brain.
13
Q
Which part of the brain is responsible for coordinating movement and balance?
A
The cerebellum
The cerebellum is located underneath the cerebrum and also has a folded cortex.
14
Q
Fill in the blank: The cerebellum is important for _______.
A
Coordinating movement and balance
Proper functioning of the cerebellum is crucial for motor control.
15
Q
What is the main function of a CT scanner?
A
To produce cross-section images of the brain using X-rays
CT scans show major structures in the brain but do not indicate their functions directly.
16
Q
What type of images do CT scans produce?
A
Cross-section images of the brain
CT scans can show damaged or diseased areas of the brain.
17
Q
How do CT scans help in medical diagnosis?
A
They show damaged or diseased areas, such as bleeding after a stroke
Blood shows up as a lighter color on a CT scan due to different density.
18
Q
What is a significant risk associated with CT scans?
A
They use X-rays, which can cause mutations in DNA
The risk of developing cancer from a CT scan is very low.
19
Q
What technology do MRI scanners use to produce images?
A
Strong magnetic fields and radio waves
MRI scanners provide higher quality images compared to CT scans.
20
Q
What advantage do MRI scans have over CT scans?
A
Higher quality images for soft tissue and better resolution between tissue types
MRIs can clearly differentiate between normal and abnormal brain tissue.
21
Q
What can MRI scans reveal about brain tumors?
A
The size and location of the tumor
Tumor cells respond differently to magnetic fields than healthy cells, appearing lighter on the scan.
22
Q
Fill in the blank: CT scans show _____ areas of the brain.
A
damaged or diseased
23
Q
True or False: MRI scans can indicate brain function directly.
A
False
Brain function can only be inferred by examining damaged areas.
24
Q
What can be inferred if a CT scan shows a patient can’t see?
A
The damaged area involved in vision
This inference is based on the relationship between structure and function.
25
What is the primary use of CT scans in medical diagnosis?
To identify bleeding and its extent in the brain
## Footnote
This helps determine which blood vessels are damaged and related brain functions affected.
26
What does an MRI scan provide?
A detailed, high resolution picture of the brain's structure
## Footnote
MRI scans can also be used to research brain function.
27
How does an fMRI scan work?
It measures brain activity by detecting changes associated with blood flow
## Footnote
Active areas of the brain are highlighted during specific tasks.
28
What can MRI scans show in terms of medical diagnosis?
Damaged or diseased areas of the brain and conditions caused by abnormal activity
## Footnote
Some conditions may not have an obvious structural cause.
29
What is the purpose of using an fMRI scan before and during a seizure?
To pinpoint which part of the brain is not functioning properly
## Footnote
This assists in determining the cause of the seizure.
30
What does a PET scan use to show brain activity?
Radioactive material
## Footnote
A radioactive tracer is introduced into the body and absorbed into the tissues.
31
How does a PET scan build a map of radioactivity?
By detecting the radioactivity of the tracer
## Footnote
Different tracers can be used for various metabolic studies.
32
What is a common tracer used in PET scans?
Radioactively labelled glucose
## Footnote
It is used to examine glucose metabolism in the brain.
33
What condition can PET scans help study?
Alzheimer's disease
## Footnote
They show reduced metabolism in certain brain areas.
34
True or False: PET scans can show if areas of the brain are unusually inactive or active.
True
## Footnote
This helps in studying disorders that affect brain activity.
35
Fill in the blank: MRI scans can help assess suspected _______ in the brain.
bleeding
## Footnote
MRI scans provide detailed information about bleeding.
36
What type of information can a doctor get from an MRI scan regarding bleeding?
Information about the location and extent of the bleeding
## Footnote
This is crucial for effective treatment.
37
What brain function is typically investigated using an fMRI scan?
Movement of body parts
## Footnote
For example, moving the left hand activates specific brain areas.
38
What is the primary advantage of using fMRI over traditional MRI?
It allows real-time observation of brain activity during tasks
## Footnote
This provides insights into functional areas of the brain.
39
Which side of the brain controls the left side of the body?
The right side
## Footnote
This is why the right side is active when the left hand moves.
40
What is habituation?
Habituation is a type of learned behavior where an animal reduces its response to an unimportant stimulus after repeated exposure over time.
## Footnote
It helps animals conserve energy and focus on more critical survival activities.
41
Why is habituation important for animals?
Habituation increases the chance of survival by allowing animals to differentiate between important and unimportant stimuli.
## Footnote
This helps them avoid wasting energy on non-threatening stimuli.
42
Give an example of habituation in prairie dogs.
Prairie dogs use alarm calls to warn others of a predator but have habituated to humans, no longer making alarm calls when they see them.
## Footnote
This demonstrates that they do not perceive humans as a threat.
43
What happens to an animal's response to an unimportant stimulus when habituation occurs?
The animal learns to ignore the unimportant stimulus, leading to a reduced response over time.
## Footnote
This allows them to engage in other survival activities, such as feeding.
44
How can you demonstrate habituation in a snail?
Gently brush something soft across the snail's skin and time how long it takes for the snail to fully extend its tentacles again after being touched.
## Footnote
Repeating this process will show quicker re-extension if habituation has occurred.
45
What physiological changes occur during habituation?
Fewer electrical impulses are sent to effectors due to reduced calcium ion influx and decreased neurotransmitter release.
## Footnote
This results in a lower chance of reaching the action potential threshold on the postsynaptic membrane.
46
Fill in the blank: Habituation allows animals to conserve energy by _______.
[ignoring unimportant stimuli]
47
True or False: Habituation means that animals become less alert to all stimuli.
False
## Footnote
Animals remain alert to important stimuli that could threaten their survival.
48
What is the effect of repeated exposure to a stimulus on neurotransmitter release during habituation?
Repeated exposure decreases the amount of neurotransmitter released from vesicles into the synaptic cleft.
## Footnote
This results in fewer signals sent to effectors.
49
Why do snails still react to unfamiliar stimuli even after habituation?
Snails remain alert to unfamiliar stimuli, which may pose a threat, leading to a withdrawal response.
## Footnote
This shows that habituation does not mean complete unresponsiveness.
50
What is the visual cortex?
An area of the cerebral cortex at the back of the brain that receives and processes visual information.
51
What are ocular dominance columns?
Grouped neurones in the visual cortex that receive information from either the left or right eye.
52
What are the two types of ocular dominance columns?
* Left ocular dominance columns
* Right ocular dominance columns
53
How are ocular dominance columns arranged?
In an alternating pattern (left, right, left, right) across the visual cortex.
54
Who studied the visual cortex and how?
Hubel and Wiesel used animal models to study the electrical activity of neurones in the visual cortex.
55
What did Hubel and Wiesel find about ocular dominance columns in kittens?
The stitched-up eye was blind, and the columns for the open eye were larger than normal.
56
What happens when one eye is stitched shut in young kittens?
The ocular dominance columns for the stitched-up eye become smaller, and those for the open eye expand.
57
What were the results of stitching shut an adult cat's eye?
The adult cat's eye did not go blind, and ocular dominance columns remained the same.
58
What do Hubel and Wiesel's experiments suggest about visual cortex development?
The visual cortex develops normal ocular dominance columns only if both eyes are stimulated early in life.
59
What is the critical period in visual development?
A period in early life when exposure to visual stimuli is essential for proper visual cortex development.
60
What did scientists find about cataracts in infants?
Cataracts must be removed within the first few months for normal visual system development.
61
What happens to adults with cataracts when they are removed?
Normal vision returns immediately because the visual system is already developed.
62
Fill in the blank: Hubel and Wiesel's experiments provide evidence for a _______ in humans.
[critical period]
63
True or False: The human visual cortex has ocular dominance columns.
True
64
What occurs to synapses during the critical period?
Synapses that are not used are removed from the visual cortex.
65
What is the significance of visual stimuli during the critical period?
They are crucial for the proper organization of the visual cortex.
66
What did Hubel and Wiesel's experiments demonstrate about visual stimulation?
They showed that lack of visual stimulation can lead to blindness in the non-stimulated eye.
67
What are some arguments against using animal models in experiments?
* Animals are different from humans
* Different species may have varying brain structures
68
What are alternative methods to study visual development in humans?
* Observing cataracts
* Studying children with visual impairments
69
What are ocular dominance columns?
They are structures in the visual cortex that process visual information from each eye.
## Footnote
Ocular dominance columns are essential for understanding how the brain processes visual stimuli.
70
Where in the brain are ocular dominance columns found?
In the visual cortex.
71
What is the significance of visual stimulation during the critical period of development?
Visual stimulation is necessary for the proper organisation of neurones in the visual cortex.
72
What happens to synapses that receive visual stimulation during the critical period?
They are retained.
73
What happens to synapses that do not receive visual stimulation during the critical period?
They are removed.
74
What is the consequence of a lack of visual stimulation during the critical period?
The visual cortex will not develop properly as many synapses will be destroyed.
75
List two arguments against using animals in medical research.
* Animals may experience pain and distress
* Animals are different from humans, so drug effects may vary.
76
List two arguments for using animals in medical research.
* Research has led to significant medical breakthroughs
* Animal experiments are only conducted when absolutely necessary.
77
True or False: Hubel and Wiesel conducted their experiments on humans.
False.
78
What ethical issues arise from using animals in medical research?
Concerns about animal rights and the potential for causing pain and distress.
79
Fill in the blank: Proper organisation of the visual cortex involves the elimination of unnecessary _______.
[synapses].
80
What do Hubel and Wiesel's experiments provide evidence for?
A critical period in the development of the visual system.
81
What is a critical period in the context of visual system development?
A specific time frame during which visual stimulation is crucial for proper development.
82
What kind of pattern are ocular dominance columns arranged in?
A striped pattern corresponding to the input from the left and right eyes.
83
Describe one piece of evidence that suggests a critical 'window' exists for human visual system development.
Evidence from animal studies, such as those by Hubel and Wiesel, indicates a period where visual input is essential.
84
What alternatives exist to using animals in research?
* Cultures of human cells
* Computer models to predict effects.
85
What did Hubel and Wiesel's experiments on kittens and monkeys reveal?
They provided significant insights into the development of the visual cortex.
86
Fill in the blank: The visual cortex is organized during the critical period based on _______ stimulation.
[visual].
87
What role do painkillers and anaesthetics play in animal experiments?
They minimize pain and distress to the animals.
88
What is brain development?
How the brain grows and how neurones connect together.
89
What are measures of brain development?
Measures include the size of the brain, the number of neurones, and the level of brain function (e.g. speech, intelligence).
90
What is the nature-nurture debate?
The argument about whether nature or nurture influences brain development the most.
91
Why is it difficult to investigate the effects of nature and nurture?
Genetic and environmental factors interact, making it hard to know which one is the main influence.
92
What are two key factors that complicate the study of nature and nurture?
The existence of many different genes and various environmental factors.
93
What is one method scientists use to investigate brain development?
Animal experiments.
94
How do animal experiments help study nurture?
By studying the effects of different environments on genetically similar animals.
95
What do studies on rats raised in stimulating environments suggest?
Nurture plays a big role in brain size and the development of problem-solving skills.
96
What do studies suggest about rats reared in isolation?
They exhibit brain abnormalities similar to those found in schizophrenic patients, indicating the influence of nurture.
97
What effect does the absence of the Lgli gene have on mice?
It leads to enlarged brain regions and fluid buildup in their brains, suggesting nature's role in brain development.
98
What is the significance of twin studies in understanding brain development?
They allow comparison of brain development between genetically identical individuals raised in different environments.
99
What do IQ scores of identical twins suggest?
Nature plays a big role in intelligence.
100
What is a limitation of comparing identical twins raised separately?
They still share the same environment in the womb, complicating the separation of environmental and genetic factors.
101
What does the comparison between identical and non-identical twins help determine?
It helps to cancel out environmental influences and assess the role of nature.
102
What does the higher incidence of stuttering in identical twins suggest?
Nature plays a significant role in developing the speech area of the brain.
103
What does the lack of difference in reading ability between identical and non-identical twins suggest?
Nurture plays a big role in reading ability.
104
Fill in the blank: The _______ is the argument about whether nature or nurture influences brain development the most.
nature-nurture debate.
105
What are the two main influences on brain development?
Nature and nurture
## Footnote
Nature refers to genetic factors, while nurture refers to environmental influences.
106
What do cross-cultural studies reveal about brain development?
Differences in brain development are more likely due to nurture, while similarities are more likely due to nature
## Footnote
Cross-cultural studies compare children from different cultures to assess the impact of upbringing.
107
What abilities are newborn babies born with?
Crying, feeding, and recognizing a human face
## Footnote
These abilities suggest that nature plays a significant role in these functions.
108
True or False: Newborn babies have the ability to speak.
False
## Footnote
This indicates that nurture plays a significant role in the ability to speak.
109
How does brain damage affect children's brain development?
Children can still develop functions despite brain damage, suggesting nurture plays a role
## Footnote
Studies indicate that children with brain damage can eventually reach language milestones similar to those without damage.
110
Fill in the blank: The brain of a newborn baby has been affected a bit by the _______.
environment in the womb
111
What can scientists study by comparing children with and without brain damage?
The development of specific functions
## Footnote
This comparison helps determine if development is influenced more by nature or nurture.
112
What happens to language development in children aged 1-3 with brain damage?
They show a delay in major language milestones
## Footnote
However, by age 5, their language skills can become comparable to those without damage.
113
What is the significance of determining whether characteristics are influenced more by nature or nurture?
It helps in figuring out how to improve brain function by changing the environment
## Footnote
Understanding the influence can guide interventions for developmental issues.
114
What is meant by 'nature' in the context of brain development studies?
Genetic factors that influence brain functions
## Footnote
Nature encompasses inherited traits and biological predispositions.
115
Describe two other types of studies that could be used to research nature and nurture on brain development.
Twin studies and adoption studies
## Footnote
These studies help isolate genetic influences from environmental ones.
116
What are neurotransmitters?
Chemicals that transmit nerve impulses across synapses.
117
How are depression and serotonin levels related?
Depression is linked to a low level of serotonin.
118
What is Parkinson's disease?
A brain disorder that affects motor skills.
119
What neurotransmitter is associated with Parkinson's disease?
Dopamine.
120
What happens to neurons in the brain of a person with Parkinson's disease?
Neurons that control movement are destroyed.
121
How do selective serotonin reuptake inhibitors (SSRIs) work?
They increase serotonin levels by preventing its reuptake at synapses.
122
What is L-dopa used for?
To treat the symptoms of Parkinson's disease.
123
Why can't dopamine be directly administered to treat Parkinson's disease?
Dopamine can't enter the brain.
124
What does L-dopa get converted into in the brain?
Dopamine.
125
What is the effect of increased dopamine levels in the brain?
More nerve impulses are transmitted across synapses, improving movement control.
126
What is MDMA commonly known as?
Ecstasy.
127
How does MDMA affect serotonin levels?
It increases serotonin levels by inhibiting its reuptake and triggering its release.
128
What is the primary effect of MDMA on mood?
Mood elevation.
129
Fill in the blank: A low level of the neurotransmitter _______ is linked to depression.
serotonin.
130
True or False: L-dopa directly replaces serotonin in the brain.
False.
131
What are the symptoms caused by a lack of dopamine in Parkinson's disease?
Tremors and slow movement.
132
What enzyme converts L-dopa into dopamine?
Dopa-decarboxylase.
133
Fill in the blank: MDMA binds to and blocks the _______ proteins on the presynaptic membrane.
reuptake.
134
What is the Human Genome Project (HGP)?
A 13-year project that identified all of the genes found in human DNA.
135
Where is the information obtained from the Human Genome Project stored?
In databases.
136
How do scientists use the databases from the Human Genome Project?
To identify genes and proteins involved in disease.
137
What is an example of a drug being developed using information from the Human Genome Project?
A drug that inhibits an enzyme helping cancer cells to spread.
138
What do common genetic variations identified by the HGP affect?
The effectiveness of some drugs.
139
What are personalized medicines?
Drugs designed to be tailored to people with specific genetic variations.
140
How can doctors personalize a patient's treatment?
By using genetic information to predict drug response.
141
True or False: The development of drugs for specific genetic variations may lead to a two-tier health service.
True
142
What might happen if a person's genetic makeup indicates that an expensive drug will not be effective?
They might be refused the drug, even if it's the only option available.
143
What ethical issue arises from the information held within a person's genome?
It could be used by employers or insurance companies to discriminate.
144
How can revealing that a drug might not work for a person be psychologically damaging?
It could diminish their hope for treating a disease.
145
Fill in the blank: A disorder linked to a low level of serotonin is _______.
Parkinson's disease
146
Describe one way that MDMA increases the level of serotonin in the brain.
MDMA releases more serotonin into the synaptic cleft.
147
Name a drug used to treat Parkinson's disease.
Levodopa
148
Explain the role of dopamine in controlling movement.
Dopamine transmits signals that coordinate movement and balance.
149
Describe and explain the effects that Parkinson's disease has on the brain.
It leads to the degeneration of dopamine-producing neurons.
150
Give three ethical issues surrounding the development of personalized medicines.
* Increased research costs for drug companies
* Potential discrimination based on genetic information
* Psychological impact of knowing a drug won't work
151
True or False: Chocolate can also increase serotonin levels.
True
152
What is the impact of genetic variations on asthma drugs?
Some asthma drugs are less effective for people with particular mutations.
153
What are genetically modified organisms (GMOs)?
Organisms that have had their DNA altered
## Footnote
GMOs are used in various applications, including drug production.
154
What types of drugs can be produced by genetically modified organisms?
Only drugs that are proteins
## Footnote
This includes various therapeutic proteins such as insulin.
155
What is the first step in genetically engineering microorganisms to produce drugs?
Isolating the gene for the protein using restriction enzymes
## Footnote
Restriction enzymes are enzymes that cut DNA at specific sequences.
156
What process is used to copy the gene for the drug?
PCR (Polymerase Chain Reaction)
## Footnote
PCR is a technique used to amplify a segment of DNA.
157
What are plasmids?
Small circular molecules of DNA
## Footnote
Plasmids are often used as vectors to transfer genetic material.
158
What is the role of plasmids in drug production using GMOs?
Plasmids are transferred into microorganisms to produce proteins
## Footnote
The modified microorganisms then divide and produce the useful protein.
159
Give an example of a drug produced from genetically modified bacteria.
Human insulin
## Footnote
Human insulin is used to treat Type 1 diabetes.
160
What is the first step in genetically engineering plants to produce drugs?
Inserting the gene for the protein into a bacterium
## Footnote
The bacterium acts as a vector to transfer the gene.
161
How does the bacterium modify the plant cell?
The bacterium inserts the gene into the plant cell DNA
## Footnote
This results in the plant cell becoming genetically modified.
162
What is a way the protein produced in genetically modified plants can be used?
Purified from the plant tissues or delivered by eating the plant
## Footnote
This method allows for the direct consumption of therapeutic proteins.
163
What is the first step in genetically engineering animals to produce drugs?
Injecting the gene into the nucleus of a fertilized animal egg cell
## Footnote
This process allows for the gene to be incorporated into the animal's genome.
164
How is the gene expressed in genetically modified animals?
The egg cell is implanted into an adult animal
## Footnote
The animal grows with the gene present in every cell.
165
Where is the protein produced by genetically modified animals typically purified from?
The milk of the animal
## Footnote
This method is commonly used for proteins that can be secreted into milk.
166
True or False: Genetically modified plants can produce human insulin.
True
## Footnote
Some genetically modified plants have been engineered to produce insulin.
167
Fill in the blank: The bacterium used in plant genetic engineering is a _______.
vector
## Footnote
Vectors are essential for transferring genes into target cells.
168
What is a genetically modified organism?
An organism whose genetic material has been altered using genetic engineering techniques.
169
Describe how a genetically modified plant is created.
By introducing specific genes into the plant's DNA, often using methods like agrobacterium-mediated transformation or gene guns.
170
Describe how a genetically modified animal is created.
By incorporating foreign DNA into the animal's genome, often through methods like microinjection or somatic cell nuclear transfer.
171
What are the benefits of using genetically modified organisms (GMOs) in agriculture?
Benefits include higher yields, increased nutritional value, pest resistance, reduced pesticide use, and lower costs.
172
How can GMOs help reduce the risk of famine and malnutrition?
By producing crops that are higher in nutrition and yield, making food more available.
173
What is an example of a human protein produced from genetically modified organisms?
Human insulin produced from genetically modified bacteria.
174
Fill in the blank: Vaccines produced in _______ tissues don't need to be refrigerated.
plant
175
What is a concern regarding herbicide-resistant crops?
They may interbreed with wild plants, creating 'superweeds' resistant to herbicides.
176
What are some risks associated with the use of GMOs?
Potential transmission of genetic material, unforeseen consequences, and ethical concerns regarding animal modification.
177
True or False: Human proteins from genetically modified organisms can cause allergic reactions.
False
178
What is a potential benefit of producing drugs using genetically modified plants and animals?
It could make drugs more affordable, especially for people in poor countries.
179
Discuss the long-term impacts of using GMOs.
There may be unforeseen consequences and concerns about ecological balance.
180
What is the role of enzymes in industrial processes related to GMOs?
Enzymes produced from GMOs can be used in large quantities at reduced costs.
181
Fill in the blank: Some people believe it's wrong to _______ animals purely for human benefit.
genetically modify
182
How has treatment for Type 1 diabetes changed with GMOs?
It has shifted from using cow insulin to human insulin produced by genetically modified bacteria.
183
What is a stimulus?
Any change in the internal or external environment
184
What do receptors do?
They detect stimuli
185
What are effectors?
Cells that bring about a response to a stimulus
186
Give two examples of effectors.
* Muscle cells
* Gland cells (e.g., pancreas)
187
How do receptors communicate with effectors?
Via the nervous system or the hormonal system
188
What is the nervous system made up of?
A complex network of cells called neurones
189
Name the three main types of neurones.
* Sensory neurones
* Motor neurones
* Relay neurones
190
What do sensory neurones do?
Transmit electrical impulses from receptors to the CNS
191
What do motor neurones do?
Transmit electrical impulses from the CNS to effectors
192
What do relay neurones do?
Transmit electrical impulses between sensory and motor neurones
193
What happens when an electrical impulse reaches the end of a neurone?
Neurotransmitters take the information across to the next neurone
194
What are electrical impulses also called?
Nerve impulses or action potentials
195
What is the role of the CNS?
Processes information and sends impulses along motor neurones to effectors
196
Fill in the blank: The brain unconsciously processes the information, so these responses are _______.
reflexes
197
What do light receptors (photoreceptors) in dim light do?
Stimulate radial muscles to dilate pupils
198
What do light receptors (photoreceptors) in bright light do?
Stimulate circular muscles to constrict pupils
199
True or False: Hormones are substances released by glands into the bloodstream.
True
200
What is the function of hormones?
Regulate various physiological processes
201
What is an example of a stimulus that can trigger a hormonal response?
Low blood glucose concentration
202
What is a stimulus?
Any change in the internal or external environment
203
What do receptors do?
They detect stimuli
204
What are effectors?
Cells that bring about a response to a stimulus
205
Give two examples of effectors.
* Muscle cells
* Gland cells (e.g., pancreas)
206
How do receptors communicate with effectors?
Via the nervous system or the hormonal system
207
What is the nervous system made up of?
A complex network of cells called neurones
208
Name the three main types of neurones.
* Sensory neurones
* Motor neurones
* Relay neurones
209
What do sensory neurones do?
Transmit electrical impulses from receptors to the CNS
210
What do motor neurones do?
Transmit electrical impulses from the CNS to effectors
211
What do relay neurones do?
Transmit electrical impulses between sensory and motor neurones
212
What happens when an electrical impulse reaches the end of a neurone?
Neurotransmitters take the information across to the next neurone
213
What are electrical impulses also called?
Nerve impulses or action potentials
214
What is the role of the CNS?
Processes information and sends impulses along motor neurones to effectors
215
Fill in the blank: The brain unconsciously processes the information, so these responses are _______.
reflexes
216
What do light receptors (photoreceptors) in dim light do?
Stimulate radial muscles to dilate pupils
217
What do light receptors (photoreceptors) in bright light do?
Stimulate circular muscles to constrict pupils
218
True or False: Hormones are substances released by glands into the bloodstream.
True
219
What is the function of hormones?
Regulate various physiological processes
220
What is an example of a stimulus that can trigger a hormonal response?
Low blood glucose concentration
221
What is a gland?
A group of cells that are specialised to secrete a useful substance, such as a hormone
## Footnote
Example: The pancreas secretes insulin.
222
What are hormones?
'Chemical messengers' that can be proteins, peptides, or steroids
## Footnote
Example: Insulin is a peptide hormone, while progesterone is a steroid hormone.
223
How are hormones secreted?
When a gland is stimulated by a change in concentration of a specific substance or by electrical impulses
224
How do hormones travel in the body?
Hormones diffuse directly into the blood and are transported by the circulatory system
225
What are target cells?
Cells that have specific receptors for a hormone, allowing them to bind and respond to it
226
What is the role of effectors in hormonal communication?
Effectors are the target cells that respond to the hormone's signal
227
What happens when low blood glucose concentration is detected?
The pancreas releases the hormone glucagon into the blood
228
What is the response of the liver to glucagon?
Target cells in the liver convert glycogen into glucose, releasing it into the blood
229
What is a key difference between nervous and hormonal communication?
Nervous communication uses electrical impulses, while hormonal communication uses chemicals
230
Which communication method has a faster response?
Nervous communication
231
Describe the response duration of hormonal communication.
Long-lived response - hormones aren't broken down very quickly
232
Fill in the blank: Hormones travel at the _______ of blood.
[speed]
233
True or False: Hormonal communication leads to a localized response.
False
234
List two types of effectors.
* Muscles
* Glands
235
What is the role of receptors in the human eye's response to bright light?
They detect the change in light intensity and initiate a response
236
What is one way nervous communication is different from hormonal communication?
Nervous communication is short-lived while hormonal communication is long-lived
237
Give an example of a hormone and its function.
Insulin - regulates blood glucose levels
238
What are receptors specific to?
One kind of stimulus
239
What type of receptors are found on cell surface membranes?
Proteins
240
What is the voltage across the membrane called?
Potential difference
241
What generates the potential difference across the membrane?
Ion pumps and ion channels
242
What triggers an action potential?
If the change in potential difference reaches the threshold level
243
Fill in the blank: Light enters the eye through the _______.
Pupil
244
What area of the retina contains many photoreceptors?
Fovea
245
What is the blind spot?
Where the optic nerve leaves the eye with no photoreceptor cells
246
What do photoreceptors convert light into?
An electrical impulse
247
True or False: Rods provide color vision.
False
248
Where are rods mainly found?
Peripheral parts of the retina
249
Where are cones mainly found?
Packed together in the fovea
250
What type of vision do rods provide?
Monochromatic vision
251
What happens to light-sensitive pigments when light hits them?
They are bleached, causing a chemical change
252
What type of neurone connects photoreceptors to the optic nerve?
Bipolar neurone
253
Fill in the blank: The optic nerve carries impulses to the _______.
Brain
254
What occurs when sodium ions diffuse into a rod cell?
The inside of the cell becomes depolarized
255
What is the process called when light energy causes a change in photoreceptors?
Bleaching
256
What happens to the neurotransmitter release when it is dark?
No information is sent to the bipolar neurone
257
What happens to sodium ions when it's light?
They cannot diffuse into the cell
258
What are receptors?
Proteins found in the nervous system that detect stimuli
259
What happens during active transport regarding sodium ions?
Sodium ions (Na+) are pumped out of the cell
260
What occurs when sodium ions diffuse back into the cell?
The cell membrane is said to be depolarised
261
What is released when an inhibitory neurotransmitter is released?
No action potentials in the bipolar neurone
262
What triggers the release of neurotransmitters in rod cells?
Light energy causing the breakdown of rhodopsin
263
What is the process called when rhodopsin breaks apart into retinal and opsin?
Bleaching
264
What happens when sodium ion channels close in rod cells?
Sodium ions cannot diffuse back in
265
What is the result of sodium ions building up outside the rod cell?
The cell membrane becomes hyperpolarised
266
What does hyperpolarisation of the rod cell lead to?
Stops releasing neurotransmitters
267
What occurs when the bipolar neurone is no longer inhibited?
It depolarises
268
What is the outcome if the change in potential difference reaches the threshold?
An action potential is transmitted to the brain via the optic nerve
269
Fill in the blank: 'Depolarised' means there's not much _______ in charge across the membrane.
difference
270
What type of channels are sodium channels?
Cation channels
271
What do photoreceptors convert light into?
Electrical signals
272
When it's dark, is a bipolar neurone inhibited or uninhibited?
Inhibited
273
What is rhodopsin?
A light-sensitive pigment that's broken apart by light energy when rod cells are stimulated
274
What is the bundle of neurones that links the eye to the brain?
Optic nerve
275
True or False: Action potentials are sent along the bipolar neurone when it is inhibited.
False
276
What is the blind spot?
Area in the retina where no photoreceptors are present
277
What do neurones carry in the form of action potential?
Nerve impulses
## Footnote
Neurones carry nerve impulses to other parts of the body.
278
What are the main extensions of a neurone that connect to other neurones?
Dendrites and axons
## Footnote
Dendrites carry impulses towards the cell body, while axons carry impulses away.
279
What is the primary function of motor neurones?
Carry nerve impulses from the CNS to effector cells
## Footnote
Motor neurones have many short dendrites and one long axon.
280
What is the structure of sensory neurones?
One long dendron and one short axon
## Footnote
The cell body is located in the middle of the neurone.
281
What do relay neurones do?
Transmit action potentials through the CNS
## Footnote
They connect sensory neurones to motor neurones.
282
What is the resting potential of a neurone?
-70 mV
## Footnote
This is the voltage across the membrane when the neurone is at rest.
283
What creates and maintains the resting potential in a neurone?
Sodium-potassium pumps and potassium ion channels
## Footnote
These structures regulate ion concentrations across the neurone membrane.
284
What is the function of sodium-potassium pumps?
Move three sodium ions out for every two potassium ions in
## Footnote
This process requires ATP and is an example of active transport.
285
What happens to sodium ions in a neurone's resting state?
They cannot diffuse back in
## Footnote
The membrane is not permeable to sodium ions.
286
What causes the outside of a neurone to be positively charged?
More positive ions outside than inside
## Footnote
This difference in charge is due to the action of sodium-potassium pumps.
287
Fill in the blank: The membrane of a neurone is _______ at rest.
Polarised
288
What is the term for the rapid change in a neurone's membrane potential triggered by a stimulus?
Depolarisation
## Footnote
This process is essential for the propagation of action potentials.
289
True or False: The outside of the neurone is negatively charged at rest.
False
## Footnote
The outside is positively charged compared to the inside.
290
What happens during repolarisation?
Potassium ions diffuse out of the neurone
## Footnote
This process restores the resting potential.
291
What is hyperpolarisation in the context of neurones?
An overshoot of the resting potential
## Footnote
This occurs when the membrane potential becomes more negative than the resting state.
292
What is depolarisation in a neurone?
A process where sodium ion channels open, allowing sodium ions to diffuse into the neurone, making the inside less negative.
## Footnote
Depolarisation occurs when the potential difference reaches the threshold of around -55 mV.
293
What happens during repolarisation?
Sodium ion channels close and potassium ion channels open, allowing potassium ions to diffuse out of the neurone.
## Footnote
This process helps return the membrane potential towards its resting state.
294
What is hyperpolarisation?
A phase where potassium ion channels are slow to close, leading to an overshoot where the potential difference becomes more negative than the resting potential.
## Footnote
This can result in a potential difference of less than -70 mV.
295
What is the resting potential of a neurone?
The state where the ion channels are reset and the sodium-potassium pump maintains the membrane potential until the neurone is excited again.
## Footnote
The resting potential is typically around -70 mV.
296
What is the refractory period?
The recovery phase after an action potential during which the neurone cannot be excited again due to closed ion channels.
## Footnote
Sodium channels are closed during repolarisation and potassium channels are closed during hyperpolarisation.
297
What causes the change in potential difference during an action potential?
The opening and closing of voltage-gated sodium and potassium channels in response to changes in membrane potential.
## Footnote
This process is essential for the transmission of action potentials along the neurone.
298
What are the roles of sodium and potassium channels in action potentials?
Sodium channels facilitate depolarisation, while potassium channels facilitate repolarisation and hyperpolarisation.
## Footnote
Both types of channels are voltage-gated and open at specific voltages.
299
Fill in the blank: The sodium-potassium pump helps maintain the neurone's _______.
resting potential
300
True or False: Potassium ions diffuse into the neurone during depolarisation.
False
## Footnote
During depolarisation, sodium ions diffuse into the neurone.
301
What is the threshold potential for depolarisation in a neurone?
-55 mV
302
How does hyperpolarisation affect the neurone's potential?
It makes the potential difference more negative than the resting potential.
## Footnote
This occurs due to the slow closure of potassium channels.
303
What happens after an action potential in terms of ion channels?
Ion channels reset, and the sodium-potassium pump restores resting potential.
## Footnote
This process is crucial for preparing the neurone for the next potential action.
304
What is the potential difference across the membrane during resting potential?
-70 mV
305
Name the two main types of ion channels involved in action potentials.
* Sodium ion channels
* Potassium ion channels
306
What is the process called when sodium ions enter a neurone and diffuse sideways?
Wave of depolarisation
307
What happens to sodium ion channels in the next region of the neurone when an action potential occurs?
They open and sodium ions diffuse into that part
308
What effect does the refractory period have on action potentials?
Prevents overlap and ensures they are discrete impulses
309
True or False: The refractory period allows action potentials to travel in both directions.
False
310
What is the relationship between the size of a stimulus and the frequency of action potentials?
A bigger stimulus causes more frequent impulses
311
Fill in the blank: Local anaesthetics work by binding to _______ in the membrane of neurones.
Sodium ion channels
312
What is the effect of local anaesthetics on action potentials?
They prevent action potentials from being conducted
313
What does reaching the threshold in a neurone signify?
An action potential will always fire with the same change in voltage
314
What is the outcome if the threshold is not reached in a neurone?
An action potential won't fire
315
How does the refractory period contribute to the directionality of action potentials?
It ensures action potentials are unidirectional
316
What analogy is used to describe the wave of depolarisation in neurones?
A Mexican wave travelling through a crowd
317
What occurs during the refractory period regarding ion channels?
Ion channels are recovering and can't be opened
318
How does a small stimulus compare to a big stimulus in terms of action potential?
A bigger stimulus causes them to fire more frequently
319
What is the term for the potential when a neurone is at rest?
Resting potential
320
What is the primary effect of sodium ions rushing into a neurone?
Causes depolarisation
321
What does the term 'discrete impulses' refer to in the context of action potentials?
Separate action potentials that do not overlap
322
What is the myelin sheath?
An electrical insulator made of Schwann cells
323
What are the nodes of Ranvier?
Tiny patches of bare membrane between Schwann cells
324
What is the role of sodium ion channels at the nodes of Ranvier?
They are concentrated at the nodes and allow sodium ions to enter
325
How does depolarisation occur in myelinated neurones?
It only happens at the nodes of Ranvier
326
What is saltatory conduction?
The 'jumping' of impulses from node to node
327
How does the conduction velocity relate to impulse speed?
A high conduction velocity means the impulse is travelling quickly
328
What happens in a non-myelinated neurone?
The impulse travels as a wave along the whole length of the axon membrane
329
Fill in the blank: In a myelinated neurone, the impulse _______ from node to node.
[jumps]
330
True or False: Impulses travel faster in myelinated neurones than in non-myelinated neurones.
True
331
What is one function of Schwann cells?
To form the myelin sheath around neurones
332
What is the effect of a bigger stimulus on the size of an action potential?
It does not affect the size of the action potential
333
What characterizes multiple sclerosis?
Damage to the myelin sheaths of neurones
334
How fast can shrimps conduct nerve impulses?
Faster than 200 ms
335
What is a synapse?
A junction between a neurone and another neurone, or between a neurone and an effector cell.
## Footnote
An effector cell can be a muscle or gland cell.
336
What is the tiny gap between cells at a synapse called?
The synaptic cleft.
337
What does the presynaptic neurone contain at the synapse?
A synaptic knob filled with synaptic vesicles containing neurotransmitters.
338
What triggers the release of neurotransmitters into the synaptic cleft?
An action potential arriving at the end of a neurone.
339
What happens when neurotransmitters bind to receptors on the postsynaptic membrane?
They might trigger an action potential, cause muscle contraction, or cause hormone secretion.
340
True or False: Synapses allow impulses to travel in both directions.
False.
341
How are neurotransmitters removed from the synaptic cleft?
They are taken back into the presynaptic neurone or broken down by enzymes.
342
Name two examples of neurotransmitters.
* Acetylcholine
* Dopamine
343
What role does acetylcholine play in the body?
It is involved in muscle contraction and the control of heart rate.
344
What causes calcium ions to diffuse into the synaptic knob?
The arrival of an action potential that stimulates voltage-gated calcium ion channels to open.
345
What is exocytosis in the context of neurotransmitter release?
The process by which vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.
346
What happens to calcium ions after they diffuse into the synaptic knob?
They are pumped out afterwards by active transport.
347
What is the function of mitochondria in synaptic knobs?
They produce ATP, which is needed for active transport and the movement of vesicles.
348
Fill in the blank: The influx of calcium ions into the synaptic knob causes synaptic vesicles to move to the _______.
presynaptic membrane.
349
What is the role of neurotransmitter receptors on the postsynaptic membrane?
To bind neurotransmitters and initiate a response in the postsynaptic cell.
350
What ensures that synaptic transmission is unidirectional?
The presence of receptors only on the postsynaptic membranes.
351
What is a synapse?
A synapse is the junction between two neurons where information is transmitted.
352
What name is given to the tiny gap between the cells at a synapse?
Synaptic cleft
353
How do synapses ensure that nerve impulses are unidirectional?
Neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron.
354
What is synaptic divergence?
Synaptic divergence occurs when one neuron connects to many neurons, allowing information to be dispersed.
355
What is synaptic convergence?
Synaptic convergence occurs when many neurons connect to one neuron, amplifying information.
356
Fill in the blank: The neurotransmitter diffuses across the synaptic cleft and binds to specific _______.
[receptors]
357
What happens to sodium ion channels in the postsynaptic neuron when the neurotransmitter binds to receptors?
Sodium ion channels open.
358
What causes depolarization in the postsynaptic membrane?
The influx of sodium ions.
359
What is generated if the threshold is reached in the postsynaptic membrane?
An action potential.
360
True or False: The neurotransmitter remains in the synaptic cleft to prolong the response.
False
361
What is summation at synapses?
Summation is the additive effect of neurotransmitter released from many neurons or one neuron stimulated repeatedly.
362
What is the role of synaptic knobs?
Synaptic knobs contain mitochondria that produce ATP for active transport and movement of vesicles.
363
Describe the sequence of events from the arrival of an action potential at the presynaptic membrane to the generation of a new action potential at the postsynaptic membrane.
1) Action potential arrives at presynaptic membrane. 2) Neurotransmitter is released into synaptic cleft. 3) Neurotransmitter binds to postsynaptic receptors. 4) Sodium channels open, causing depolarization. 5) If threshold is reached, a new action potential is generated.
364
What is a response in plants?
Plants respond to stimuli to increase their chances of survival.
365
Why do plants need to respond to stimuli?
To increase their chances of survival by adapting to environmental changes.
366
What is a tropism?
A tropism is a plant's growth response to a directional stimulus.
367
What is a positive tropism?
Growth towards the stimulus.
368
What is a negative tropism?
Growth away from the stimulus.
369
What is phototropism?
The growth of a plant in response to light.
370
How do shoots and roots respond to light in phototropism?
* Shoots grow towards light (positively phototropic)
* Roots grow away from light (negatively phototropic)
371
What is geotropism?
The growth of a plant in response to gravity.
372
How do shoots and roots respond to gravity in geotropism?
* Shoots grow upwards (negatively geotropic)
* Roots grow downwards (positively geotropic)
373
How do plants respond to stimuli without a nervous system?
Plants use growth factors, which are chemicals that speed up or slow down growth.
374
Where are growth factors produced in plants?
In the growing regions of the plant, such as shoot tips and leaves.
375
What is the role of auxins in plant growth?
Auxins stimulate shoot growth by promoting cell elongation.
376
What effect do high concentrations of auxins have on roots?
They inhibit growth in roots.
377
Name other important plant growth factors.
* Gibberellins — stimulate flowering and seed germination
* Cytokinins — stimulate cell division and differentiation
* Ethene — stimulates fruit ripening and flowering
* Abscisic acid (ABA) — involved in leaf fall
378
What are phytochromes?
Proteins that detect light and help regulate plant responses to light.
379
What is the significance of different wavelengths of light for phytochromes?
They respond to different wavelengths, influencing plant growth and development.
380
Fill in the blank: A _______ is a plant's growth response to a directional stimulus.
tropism
381
True or False: All plants respond to stimuli in the same way.
False
382
What is the role of auxin in plants?
Auxin regulates growth and responses to stimuli in plants.
383
What is the significance of IAA in plant growth?
IAA (Indole-3-acetic acid) is an important auxin that influences growth direction.
384
How does IAA affect phototropism?
IAA moves to shaded parts of the plant, causing cells to elongate and the shoot to bend towards the light.
385
How does IAA influence root growth in response to light?
IAA moves to the side of the root away from light, inhibiting growth on that side and causing the root to bend away.
386
Define geotropism in relation to IAA.
Geotropism is the growth response of plants to gravity, where IAA accumulates on the underside, causing uneven growth.
387
What are phytochromes?
Phytochromes are photoreceptors in plants that detect light.
388
Where are phytochromes found in plants?
Phytochromes are found in leaves, seeds, roots, and stems.
389
What light wavelengths do phytochromes absorb?
Phytochromes absorb red light at 660 nm and far-red light at 730 nm.
390
What happens to phytochromes when exposed to red light?
P660 is quickly converted into PFR when exposed to red light.
391
What occurs to phytochromes in darkness?
PFR is slowly converted back into PR in darkness.
392
How do the levels of PR and PFR change throughout the day?
Daylight contains more red light, leading to higher levels of PFR compared to PR at night.
393
Why do some plants flower in summer?
Differing amounts of PR and PFR regulate gene transcription involved in flowering, leading to summer blooms.
394
Fill in the blank: Plants respond to stimuli to _______.
survive and adapt to their environment.
395
What is a tropism?
A tropism is a growth response of a plant to a directional stimulus.
396
True or False: IAA promotes growth on the side of the plant that is exposed to light.
False.
397
What stimulates iris plants to flower?
High levels of PFR.
398
What time of year would an iris flower?
In spring or summer when light levels are high.
399
What is the role of auxin in plants?
Auxin regulates growth and responses to stimuli in plants.
400
What is the significance of IAA in plant growth?
IAA (Indole-3-acetic acid) is an important auxin that influences growth direction.
401
How does IAA affect phototropism?
IAA moves to shaded parts of the plant, causing cells to elongate and the shoot to bend towards the light.
402
How does IAA influence root growth in response to light?
IAA moves to the side of the root away from light, inhibiting growth on that side and causing the root to bend away.
403
Define geotropism in relation to IAA.
Geotropism is the growth response of plants to gravity, where IAA accumulates on the underside, causing uneven growth.
404
What are phytochromes?
Phytochromes are photoreceptors in plants that detect light.
405
Where are phytochromes found in plants?
Phytochromes are found in leaves, seeds, roots, and stems.
406
What light wavelengths do phytochromes absorb?
Phytochromes absorb red light at 660 nm and far-red light at 730 nm.
407
What happens to phytochromes when exposed to red light?
P660 is quickly converted into PFR when exposed to red light.
408
What occurs to phytochromes in darkness?
PFR is slowly converted back into PR in darkness.
409
How do the levels of PR and PFR change throughout the day?
Daylight contains more red light, leading to higher levels of PFR compared to PR at night.
410
Why do some plants flower in summer?
Differing amounts of PR and PFR regulate gene transcription involved in flowering, leading to summer blooms.
411
Fill in the blank: Plants respond to stimuli to _______.
survive and adapt to their environment.
412
What is a tropism?
A tropism is a growth response of a plant to a directional stimulus.
413
True or False: IAA promotes growth on the side of the plant that is exposed to light.
False.
414
What stimulates iris plants to flower?
High levels of PFR.
415
What time of year would an iris flower?
In spring or summer when light levels are high.
