Ch 2: neurobiology Flashcards
1
Q
What is the nervous system responsible for?
A
thought processes, heartbeat, visual-motor coordination, etc.
2
Q
What does the nervous system comprise of?
A
The brain, spinal cord & other parts that help us receive info from the outside world.
Composed of cells (mostly neurons)
3
Q
Neuron definition
A
Specialized cell of the nervous system that receives (info gathering) and transmits (fire) electrochemical signals
4
Q
What are the 3 essential parts of a neuron?
A
1) Dendrites (receive impulses)
2) Cell body (soma)
3) Axon (sends impulses)
5
Q
What is a dendrite?
A
Branch-like structures, attached to the cell body of a neuron, that receive impulses from other neurons
6
Q
What is a cell body (soma)?
A
It contains the core or nucleus of the cell
7
Q
What is a nucleus?
A
It uses oxygen and nutrients to generate the energy needed to carry out the work of the cell.
8
Q
What is an axon?
A
It’s a long, thin part of a neuron that transmits impulses to other neurons from branching structures called terminal buttons
9
Q
What are terminal buttons?
A
They are small, rounded knobs at the ends of axons that release neurotransmitters
10
Q
Neuron carry info one-way. How does it travel?
A
Info is received by the dendrites -> cell body —- (through)–> axon -> axon terminal
Messages then transmitted from the terminal to other neurons, muscles or glands
11
Q
What is a synapse/synaptic cleft (gap)?
A
It’s a tiny fluid-filled junction between the axon terminals of one neuron and the dendrites or cell body of another neuron
12
Q
What are glial cells?
A
cells that nourish and insulate neurons, direct their growth, and remove waste products from the nervous system
13
Q
Define the myelin sheath.
A
A fatty substance that encases and insulates axons, facilitating transmission of neural impulses
14
Q
The fat (from the myelin) insulates the axon from electronically charged atoms (or ions) found in the fluid that surround the nervous system. Why is this important?
A
It minimizes leakage of the electrochemical current being carried along the axon, thereby allowing messages to be conducted more efficiently.
15
Q
Define myelination.
A
It’s part of the maturation process that leads to a child’s ability to walk during the 1st yr
16
Q
What happens when myelination is disrupted.
A
In ppl w/ MS, myelin is replaced with a hard fibrous tissue that throws off the timing of neural impulses and disrupts muscular control
17
Q
Name the main 3 types of neurons.
A
1) Sensory neurons
2) Interneurons
3) Motor neurons
18
Q
What is a sensory neuron?
A
Neurons that transmit messages from sensory receptors to the spinal cord and brain (also called afferent neurons)
19
Q
What are interneurons?
A
Neurons that connect sensory and motor neurons
20
Q
What are motor neurons?
A
Neurons that transmit messages from the brain or spinal cord to muscles and glands (also called efferent neurons)
21
Q
What is a neural impulse?
A
The electrochemical discharge of neurons
22
Q
True or false: Chemical changes take place within neurons that cause an electrical charge to be transmitted along their lengths
A
True
23
Q
Define polarize
A
To ready a neuron for firing by creating an internal negative charge in relation to the body fluid outside the cell membrane
The difference in electrical charge readies a neuron for firing
24
Q
Define resting potential
A
The electrical potential across the neural membrane when it is not responding to other neurons is about –70 millivolts in relation to the body fluid outside the cell membrane.
25
Define depolarize.
To reduce the resting potential of a cell membrane from about –70 millivolts toward +40 millivolts
26
Define action potential.
The electrical impulse that provides the basis for the conduction of a neural impulse along an axon of a neuron
27
What does neuron firing mean?
the conduction of the neural impulse along the length of a neuron is what is meant by firing.
Neurotransmitters are what is fired
28
What is the all or nothing principle?
The fact that a neuron fires an impulse of the same strength whenever its action potential is triggered (either a neuron fires or it doesn’t)
29
True or false: Stronger stimuli cause more frequent firing, but the strength of each firing remains the same
True
30
What is a refractory period?
It is a phase following firing during which a neuron is less sensitive to messages from other neurons and will not fire
31
The neural impulse is electrical. Does that mean it jumps like a spark across the synaptic gap?
No, the electrochemical pulse forces stored chemicals through the cell membrane into the synaptic cleft (neurotransmitters are released instead)
32
What are neurotransmitters?
It's a chemical substances involved in the transmission of neural impulses from one neuron to another
33
Where are neurotransmitters located?
Sacs called synaptic vesicles in the axon terminals contain neurotransmitters
34
How are neurotransmitters released?
When a neural impulse (action potential) reaches the axon terminal, the vesicles are forced toward the cell membrane and release varying amounts of neurotransmitters—the chemical keys to communication—into the synaptic cleft
35
What is a receptor site?
A location on a dendrite of a receiving neuron tailored to receive a neurotransmitter (lock and key type of fit)
36
Define reuptake.
Reabsorption of the released neurotransmitter by the releasing neuron
Loose” neurotransmitters are usually either broken down or reabsorbed by the axon terminal they came from
37
How does an excitatory neurotransmitter affect other neurons?
It causes other neurons to fire
38
How does an inhibitory neurotransmitter affect other neurons?
It prevents the neurons from firing
39
What is Acetylcholine (ACh)?
A neurotransmitter that controls voluntary muscle contractions
40
How does ACh allow for voluntary movement?
ACh activates the muscles by binding to receptors in the skeletal muscles which causes them to contract.
41
What is the danger of ACh not binding?
Both botulism (the disease) and curare (the poison) prevent ACh from binding to the receptor site on neurons. The victim will be unable to contract the muscles necessary to breathe, thus making them suffocate to death
42
ACh is normally prevalent in the hippocampus (memory centre). What happens if the amount decreases?
Memory formation can be impaired, leading to Alzheimer's
43
What is dopamine?
It's a neurotransmitter that acts in the brain and affects the ability to perceive pleasure, voluntary movement, learning and memory
44
What happens when there is too much dopamine in the brain?
Schizophrenia (characterized by confusion and false perceptions)
Ppl w/ it may have more receptor sites for dopamine in an area of the brain that is involved in emotional responding -> they may “overutilize” the dopamine available in the brain, which is connected with hallucinations and disturbances of thought and emotion
45
What happens when there is too little dopamine in the brain?
Linked to Parkinson’s disease, in which people progressively lose control over their muscles
46
What is norepinephrine?
A neurotransmitter whose action is similar to that of the hormone epinephrine and that may play a role in depression
47
True or false: Norepinephrine is produced largely by neurons in the brain stem & acts as a neurotransmitter AND a hormone
True
48
Is norepinephrine an excitatory or inhibitory neurotransmitter?
It's an excitatory neurotransmitter that speeds up HR, general arousal, learning & memory, and eating
49
What happens if there is a deficiency in norepinephrine?
Like ACh, memory formation is impaired
50
What happens if there is an increase in norepinephrine?
The stimulants cocaine and amphetamines (“speed”) boost norepinephrine (as well as dopamine) production, increasing the firing of neurons and leading to persistent arousal. Amphetamines both facilitate the release of these neurotransmitters and prevent their reuptake. Cocaine also blocks reuptake.
51
What is serotonin?
is involved in emotional arousal and sleep
52
What happens if there is a deficiency in serotonin?
Depression, eating disorders, alcoholism, aggression and insomnia
53
What effect does LSD have on the body?
It inhibits serotonin and increases the release of dopamine, leading to hallucinations
54
What is glutamate?
It's an abundant excitatory neurotransmitter, and one that is so active that it can even excite cells to death!
55
True or false: glutamate has an important role in memory and learning
True
56
What is the most important role glutamate has?
It plays a role in neuroplasticity
57
What is neuroplasticity?
The ability of neural networks to grow, change, and adjust due to experiences
58
What is gamma-aminobutyric acid (GABA
It's is an inhibitory neurotransmitter that may help calm anxiety reaction
59
True or false: tranquillizers and alcohol may lower anxiety by binding with GABA receptors and amplifying the effects
True
60
What happens if there is a deficiency in GABA?
Depression
61
What are endorphins?
They are inhibitory neurotransmitters that are composed of amino acids and occur naturally in the brain and in the bloodstream and are similar to the narcotic morphine in their functions & effects
62
What are the benefits of endorphins?
They block pain receptors.
Endorphins may also increase our sense of competence, enhance the functioning of the immune system, and be connected with the pleasurable “runner’s high” reported by many long-distance runners
63
What are the divisions of the nervous system
Nervous system -> Peripheral nervous system -> Somatic system
Nervous system -> Peripheral nervous system -> autonomic system -> sympathetic system -> parasympathetic
Nervous system -> central nervous system -> brain & spinal cord
64
What is a nerve?
Bundle of axons from many neurons
65
What does the CNS consist of?
brain & spinal cord
66
What is the spinal cord?
It's a column of neurons within the spine that transmits messages from sensory receptors to the brain and from the brain to muscles and glands throughout the body
67
What is a spinal reflex?
It's a simple, unlearned response to stimulation that may involve only two neurons (a sensory & motor neuron)
68
What is the difference b/w grey and white matter?
Grey = nonmyelinated neurons
White = long, myelinated neurons
69
What is the peripheral nervous system?
It's the part of the nervous system consisting of the somatic nervous system and the autonomic nervous system
70
What is the somatic nervous system?
It's the division of the peripheral nervous system that connects the central nervous system with sensory receptors, skeletal muscles, and the surface of the body
The S's "sense organs & skeletal muscles"
71
True or false: The SNS transmits messages about sights, sounds, smells, temperature, body positions, etc to the CNS
True
Messages transmitted from the brain and spinal cord to the somatic nervous system control purposeful body movements such as raising a hand, winking, or running, as well as the tiny, almost imperceptible movements that maintain our balance and posture.
72
Does the SNS control voluntary or unvoluntary movements?
Voluntary
73
What is the autonomic nervous system (ANS)?
It's the division of the peripheral nervous system that regulates glands and activities such as heartbeat, respiration, digestion, and dilation of the pupils
74
Is the ANS voluntary or involuntary?
involuntary
-think "automatic"
However, some can be purposeful (you can breathe at a purposeful pace -> ex: yoga)
75
What is the ANS subdivided into?
The sympathetic & parasympathetic nervous system
76
What is the sympathetic nervous system?
It's the branch of the ANS that is most active during emotional responses, such as fear and anxiety, that spend the body’s reserves of energy
77
True or false: the ANS is activated during fight or flight
True
It incr HR & inhibits digestion
78
What is the parasympathetic nervous system?
It's the branch of the ANS that is most active during processes (such as digestion) that restore the body’s reserves of energy
79
Which branch of the nervous system is known as for "rest and digest?"
PNS
It decr HR & stimulates digestion
80
What is an electroencephalograph (EEG)?
It's a method of detecting brain waves by means of measuring the current between electrodes placed on the scalp
81
What does an EEG do?
It detects minute amounts of electrical activity (brain waves) that pass between the electrodes.
Certain brain waves are associated with feelings of relaxation, with various stages of sleep, and with neurological problems such as epilepsy.
82
List the various brain-imaging techniques (5)
1) Computerized axial tomography (CAT or CT scan)
2) Positron emission tomography (PET scan)
3) Magnetic resonance imaging (MRI)
4) Functional MRI (fMRI)
5) Diffusion tensor imaging (DTI)
83
What is a Computerized axial tomography (CAT or CT scan)
It's a method of brain imaging that passes a narrow X-ray beam through the head and measures structures that reflect the rays from various angles, enabling a computer to generate a three-dimensional image
84
What can a CAT scan detect?
They can reveal deformities in shape and structure that are connected with blood clots, tumors, and other health problems
85
What is a Positron emission tomography (PET scan)?
It's a method of brain imaging that injects a radioactive tracer into the bloodstream and assesses activity of parts of the brain according to the amount of glucose they metabolize
86
How does the PET scan work?
More glucose is metabolized in more active parts of the brain.
To trace the metabolism of glucose, a harmless amount of a radioactive compound (tracer) is mixed with glucose and injected into the bloodstream.
When the glucose reaches the brain, the patterns of activity are revealed by measurement of the positrons—positively charged particles—that are given off by the tracer.
87
Why are PET scans used?
Used to see which parts of the brain are most active when we are doing certain things (ex: listening to music or using language, etc)
88
What is a Magnetic resonance imaging (MRI)?
It's a method of brain imaging that places a person in a magnetic field and uses radio waves to cause the brain to emit signals that reveal shifts in the flow of blood, which, in turn, indicate brain activity
89
What does the MRI machine heavily rely on?
It relies on subtle shifts in blood flow.
More blood flows to more active parts of the brain, supplying them with oxygen.
90
What is a Functional MRI (fMRI)?
It's a form of MRI that enables researchers to observe the brain “while it works” by taking repeated scans
91
How does an fMRI work?
It takes repeated scans while subjects engage in activities such as mental processes and voluntary movements.
It can be used to show which parts of the brain are active when we are doing things such as listening to music, using language, or playing chess
92
What is a Diffusion tensor imaging (DTI)?
It's an MRI-based imaging method that identifies the location and direction of neural pathways
93
How does a DTI work?
It works by measuring the movement of water molecules in and around neuronal structures. This measurement tool enables researchers to see the neural pathways in the brain
It visually depict the connections b/w various structures of the brain, allowing for increased understanding of how various brain regions function interactively with each other
94
What is the hindbrain?
It's where the spinal cord rises to meet the brain
95
What are the 3 major structures of the hindbrain?
Medulla
Pons
Cerebellum
96
What is the medulla?
It's an oblong area of the hindbrain involved in regulation of heartbeat, BP and respiration
97
What are the pons?
It's a bulge in the hindbrain that lies forward of the medulla involved in respiration, sleep, and arousal
98
True or false: the pons transmit info about body movement and is involved in functions related to regulation of movement, sleep and alertness, and respiration
True
99
What is the cerebellum?
It has 2 hemispheres that are involved in maintaining balance and in controlling motor (muscle) behaviour.
100
What is another name for the cerebellum?
Also known as little brain
101
What is reticular formation?
It's a part of the brain involved in attentiveness, sleep, and arousal
102
What will happen if the reticular formation is injured?
It will result in a coma
103
What happens during stimulation of the reticular formation?
Stimulation of the reticular formation causes it to send messages to the cerebral cortex, making us more alert to sensory information
104
True or false: central nervous system depressants, such as alcohol, are thought to work, in part, by lowering reticular formation activity.
True
105
What is the forebrain?
It's the forward-most part of our brain
106
What are the parts of the forebrain? (6)
1) Cerebrum
2) Thalamus
3) Hypothalamus
4) Pituitary gland
5) Limbic system
6) Olfactory bulb.
107
What is the thalamus?
It's an area near the centre of the brain involved in the relay of sensory information to the cortex and in the functions of sleep and attentiveness
108
What is the function of the thalamus?
The thalamus is involved in relaying sensory information to the cortex and regulating sleep and attentiveness.
It serves as a relay station for sensory input, sending information from sensory systems to the cerebral cortex.
109
How does the thalamus relay sensory information?
Nerve fibers from sensory systems enter the thalamus from below, and their information is transmitted to the cerebral cortex by fibers that exit from above.
110
What role does the thalamus play in sleep and attentiveness?
The thalamus helps regulate sleep and attentiveness, working in coordination with other brain structures, including the reticular formation.
111
Where is the hypothalamus located and what is its primary function?
The hypothalamus is located below the thalamus and above the pituitary gland. It regulates body temperature, concentration of fluids, storage of nutrients, motivation, and emotion.
112
What behaviors is the hypothalamus involved in?
The hypothalamus is involved in hunger, thirst, sexual behavior, caring for offspring, and aggression.
113
What types of behaviors can stimulation of the hypothalamus trigger in lower animals?
Stimulation of different areas of the hypothalamus can trigger instinctual behaviors such as fighting, mating, or nest building.
114
What is the limbic system, and what does it control?
The limbic system is a group of structures that controls memory, motivation, and emotion. It forms a fringe along the inner edge of the cerebrum.
115
What is the role of the amygdala in the limbic system?
The amygdala facilitates aggressive responses and is involved in emotions, learning, memory, and focus. Electrical stimulation can trigger aggressive behavior or fear responses
116
What happens if the amygdala is electrically stimulated in certain areas?
Electrical stimulation of the amygdala can lead to aggressive behavior (rage) or a fear response, depending on the area stimulated.
117
What is the result of destroying parts of the amygdala in animals?
Destruction of certain areas of the amygdala can make animals more docile and less aggressive.
118
What is the cerebrum and what is its function?
The cerebrum is the large mass of the forebrain, consisting of two hemispheres, and is responsible for thinking and language.
119
What is the role of the corpus callosum?
The corpus callosum is a thick bundle of nerve fibers (200 million) that connects the two hemispheres of the cortex, facilitating communication between them.
120
How is the cerebrum divided, and what are its major parts?
The cerebrum has two hemispheres (left and right), each divided into four lobes: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.
121
What does the frontal lobe control?
The frontal lobe is responsible for decision-making, voluntary muscle movement, and is located in front of the central fissure.
122
What is the function of the parietal lobe?
The parietal lobe is the center for touch sensations, receiving signals from the skin to feel pressure, cold, and other sensations. It is located behind the central fissure.
123
What is the role of the temporal lobe?
The temporal lobe is involved in language production and understanding. It also processes auditory information, with sounds being relayed from the ear to the auditory area of the cortex.
124
How does the occipital lobe contribute to vision?
The occipital lobe processes visual information. Light strikes the eye, and neurons in the occipital lobe fire, allowing us to "see."
Stimulating this area electrically can cause visual perceptions, even in darkness.
125
What is the somatosensory cortex, and where is it located?
The somatosensory cortex is located just behind the central fissure in the parietal lobe.
It processes sensory stimulation like cold, touch, pain, and movement. Injury to one side of the brain affects sensation and movement on the opposite side of the body.
126
What is the motor cortex, and where is it located?
The motor cortex, located in the frontal lobe just across from the somatosensory cortex, controls voluntary muscle movements. Electrical stimulation in this area causes muscle contractions.
127
What are association areas of the cerebral cortex?
Association areas are regions of the cerebral cortex that are not primarily involved in sensory or motor activity. They are involved in higher functions like decision-making, planning, and solving problems.
128
How does the pre-frontal cortex contribute to cognition?
The pre-frontal cortex processes information related to decision-making, planning for the future, and problem-solving. It also retrieves and manipulates memories.
129
What happens if certain parts of the brain, like the parietal lobe, frontal lobe, hippocampus, limbic system or thalamus are damaged?
Damage to these areas can result in cognitive disabilities.
130
How do association areas integrate visual information in the occipital lobe?
Neurons in the occipital lobe fire in response to visual stimuli like vertical or horizontal lines.
The association areas process and integrate this information to create a coherent visual perception.
131
Where is the somatosensory cortex located, and what is its function?
The somatosensory cortex is located just behind the central fissure at the top of the brain in the parietal lobe. It receives sensory messages from skin senses all over the body.
132
What is the role of the left hemisphere in language for most right-handed and left-handed people?
The left hemisphere is responsible for language functions in nearly all right-handed people and about two-thirds of left-handed people.
133
What is aphasia?
Aphasia is a disruption in the ability to understand or produce language, typically resulting from damage to areas in the brain responsible for language processing.
134
Where is Broca's area located and what is its role?
Broca's area is located in the frontal lobe, near the motor cortex, and is responsible for processing language information and relaying it to the motor cortex for speech production.
135
What is Broca's aphasia?
Broca's aphasia is a language disorder characterized by slow, laborious speech and the omission of small but important words (e.g., "is," "and," "the").
A person might say "walk dog" instead of "I will walk the dog."
136
Where is Wernicke's area located, and what is its function?
Wernicke's area is located in the temporal lobe, near the auditory cortex, and is responsible for understanding language and the relationships between words and their meanings.
137
What is Wernicke's aphasia?
Wernicke's aphasia is a language disorder that impairs the comprehension of spoken language and the ability to find the right words to express thoughts, often leading to fluent but nonsensical speech.
138
What is a split-brain operation, and why is it performed?
A split-brain operation involves severing the corpus callosum to limit seizures to one hemisphere, often done to treat epilepsy and prevent seizures from affecting both hemispheres.
139
What happens to a person after a split-brain operation?
After a split-brain operation, a person may experience a loss of interconnectedness between the two hemispheres. For example, they may describe an object held in one hand (which is processed by the left hemisphere), but not in the other hand (which is processed by the right hemisphere).
140
What is brain plasticity?
Brain plasticity is the brain's ability to adapt and change, particularly in response to environmental experiences or injury.
141
How does brain plasticity relate to experience?
Brain plasticity allows the brain to form and change in response to environmental factors. For example, London cab drivers have a larger hippocampus due to the mental mapping required in their profession.
142
How does brain plasticity work in children who lose part of their brain?
Children who lose the left hemisphere of their brain (due to medical issues) can sometimes transfer speech functions to the right hemisphere, demonstrating the brain's adaptability. This process is age-dependent.
