Weeks 1-3 Flashcards
What kinds of cells does the nervous system comprise?
Neurons
Glia
What is the function of neurons?
Receive information and transmit it to other cells
Roughly how many neurons are there in the adult human brain?
86 billion
Which two scientists are considered the main founders of neuroscience?
Santiago Ramon y Cajal (Chapter 1) Charles Sherrington (Chapter 2)
Do sodium ions enter cells in the resting state?
Yes
What is the mind-brain or mind-body problem?
How does the mind relate to the brain?
Why is there such a thing as consciousness?
Why are certain types of brain activity conscious?
What is biological psychology?
The study of the physiological, evolutionary, and developmental mechanisms of behaviour and experience.
Describe the size and function of neurons.
Convey messages to one another, and to muscles and glands.
Vary greatly in size, shape, and function.
Describe the size and function of glia.
Generally smaller than neurons.
Have many functions but do not convey information over great distances.
What is monism?
Mental activity and certain types of brain activity are the same thing.
The universe consists of only one type of being.
Supported by almost all neuroscientists and philosophers.
What is dualism?
The idea that minds are one type of substance and matter is another.
What is a physiological explanation?
Relate a behaviour to the activity of the brain and other organs
What is an ontogenic explanation?
Describes how a structure or behaviour develops, including the influences of genes nutrition, experiences, and their interactions.
E.g. Males and female differ on average in several way, which can be traced to the effects of genes or prenatal hormones, or to cultural influences, or to both.
What is an evolutionary explanation?
Reconstructs the evolutionary history of a structure of behaviour. Characteristic features of an animal are almost always modifications of something found in ancestral species.
E.g. Bat wings are modified arms.
What is a functional explanation?
Describes why a structure or behaviour evolved as it did. Characteristics that promote survival are more likely to be seen as desirable in a mate, and therefore proliferate.
E.g. Many species have an appearance that matches the background they rest on.
How is an evolutionary explanation different from a functional explanation?
An evolutionary explanation states what evolved from
what. For example, humans evolved from earlier primates and therefore have certain features that we inherited from those ancestors, even if the features are not useful to us
today.
A functional explanation states why something was advantageous and therefore favored by natural selection.
Why do biological psychologists study non-humans?
- The underlying behaviour mechanisms are similar across species and sometimes easier to study in a non-human species.
- We are interested in animals for their own sake.
- What we learn about animals sheds light on human evolution.
- Legal or ethical restrictions prevent certain kinds of research on humans.
Of the following, which one is an example of an evolutionary explanation (as opposed to a functional explanation)?
A. People evolved a fear of snakes because many snakes are dangerous.
B. Humans have a (tiny) tailbone because our ancient monkey-like ancestors had a tail.
C. People evolved an ability to recognize faces because that ability is essential for cooperative social behaviors.
D. People evolved a tendency to form long-term male–female bonds because human infants benefit from the help of two parents
B. Humans have a (tiny) tailbone because our ancient monkey-like ancestors had a tail.
Of the following, which is a reason favoring the use of animals in biological psychology research aimed at solving human
problems?
A. Nonhuman animals engage in all the same behaviors as humans.
B. One human differs from another, but nonhumans are
nearly the same as one another.
C. The nervous system of nonhuman animals resembles that of humans in many ways.
D. Researchers can study nonhuman animals without
any legal restraints.
C. The nervous system of nonhuman animals resembles that of humans in many ways.
What does a “minimalist” favor with regard to animal research?
A. All research should have a minimum of at least 10
animals per group.
B. A minimum of three people should review each
research proposal.
C. Interference with animal research should be held to a
minimum.
D. Animal research is permissible but should be held to a minimum.
D. Animal research is permissible but should be held to a minimum.
An ontogenetic explanation focuses on which of the following?
A. How a behavior develops
B. The brain mechanisms that produce a behavior
C. The conscious experience that accompanies a behavior
D. The procedures that measure a behavior
A. How a behavior develops
What is the surface of a cell called?
Membrane
How can chemicals cross the membrane?
Protein channels permit a controlled flow of waqter, oxygen, sodium, potassium, calcium, chloride, and other important chemicals.
Which kinds of animal cells do not have a nucleus?
Mammalian red blood cells
What is structures perform metabolic activities?
What does this mean?
Mitochondria
They provide the energy that the cell uses for all other activities.
Mitochondria have genes separate from those in the nucleus of the cell. What are some outcomes of genetically different mitochondria?
Overactive mitochondria burn their fuel rapidly and overheat.
People with less active mitochondria are predisposed to depression and pains.
Mutated mitochonrial genes are a possible cause of autism.
What is a ribosome?
Where are they found?
The site within a cell that synthesizes new protein molecules.
Some float freely within the cell, but others are attached to the endoplasmic reticulum, a network of thin tubes that transport newly synthesized proteins to other locations.
What do proteins in cells do?
Provide building materials for the cell and facilitate chemical reactions.
What is a soma?
Cell body
Describe a motor neuron.
What is its function?
What components does it have?
Sends impules to muscles.
Soma in the spinal cord
Receives excitation through its dendrites
Conducts impules along its axon to a muscle
What does a sensory neuron do?
Specialised at one end to be highly sensitive to a particular type of stimulation, such as light, sound, or touch.
E.g. Conducting touch information from the skin to the spinal cord
What are dendrites?
Branching fibres that get narrower near their ends.
Surface is lined with specialised synaptic receptors, at which the dendrite receives information from the other neurons.
What does a greater surface area mean for dendrites?
They can receive more information.
What formations increase the surface area available for synapse?
Dendritic spines
What structure contains the nucleus, ribosomes, and mitochondria?
The soma
Describe the function of the soma.
Most of a neuron’s metabolic work occurs here.
How large are soma?
0.005mm to 0.1mm in mammals.
How are soma and dendrities similar?
In many neurons they are covered with synapses on their surfaces.
Describe the axon.
A thin fibre of constant diameter.
Conveys an impules toward other neurons, an organ, or a muscle.
Can be more than a metre in length. E.g. Axons from the spinal cord to the feet.
What material covers the axon?
What does it do?
Myelin sheath
Insulating materials
What are the nodes of Ranvier?
Interruptions in the myelin sheath
There can only be one axon, but axons can have branches. What occurs at the end of each branch of an axon?
A swelling called a presynaptic terminal or end bulb that releases chemicals that cross the junction between that neuron and another cell.
What does an afferent neuron do?
Brings information into a structure
Afferent starts with A and “admits” information.
What is an example of an afferent neuron?
Sensory neurons are afferent to the rest of the nervous system
What does an efferent neuron do?
Carries information away from a structure
Efferent starts with E and is an “exit”
What is an example of an efferent neuron?
Motor neurons are efferent to the nervous system.
How do afferent and efferent neurons interact?
Within the nervous system, a given neuron is efferent from one structure and afferent to another.
What is a neuron called if its dendrites are entirely contained within a single structure?
An interneuron or intrinsic neuron?
E.g. An intrinsic neuron of the thalamus has its axon and all its dendrites within the thalamus.
Where would you find more glia that neurons?
Cerebral cortex
What do the star-shaped glia called astrocytes do?
Why are they important?
Wrap around synapses of functionally related axons to shield it from checmical circulating in the surround.
Helps synchronise closely related neurons, enabling their axons to send messages in waves.
Important for generating rhythms, such as rhythm of breathing.
Dilate blood vessels to bring more nutrients into brain areas that have heightened activity.
Which cells act as part of the immune system, removing viruses and fungi from the brain?
Microglia
When do microglia proliferate?
After brain damage, removing dead or damaged neurons.
What are oligodendrocytes and Schwann cells?
How do they differ?
The build the myelin sheaths that surround and insulate certain vertebrate axons.
They supply an axon with nutrients.
Olgiodendrocytes occur in the brain and spinal cord.
Schwann cells occur in the periphery of the body.
Which glia guide the migration of nurons and their axons and dendrites during embryonic development?
Radial glia
What are the four major structures that compose a neuron?
Dendrites
Soma
Axon
Presynaptic terminal
Which kind of glia wraps around the synaptic terminals of axons?
Astrocytes
What is the blood-brain barrier?
A mechanism that excludes most chemicals from the brain
Why is the blood-brain barrier needed?
It protects the non-renewable cells of the brain from viruses, bacteria and unwanted chemicals
What happens to a cell when it is infected with a virus?
Mechanisms within the cell extrude virus particles through the membrane so that the immune system can find and kill them. Both cell and virus are killed in this way.
How do brain cells differ from skin or blood cells when dealing with viruses?
The brain’s blood vessels are lined with tightly packed cells that keep out most viruses, bacteria and harmful chemicals.
Microglia mount an inflammatory response that fights the virus without killing the neuron.
What are some examples of viruses that can enter the brain?
Rabies
Syphilis
Why don’t we have similar walls to the blood-brain barrier around all our other organs?
The barrier keeps out useful chemicals as well as harmful ones. This includes all fuels and amino acids, the building blocks for proteins.
What kinds of molecules can cross the blood-brain barrier?
Small, uncharged molecules such as oxygen and carbon dioxide.
Molecules that dissolve easily in fats, such as Vitamin A and D.
Drugs that affect the brain such as antidepressants as well as illegal drugs.
Which chemicals cross the blood-brain barrier passively?
Water, through special protein channels in the wall of the endothelial cells.
Which chemicals cross the blood-brain barrer through active transport?
Glucose - the brains main fuel Amino acids - building blocks of proteins Purines Choline Some vitamins Iron Insulin
In what situation might the blood-brain barrier prevent medical treatment?
Drugs used for chemotherapy fail to cross the blood-brain barrier.
What is the main nutrient for neurons?
Glucose
What other chemical is required to metabolise glucose?
Oxygen
How much of the body’s oxygen and glucose does the brain use?
20% of its oxygen
25% of its glucose
Why do neurons depend so heavily on glucose?
It is the only nutrient that crosses the blood-brain barrier in large quantities.
What condition is linked to the inability to metabolise gluten due to thiamine deficiency?
Chronic alcoholism causes thiamine deficiency and an inability to use glucose, causing the death of neurons and severe memory impairment.
What may cause faster uptake of a chemical in the brain?
Greater solubility in fats
- Santiago Ramón y Cajal was responsible for which of these discoveries?
A. The human cerebral cortex has many specializations
to produce language.
B. The brain’s left and right hemispheres control different
functions.
C. The nervous system is composed of separate cells.
D. Neurons communicate at specialized junctions called
synapses.
C. The nervous system is composed of separate cells.
2. Which part of a neuron has its own genes, separate from those of the nucleus? A. The ribosomes B. The mitochondria C. The axon D. The dendrites
B. The mitochondria
- What is most distinctive about neurons, compared to other cells?
A. Their temperature
B. Their shape
C. Their internal components, such as ribosomes and
mitochondria
B. Their shape
- Which of these do dendritic spines do?
A. They synthesize proteins.
B. They increase the surface area available for synapses.
C. They hold the neuron in position.
D. They metabolize
B. They increase the surface area available for synapses.
5. What does an efferent axon do? A. It controls involuntary behavior. B. It controls voluntary behavior. C. It carries output from a structure. D. It brings information into a structure.
C. It carries output from a structure.
- Which of the following is a function of astrocytes?
A. Astrocytes conduct impulses over long distances.
B. Astrocytes build myelin sheaths that surround and
insulate axons.
C. Astrocytes create the blood–brain barrier.
D. Astrocytes synchronize activity for a group
of neurons.
D. Astrocytes synchronize activity for a group
of neurons.
- Which of the following is a function of microglia?
A. Microglia remove dead cells and weak synapses.
B. Microglia build myelin sheaths that surround and
insulate axons.
C. Microglia dilate blood vessels to increase blood supply
to active brain areas.
D. Microglia synchronize activity for a group of neurons.
A. Microglia remove dead cells and weak synapses.
8. Which of these can easily cross the blood–brain barrier? A. Fat-soluble molecules B. Chemotherapy drugs C. Proteins D. Viruses
A. Fat-soluble molecules
- Which of these chemicals cross the blood–brain barrier by active transport?
A. Oxygen, water, and fat-soluble molecules
B. Glucose and amino acids
C. Proteins
D. Viruses
B. Glucose and amino acids
10. What is the brain’s main source of fuel? A. Glucose B. Glutamate C. Chocolate D. Proteins
A. Glucose
11. For the brain to use its main source of fuel, what does it also need? A. Steroid hormones B. Vitamin C C. Thiamine D. Acetylsalicylic acid
C. Thiamine
Which impulse would reach the brain first; a touch on your toe, or a touch on your neck?
Neck, but in most cases you would not notice the difference because there is no need.
In what part of the body does an impulse from further away from the brain travel faster than one closer to the brain?
The retina
This ensures that impules that information received simultaneously by the retinas is transmitted to the brain at the same time.
What is another term for the electrical gradient of a membrane at rest?
Polarisation
What is an electrical gradient / polarisation?
A difference in charge between the inside and outside of a cell
Why is the electrical potential inside the membrane slightly negative compared to the outside?
What is this difference called?
Mainly because of negatively charged proteins inside the cell.
Resting potential
Typical level of -79 millivolts (mV)
How is resting potential measured?
By inserting a very thin microelectrode into the cell body.
What would happen if charged ions could flow freely across the membrane?
The membrane would depolarise.
What is selective permeability?
Some chemicals can pass through membranes more freely than others, preventing depolarisation.
What are membrane channels?
Channels through the membrane that can open and close that allow certain ions to pass through, including socidum, potassium, calcium and chloride.
What state are membrane channels in when the membrane is at rest?
Closed
Almost no sodium and a small amount of potassium can flow through when the membrane channels are closed.
What is the sodium-potassium pump and how does it work?
A protein complex that repeatedly transports three sodium ions out of the cell while drawing two potassium ions into it.
It is an active transport that requires energy.
Where are sodium and potassium ions most concentrated?
Sodium - outside the membrane
Potassium - inside the membrane
Why is the sodium-potassium pump effective?
Because of membrane permeability; sodium ions that were pumped out of the neuron are prevented from flowing back in.
However some of the potassium ions in the neuron slowly leak out, carrying a positive charge with them. That leakage increases the electrical gradient across the membrane.,
How does the electrical gradient affect sodium?
Pushes it into the cell; sodium is positively charged, interior of the cell is negatively charged; opposites attract.
How does the concentration gradient affect sodium?
Pushes it into the cell.
Sodium is more concentrated outside the cell, so it is more likely to enter a cell than leave it EXCEPT because the sodium channels are closed when the membrane is at rest almost no sodium flows except for what the sodium-potassium pump forces OUT of the cell.
How does the electrical gradient affect potassium?
Pulls it into the cell.
Potassium is positively charged and the inside of the cell is negatively charged, so the electrical gradient tends to pull potassium in.
How does the concentration gradient affect potassium?
Pushes it out of the cell.
Potassium is more concentrated inside the cell, so the concentration gradient tends to drive it out.
How is the negative charge inside a cell maintained?
Negatively charged proteins inside the cell
Why does the body maintain resting potential?
Excitation of the neuron opens channels that allow sodium to enter the cell rapidly. Because the membrane did its work in advance by maintaining the concentration gradient for sodium, the cell is prepared to respond vigorously to a stimulus.
What is an action potential?
A message sent by an axon.
What is hyperpolarisation?
When a neuron becomes more negatively charged than at its resting potential.
What is depolarisation?
When a neuron becomes less negatively charged that at its resting potential.
What happens to a neuron that does not achieve stimulation that will exceed the threshold of excitation?
Its charge returns to its resting level.
What happens when a neuron reaches the threshold of excitation?
Massive depolarisation of the membrane.
The membrane opens its sodium channels and lets sodium ions flow into the cell.
The potential shoots up far beyond the strength that the stimulus provided.
What is the peak charge of an action potential?
It varies from one axon to another.
What is the range in amplitude and speed of action potentials?
What is this principle called?
For a given neuron, all actions are roughly equal in amplitude and velocity regardless of the intensity of the stimulus. However, different neurons may have different characteristics.
The all-or-none law
Amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it, provided the stimulus reaches the threshold.
How does the thickness of the axon affect action potentials?
Thicker axons convey action potentials at faster velocities and more action potentials per second.
Does the all-or-none law apply to dendrites?
No, because dendrites do not have action potentials.
What three events occur during an action potential?
- At the start, sodium ions are mostly outside the neuron and potassium ions are mostly inside
- When the membrane is depolarised, sodium and potassium channels in the membrane open
- At the peak of the action potential, the sodium channels close
How does sodium or potassium cross the membrane?
Through a cylindrical protein that allows that particular type of ion to cross the membrane; which ion depends on the size and shape of the opening.
Describe the protein channels when the membrane is at resting potential.
Sodium channels are fully closed, allowing no flow.
Potassium channels are almost closed, allowing a small flow.
