Test 1 Flashcards
What is consciousness?
the state or quality of awareness- awareness of our thoughts, perceptions, memories, and feelings
What is a frontal lobotomy?
used to treat psychosis, depression, anxiety, etc. (experimental)
- Cuts off pieces of the brain
What is the split brain operation?
- Used to cure severe epilepsy, when both sides of the brain exhibit excessive and uncontrolled neural activity
- An outdated approach that involves cutting the corpus callosum, the bundle of nerve fibers that connect the left and right sides of the cerebral cortex
Patients cannot verbalize any stimuli directed to their _____ brain
Right
Which hand is always consistent with conscious awareness?
The right hand
What is the corpus callosum?
- A bundle of fibers that interconnects the two cerebral hemispheres
- Enables both hemispheres to share information with each other
- If it is cut, the two hemispheres cannot directly talk to each other, but they can send information down the spine and to the lower brain
What is the function of the spine and lower brain?
They help with balance and coordinating body movements
Where is our comprehension of language and our ability to talk and write is generally located in?
The left cerebral cortex
What is Gazzaniga’s interpreter theory?
he argued that our ability to communicate and make up stories might have given rise to our ability to think and be aware of our own existence; the evolution of speech gave rise to storytelling, which in turn gave rise to consciousness
What is mind-body dualism?
while the body may be a mechanical device and the world deterministic, the mind is something else, something immaterial that exists outside of the body
What are the main elements of cells?
H, O, C, N
- we breathe mostly O and N
What is RNA?
A strand of a certain type of nucleic acid, specifically ribonucleic acids
- it easily breaks apart
- not much diversity
- sections of DNA are transcribed in RNA
What are RNA-based enzymes?
They can catalyze chemical reactions
What is a phospholipid bilayer?
- Strands of fat with a phosphate cap
- Lipids interact with each other, while phosphate groups prefer to interact with water
What are micelles?
Shaken up phospholipids
What are liposomes?
- When micelles explode
- Diffusion through the membrane is limited
- The interior is full of saltwater
What floats in the cytoplasm of a prokaryotic cell?
Chromatin, ribosomes, proteins
What is chromatin?
consists of loose strings of nucleic acids (DNA)
What are ribosomes?
Consist of nucleic acids (mostly RNA) and proteins
- Function: make proteins by linking together amino acids in the order dictated by the DNA genetic code
What are proteins?
- Catalyze all chemical reactions (specifically enzymes)
- Receptors are proteins that sense things and react accordingly
- Proteins make up roads of the cell and mediate transport and storage
- Serve as messengers
What is different about a eukaryotic cell?
- The loose chromatin DNA is compacted into a nucleus, which is called a chromosome
- It has mitochondria, which are responsible for extracting energy from nutrients
- This energy is typically stored in the molecular bonds of the molecule ATP
What is a neutron typically defined by?
Where the soma (cell body) is located
What is a gene?
Section of a chromosome that encodes a specific protein
• When a gene is being read, copies of it are made (transcribed) into DNA
What is the genome of a cell?
Refers to all the DNA sequences in the soma
- Provides the info necessary to synthesize all the proteins for a particular organism
What are isoforms?
Genes can often be read in alternative ways, resulting in there being different versions of one type of protein
What is neoteny?
extended youth- prolongation of maturation
What is a kinesin motor protein?
uses ATP to walk and carry information
What is a crystal structure?
aggregates of one kind of molecule
What are processes?
The parts of the neutron that extend out of the soma
What are dendrites?
branched extensions responsible for sensing the external world
What are axons?
varies in length and communicates info through action potential (faster than other forms of transport)
What is electrical potential?
Potential for electricity to flow
What is the charge difference?
The difference between inside and outside of the cell
- Solution outside of cell: ground (0 mV)
- Solution inside cell: # of mV
What is the difference between a cation and an anion?
Cation: positive charge
Anion: negative charge
What is electrostatic pressure?
Attractive force between molecules that are oppositely charged (- and +) or repulsive force between molecules that are similar charged (+ and +)
What are ion channels?
Specialized protein molecules that sit in the cell membrane
- They have a pore (hole) in them through which specific ions can enter or leave cells
What is a leak channel?
an ion channel protein that is in the membrane and has a pore that is always open
What is the 2% “others” composition of cells is made up of?
Positively charged: monovalent cations (1 charge) and divalent (2 charges)
Negatively charged: monovalent anions (1 charge)
- Na, Ca, Mg, Cl: more abundant outside of cell
- K: more abundant inside of cell
What does equal concentration on either side of the membrane mean?
Outside the cell = 0 mV
Inside the cell = 0 mV
What is a sodium-potassium transporter?
It requires ATP, concentrates sodium and potassium outside and inside the cell
- Pumps K+ ions in and Na+ ions out of the cell
- 30x more K+ on inside and 15x more Na+ on the outside
• This never changes, unless the cell dies
What causes the concentration gradient within the membrane?
Because of the force of diffusion, K+ wants to leave, but it can’t because of the bilayer, so it causes a potential energy (concentration gradient)
What are leak potassium channels?
Always open, the number of these channels determines the resting membrane potential
- With the freedom to cross the membrane whenever they want, K+ ions start to leave the cell because of the force of diffusion
- Very few K+ leave because whenever it leaves, it creates an imbalance in the charges –> a negative charge builds up
- *The more K+ leak channels = the more permeable it will be to K+ **
What is electrochemical equilibrium?
when the concentration gradient and electrical force are EQUAL due to more potassium leak channels
What is membrane potential?
electrical charge across a cell membrane; difference in electrical potential inside and outside the cell
What is resting potential?
Membrane potential of a neuron when it is not being altered by signalling molecules that cause excitatory or inhibitory postsynaptic potentials
- At rest: membrane potential ranges between -40 mV and -90 mV across different types of neurons
Why does Na+ build up on the outside of the cell?
Because both diffusion and electric pressure are pushing it
- This desire for sodium to come in will launch an electrical signal
What is depolarization?
When the membrane potential of a cell becomes less negative than it normally is at rest
- Ex: an acute influx of positive ions such as Na+
What is hyper polarization?
When the membrane potential of a cell becomes more negative than it normally is at rest
- Ex: an acute influx of negative ions such as Cl-
What are voltage-gated ion channels?
They have an electrically charged door (pore) that can be opened or closed by graded changes in the membrane potential
- This gives rise to ACTION POTENTIAL if the change is strong enough
What are the 2 proteins that set up the resting membrane potential?
Sodium potassium transporter and leak potassium channels
What is the voltage-gated sodium channel?
Function: to initiate and propagate the action potential
What is the voltage-gated potassium channel?
Function is to restore the resting membrane potential
What is the voltage-gated calcium channel?
Located in the axon terminal; triggers release of neurotransmitters
• These channels open when the axon terminal becomes depolarized
• Calcium is 1000x more concentrated outside the cell than in
• The calcium that enters through these channels and binds to proteins that control the release of neurotransmitters and activates vesicle release machinery
When are the voltage-gated sodium channels closed?
When the membrane potential os more negative than -40 mV
What is action potential?
• It is a brief electrical impulse that provides the basis for conduction of information along the axon
- It is a rapid change in the membrane potential that is caused by the active opening and closing of ion channels
What is the threshold of excitation?
The value of the membrane potential that must be reached to produce an action potential
What is synaptic transmission?
Transmission of messages from one neuron to another via the presynaptic release of a chemical (neurotransmitter) that crosses the synapse and binds to receptors located on the post-synaptic membrane
What is the all-or-none law?
States that the action potential occurs or does not occur, and once triggered, will propagate down the axon without growing or diminishing in size
What is the rate law?
States that the strength of the stimulus is represented by the rate of the firing axon
What is a hydration shell?
An atom surrounded by water
Why can only K+ get through K+ ion channels even though Na+ is smaller?
- There are carbon-oxygen molecules sticking out into the pore that provide the perfect way for K+ to get through
- The water shell naturally separates because the K+ charge is perfectly balanced by the atoms in the pore
- The Na+ is too small for optimal interaction with the atoms
What is a promoter?
a region of DNA that initiates transcription of a particular gene
What are neuroglia/glial cells?
- Found all around neurons and even physically encapsulate some parts of them
- They help traffic nutrients and maintain molecular (ionic) stability in the extracellular space
- They support many functions of the nervous system
- They outnumber neurons in the brain
- They DON’T have action potentials
What is an astrocyte?
Glial cell that provides physical support and cleans up debris in the brain through phagocytosis
- They control the chemical composition of the surrounding environment and help nourish neurons
What is microglia?
Smallest of the glial cells
- They provide an immune system for the brain and protect the brain from invading microorganisms
What are ogliodendrocytes?
Produce the myelin sheath, which encapsulates axons
• During development of the CNS, they form processes shaped like canoe paddles
Why do ions aggregate at the cell membrane?
Membrane because that’s where they feel the electrical pressure
- Once you move away from the membrane, there’s no electrical charge because + and – are balanced
What is saltatory conduction?
the conduction of action potentials by myelinated axons
What are synaptic vesicles?
Contain molecules of neurotransmitter
- They attach to the presynaptic membrane and release neurotransmitter into synaptic cleft
What is the synaptic cleft?
Space between the pre- and postsynaptic membranes
- Filled with an extracellular fluid
What is postsynaptic density?
a protein dense specialization attached to the postsynaptic membrane
What is electron microscopy?
allows us to see small anatomical structures using a special electron microscope
What are ligands?
Neurotransmitters (or general term for a signalling molecule)
What are the two kinds of neurotransmitter receptors?
- Ionotropic receptors: on ion channels
- Metabotropic receptors: g protein coupled receptors that can open ion channels through an intracellular signalling cascade
What is a ligand-gated ion channel (ionotropic receptor)?
a receptor that is an ion channel that opens when the neurotransmitter binds to it
What are the types of terminations of post-synaptic potentials?
- Enzymatic deactivation: destruction of neurotransmitter by enzyme after release
- Reuptake: reentry of a neurotransmitter back into presynaptic membrane
What is postsynaptic potential?
Alterations in the membrane potential of a postsynaptic neuron, produced by neurotransmitter release into the synapse and receptor activation
- Can either be excitatory (due to influx of positive Na+ ions) or inhibitory (due to influx of negative Cl- ions)
What is excitatory postsynaptic potential (EPSP)?
excitatory depolarization of postsynaptic membrane caused by neurotransmitter binding to a postsynaptic receptor protein
What is inhibitory postsynaptic potential (IPSP)?
inhibitory hyperpolarization of postsynaptic caused by neurotransmitter binding to a postsynaptic receptor protein
- decreases the likelihood that the cell will fire
What are metabotropic receptors?
Receptors that turn toward metabolism to mediate their effect
- use G proteins
What are G proteins?
They are like molecular switches – when a g protein is bound its GTP is “on” or activated, because in this state it can turn on specific enzymes
- G proteins clip off the third phosphate group in GTP at some rate (GTP becomes GDP), and when this happens the g protein is “off” or inactivated
What is presynaptic inhibition?
hyperpolarizes the axon terminal of that neuron so its voltage-gated calcium channels may not open at all or for very long when an action potential arrives
What is presynaptic facilitation?
depolarizes the axon terminal of that neuron, so when an action potential comes, more calcium channels open
What is an auto receptor?
Receptor located on the presynaptic neuron
- gated by neurotransmitter the cell releases
- generally metabotropic and inhibitory
- main source of presynaptic inhibition
What is the central nervous system?
The brain and spinal cord
What is an interneuron?
A neuron located entirely in the CNS
- Only used for CNS neurons whose axon stays local (they only form synapses on cells located in the same brain area)
What is a projection neuron?
neurons that have an axon that travels outside the area where the soma is located
What is the peripheral nervous system?
Any part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and spinal cord
- Myelin is created by Schwann cells
What is a motor neuron?
Efferent fibers (bring information away from the CNS)
- They control muscle contract ion and gland secretion
- The soma of motor neurons is located within the spinal cord
What is a sensory neuron?
Detect changes in the external and internal environment
- They send this information to the central nervous system
What is interstitial fluid?
the fluid that surrounds cells in the body
What is lymph?
Interstitial fluid for all cells in the body outside of the CNS
- It flows around the cells of the body picking up waste and bacteria
- Lymph is collected into lymph vessels and taken to lymph nodes/organs, which detect and destroy invading organisms and foreign particles
- Eventually lymph is returned to the circulatory system (the blood stream)
What is the blood-brain barrier?
Semipermeable barrier between the blood and the brain
- The blood capillaries that flow through the CNS have no gaps in them
What is cerebrospinal fluid (CFS)?
- It’s made fresh from stuff in the blood
- It flows around the cells of the body picking up waste and bacteria and eventually returns to the blood
What is the chloride plexus?
Ventricles in tissue of the brain where CSF is produced
What are the 4 ventricles filled with CSF?
- The lateral ventricles: the largest, they sit underneath the cerebrum
- The third ventricle: lies between the two thalamic nuclei
- The fourth ventricle: sits between the pons and cerebellum
(The cerebral aqueduct: a long, tube like structure that connects the third and fourth ventricle)
What are meninges?
Tough, connective tissues that surround the brain
What is the dura meter?
outer layer – thick, though, unstretchable tissue
What is the arachnoid membrane?
middle layer – soft and spongy with a web-like appearance
What is Pia mater?
third layer that sits closest to the brain – this layer and the space above it has blood vessels in it
What is the subarachnoid space?
between the arachnoid membrane and pia mater – filled with CSF
What is contralateral?
structures on opposite side of the body
What is ipsilateral?
structures on the same side of body
What is brain nuclei?
a group of neighboring neurons that have roughly similar connections (inputs/outputs) and functions
What are neural progenitor cells?
Stem cells that can make neurons/neural tube
What is symmetrical division?
Division of a neural progenitor cell that gives rise to 2 identical progenitor cells
What is asymmetrical division?
Division of a neural progenitor cell that gives rise to another progenitor cell and a new glial cell or neuron
What is neurogenesis?
Production of new neurons
What is apoptosis?
A process of programmed cell death that occurs in multicellular organisms
What is a nerve?
- Collection of bundles of axons
- Has blood vessels, motor proteins, and microtubules
- No oligodendrocytes, so myelination is from Schwann cells
- There is a nerve-blood barrier because there’s not much connective tissue
What is the vagus “wandering” nerve?
it leaves the head and invades many organs
- 10th cranial nerve
What is the spinal cord?
- Long, conical structure
- Principal function: distribute motor fibers to the effector organs of the body (glands and muscles) and to collect somatosensory information to be passed on to the brain
- Has a certain degree of autonomy from the brain; various reflexive control circuits are located there
- Has white matter (myelinated axons) and grey matter
What is the somatic nervous system?
Part of PNS that controls skeletal muscle movements and processes sensory information that relates to the outside world
What is the autonomic nervous system?
Part of the PNS concerned with sensation and regulation of smooth muscle, cardiac muscle, and glands
- efferent ANS consists of the parasympathetic and sympathetic nervous system
What is the sympathetic nervous system?
Part of the efferent autonomic nervous system that primes the body for action (fight-or-flight)
What is the parasympathetic nervous system?
Part of the efferent autonomic nervous system that supports activities that occur when the body is in a relaxed state and all is well (feed-and-breed, rest-and-digest)
What is the brainstem?
Where cranial nerves are processed
- tons of nuclei and axon pass through
What is the medulla?
Controls heart rate and other autonomic information
- Bumps in the medulla are a collection of motor axons
- Primary crossing of motor axons and nervous system
What is the area postrema?
where the blood-brain barrier is weak; poisons detected here can initiate vomiting
What is the pons?
Large bulge in brainstem that relays information between cerebellum and other structures
- Contains reticular formation: controls sleep and arousal
What is the function of the 4th ventricle?
where cerebrospinal fluid is made
What is the cerebellum?
Provides coordination and balance
- Integrates sensory information and motor commands for movement
- Plays an important role in motor learning
What is the cerebellar cortex?
Continuous thin layer of tissue tightly folded in the style of an accordion
• Surrounds a collection of deep cerebellar nuclei, which provide the output fibers
What is the function of the midbrain?
regulates aspects of vision, hearing, motivation, movement, and arousal
What is the tectum?
Appear as two pairs of bumps on the dorsal surface of brain stem
- Top bumps: superior colliculi – involved in directing behaviour towards specific areas of visual space
- Bottom bumps: inferior colliculi – involved in sound localization
What is the tegmentum?
Includes rostral reticular formation (sleep and arousal), the periaqueductal gray (pain sensations and behavioural responses to threat), the red nucleus (motor coordination), and the substantia nigra (motivation and regulation of purposeful movement)
What is the hypothalamus?
Bilateral structure made up of several nuclei, which generally regulate autonomic nervous system activity
- Involved in in 4 Fs: feeding, fighting, fleeing, and mating
- Different hypothalamic nuclei control body temperature, sleep-wake cycles, hunger, and social behaviour
- Links the nervous system to the endocrine system (release of hormones into the bloodstream) via the pituitary gland
What is a hormone?
signalling molecule that acts at a distance (released by an endocrine gland)
What is the thalamus?
Bilateral structure that is divided into several nuclei, many of which relay ascending sensory information to different regions of the cerebral cortex
What is the cerebral cortex?
Processes complex information and forms action plans
- Not made up of nuclei, but a multilayered structure
- Largest site of neural integration in the CNS
- Plays a key role in attention, perception, awareness, thought, memory, language, decision making, and consciousness
What is the cerebral cortex highly convoluted with?
- Sulci: small grooves
- Fissures: large or major grooves
- Gyri: ridges between sulci or fissures
What is a longitudinal fissure?
separates the 2 hemispheres
What is a lateral fissure?
separates frontal from temporal lobe
What do the 4 lobes control?
• Frontal lobe: controls movement
• Parietal lobe: processes touch information
• Occipital lobe: processes visual information
• Temporal lobe: processes auditory information
- Taste and smell: processed near the junction of the frontal, parietal, and temporal lobes inside the lateral fissure
What is the basal ganglia?
Forms a neural network that regulates motivation and purposeful (voluntary) movement
- Receives inputs from throughout the brain and directly regulates descending motor commands + decision making processes in the prefrontal cortex
- Implicated in reinforcement learning, habit learning, and compulsive behaviour
- Located underneath cerebral cortex
What is the limbic system?
Regulates emotions and episodic memories
- Comprised of several distinct, interconnected structures that include the hippocampus, amygdala, septum, and cingulate cortex
What is the function of the hippocampus?
critical explicit memory formation
What is the function of the amygdala?
critical for both feeling and recognizing emotion, particularly fear
What is the sensory association cortex?
Where each primary sensory area of the cortex sends information
- Perception takes place there and memories are stored there
- Regions of the association cortex located closest to primary sensory areas receive information from only one sensory system
What is glutamate?
Main excitatory NT in the brain
- Not all glutamate is excitatory, only ionotropic glutamate are
- Induces EPSCs
- Generally released by sensory neurons
What are agonists?
drugs that activate a receptor like the normal ligand
What are antagonists?
a type of ligand or drug that avoids or dampens a biological reaction
What do agonists of glutamate do?
often causes seizures and excitotoxicity –> apoptosis is triggered, leaves holes in the brain
What do antagonists of glutamate do?
dissociative anesthetics
What is GABA?
Main inhibitory NT in the brain
- Ionotropic are inhibitory
- Induces IPSCs
What do antagonists of GABA do?
cause seizures
What do agonists of GABA do?
anesthetics, anticonvulsants, muscle relaxants, sleeping pills, anti-anxiety
What are the main neuromodulators in the brain?
Dopamine, norepinephrine, acetylcholine, serotonin
What are neuromodulators?
- They don’t typically produce simple excitatory or inhibitory effects in the CNS
- Most of their receptors are g-protein coupled receptors, not ion channels
- They often diffuse short distances outside of the synapse and can influence activity of neighboring neurons
What is acetylcholine?
• In the CNS, it acts as a neuromodulator, often at axoaxonic receptors
- It primarily activates metabotropic receptors
• In the PNS, it is released by motor neurons at the neuromuscular junction, where it activates the fast-excitatory ionotropic receptors on muscle cells that cause muscle contraction
What is the main NT for motor neurons?
acetylcholine
What is the transporter for monoamine neuromodulators?
the vesicular monoamine transporter (VMAT)
What are Catecholamines?
dopamine and norepinephrine (they are super similar)
What are Indolamines?
serotonin
What are principal neurotransmitters?
- Mostly amino acid derivatives
- Synthesized locally in axon terminals
- Usually secreted from small synaptic vesicles that dock very close to the site of Ca entry in the axon terminal
- Generally activate ionotropic and metabotropic receptors
- Typically recaptured after secretion and reused
- Usually bind to receptors that are directly across the synapse
What are neuropeptides?
- Short string of amino acids
- Synthesized in the cell soma, transported down the axon while undergoing additional processing, and released just once (no recycling or recapture)
- Usually secreted from large dense core vesicles that dock a ways back from the site of Ca entry in the axon terminal
- ONLY activate metabotropic receptors
- Non-synaptic communication
What are lipid-based signalling molecules?
- Are synthesized and released on demand (no preparation)
- Secreted in a non-vesicular manner, typically from postsynaptic neurons
- Only activate metabotropic receptors, typically located on the presynaptic axon terminal
What is venom?
A toxic protein
What does black widow venom do?
Her venom causes a massive release in NT vesicles, particularly those that contain acetylcholine
- Causes muscles cramps and nausea
- The protein gets in the extracellular solution and sneaks in the vesicle (can’t just jump inside)
- When it docks, it releases the NT even if there’s no action potential
What is botox?
Produced by bacteria that grow in improperly canned food
- Acetylcholine system antagonist; it prevents the release of acetylcholine, causing muscle paralysis
- Enters the body the same way as the toxic protein, but it blocks the calcium binding site
- The vesicles build up and never release (could cure wrinkles)
What is neostigmine?
Drug that inhibits activity of acetylcholinesterase, which is the enzyme that breaks down acetylcholine in the synaptic cleft
- Causes acetylcholine to hang around in the synapses for a longer period of time
- Could cure myasthenia gravis
What is myasthenia gravis?
A hereditary autoimmune disorder in which the person’s own immune system attacks their healthy acetylcholine receptors
- People with this disorder become noticeably weaker and weaker over time (fatigability)
- Neostigmine could cure this
