What characteristic of chemical messenger structure has the most significant impact on its signalling mechanism?
What effector(s) (and 2nd messenger(s)) are stimulated by Gαs?
Adenylyl cyclase (cAMP, PKA).
What does the Goldman-Hodgkin-Katz equation define?
The membrane potential of a cell based on distribution, relative permeability, and charge of ions across the membrane.
What 2 variables affect the time constant (τ)?
- Resistance of the cell membrane (rm)
- Capacitance of the cell membrane (cm)
What type of steroid hormone is aldosterone?
Do GABAA receptors cause depolarization (excitatory) or hyperpolarization (inhibitory)?
What type of chemical messenger is norepinephrine?
Which type of pancreatic cell is destroyed in type 1 diabetes?
β cells only.
How is the medulla oblongata positioned in the brain?
At the top of the spinal cord.
Where is GLUT1 found?
In all tissues of the body.
What are the 2 major elements of the cytoskeleton?
What type of channel are nicotinic acetylcholine receptors (nAChRs)?
Ligand-gated cation channels (for Na+, Ca2+, and K+ flux).
Which ions are transported through NMDA receptors?
What is the main function of Na+/K+ ATPase?
To maintain the concentration gradients of Na+ and K+ across the cell membrane.
What is our blood glucose level after feeding?
What pathway occurs when receptor guanylyl cyclase is activated by atrial natriuretic peptide (ANP)?
- Receptor converts GTP to cGMP
- cGMP activates PKG
- PKG phosphorylates target proteins that relax smooth muscle
- Smooth muscle relaxation causes vasodilation
- Blood pressure is lowered
What type of chemical messenger are catecholamines?
What is described by the electrochemical driving force of a cell?
How far the membrane potential is from equilibrium.
What type of chemical messenger is aldosterone?
What triggers oxytocin release for positive feedback regulation of uterine contraction?
Stretch receptors in the cervix, activated by contraction, send signals to the hypothalamus that are relayed to the posterior pituitary gland, which releases oxytocin to stimulate further contraction.
What is the equation for the time constant (τ)?
τ = rmcm
- r = resistance of the cell membrane
- c = capacitance of the cell membrane
Which 2 motor proteins are associated with microtubules?
How many subunits are in a complete nicotinic acetylcholine receptor (nAChR)?
What effector(s) (and 2nd messenger(s)) are inhibited by Gαi?
Adenylyl cyclase (cAMP, PKA).
What is the typical age of onset for type 1 diabetes?
Very young (childhood onset).
What are 2 major capping proteins associated with microfilaments?
Why is it important that a small number of steroid hormones in circulation are not bound to carrier proteins?
Any unbound molecules leaving circulation for the target cell cause a significant decrease in the concentration of free hormone, so more hormones are released from their carrier proteins to reach chemical equilibrium and are then free to diffuse into the target cell.
At what end do microfilaments tend to shrink?
What is the basic structure of cilia and flagella?
9 pairs of microtubules bundled in parallel around a central pair, arranged into an axoneme.
Which type of G-protein is involved in inositol-phospholipid signalling?
What type of chemical messenger is AMP?
What are the 2 main advantages of the greater number of neurons and synapses that comes with a more complex nervous system?
- Integration of information happens at synapses: greater potential for complex behaviours
- Memories are stored in synapses: greater potential for learning
What is MEK?
A protein kinase activated by Raf-1 that phosphorylates and activates MAP-kinase as part of the Ras-MAP-kinase signalling pathway.
What is GLUT4?
An intracellular glucose receptor that is translocated to the surface of a pancreatic β cell as a result of signal transduction in response to elevated blood glucose levels.
What region of the brain is the master controller of circadian rhythm?
Suprachiasmatic nucleus (SCN).
How is conductance related to resistance?
Conductance is the reciprocal of resistance.
What property of action potentials prevents backward transmission and summation of action potentials along an axon?
The absolute refractory period.
Which region of the brain is responsible for converting short-term memory to long-term memory?
Hippocampus (limbic system).
Which 2 scientists at the Montreal Neurological Institute determined the somatotropic organization of the cerebral cortex?
- Wilder Penfield
- Herbert Jasper
How are peptide hormones usually stored?
In intracellular vesicles, as prohormones.
Who won the 1923 Nobel for discovering insulin?
How do ions flow through chemical synapses?
Across the synaptic cleft and into postsynaptic channels.
What is the main role of eicosanoids?
Inflammation and pain.
How are steroid hormones released?
They freely diffuse through the membrane and into the blood, where they are bound to carrier proteins for delivery to target cells.
In addition to GLUT1, which is expressed in all tissues, which glucose receptor is well expressed and working constantly in the brain?
What is synaptotagmin?
A protein found in the synaptic vesicle membranes of chemical synapses; when activated by Ca2+, it binds SNARE proteins to bring vesicle and presynaptic membranes closer together in preparation for membrane fusion and neurotransmitter release.
What are tropic hormones?
Hormones that cause the release of another hormone.
What is the somatosensory function of muscle spindle receptors?
Which region of the brain is responsible for maintaining homeostasis?
Hypothalamus (limbic system).
Where is acetyl CoA synthesized?
In a chemical synapse, what is the first thing that happens when an action potential reaches the presynaptic terminal?
Depolarization causes opening of voltage-gated Ca2+ channels.
What is a first-order endocrine pathway?
A signalling pathway in which the component receiving sensory input also acts as the integrating centre for the signal.
In what direction does kinesin move along microtubules?
Toward the positive end.
Which 2 types of receptors in the digestive tract relay information to the pancreas to regulate insulin secretion?
Glucose and stretch receptors.
What effector is activated by Gαo and Gαq?
At which end do microtubules grow by dimer addition?
What types of G-proteins are involved in cAMP signalling?
Gs and Gi.
Does cortisol have an additive or a synergistic effect on glucagon and epinephrine?
What conditions do NMDA receptors require before they can open?
- Membrane depolarization (to relieve Mg2+ block)
- Binding of glutamate and glycine
What is the general value of capacitance for cells (lipid bilayer)?
What is the reversal (equilibrium) potential for nicotinic acetylcholine receptors (nAChRs)?
Approx. 0 mV.
What is glutaminase?
An enzyme that catalyzes the conversion of glutamine to glutamate, which can be released as a neurotransmitter.
What are the 2 main functions of the cortex?
- Integrate/interpret sensory information
- Initiate voluntary movements
Which region of the brain is responsible for reward and addiction?
Nucleus accumbens (limbic system).
Do glutamate receptors cause depolarization (excitatory) or hyperpolarization (inhibitory)?
What is white matter?
The portion of brain/spinal cord tissue made up of tracts of axons and their myelin sheaths.
How does the absolute refractory period ensure unidirectional signalling along axons?
As depolarization travels down the axon, Na+ channels immediately behind a region of depolarization are in their absolute refractory period (inactive state) and cannot initiate another action potential, so further depolarization can only happen further away from the axon hillock.
What is the effect of lower resistance of the cell membrane on conductance?
Lower conductance (greater decrease in voltage along the axon).
In crustaceans, where is crustacean hyperglycemic hormone (CHH) synthesized and secreted?
Sinus gland cells in the eyestalks.
What does it mean for hormones to be additive?
The effect of the combined hormones on the target cell is equal to the sum of the individual effects of each hormone.
What enzyme synthesizes phosphatidyl inositol?
What type of chemical messenger is thyroxine?
What is MAP-kinase?
An effector protein activated by MEK as part of the Ras-MAP-kinase signalling pathway that can phosphorylate many different cellular proteins, including transcription factors, to have many different effects in the cell.
Which somatosensory receptors have the lowest conduction velocity?
C-type free nerve endings (pain, temperature, itch): 0.5-2 m/s.
At what end do microfilaments tend to grow?
What is the role of Gαolf?
To stimulate adenylyl cyclase in olfactory sensory neurons.
What are the main 3 hormones involved in the HPA axis of the stress response?
- Corticotropin-releasing hormone (CRH)
- Adrenocorticotropic hormone (ACTH)
What are the 2 main disadvantages of large axons (as a means of increasing conduction speed)?
- Take up more space, limiting number of neurons that can be packed into the nervous system
- Require greater volume of cytoplasm, making them expensive to produce and maintain
What type of chemical messenger is ATP?
In myelinated axons, what are internodes?
Myelinated regions between nodes of Ranvier.
What growth factor activates type II receptor serine/threonine kinases?
What is the glucose affinity of GLUT1 and GLUT3?
What type of chemical messenger is vasopressin?
What is crustacean hyperglycemic hormone (CHH)?
A neurohormone secreted from crustacean eyestalks to control glucose levels in crustaceans.
What 2 properties of an axon can increase its speed of conductance?
- Increased axon diameter
Why does a greater value of λ (length constant) increase the speed of conduction along an axon?
Higher λ means lesser decay of current over distance, so electrotonic current flow within the axon after an action potential is faster.
What motor protein is associated with microfilaments?
What is the monomeric form of actin?
Which 3 parts of the brain are permeable (i.e. are not shielded by the blood-brain barrier)?
- Pineal gland
- Pituitary gland
- Parts of the hypothalamus
What is the equation for current (electrochemical driving force)?
Ix = gx(Vm - Ex)
- Ix = current for ion x
- gx = conductance of ion x
- Vm = membrane potential (from Goldman-Hodgkin-Katz equation)
- Ex = equilibrium potential of ion x (from Nernst equation)
What are ventricles (brain)?
Cavities in the brain that contain cerebrospinal fluid (CSF).
How does the number of K+ leak channels along an axon affect its ability to conduct electrical signals?
More K+ leak channels means more loss of positive charge for greater current loss and voltage decrease along the axon.
How are the different regions of the cerebral cortex organized?
Each region corresponds to a specific part of the body that it controls by motor output or from which it receives sensory input.
What type of chemical messenger is GTP?
What type of steroid hormone is estrogen?
What is the value of the gas constant, R?
What are the 3 layers of the mammalian cranial and spinal meninges?
- Dura mater (outer)
- Arachnoid mater (middle)
- Pia mater (inner)
What happens when a cell membrane depolarizes?
The membrane potential becomes more positive.
How are white and grey matter organized in the spinal cord?
- White matter on the surface
- Grey matter on the inside
What are the 3 subsystems of the somatosensory system?
- Cutaneous mechanoreceptors (touch, vibration, pressure)
- Proprioception (limb position, load on joints)
What is the frequency of type 1 diabetes in the general population?
Approx. 1-2 in 10,000.
What action is responsible for dynamic instability in microtubules?
Intrinsic GTPase activity of β-tubulin.
Where are the adrenal glands in mammals?
On top of the kidneys.
What type of steroid hormone is progesterone?
Do 5-HT3 channels cause depolarization (excitatory) or hyperpolarization (inhibitory)?
Which region of the brain is responsible for aggression and fear responses?
Amygdala (limbic system).
What types of somatosensory receptors are involved in pain, temperature, and itch sensation?
Free nerve endings.
What is a connexin?
A protein complex forming part of each hemichannel in a gap junction.
What type of chemical messenger is epinephrine?
What is the axon hillock?
The region of a neuron cell body where incoming signals from dendrites converge just before the axon and may summate to produce an action potential.
Which motor protein moves toward the negative end of microtubules?
What type of receptor does crustacean hyperglycemic hormone (CHH) bind in glucose control pathways?
A receptor guanylyl cyclase.
What is a threshold potential?
A minimum level of depolarization that must be reached at an axon hillock in order for an action potential to fire.
Where is GLUT2 well expressed?
Pancreatic β cells and liver cells.
What type of chemical messenger is histamine?
What is the hippocampus?
The region of the limbic system responsible for converting short-term memory to long-term memory.
How do ions flow through electrical synapses?
Through gap junctions.
Which 2 groups of vertebrates have discrete adrenal glands?
Birds and mammals.
What is the effect of glucagon on blood glucose levels?
Glucagon raises blood glucose levels.
What type of chemical messenger is melatonin?
How does increased surface area of conducting surfaces affect capacitance?
Which somatosensory receptors have the highest conduction velocity?
Muscle spindles (proprioception): 80-120 m/s.
What is the cerebral cortex?
The outer layer of the cerebrum.
What is CapZ?
A capping protein that associates with microfilaments at the (+) end to prevent actin polymerization, slowing growth.
In what type of signalling pathway are Gq proteins involved?
Are amine hormones hydrophilic or hydrophobic?
Hydrophilic (except for thyroid hormones).
What happens when phospholipase C reacts with PIP2?
PIP2 is cleaved into IP3 and DAG, each of which can have several downstream effects.
Which tissue types have large intracellular pools of GLUT4 receptors?
Muscle and fat tissue.
What fuels the movement of kinesin and dynein along microtubules?
What is the Nernst equation?
- Ex = Nernst potential for ion x
- R = gas constant (8.31 J/mole·K)
- T = temperature (K; 295 K at room temp.)
- F = Faraday's constant (96,500 coulombs/mole)
- z = valence of ion x
- [x]o/[x]i = concentration of ion x outside/inside the cell
What type of receptor are insulin receptors?
Receptor tyrosine kinase (RTK).
What is the main function of the mesencephalon (midbrain)?
Coordinating and initiating reflex responses to auditory and visual input.
What is the olfactory bulb?
The region of the limbic system responsible for sense of smell.
Which region of the brain is reduced in size and function in mammals, compared to the same region in fish and amphibians?
What type of chemical messenger is triiodothyronine?
What is the equation for the length constant (λ)?
λ = [rm ÷ (ri + ro)]½
- rm = resistance of the membrane
- ri = resistance of intracellular fluids
- ro = resistance of extracellular fluids
Which glutamate receptor subunits are found in NMDA receptors?
What type of chemical messenger is atrial natriuretic peptide (ANP)?
Which glucose receptor is well expressed and constantly working in all tissue types?
What is the main function of the cerebellum?
What electrical property is an approximation of ion permeability in a cell membrane?
Which hormone lowers blood glucose levels?
Where are steroid hormones synthesized?
At the smooth ER or in the mitochondria.
Which ion is transported through GABAA receptors?
How does myelination affect the length constant (λ) of axons?
Myelin increases membrane resistance, which increases λ.
How are microtubules formed?
- Tubulin dimers associate end-to-end to form a protofilament
- Protofilaments line up laterally to form a sheet
- Sheet rolls up into a tube
- Microtubule grows at (+) end by addition of new dimers (and shrinks at (-) end)
In what form are peptide hormones usually synthesized?
What types of molecules can travel through gap junctions?
Ions and hydrophilic chemical messengers.
What is the main endocrine function of the pancreas?
Secrete insulin and glucagon to regulate blood glucose levels.
What are the 4 general components of a signal transduction pathway?
- Receiver (ligand-binding region of receptor)
- Transducer (conformational change of receptor)
- Amplifier (increases number of molecules affected by signal)
- Responder (molecular functions that change in response to signal)
What is cerebrospinal fluid (CSF)?
A fluid that fills spaces within the central nervous system and acts as a shock absorber.
What 3 major steroid hormones are made directly from progesterone?
Where are the receptors involved in proprioception located?
How does increased thickness of an insulating layer affect capacitance?
What is the effect of increased resistance of extracellular and intracellular fluids on conduction over distance?
Lower conductance (greater decrease in voltage along the axon).
True or false: The opening and closing of gap junctions can be regulated.
What organ secretes epinephrine during the stress response?
What proportion of diabetics have type 1 diabetes?
What is the limbic system?
A network of connected structures between the cortex and the rest of the brain that influences emotions, motivation, and memory (the "emotional brain").
What molecule is intermediate between progesterone and aldosterone?
How many neurons are in the brain?
What type of chemical messenger is serotonin?
What are the 5 main regions of the prosencephalon (forebrain)?
- Limbic system
Which region of the somatosensory system is responsible for relaying sensory information from the head and face?
Cranial root ganglia.
What feature of the central nervous system (CNS) is unique to vertebrates?
Hollow dorsal nerve cord (spinal cord).
What is Ras?
A protein kinase activated by SOS that activates Raf-1 as part of the Ras-MAP-kinase signalling pathway.
How are steroid hormones stored?
They can't be stored because they are hydrophobic--they have to be made on demand.
What happens to tyrosine kinase receptors (RTKs) when they are bound by a ligand?
One RTK dimerizes with another, and they phosphorylate each other to become active and recruit other kinases.
What are the 2 main parameters regulated by atrial natriuretic peptide (ANP)?
- Extracellular fluid volume
- Blood pressure
What causes intracellular GLUT4 to be translocated to the cell surface?
Phosphorylation during insulin signal transduction.
What are the 3 main classes of steroid hormones?
- Reproductive hormones
What type of chemical messenger is acetylcholine?
Which nicotinic acetylcholine receptor (nAChR) subunits are found in muscle nAChRs?
What nicotinic acetylcholine receptor (nAChR) subunits are found in neuronal nAChRs?
- α2 - α10
- β2 - β4
What causes the symptoms of type 1 diabetes?
Autoimmune destruction of pancreatic β cells (mediated by T cell lymphocytes), leading to a lack of insulin production.
What is the effect of insulin on blood glucose levels?
Insulin lowers blood glucose levels.
How many meninges do mammals have?
What effect does the opening of Na+ channels have on the cell membrane?
What two signalling pathways are involved in the stress response?
- Sympathetic nervous system
- Hypothalamus-pituitary-adrenal cortex (HPA) axis
What type of chemical messenger is GMP?
How many pairs of cranial nerves do vertebrates have?
What are the cranial root ganglia?
Cell bodies of afferent fibres that relay sensory information from the face and head.
Do P2X receptors cause depolarization (excitatory) or hyperpolarization (inhibitory)?
What are 5 major factors affecting growth/shrinkage of microtubules?
- Local tubulin concentration
- Dynamic instability
- Microtubule-associated proteins (MAPs)
- Chemicals (e.g. poisons)
Where do neurons of the hypothalamus terminate?
Once acetylcholine (ACh) has been broken down in the synaptic cleft by acetylcholinesterase (AChE) into choline and acetate, what happens to the choline and acetate?
- Choline: taken up and recycled by the presynaptic neuron
- Acetate: diffuses out of the synapse
Do glycine receptors cause depolarization (excitatory) or hyperpolarization (inhibitory)?
What are the 3 main regions of the vertebrate rhombencephalon (hindbrain)?
What protein makes up microtubules?
What effect does the opening of K+ channels have on the cell membrane?
What is the main function of the hypothalamus?
What is the cingulate cortex?
The region of the limbic system responsible for executive function of the brain, including decision-making, motivation, and planning.
What 2 subunits make up a tubulin dimer?
What proportion of type 2 diabetes patients are obese?
What is the major downstream effect of increased cortisol secretion from the adrenal cortex during the stress response?
Increased blood glucose in many tissues throughout the body.
What is the polarity of each subunit in a tubulin dimer?
- α-tubulin: (-)
- β-tubulin: (+)
What type of chemical messenger is glutamate?
How are microtubules oriented in axons w.r.t. polarity?
- (-) end: toward cell body
- (+) end: toward axonal terminals
Which organ secretes adrenocorticotropic hormone (ACTH) during the stress response?
Which region of the brain contains half of all of the neurons in the brain?
What is the polymeric form of actin?
What is the thalamus?
A large grouping of grey matter above the hypothalamus that receives input from the limbic system and all senses (except olfactory) and relays sensory information to the cortex and has a major role in sleep/wake regulation.
After an action potential triggers opening of Ca2+ channels in the presynaptic terminal of a chemical synapse, what is triggered by the influx of Ca2+?
Fusion of synaptic vesicles with the presynaptic membrane, followed by release of neurotransmitters into the synaptic cleft.
In what 3 types of signalling does the pancreas participate?
- Direct feedback loops
- Neural signalling
- Hormonal signalling
What are the 4 main types of receptor?
- Intracellular receptors
- Ligand-gated ion channels
- G-protein-coupled receptors
What are the 4 lobes of the brain?
- Frontal lobe
- Temporal lobe
- Parietal lobe
- Occipital lobe
What are melanophores?
Cells containing aggregate pigment granules that can be compressed or spread out by microtubules to cause colour change in some animals.
What type of ligands bind to intracellular receptors?
How many layers are present in the cortex of the brain?
What is the main type of effect caused by ligand-gated ion channels?
Change in cell membrane potential.
Which 2 animal phyla have well developed nervous systems but no cephalization?
What hormone is secreted by the hypothalamus during the stress response?
Corticotropin-releasing hormone (CRH).
What are the two parts of the adrenal gland?
- Adrenal cortex
- Adrenal medulla
What molecule activates tubulin monomers, causing them to dimerize?
What type of somatosensory receptors are involved in proprioception?
Muscle spindle receptors.
How do the 6 layers of the cortex differ from each other?
- Shape and density of neurons
- Number of connections between neurons
During the stress response, does secretion of epinephrine from the adrenal medulla increase or decrease blood glucose levels?
What type of chemical messenger is glycine?
Which 2 hormones secreted during the stress response result in elevated blood glucose levels?
What happens after a type II receptor serine/threonine kinase has bound TGF--β?
It recruits and dimerizes with a type I receptor, then phosphorylates the type I receptor at the GS box.
Where is glucagon synthesized?
Pancreas (α cells).
How does temperature affect microtubule growth/shrinkage?
Low temperature causes disassembly of microtubules.
What is the isocortex?
The outer layer of the cortex, necessary for cognition and higher brain functions.
What is the main role of cAMP?
To activate protein kinases (usually PKA), which phosphorylate proteins and open/close ion channels.
What does the Nernst equation describe?
The equilibrium potential across a cell membrane for a particular ion.
What type of steroid hormone is cortisol?
Which part of the adrenal gland secretes epinephrine (adrenaline)?
Do nicotinic acetylcholine receptors (nAChRs) cause depolarization (excitatory) or hyperpolarization (inhibitory)?
What is the value of Faraday's constant, F?
What type of receptor are EGF receptors?
Receptor tyrosine kinase (RTK).
What is antagonistic pairing?
A type of signalling pathway involving separate hormones with opposite effects (e.g. stimulatory vs. inhibitory).
What happens when a cell membrane hyperpolarizes?
The membrane potential becomes even more negative than its (negative) resting value.
True or false: Graded potentials decay over distance.
What are the 4 main parameters regulated by the medulla oblongata?
- Breathing rate
- Heart rate
- Blood vessel diameter
- Blood pressure
What is the nucleus accumbens?
The region of the limbic system responsible for reward and addiction.
How are responses at nicotinic acetylcholine receptors (nAChRs) kept brief?
Acetylcholinesterase (AChE) quickly hydrolyzes acetylcholine (ACh) in the synaptic cleft to limit the duration of the signal.
What is the role of Gαt?
To activate cGMP phosphodiesterase in vertebrate rod photoreceptors.
What change occurs in the conversion of preprovasopressin to provasopressin?
The signal peptide is cleaved off.
How does myelination affect membrane resistance in axons?
Myelin insulation reduces current loss through leak channels, which increases membrane resistance.
How are microtubules anchored in the cell?
- (-) end: microtubule organization centre (MTOC)
- (+) end: integral proteins in the plasma membrane
What are the 2 types of summation that influence net change in membrane potential during integration of postsynaptic potentials?
- Spatial summation
- Temporal summation
What are the 3 main regions of the vertebrate brain?
- Rhombencephalon (hindbrain)
- Mesencephalon (midbrain)
- Prosencephalon (forebrain)
What type of chemical messenger is testosterone?
In what region of the brain is the cerebellum located?
What enzyme synthesizes cGMP?
How does myelination affect the membrane capacitance of axons?
Myelin increases the thickness of the insulating layer between intracellular and extracellular fluid, which decreases membrane capacitance.
What is the main role of reproductive hormones?
To regulate sex-specific characteristics.
What is saltatory conduction?
A very rapid form of conduction along myelinated axons in which the action potential "leaps" from node to node:
- APs occur at nodes of Ranvier
- Current spreads electrotonically through internodes
What happens when SMAD proteins interact with receptor serine/threonine kinases?
The SMAD proteins are phosphorylated by receptor serine/threonine kinases, then translocated to the nucleus to regulate gene expression.
What polymer is made up of actin?
What is resistance (R)?
The force opposing the flow of electrical current.
What does it mean for a transmembrane receptor (e.g. Na+/K+ ATPase) to be electrogenic?
Its activity produces an electrical current across the membrane.
What type of receptor is IGF1 receptor?
Receptor tyrosine kinase (RTK).
What second messenger is synthesized by guanylyl cyclase?
What type of chemical messenger is insulin?
A peptide hormone.
What is a GS box?
A region on type I receptor serine/threonine kinases that is phosphorylated by type II receptors during dimerization.
What is the Goldman-Hodgkin-Katz equation?
- Vm = membrane potential
- R = gas constant (8.31 J/mol·K)
- T = temperature (K)
- F = Faraday's constant (96,500 coulombs/mol)
- Px = permeability of ion x
What type of chemical messenger are leukotrienes?
Where is oxytocin synthesized?
What type of chemical messenger are prostaglandins?
What are gyri?
Folds in the isocortex of the brain.
What is voltage (V)?
A change in electrical potential.
How does the hypothalamus interact with the pituitary gland to help maintain homeostasis?
By regulating secretion of pituitary hormones.
What is the equation for electrical conductance?
g = 1/R
- g = conductance
- R = resistance
Which hormone raises blood glucose levels?
What happens in temporal summation of postsynaptic potentials?
Postsynaptic potentials that occur at slightly different times influence net change in membrane potential.
From what molecule are steroid hormones derived?
What are the dorsal root ganglia?
Cell bodies of afferent fibres relaying sensory information from every part of the body except the head and face.
What are the 2 main functions of the pons?
- Control alertness
- Initiate sleep/dreaming
Which ions are transported through AMPA and kainate receptors?
Which region of the rhombencephalon (hindbrain) contains pathways between the spinal cord and the brain?
What type of chemical messenger is estrogen?
In what direction does dynein move along microtubules?
Toward the negative end.
What type of steroid hormone is corticosterone?
What is an inhibitory postsynaptic potential (IPSP)?
A synaptic transmission involving inhibitory neurotransmitters that cause hyperpolarization of the postsynaptic membrane, making the postsynaptic cell less likely to generate an action potential.
In what type of signalling are eicosanoids mainly involved?
Paracrine and nervous signalling.
What are the 2 main regions of the vertebrate prosencephalon (forebrain)?
How did Alan Hodgkin and Andrew Huxley win the 1963 Nobel prize?
By developing a theory of action potential initiation based on measured Na+ and K+ currents in squid giant axons.
What type of receptors do peptide hormones bind?
What is an excitatory postsynaptic potential (EPSP)?
A synaptic transmission involving excitatory neurotransmitters that cause depolarization of the postsynaptic membrane, making the postsynaptic cell more likely to generate an action potential.
Which subunit of a tubulin dimer is able to hydrolyze bound GTP?
What do pancreatic β cells produce?
What are the 3 major glutamate receptors?
What is cofilin?
A regulatory protein that binds actin in microfilaments to promote disassembly.
What type of chemical messenger is cortisol?
How are cnidarian nervous systems organized differently compared to other animals?
- Neurons are not specifically divided into sensory or motor function
- Neurons carry action potentials in both directions
- Nervous system is an interconnected web (nerve net)--no central nerve cord
How many synapses are in the brain?
Approx. 1014 to 1015.
What type of proteins are able to dock to activated receptor tyrosine kinases?
Proteins containing SH2 domains.
What is grey matter?
The portion of brain/spinal cord tissue made up of neuronal cell bodies.
What is the glucose affinity of GLUT2?
What is the somatosensory system?
The division of the nervous system that receives input from receptors in skin, muscle, and tendons to mediate a diverse range of sensations (touch, pressure, pain, vibration, limb position, temperature, etc.).
What type of chemical messenger are thyroid hormones?
What 2 parameters determine the membrane potential of a cell?
- Relative permeability of the membrane to specific ions
- Transmembrane concentration gradients of specific ions
What is Ohm's law?
V = I · R
- V = voltage
- I = current
- R = resistance
What are the 4 main classes of cellular signalling?
What are the 2 main groups of components of the peripheral nervous system (PNS)?
- Sensory components (afferent neurons)
- Motor components (efferent neurons)
How are microtubules oriented in neuronal dendrites w.r.t. polarity?
Mixed: (+)/(-) ends can be oriented toward or away from the cell body.
Where are peptide hormones synthesized?
On the rough ER.
What molecule is intermediate between cholesterol and progesterone?
What does it mean for hormones to be synergistic?
The effect of the combined hormones on the target cell is greater than the sum of their individual effects; 1 hormone enhances the effect of the other.
Is the combined effect of glucagon and epinephrine additive or synergistic?
Which is more common: type 1 or type 2 diabetes?
Type 2 (80-90% of diabetics).
What are rapidly adapting afferents?
Somatosensory afferents whose action potentials become quiescent with continued stimulation.
What are the 2 regions of the mesencephalon (midbrain) in mammals?
- Inferior colliculi (auditory input)
- Superior colliculi (visual input)
Which skin mechanoreceptor has the highest spatial resolution?
Merkel cell afferents (0.5 mm).
What is the major difference between more advanced and less advanced mammals with respect to the isocortex?
The isocortex is more heavily folded in more advanced mammals.
What type of chemical messenger is aspartate?
What is a relative refractory period?
An interval of repolarization following hyperpolarization of a neuron, during which it is more difficult to generate a new action potential.
Which motor protein moves toward the positive ends of microtubules?
What causes the movement of cilia and flagella?
Asymmetrical activation of dynein.
What is SOS?
A protein recruited by GRB2 that activates Ras as part of the Ras-MAP-kinase signalling pathway.
What structure allows direct cell signalling?
Where are Na+ channels concentrated in myelinated axons?
On the axonal membrane at nodes of Ranvier.
What type of chemical messenger is dopamine?
During the stress response, do blood glucose levels increase or decrease?
Where is GLUT3 found?
In the brain.
What conditions do AMPA and kainate receptors require before they can open?
Binding of glutamate.
In what region of the brain is the pons located?
What determines the rate of movement of kinesin and dynein along microtubules?
ATPase activity of the ATPase domains of the motor proteins and of regulatory proteins.
What is the most common carrier protein for steroid hormones?
What is the glucose affinity of GLUT4?
What is the reversal (equilibrium) potential of glutamate receptors?
Approx. 0 mV.
How many meninges do amphibians, reptiles, and birds have?
Are steroid hormones hydrophilic or hydrophobic?
What ligand activates receptor guanylyl cyclase to regulate extracellular fluid volume and blood pressure?
Atrial natriuretic peptide (ANP).
Which 3 variables affect the value of the length constant (λ)?
- rm (resistance of the membrane)
- ri (resistance of intracellular fluids)
- ro (resistance of extracellular fluids)
What is GRB2?
An SH2-containing protein that docks to activated receptor tyrosine kinases and recruits SOS as part of the Ras-MAP-kinase signalling pathway.
What are slowly adapting afferents?
Somatosensory afferents that continue to respond with action potentials for the duration of the stimulus.
In what form are peptide hormones usually stored?
What second messenger is synthesized by phospholipase C?
What is an islet of Langerhans?
A cluster of cells within the pancreas that contains the α and β cells responsible for synthesizing glucagon and insulin, respectively.
How does myelination affect the time constant (τ) of axons?
Myelin decreases membrane capacitance, which decreases τ.
What is the full name of type 2 diabetes?
Non-insulin-dependent diabetes mellitis.
What are nodes of Ranvier?
Areas of exposed axonal membrane between myelin on myelinated axons.
What protein makes up microfilaments?
Where is the microtubule organization centre (MTOC) positioned in the cell?
Near the nucleus.
Which two organs are stimulated by the sympathetic nervous system during the stress response?
- Adrenal medulla
What is the corpus callosum?
A region of the cerebrum serving as a bridge between the left and right hemispheres where neurons cross over to innervate the opposite side of the body.
Which organ secretes corticotropin-releasing hormone (CRH) during the stress response?
At which end do microtubules shrink by dimer removal?
What is the main role of mineralocorticoids?
Which organ secretes cortisol during the stress response?
How does a decrease in time constant (τ) affect electrical signalling across a cell membrane?
- Capacitor becomes full more quickly
- Faster depolarization
- Faster conductance
In what region of the brain is the medulla oblongata located?
What proportion of diabetics have type 2 diabetes?
Which region of the brain serves as a pathway between the medulla, the cerebellum, and the forebrain?
What is the main type of effect caused by receptor-enzymes?
Changes in intracellular enzyme activity.
How are peptide hormones released?
They are stored in vesicles that are secreted by exocytosis.
What is the length constant (λ)?
The distance over which an electrical signal will decay to 37% of its maximum value.
In what type of signalling are gases usually involved as chemical messengers?
What is glutamine synthetase?
An enzyme that catalyzes the conversion of glutamate (a neurotransmitter) to glutamine for recycling to the presynaptic neuron.
What is acetylcholinesterase (AChE)?
An enzyme that breaks down acetylcholine (ACh) into choline and acetate in the synaptic cleft to terminate an ACh-mediated signal in the postsynaptic cell.
Where is insulin synthesized?
Pancreas (β cells).
What type of chemical messenger is GABA?
What 2 types of molecules are allowed through transporters at the blood-brain barrier?
- Amino acids
What type of receptor do steroid hormones bind to?
Transmembrane or intracellular receptors.
Which region of the somatosensory system is responsible for relaying sensory information from every part of the body except for the head and face?
Dorsal root ganglia.
Are eicosanoids hydrophilic or hydrophobic?
What are the 4 functional zones of a neuron?
- Signal reception (dendrites & cell body)
- Signal integration (axon hillock)
- Signal conduction (axon)
- Signal transmission (synapse)
What is the blood-brain barrier?
A region of tight junctions in the brain capillary endothelium that limits the passage of solutes from blood into the cerebrospinal fluid, protecting the brain from harmful substances.
What enzyme synthesizes cAMP?
Which type of sensory input is not received by the thalamus?
What are meninges?
Layers of connective tissue that surround the brain and spinal cord.
What is the infundibulum?
A structure in the brain connecting the hypothalamus to the pituitary gland.
What type of chemical messenger is glucagon?
What is the main exocrine function of the pancreas?
Secrete digestive enzymes into the duodenum.
Why is there no net movement of ions across a membrane at resting membrane potential?
The value of the resting potential corresponds to an electrical gradient that counteracts the chemical gradient of ions.
How does a higher value of λ (length constant) affect speed of conduction along an axon?
Higher λ allows more electrotonic current flow for faster conduction.
What are 3 major differences between electrical and chemical synapses?
- Chemical: synaptic vesicles store neurotransmitters; electrical: no vesicles
- Chemical: synaptic cleft; electrical: gap junctions
- Chemical: neurotransmitters; electrical: ions
What are the 5 sets of spinal nerves in vertebrates?
What is capacitance (C)?
The ability to store charge when a voltage difference occurs between two surfaces.
What is the main role of glucocorticoids?
What 3 factors determine the rate of removal of neurotransmitters from a synapse?
- Passive diffusion of neurotransmitters out of the synapse
- Degradation of neurotransmitters by synaptic enzymes
- Uptake of neurotransmitters by surrounding cells
How are white and grey matter organized in the brain?
- White matter on the inside
- Grey matter on the surface
What are the 6 main components of the limbic system?
- Olfactory bulbs
- Nucleus accumbens
- Cingulate cortex
What 2 factors determine the strength of synaptic transmission and the response of the postsynaptic cell?
- Amount of neurotransmitter in the synapse
- Number/density of receptors on the postsynaptic cell
Which portion of receptor-enzymes have intrinsic kinase activity?
The cytosolic domain.
What type of mechanoreceptor is especially well expressed in fingertips?
Merkel cell afferents.
What is GLUT2?
A transmembrane receptor that transports glucose into pancreatic β cells (if blood glucose is high) or out of pancreatic α cells (if blood glucose is low).
Where are the adrenal glands in birds?
Embedded within the kidneys.
What are the 3 functional divisions of the nervous system?
- Afferent sensory
- Efferent motor
What are tropomodulins?
Capping proteins that associate with microfilaments at the (-) end to prevent actin dissociation, stabilizing the microfilament.
What is glycogen phosphorylase kinase (GPK)?
A kinase activated by PKA in response to glucagon (signalling low blood glucose) that leads to the breakdown of glycogen to glucose, which is then released into the blood to raise blood glucose levels.
What happens to the membrane potential of a cell as permeability to a specific ion increases?
The membrane potential will approach that ion's equilibrium potential (as defined by the Nernst equation).
How does the structure of a cell correspond to the structure of an electrical capacitator?
- 2 conducting layers:
- Intracellular fluid
- Extracellular fluid
- Insulating layer between conducting layers:
- Intracellular fluid
- Extracellular fluid
Which region of the brain is responsible for executive function of the brain, including decision-making, motivation, and planning?
Cingulate cortex (limbic system).
What type of chemical messenger are eicosanoids?
How is the cerebellum positioned in the body?
2 hemispheres at the back of the brain.
What second messenger is synthesized by adenylyl cyclase?
Which is faster: kinesin or dynein?
Neither--they travel at approximately the same speed (1.5 μm/s for kinesin, 1.7 μm/s for dynein).
What is profilin?
A regulatory protein that binds to G-actin and promotes assembly of microfilaments.
What are the 4 components of preprovasopressin?
- Signal peptide
- Arginine vasopressin (AVP)
Are peptide hormones hydrophobic or hydrophilic?
What is the time constant (τ)?
The time over which a membrane potential will decay to 37% of its maximum value; a measure of how well the membrane holds its charge.
What are the 4 major effects of epinephrine secreted by the adrenal medulla during the stress response?
- Increased heart rate
- Increased breathing rate
- Redistribution of blood flow from periphery
- Increased blood glucose
What is the reversal (equilibrium) potential of GABAA receptors?
-99 mV (the Nernst potential for Cl-).
Which hormone regulates uterine contraction in a positive feedback loop during childbirth?
What does the "brainstem" refer to?
A grouping of the mesencephalon (midbrain), the pons, and the medulla oblongata.
Which glucose transporter has the highest affinity for glucose?
How are incoming signals at the dendrites of a neuron conveyed to the axon hillock?
Input is converted to a change in membrane potential, which is propagated through the cell body toward the axon hillock.
What type of receptor does atrial natriuretic peptide (ANP) bind to regulate extracellular fluid volume and blood pressure?
Receptor guanylyl cyclase.
What is the main role of cGMP?
To activate protein kinases (usually PKG), which phosphorylate proteins and open/close ion channels.
What hormone is released by the adrenal cortex during the stress response?
What are ependymal cells?
Ciliated cells that line ventricles in the vertebrate brain and circulate cerebrospinal fluid (CSF).
What hormone controls glucose levels in crustaceans?
Crustacean hyperglycemic hormone (CHH).
What happens when a cell membrane repolarizes?
The membrane potential returns to its resting (negative) value.
What is the amygdala?
The region of the limbic system responsible for aggression and fear responses.
Which glutamate receptor subunits are found in kainate receptors?
What are the 2 main roles of phosphatidyl inositol?
- Activate protein kinase C (PKC)
- Stimulate Ca2+ release from intracellular stores
Which region of the brain is responsible for initiating voluntary movements?
Why is cortisol able to have more rapid effects than other steroid hormones?
It binds to transmembrane receptors to cause non-genomic effects, which are faster than effects on transcription.
What happens in the pancreas during the stress response?
- Decreased insulin secretion
- Increased glucagon secretion
In crustaceans, is glucose control by crustacean hyperglycemic hormone (CHH) a positive or negative feedback loop?
- Positive: CHH secreted in response to low glucose causes downstream glycogenolysis resulting in production of lactate, which stimulates further CHH release.
- Negative: Glycogenolysis also results in production of glucose, which inhibits CHH release once the system reaches a certain level of glucose.
What is tubulin?
The protein that polymerizes to make microtubules.
What happens in spatial summation of postsynaptic potentials?
Postsynaptic potentials from multiple different sites influence the net change in membrane potential.
What is the typical age of onset for type 2 diabetes?
What is our resting blood glucose level?
What is choline acetyl transferase?
An enzyme that catalyzes the conversion of acetyl CoA and choline to acetylcholine (ACh).
Which region of the brain is responsible for sense of smell?
Olfactory bulb (limbic system).
What are sulci?
Grooves in the isocortex of the brain.
What are the 2 SNARE proteins found in chemical synapses?
True or false: Action potentials decay over distance.
What type of steroid hormone is cortisone?
What do pancreatic α cells produce?
Is glucose hydrophobic or hydrophilic?
What 3 factors cause decay of graded potentials?
- Leakage of charged ions across the membrane
- Electrical resistance of the cytoplasm
- Electrical resistance of the membrane
What is a dermatome?
The territory innervated from a single dorsal root ganglion and its spinal nerve.
Which region of the brain has taken over many midbrain functions in lower vertebrates?
How is the firing frequency modulated in mechanosensory afferent nerve endings?
Firing frequency is proportional to strength of stimulus: stimulus alters ion permeability of cation channels, which alters magnitude of depolarization; greater stimulus means greater depolarization for generating action potentials.
What type of receptor are NGF receptors?
Receptor tyrosine kinase (RTK).
What is an absolute refractory period?
An interval between depolarization and repolarization of a neuron, during which the cell is incapable of generating a new action potential.
How is the pons positioned in the body?
Rostral to the medulla oblongata (which is at the top of the spinal cord).
What hormone is secreted by the anterior pituitary during the stress response?
Adrenocorticotropic hormone (ACTH).
How many meninges do fish have?
What 2 processes are stimulated by glucagon release?
What is the full name of type 1 diabetes?
Insulin-dependent diabetes mellitis.
Which part of the adrenal gland secretes cortisol and aldosterone?
What are the 2 main functions of the prosencephalon (forebrain)?
- Processing/integrating sensory information
- Coordinating behaviour
What causes the symptoms of type 2 diabetes?
Impaired signal transduction mechanisms in insulin receptors lead to insulin resistance, and pancreatic β cells are no longer responsive to elevated blood glucose levels.
Which glutamate receptor subunits are found in AMPA receptors?
Where is arginine vasopressin synthesized?
What is the exchange rate of Na+/K+ ATPase per molecule of ATP hydrolyzed?
- 3 Na+ ions transported out of the cell
- 2 K+ ions transported into the cell
How many subunits are in a complete ionotropic glutamate receptor?
What type of receptor are VEGF receptors?
Receptor tyrosine kinase (RTK).
Which 4 major types of somatosensory receptors are involved in touch?
What type of steroid hormone is testosterone?
What form does adrenal tissue take in animals that don't have discrete adrenal glands?
They have chromaffin and interrenal cells dispersed throughout or near the kidney.
What type of nucleotides are G-proteins able to bind?
What is ecdysone?
The hormone that regulates molting in ecdysozoans.
How many people in the world are addicted to smoking?
Over 1 billion.
How many people in the world die each year from smoking-related illnesses?
Over 4 million.
How do rates of cardiovascular disease differ in smokers vs. non-smokers?
Cardiovascular disease rates are 70% higher in smokers.
What percentage of all cancer deaths are caused by smoking?
What percentage of all lung cancers is caused by smoking?
What 2 types of disease have the greatest increase in risk associated with smoking?
- Cardiovascular disease
- Cancer (especially lung cancers)
What are the 3 main characteristics of drug addiction?
- Compulsion to obtain and take the drug
- Inability to control or limit intake of the drug
- Withdrawal symptoms when access to the drug is blocked
Which has greater expression of nicotinic receptors: dopaminergic or GABAergic neurons?
Dopaminergic (~twice as many nAChRs).
What are the 2 regions of the substantia nigra?
- SNC (substantia nigra compacta)
- SNR (substantia nigra reticulata)
Which type of neuron is more numerous in the substantia nigra compacta (SNC): dopaminergic or GABAergic?
Which type of neuron is more numerous in the substantia nigra reticulata (SNR): dopaminergic or GABAergic?
Which neurons degenerate in Parkinson's disease, causing loss of movement?
Dopaminergic neurons in the substantia nigra.
Which region of the brain is associated with feelings of pleasure and craving relief in addiction?
Mesolimbic dopaminergic pathway.
Which regions of the brain are associated with increased cognitive function, attention, and learning/memory that come with abused drug use?
- Anterior cingulate cortex
Which regions of the brain are associated with feelings of decreased stress and anxiety with abused drug use?
- Lateral septum
Which regions of the brain are associated with decreased appetite that comes with drug addiction?
- Lateral hypothalamic area
- Paraventricular/arcuate nuclei
Which regions of the brain are associated with feelings of reduced depression in drug addiction?
- HPA axis
- Frontal cortex
What does VTA stand for?
Ventral tagmental area.
What was the key finding of the U of T study (1992) on self-administration of nicotine in rat models?
The mesolimbic pathway plays a critical role in addiction.