Ans

capacitance is the ability of a material to seperate charge resistance of a circuit describes the ease with which charges move when current is injected into the circuit, the voltage across the circuit will change exponentially and then reach a steady state if charges are injected into a cell, the rate at which the voltage across the membrane changes depends on what? membrane resistance and capacitance conditions for nernst potential 1. the membrane must have some permeability to a charged particle. 2. there must be different concentrations of the charged particle on each side of the membrane. 3. the permeability of the other charged particles must be zero. driving force describes the net electrochemical force an ion feels Inhibition of the Na+K+ ATPase does what depolarizes the cell towards 0mV plasma fluid and cells inside circulation interstitial compartment fluid surrounding all cells of the body intracellular compartment fluid inside cells main systems to control internal environment nervous, endocrine, immune In negative feedback loops an initial increase in the variable leads to a subsequent decrease in the variable to bring it back to the initial level In positive feedback loops an initial increase in the variable triggers a further increase in that variable. TBW large fraction of body is composed of water 60-40-20 rule 60% of body weight is water 40% of body weight is ICF 20% of body weight is ECF osmolarity the total number of solutes per volume hematocrit the % of the total blood volume that is cells moles number of molecules in a given substances molarity the concentration of a substance - 1 Molar = 1 mole/(Liter of solvent) Molality: the concentration of a substance - 1 Molal = 1 mole/(Kg of solvent) Osmolarity is different than molarity for substances that . dissociate Osmolarity: the concentration of particles - 1 Osmolar = 1 osmole/(Liter of solvent) Osmolality: the concentration of particles - 1 Osmolal = 1 osmole/(Kg of solvent) isosmotic solutions with the same concentrations of solute particles hyperosmotic higher osmolarity tonicity what will happen to cell volume if a cell is placed in a given solution cell volume will decrease if a cell is placed in a hypertonic solution cell volume will increase if a cell is placed in a hypotonic solution what seperates the intraceullar compartment from the extracellular compartment single lipid bilayer lipid bilayer is permeable to gases and hydrophobic hormones interstitial space is seperated from plasma by a blood vessel wall blood vessel wall is peremeable to small substances sodium concentration in extracellular space is low potassium concentration in intracellular space is high calcium concentration is low inside where? cells Na+ and K+ have a _____ permeability low what molecules can diffuse across the membrane and do not need proteins to facilitate their transport? hydrophobic molecules what molecules can diffuse themselves through the membrane but sometimes need protein transport? water and urea what types of molecules do not diffuse easily and require proteins to transport? large uncharged and ions oncotic pressure The osmotic pressure in the blood vessels due only to plasma proteins dehydration = decreae in overall water in body = ___ interstitial osmolarity = movement of water from ___ to _____ = _____ in cell volume dehydration = decrease in overall water in body = increase interstitial osmolarity = movement of water from ICF to ECF = decrease in cell volume what is the greatest consumer of oxygen and glucose? nervous system psuedounipolar round cell body with ONE single process which divides into two branches bipolar neurons oval shaped cell body with ONE large process projecting from each end of the cell body multipolar multiple dendrites and ONE axon purkinje cell cerebral cortex dendrites function to receive signals what are the sites of synaptic contacts called for dendrites? dendritic spines what 5 elements do LARGER dendrites contain? 1. microtubules 2. neurofilaments 3. mitochondria 4. endoplasmic reticulum 5. polyribosomes and free ribosomes cell bodies are the metabolic center of the nerve cell cell bodies contain (4) 1. large nucleus 2. ribosomes 3. Golgi 4. RER what is the difference between axons and dendrites when viewing under a microscope? dendrites have ribosomes; while axons do not what is the name of the synapses between axons? terminal boutons in anterograde axonal transport, what protein is responsible for FAST movement? kinesin in retrograde axonal transport, what protein is responsible for movement? dynein Retrograde Tracers such as pseudorabies virus and horseradish peroxidase are used as research tools in order to label neurons within a specific pathway. neuroglia function support and protect neurons types of neuroglia 1. Astrocytes (CNS)/ Satellite cells (PNS) 2. Oligodendrocytes (CNS)/ Schwann cells (PNS) 3. Microglia 4. Ependymal cells astrocytes during neuronal development function provide support and framework for neuronal migration many tumors are of what origin? astrocytic what neuroglial cell produces myelin? oligodendrocytes microglia function as phagocytic scavengers microglial produce cytokines ependymal cells produce CSF what makes up the choroid plexus? ependymal cells, pia mater and capillaries How is CSF produced? Produced as a trasudate of plasma (CSF has higher Cl content and lower protein/glucose). This builds hydrostatic pressure in capillaries and forces fluid into connective tissue where it is taken up by ependymal cells and released into ventricles blood brain barrier consists of tight junctions between endothelial cells what 6 places lack the BBB? 1. Choroid Plexus 2. Pineal Body 3. Subcommissural organ 4. Area Postrema 5. Neurohypophysis 6. Median Eminence and Infundibulum in the PNS, satellite cells = astrocytes in the PNS, schwann cells = oligodendrocytes Satellite cells surround cell bodies of neurons in sensory and autonomic ganglia Schwann cells - ensheath axons of peripheral nerves. what helps ANCHOR and protect nerves in the PNS? connective tissue- epineurium, perineurium, endoneurium afferent nerve = a nerve projecting from the PERIPHERY to the CNS efferent nerve = a nerve projecting from the CNS to the periphery outside of the basal lamina, what connective tissue sheath is between individual nerve fibers? endoneurium outside of the basal lamina, what connective tissue sheath surrounds each fascicle of axons? perineurium outside of the basal lamina, what connective tissue sheath is around the peripheral nerve? epineurium do neuronal cell bodies proliferate? no 3 names of sensory ganglia 1. DRG 2. Trigeminal Ganglia (CN5) 3. Visceral sensory ganglia (CN7,9,10) why is the BBB of clinical importance? it can prevent the passage of drugs into NS when will CSF appear cloduy? bacterial meningitis Myastenia Gravis is a disease in which the immune system produces antibodies to the nicotinic acetylcholine receptor site Myastenia Gravis is a disease in which the immune system produces antibodies to the nicotinic acetylcholine receptor site which is located postsynaptically at the neuromuscular junction. Myastenia Gravis symptoms results in muscle weakness. what virus and toxin travel in retrograde fashion? rabies virus and bacterium Clostridum tetani what cells make up the central canal ependymal cells the central canal is continuous with the ventricular system the gray matter consists of 3 cell layers: an inner granular layer, and outer molecular layer, and Purkinje cells are seen the three layers of gray matter constitute the cerebral cortex what are the distinguishing features of the autonomic ganglion? cell bodies appear to be ovoid and slightly angular in shape, many of the nuclei of the neurons tend to be located in an eccentric position autoreceptor a receptor molecule located on a neuron that responds to the neurotransmitter released by that neuron Hetero-receptors receptors located on presynaptic neurons that are activated by a neurotransmitter that is different from what is released by the presynaptic neuron desensitization uncoupling of the receptor from intracellular components increase membrane resistance decrease open ion channels, decrease membrane surface area, increase membrane thickness increase membrane capacitance increase membrane surface if a positive charge is injected into the cell, the membrane potential will become more positive depolarization membrane potential becomes more positive hyperpolarization membrane potential becomes more negative threshold the voltage in a cell above which an AP. will be elicited and below whcih an AP will not be elicited subthreshold response at axon hillock response does not rise above threshold suprathreshold response at axon hillock rises above threshold and initiates an AP during the upstroke phase the membrane potential is depolarizing during the repolarization phase the membrane potential hyperpolarizes If the membrane potential is artificially set at -80 mV (near the normal resting membrane potential in an axon) then all of the sodium channels in the cell will be closed and the current flowing through the sodium channels will be zero. If the membrane potential is artificially set to -60 mV some of the sodium channels will open and the current through the membrane will increase. second type of closed state (after channels have opened and closed once) inactivated state If the membrane potential is artificially set to a large positive value (+60 mV in this example), all the sodium channels in the membrane will open and the current will increase to its maximum value. The sodium channels will then inactivate. The difference between potassium channels and sodium channels are that when the membrane potential is set at -60mV and the channels open the current through the membrane will increase. Then? the sodium channels will inactivate; the potassium channels will NOT is the inactivation gate of sodium sensitive to voltage no is the activation gate of sodium sensitive to voltage yes the activation gate of the sodium channel moves in response to membrane depolarization and opens the sodium channel the inactivation gate after the activation gate opens plugs the pore of the channel almost immediately and inactivates the channel 2 gated voltage gated sodium channels are responsible for the upstroke of the AP opening of Na+ channels is a ______ feedback loop positive opening of K+ channels is a ______ feedback loop negative the peak of action potential occurs when the RATIO of sodium permeability to potassium permeability is HIGHEST the density of voltage gated sodium channels is highest in the axon hillock why can an AP not fire during an absolute refractory period most Na+ channels are inactivated why can an AP fire during a relative refractory period? some sodium channels are still inactivated; K+ channels are still open channel types for a stimulus signal stretch-gated ligand-gated voltage-gated channel type for resting membrane potential signal leak channel type for action potential signal voltage-gated the decay of AP signal is determined by membrane resistance (loss of ions through leak) and cytoplasmic resistance (loss of energy to heat) a short length constant means that the size of the signal decreases more a given distance from the initiation of the signal increase cytoplasmic resistance decrease diameter of axon increase in membrane resistance = _______ charge leaks out LESS increase in axon diameter = ____ velocity increase velocity what does myelin have no effect on cytoplasmic resistance nerve depletion of ATP can occur as a result of hypoxia, hypoglycemia, and seizures what toxin blocks Na+ channels? Tetrodotoxin what toxin blocks K+ channels? tetraethylamonium temporal summation ONE dendrite recieves a number of excitatory responses one after the other spatial summation TWO dendrites receive an excitatory response at the same time how much time can pass before the two signals will not be able to add to eachother? shorter than 50msec most acetylcholine-induced organ effects are P-ANS functions except thermoregulatory sweating (S-ANS), release of epinephrine from the adrenal medulla (S- ANS) and somatic control of muscle contraction (activation of nicotinic receptors) SNARE complex proteins SNAP-25, syntaxin, synaptobrevin, synaptotagmin 5 criteria for neurotransmitter 1. Present in the nerve terminal 2. Released by electrical stimulation of neuron 3. Specific receptors exist 4. Direct application of substance mimics neuronal stimulation 5. There is a mechanism for terminating the action amino acid NT names glutamate, aspartate, GABA, glycine purine NT name ATP catecholamines NT name dopamine, norepi, epinephrine indoleamine NT name serotonin imidazoleamine NT name histamine small-clear core vesicles usually contain small NT large dense core vesicles usually contain peptide NT or biogenic amines biogenic amines names catecoleamines, indoleamine, imidazoleamine glutamate is changed to glutamine in what cell glial cell μ receptor endogenous peptide affinity endorphins > enkephalins > dynorphins K receptor endogenous peptide affiity enkephalins > endorphins and dynorphins delta receptor endogenous peptide affinity dynorphins >> endorphins and enkephalins Ach processed where post synaptic cell Glycine processed where post synaptic cell catecholamines processed where presynaptic terminal what stops NT action? difussion away from site of action, reuptake into cells, enzymatic cleavage what determines what the signal will look like when it reaches axon hillock? sign of postsynaptic response, time constant, length constant of neuron a neuron will response to the integration of all its inputs by either not firing an AP or firing an AP what maintains length of thin filaments nebulin what hold thin filaments at the Z disc alpha actinin what positions thick filaments titin thin filaments are made of actin, troponin, tropomyosin a triad is made of 1 t-tubule and 2 SR cardiac cells have diads that are made of 1 t-tubule 1 SR where do thin filaments attach in smooth muscle sarcolemma atdense bodies muscle fibers are made up of how many cells one striated muscle undergoes _______ contraction and of ______ duration very powerful, short smooth muscle undergoes _______ contraction and of ______ duration slower/weaker and longer duration myofibrils are groups of cytoskeletal filaments myofibrils do what? contractile apparatus of muscle fibers the distance betwen two consecutive Z-lines defines a sarcomere thick filaments are Myosin II contraction of skeletal muscle 2 steps 1) Depolarization of the plasma membrane (sarcolemma) of the muscle fiber (similar to an action potential) 2) Release of Ca2 + from the endoplasmic reticulum (sarcoplasmic reticulum) of the muscle fiber into the cytoplasm of the muscle. cardiac muscles contain _____ at the interfaces of adjacent cells intercalated disks cell-cell junction on transverse side of intercalated discs fascia adherens what attached to the fascia adherens actin The longitudinal region of the intercalated disk between two adjacent cells is a gap junction. the longitudinal region of the intercalated disc allows for cardiac muscle cells contracting in synchrony Z lines The ends of a saromere. stress is load, tension, or force per unit area velocity of shortening is measured by determining how far the muscle contracts in a given time. sarcomere tension vs length (max overlap) max overlap occurs when the maximum number of cross-bridges on the thick filament will be able to interact with the thin filaments small loads. the crossbridges cycle quickly at very large loads during a lengthining contraction, what will happen? cross bridges will detach and muscle will rapidly stretch Once myosin can bind to actin, ATP is required for the conformational changes necessary for cross-bridge cycling motor unit is the lower motor neuron and all of the muscle fibers that it innervates in cardiac cells, the AP spreads through the t Tubule system causing opening on Ca2+ voltage gated channels which enters the cell and activates the calcium channel at the SR = calcium induced calcium release calcium concentration is restored in heart by a. Ca2+-ATPase located in the plasma membrane b. Na+-Ca2+ exchanger located in the plasma membrane (3 Na+ for 1 Ca2+). c. Ca2+-ATPase located in the membrane of the sarcoplasmic reticulum cardiac muscle, the duration of the twitch is similar to the duration of the AP the heart cannot undergo teatnus or summation what mechanically links smooth body cells? dense body what links dense bodies to cytoskeletal network? intermediate filaments termination of smooth muscle contraction by myosin light chain phosphatase what does Ca2+ bind to for smooth muscle contraction? calmodulin what does Ca2+ bind to for skeletal and cardiac muscle contraction? troponin cardiac and smooth muscle allow for Ca2+ to come from _____ and ______ SR and extracellular smooth muscle cells do not contain troponin calcium can enter the cell via release from the SR which can be due to the IP3 pathway. Explain pathway cell surface (i.e. plasma membrane) receptor activation can lead to an increase in the 2nd messenger IP3 which directly activates an IP3 gated (i.e. a ligand gated) calcium channel in the SR depletion of calcium from SR can lead to activation of store operated calcium channels (SOCs) describe the ways calcium can enter from extracellular compartment 1. voltage gated channels 2. SOCs 3.agonist activated channels (ROCs) 4. stretch activated channels cAMP in smooth muscle will cause relaxation (b2) increased cAMP in heart muscle will cause increased force (b1) cGMP in smooth muscle causes relaxation what is different between smooth muscle contraction and skeletal muscle contraction? For smooth muscle:

  1. when ADP and Pi are bound to myosin, myosin has a low affinity for actin (skeletal has high affinity)
  2. Phosphorylation of the myosin light chain allows the myosin- ADP-Pi complex to bind to actin (Ca2+ binding to troponin allows for ADP/Pi/Myosin to bind to actin in skeletal)    in smooth muscle intracellular calcium will depend on stimulaus    max velocity in smooth muscle is dependent on 1. Myosin ATPase rate
  3. % phosphorylation    phosporylation increases what two things in smoot mucle velocity of contraction and force of contraction    latch mechanism hypothesis for smooth muscle slower crossbridge cycle = increase time for myosin head attached to thin filament = longer force    skeletal muscle contraction is crolled by the alpha motor neuron and the rceptor at the skeletal NMJ    autonomic control at smooth muscle cell can generate AP which will travel throughout cell by gap junctions    hormonal control of smooth muscle: 1. hormone bind to smooth muscle cell
  4. elicit AP
  5. cell contract by gap junctions

OR

  1. hormone bind smooth muscle cell
  2. increase Ca2+
  3. contraction without AP     three types of AP in smooth muscle 1. spikes
  4. AP with pleateaus
  5. oscillations     receptor operated channels-ROCs are activated by binding of different hormones to receptors on smooth muscle cells     ANP is released from atrial cells in response to increase in blood volume     ANP releaxes smooth muscle by 1. ANP binds to tyrosine kinase receptor which increases cGMP
  6. activates protein kinase which increases K+ channel and decreases Ca2+ channel activity
  7. myosin light chain phosphatase increases
  8. muscle releaxation     Angiotensin II causes contraction of muscle by 1. binds g protein receptor
  9. increases DAG + IP3     3, IP3 opens calcium channels in SR = muscle contraction
    1. DAG activates protein kinase which increases Ca2+ channel activity     dense core vesciles are located farther from synaptic cleft