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Physiology 1 Test 1

Cell Physiology

QuestionAnswer
Total Body Water Accounts for 50-70% of total body weight
What are the two major body fluid compartments and how much of total body water does each hold Intracellular Fluid (ICF) 2/3 of total body water Extracellular fluid (ECF) 1/3 of total body water
What are the components of the ECF and how much of each Plasma (1/4 of ECF): the fluid circulating in the blood vessels Interstital fluid (3/4 of ECF): The fluid that actually bathes the cells
How is Interstitial fluid formed It is an ultrafiltrate of plasma, formed by filtration processes across the capillary wall
Is there protein in interstitial fluid NO
What is the Principle of Macroscopic Electroneutrality Each compartment must have the same concentration of cations as of anions. Even where there is a charge difference across the membrane, charge balance is still maintained in the macroscopic solution
What is homeostasis Stable operating conditions in the internal environment. This is how the body maintains a constant internal environment despite changing external conditions
Homeostatic control mechanisms -Sensory receptor cells -Integrators -Effectors
What is negative feedback -The body responds in such a way as to reverse the direction of change -Keeps things constant
What are some factors in the body that are homeostatically regulated -Nutrients -O2/CO2 -Waste Products -pH -Water, salt, electrolytes -Temperature -Volume and Pressure
What is positive feedback -Change occurs in variable, response changes that variable even more in the same direction -EX: Oxytocin
Composition of Intracellular Fluid -40% of total body weight or 2/3 of body fluid -Similar in composition from one cell to another and even from species to species
Major cation in ECF Na+
Major anion in ECF Cl- HCO3-
Major cations in ICF K+ Mg2+
Major anion in ICF Proteins Organic phosphates
ICF vs ECF acidity ICF is more acidic
How do the total solute concentrations compare in ICF vs ECF They are the same because of the selectively permeable cell membrane
What is osmosis Diffusion of H2O from high concentration to low concentration until reaching equilibrium
What is diffusion The movement of ions from high concentration to low concentration until ions are equally distributed
Units for solute concentrations -Moles, millimoles -Equivalents -pH -Osmolarity
What are K+ and Mg2+ balanced by Proteins and Phosphates
What is Na+ balanced by HCO3- and Cl-
What creates concentration differences across membranes Na+-K+ ATPase Ca2+ ATPase Transporters
What is Na+-K+ ATPase A pump that moves Na+ and K+ against the concentration gradient
What are the transporters that create concentration differences across membranes transporting Glucose, amino acids, Ca2+, H+ (no ATP is required)
What is Gibbs-Donnan equilibrium Electroneutrality across the capillary wall
What are cell membranes composed of Phospholipids, cholesterol and glycolipids
What lipid soluble things cross the cell membrane CO2, O2, FA, Steroid hormones
What H2O soluble things cross the cell membrane Ions, glucose and AA
What types of proteins are in the cell membrane Transporter, enzymes, hormone receptors, cell surface antigens, ion and water channels
What are Integral proteins Contact both ICF and ECF but anchored to the cell membrane by hydrophobic interactions
What are Peripheral proteins -not embedded, not covalently bound, loosely attached -bound by electrostatic interactions EX: ankyrin (cytoskeleton of RBCs to Cl- HCO3- exchanger)
What is amphipathic having both hydrophilic and hydrophobic components
What are some examples of Integral proteins ligand-binding receptors, transport proteins, pores, ion channels, cell adhesion molecules and GTP-binding proteins
What is downhill transport and how does it occur -Transport down an electrochemical gradient -occurs by diffusion, either simple or facilitated (No ATP requirement)
What is uphill transport and how does it occur -Transport against an electrochemical gradient -occurs by active transport, either primary or secondary (Needs ATP)
What is facilitated diffusion -downhill -Carrier mediated -No energy in required EX: GLUT4 transporter-transports D-glucose into skeletal and adipose tissue
What is saturation Is based on the concept that carrier proteins have a limited number of binding sites for the solute.
What is Transport Maximum When all binding sites are occupied
What is Primary active transport -Uphill -Carrier mediated -Directly uses energy EX: Na-K Pump
What are the two types of secondary active transport Cotransport Countertransport
What is cotransport -Carrier mediated -Indirectly uses ATP -Solutes move in same direction as Na across the membrane
What is countertransport -Carrier mediated -Indirectly uses ATP -Solutes move in opposite direction as Na across the membrane
Why is the Na-K pump considered electrogenic -Each cycle 3 Na and 2 K are moved -This means more positive charge is pumped out of the cell than is pumped into the cell -It creates a charge separation and potential difference
What do cardiac glycosides do -They inhibit Na-K pumps
What is osmosis -Flow of water across a semi permeable membrane due to a difference in solute concentration -Primary method of water movement into and out of body fluid compartment
What is an isotonic solution A solution that has the same concentration of non-penetrating solutes as normal body cells
What is a hypotonic solution A solution with a lower concentration of non-penetrating solutes
What happen if a cell is placed in a hypotonic solution Water enters the cell via osmosis
What happens if a cell is placed in a isotonic solution Cell volume remain constant
What is a hypertonic solution A solution with a greater concentration of non-penetrating solutes
What happens if a cell is placed in a hypertonic solution Water leaves the cell via osmosis
What is the NaCl concentration in the body .9% NaCl
Na equilibrium potential +65 mV
Ca equilibrium potential +120 mV
K equilibrium potential -85 mV
Cl equilibrium potential -90 mV
What is the Nersnt Equation Calculates the equilibrium potential for an ion at a given concentration difference across a membrane
What is Resting membrane Potential -Potential difference that exists across the cell membranes of excitable cells -established by diffusion potential
What is the role of Na-K ATPase in resting membrane potential It has an electrogenic contribution and maintains concentration gradients for Na and K
What is the Chord Conductance equation -Weighs the equilibrium potential of each ion by its relative conductance -At rest the membrane is more permeable to ions like K+
What is an action potential Phenomenon of excitable cells such as nerve and muscle that consists of rapid depolarization followed by repolarization of membrane potential
What is depolarization The process of making the membrane potential less negative (more positive) -makes the interior of the cell less negative
What is hyperpolarization The process of making the membrane potential more negative
What is inward current -The flow of positive charge into the cell -Inward currents depolarize the membrane potential
What is outward current -The flow of positive charge out of the cell -outward current hyperpolarize the membrane potential
What is threshold potential the membrane potential at which occurrence of the action potential is inevitable
What is Overshoot is the portion of the action potential where the membrane potential is positive
What is undershoot the portion of the action potential, following repolarization, where the membrane potential is actually more negative than it is at rest
What is absolute refractory period a period during which another normal action potential cannot be generated
What is relative refractory period a period during which another normal action potential can be generated, however not as strongly
Steps to Action Potential 1) RMP, -70 mV, K leak channels fully open 2) Depolarization, -60 - +65 mV, Opening of voltage gated Na channels 3) Repolarization, inactivation of VG Na Channels and activation of VG K channels 4) Hyperpolarization, more negative the RMP
At rest how are the sodium gates; open or closed Activation gate is closed Inactivation gate is open
During Upstroke how are the sodium gates; open or closed Activation and Inactivation gates are open
During Repolarization how are the sodium gates; open or closed Activation gate is open Inactivation gate is closed This is the Absolute refractory period
What is conduction velocity Speed at wich impulse travels
What is conduction velocity dependent upon Nerve diameter
What is Saltatory Conduction Jumping action potential from node to node
What are the two types of synapses Electrical and Chemical
What is an Electrical synapse Current flow from one excitable cell to the other via low resistance pathways called gap junctions
What is a chemical synapse Presynaptic and postsynaptic, in between synaptic cleft
What is the neuromuscular junction gap between nerve and muscle
Are neuromuscular junctions multidirectional NO Unidirectional
What are the first 4 steps to Neuromuscular transmission 1)AP in the nerve 2)Open voltage gated Ca channels (Ca binds to ACh vesicles 3)Exocytosis of ACh vesicles 4)ACh diffuses and binds to nicotinc receptor or motor end plate
What are steps 5-7 of Neuromuscular transmission 5)Binding open ligand gated Na/K channels 6)Motor endplate depolarized because of Na and K flow (causes AP in muscle) 7)ACh is degraded by AChE into choline and acetate (choline is transported back to presynaptic terminal)
Where does synthesis of Acetylcholine happen In the Presynaptic terminal
Where does degradation of Acetylcholine happen In the Postsynaptic terminal
Describe the Acetylcholine cycle Choline+Acetyl CoA -> Acetylcholine -> Choline+Acetate
What enzyme is needed to go from Choline+Acetyl CoA -> Acetylcholine Choline acetyltransferase
What enzyme is needed to go from Acetylcholine -> Choline+Acetate acetylcholinesterase
Where is acetylcholinesterase located On surface of motor end plate membrane
What does acetylcholinesterase do Terminates acetylcholine activity at neuromuscular junction
What does Botulinus do Blocks ACh release Causes weakness
What does Hemicholinium do Prevents reuptake of choline Causes weakness
What does Neostigmine do Blocks AChE Makes ACH more available and decreases weakness
What does Curare do Binds to ACh receptors Causes weakness
What is spatial summation Occurs when two or more presynaptic inputs arrive at a postsynaptic cell simultaneously. Inputs combine and the summation determines the output
What is temporal summation Occurs when two presynaptic inputs arrive at the postsynaptic cell in rapid succesion. Because the inputs overlap in time, they summate
What is long term potentiation Occurs in storage of memorie and involves both increased release of neurotransmitter from presynaptic terminals and increased sensitivity of postsynaptic membranes to the transmitter
What is synaptic fatigue occurs where repeated stimulation produces a smaller than expected response in the postsynaptic cell, possibly resulting from the depletion of neurotransmitter stores from the presynaptic terminal
What are the criteria for something to be considered a neurotransmitter Formed in presynaptic terminal and has to be degraded after use
What is degeneration of dopominergic neurons called Parkinson's disease
Describe the synthesis of Dopamine, norepinephrine, and epinephrine Tyrosine -tyrosine hydoxylase-> L-Dopa -dopa decarboxylase-> DOPAMINE -dopamine beta-hydoxylase-> NOREPINEPHRINE -POMT-> EPINEPHRINE
Is acetylcholine excitatory or inhibitory EX
Is norepinephrine excitatory or inhibitory EX
Is epinephrine excitatory or inhibitory EX
Is Dopamine excitatory or inhibitory EX
Is serotonin excitatory or inhibitory IN
Where does serotonin act In brain and GIT
What is serotonin a precursor to Melatonin
Is glutamate excitatory or inhibitory Ex
Where is glutamate used Spinal cord and cerebellum
What are the types of glutamate There are four. Three are ionotropic including NMDA and the fourth one is metabotropic which are coupled by G proteins to ion channels
Is glycine excitatory or inhibitory IN
Where is glycine found In brain stem and spinal cord
What does glycine do Increases Cl- conductance of the post synaptic cell membrane and driving the membrane closer to equilibrium potential of chloride, leads to hyperpolarization
Is GABA excitatory or inhibitory IN via GABAergic neurons
What si GABA synthesized from Glutamate
What are the two types of GABA GABAa that is linked to Cl- channel; GABAb coubled via a G protein to a K+ channel
What disease is associated with GABA Huntington's disease
Is Nitric Oxide excitatory or inhibitory IN but short acting
Where is Nitric Oxide active in CNS and GIT, does signal transduction in vascular smooth muscles
How is Nitric oxide made Arginine is converted to citrulline and NO
NO travels uniquely. How? No packaging, simply diffuses out of presynaptic endplate to the target cell
What are neuropeptides and Purines Neuromodulators (alter the amound of NTX release in response to stimulation. ATP acts a neuromodulator with AcH
What does SKM require in order to contract 1) action potential 2) Release of Ca2+ 3) Tension
What is the process of going from action potential to contraction called Excitation contraction coupling
What are the two types of tension Isometric(tension but no change in muscle length) and isotonic(tension and change in muscle length)
What proteins make up the thin filament Actin, tropomyosin, troponin
What proteins make up the think filament Myosin
What is the purpose of tropomyosin Prevents binding of myosin to actin
What are the types of troponin and what do they do Troponin C (initiates contraction) Troponin I (inhibits actin/myosin binding) Troponin T (connects tropomyosin to troponin complex)
What are the scaffold proteins Dystrophin, titin, nebulin, alpha-actinin
Basic contractile unit of muscle Sarcomere
What does alpha-actinin do glues actin to z-disk
What does titin do goes with myosin
what does nebulin do goes with actin
What is the site of Ca storage in SKM sarcoplasmic reticulum
Step by step process of excitation-contraction coupling in SKM 1)AP->T tubules 2)depolarization of T tubules causes DHP receptor to open ryanodine receptors on sarcoplasmic reticulum 3)Ca released in ICF 4)Ca binds toponin C 5)tropomyosin moves 6)cross-bridge cycling
What is Ca bound to in the sarcoplasmic reticulum to keep its concentration down Calsequestrin
What stores Ca in sarcoplasmic reticulum SERCA
Describe Cross-bridge cycling ATP binds mysoin head -> decreases affinity of myosin/actin -> myosin released -> ATP hydrolysis happens -> myosin head binds new actin site -> Power stroke -> ADP release -> Rigor
If muscle is stimulated repeatedly there is insufficient time for SR to reaccumulate Ca and Ca concentration never returns to low level. This is called Tetanus
Smooth muscle function produce motility, propel urine along ureter and maintain tension in blood vessel walls
Where are single unit smooth muscle found GIT, bladder, uterus, and ureter cells (all use gap junctions as low resistance pathways
Where are multi unit smooth muscle found iris, cilliary muscles of the lens, and vas deferens. all are densely innervated by postganglionic fibers of parasymp and symp nervous system
What are the types of Ca channels in smooth muscle Voltage gated Ca channel, Ligand gated Ca channel, IP3-gated Ca channel (opens channels on SR)
Where is Ca stored in Smooth muscle Extracellularly
What is used instead of troponin in smooth muscle Calmodulin
Tension developed by simply stretch a muscle to different lengths Passive tension
Tension developed when a muscle is stimulated to contract at different preloads Total tension
Tension that is determined by subtracting passive tension from total tension Active Tension
Excitation-contraction coupling in smooth muscle (excitation part) 1)AP->opens volted gated Ca channels->increase IC Ca concentration 2)Ligand and IP3 gated Ca channels also contribute to increase 3)Ca binds calmodulin->activates myosin-light-chain kinase
Excitation-contraction coupling in smooth muscle (contraction part) 4)Phosphorylation of myosin light chain->increase ATPase activity->myosin binds actin 5)relaxation occurs when IC Ca concentration falls
Is myosin ever not bound to actin NO, it is just loosely bound during latch-bridge formation
What is a Dystonia Excessive, sustained, involuntary muscle contraction/spasm
What are some types of dystonia Spasmodic torticollis, blepharospasm, embouchure, writer's cramp
What is thought to cause dystonia Imbalance in input to motor neurons; too little inhibitory compared to excitatory
Created by: bmlanger