Quiz 2 - Membranes, RMP, AP, Muscle Physio, Capillary Permeability, Basic Cell Bio Flashcards
Permeability of molecules from high to low
Hydrophobic molecules > Small uncharged polar molecules > Large uncharged polar molecules > Ions O2 > Glycerol > Glucose > Cl-, K+, Na+
Peripheral Proteins
Adhere only temporarily to the membrane, usually to an integral protein
Integral protein
Incorporated into the lipid bilayer of the membrane
Amphitrophic protein
exist both as water soluble and lipid bound proteins
Fluid Mosaic Model
Idea that proteins and lipids move laterally through the membrane freely. Modified by discovery of lipid rafts.
Asymmetric distribution of phospholipids in PM
Different types of phospholipids are found in uneven ratios between inside and outside of membrane. The composition of a membrane changes depends on cell needs and functions
Examples of integral proteins
G-Protein Coupled Receptors have multiple transmembrane portions. Bacterial Rhodopsin does too.
Lipid-linked membrane proteins
Lipid chains can link proteins to the cell membrane
Cholesterol and membrane flexibility
Typically Cholesterol decreases the flexibility of the membrane, but association with different proteins can increase the flexibility
Effect of heat on bilayers
Produces thermal motion of side chains (disorganization), but bilayer maintains integrity. % of particular fatty acid ratio changes based on temperature (physiological and metabolic status)
Lateral diffusion of lipids/proteins
Uncatalyzed, very fast and spontaneous
Flippase
Catalyzes flipping a phospholipid from outside to inside the membrane.
Floppase
Catalyzes flopping a phospholipid from inside to outside the membrane.
Scramblase
Catalyzes switching sides of two phospholipids in and out of the membrane.
Lipid Raft
Regions of membrane that are thicker, enriched in sphingolipids and cholesterol that compartmentalize cell functions. Bounded by calveolins
Calveolins
Proteins involved in the endocytosis of proteins and lipid rafts
Ionophore
Membrane vesicle that transports ions through membranes
Current
Flow of electrical forces down a gradient (ions flowing through channel in/out of cell)
Voltage
Potential difference (ion gradient)
Resistance
Opposition to passage of current (Membrane. Ion channels alter resistance)
Resting Membrane Potential
Electrical voltage potential of a resting cell. -70mV to -90mV
Nernst Equation
Mathematical relationship between difference in ion concentration and the voltage across the membrane at equilibrium
Local Potential
Localized alteration of membrane potential (ex. ion channel opening from ligand binding)
Propagated/Action Potential
Change in potential that travels along membrane
Na+ and K+ relative concentrations
Na+ high outside of cell, K+ high inside cell
Action potential Initiation
Opening of Na+ channels allows Na+ to flow in, depolarizing the cell up to around +30 mV
Action potential Propagation
Depolarization from Na+ channel triggers opening of voltage-gated Na+ channels down the axon, relaying the AP
Action Potential Repolarization
Na+ channels close and inactivate, K+ channels open and allows K+ to rush out, repolarizing the cell back to around -70 mV.
Absolute refractory state
Na+ channels are inactivated and cannot be restimulated no matter how strong the stimulus
Relative refractory period
Na+ channels are reactivated and can react to stimulus, but because K+ channels are still open and repolarizing the cell, a stronger than normal stimulus is required to depolarize again during this time
Na+/K+ Pump
3 Na+ out, 2 K+ in, utilizing ATP to restore concentration gradient.
What does “All-or-nothing” mean in relation to action potentials?
APs either fire or don’t. Once a stimulus crosses the threshold, it fires. The strength of the stimulus does not change the amplitude of the action potential
Hyperkalemia
High extracellular K+ concentration. Reduces gradient for K+ out, leads to less resistance to depolarization. (Ex. poor kidney function)
Hypokalemia
Decreased EC K+ concentration, increases gradient for K+ out, leads to more resistance to depolarization. (Ex. bad diarrhea)
Cardiac muscle APs
Voltage-gated Ca2+ channels open to prolong depolarization. Excess Ca2+ can effect excitability in opposite way than K+ by charge screening
Neuromuscular junction
Site where a motor nerve unit innervates a muscle fiber
Motor unit
Alpha motor neuron and all muscle cells it innervates. Each muscle fiber connected to only one alpha neuron
Sarcoplasmic Reticulum
Stores Ca2+ in terminal cisternae and releases it through ryanodine receptors
Transverse tubules
small tubes that propagate action potentials
Sarcomere
I and H zone shorten during contraction
Excitation-Contraction Coupling
Creatine Phosphate
Stores energy to synthesize ATP. Stored energy for 15 seconds of muscle use
Anaerobic respiration
Glucose-1-Phospage broken down into lactic acid to release 2 ATP. Good for 30-45 seconds of muscle use
Aerobic respiration
Citric acid cycle and electron transport chain create 38 ATP per glucose. Fuels muscles for hours.
Isotonic contraction
Tension generated by muscle is greater than load, muscle shortens
Isometric contraction
Load is greater than max tension and muscle doesn’t shorten.
Phases of muscle twitch
Stimulus
Latent period - 2 msec delay
Contraction - tension develops
Relaxation - Loss of tension, return to rest length
Refractory - period when muscle fiber won’t respond
“All-or-none” motor unit response
Motor unit fires when action potential is received
Fractionation
As more motor units are recruited, the tension gets greater
Henneman’s Size Principle
Motor units recruited from smallest to largest.
Type 1/Slow twitch - always firing, smallest, used in light intensity exercise
Type II/Fast twitch - become recruited when needed.
Multiple Motor Unit Summation (Recruitment)
Increasing the strength of a stimulus recruits additional motor units
Wave/Temporal Summation
Increasing frequency of stimulus leads to tetanus
Treppe
“Staircase” summation, right before tetanus
Muscle Spindles
Proprioceptors sensitive to muscle length and tendon. Stretch reflexes activated when muscle spindles recognize stretch. Stimulates stretched muscle to contract
Reciprocal inhibition
Reciprocal innervation inhibits opposing muscles to contract when a stretch reflex is activated
Extrafusal fibers
Bulk of muscle, innervated by alpha-motor neurons, provide force for contraction
Intrafusal fibers
Encapsulated in collagen sheaths to form muscle spindle. Innervated by gamma-motor neurons and Group Ia and II sensory afferents
Nuclear Bag fibers - detect fast, dynamic changes in muscle length and tension
Nuclear Chain fibers - detect static changes in length and tension
Golgi Tendon Reflex
Initiated by Golgi Tendon Organs (GTOs) that detect tension in tendons. Inhibits alpha-motor neurons to relieve tension in the tendon. Protective feedback mechanism to prevent tendon damage.
Diffusion
Movement of nutrients, O2, CO2, lipid soluble substances through capillary wall down concentration gradient
Bulk Flow/Ultrafiltration
Movement of protein free extracellular fluid in and out through water-filled pores
Vesicular Transport
Translocation of macromolecules across capillary endothelium. Ex.) Pinocytosis
Hydrostatic Pressure
Force directed out of the capillary by fluid pushing against capillary wall. Higher in arteries than in capillaries, lower in veins.
Driven by heartbeat.
Crystalline Osmotic Pressure
Oncotic pressure due to small molecules in plasma. Since water soluble molecules have concentrations = on both sides of capillary, has no effect on water flow.
Oncotic pressure/Colloid osmotic pressure
Osmotic pressure exerted by plasma proteins (Albumin), pulls water back into capillary
Starling Law
Net Filtration Pressure = Net force out - Net force In
Net force out = Capillary hydrostatic pressure + Osmotic pressure due to intersticial fluid protein concentration
Net force in = Interstitial fluid hydrostatic pressure + Oncotic pressure due to protein concentration
Velocity of blood flow
Highest in arteries
Slowest in capillaries
Middle in veins
Cross-sectional area of blood vessels
Low in arteries in veins
High in capillaries
Vascular shunts/Metarteriole
Throughfare channel connecting an arteriole directly with a postcapillary venule.
Precapillary sphincter
Cut off smooth muscle that surrounds each true capillary and regulates blood flow into the capillary in response to vasomotor (sympathetic) nerves, to bypass or enter capillaries.
Big Picture of Capillary fluid movement
Outward movement of 20 L of fluid arterial side
Inward movement of 17 L of fluid venous side
3 L of fluid enters Lymphatic system
Lymphatic Capillaries
Blind ended sacs in interstitial space that abosrb lymph fluid. Low pressure, wider than capillaries
Pinocytosis
Bulk flow transport of fluid into or out of capillary lumen via vesicles
Prokaryotic Cells
Smaller, have cell wall, no membrane bound organelles, cytoplasmic DNA, nucleoid, no cytoskeleton, smaller ribosome, replicate through binary fission, genetic diversity through mutation
Eukaryotic Cells
Larger, no cell wall, membrane-bound organelles, Nuclear DNA, nucleus, cytoskeleton, larger ribosome, replicate through mitosis, genetic diversity through meiosis/recombination
Gram-positive bacteria
Stain purple, have glycoprotein and peptidoglycan cell wall
Gram-negative bacteria
Stain red, have peptidoglycan, outer membrane and lipopolysaccharide cell wall
Cytoskeleton
Microfilaments, microtubules, intermediate filaments
