Excitable Cells Flashcards
in what order is the body divided ?
cells - tissues - organ - organ system - human body
what is homeostasis ?
the ability of the body to maintain a relatively constant internal environment
what maintains homestasis ?
negative feedback loop
what are the two forms of negative feedback ?
local control or long-distance control
what are the two body fluid compartments ?
intracellular fluid (ICF) and estacellular fluid (ECF)
how much of the total body water is found in ICF ?
2/3
what do plasma membranes do ?
- provides physical separation
- regulates exchange of substances
- communication with environment
what are the 5 plasma membrane components ?
- glycoprotein
- glycolipid
- cholesterol
- transmembrane protein
- peripheral protein
what does hydrophobic mean ?
water hating
what does hydrophilic mean ?
water loving
what size molecules are easier to move across gates ?
smaller
what is simple diffusion ?
from high concentration to low with zero assistance until meets equilibrium
factors of simple diffusion ?
- hydrophobic (lipid soluble)
- small
what substances participate in simple diffusion ?
oxygen, carbon dioxide and alcohol
Fick’s law of diffusion …
SA x Concentration Gradient / Membrane Thickness
3 passive forms of diffusion :
- simple diffusion
- channel-mediated diffusion
- facilitated diffusion
in what case does diffusion require assistance ?
if it is hydrophilic and/or large
what does it mean to “require assistance” in passive diffusion ?
requires a transmembrane protein to help it across
examples of substances for channel-mediated diffusion :
ions and water
examples of substances for facilitated diffusion :
glucose and amino acids
what is channel mediated diffusion ?
transmembrane protein (open channel)
what is facilitated diffusion ?
transmembrane protein (open and closes channel)
what affects channel mediated diffusion ?
- concentration gradient
- number of channels
- size
- charge
what passive form of diffusion is selective and causes saturation ?
facilitated diffusion
what form of diffusion moves opposite to their concentration gradient ?
active transport
what is an example of active transport ?
NaKATPase Pump
what is the sodium potassium ATPase Pump ?
- 3 sodiums out
- 2 potassiums in
- need energy (ATP) to do so
where is sodium usually the highest ?
outside the cell
how do really large molecules enter/exit the cell ?
endocytosis and exocytosis
what are the two forms of local communication ?
paracrine (close distance) and autocrine (itself)
what can directly connect two cells together ?
gap junctions
what are gap junctions connected by ?
connexons
what happens if gap junctions disappear ?
your heart will stop
how does water move in the body ?
aquaporins
what way is the concentration gradient moving during diffusion ?
high concentration to low concentration
what is osmosis ?
water diffusion down its concentration gradient
“what has a higher concentration of water”
do the number mM for each molecule present (ex. CaCl2 200mm = 200 + 200 + 200 = 600 while KCl 200mM = 200 + 200 = 400) … side with more solutes = side it will move
what is tonicity ?
ability of a solution to cause osmosis across a cell
what is isotonic ?
the same (not changing)
what is hypertonic ?
more (bigger # and more solutes)
what is hypotonic ?
less (water moves into ICF, smaller number of solutes)
what is RMP affected by ?
permeability of membrane to various ions and concentration gradients of the ions
what is neutron RMP ?
-70mV
what element leak channels are present in cells ?
potassium
where is it more negative in a cell ?
inside
what are excitable cells ?
any cell that can be altered (cause impulse)
how do gated ion channels open ?
by a stimulus
what are the 3 gated channels types ?
- mechanically gated
- chemically gated
- voltage gated
what is mechanically gated ?
deforming the membrane
what is chemically-gated ?
a chemical binding the channel
what is another name for chemically-gated ?
ligand-gated
what is voltage-gated ?
voltage changes in the cell
what 7 features are on the neurons ?
- dendrites
- soma
- axon hillock
- axon
- myelin sheath
- node of ranvier
- axon terminal
what does axon terminal do ?
sends signals
what does the axon hillock do ?
connect axon and the soma
what is a myelin sheath ?
speeds up reaction
what is the input zone ?
dendrites and soma (graded potential)
what is the conducting zone ?
action potential travels here (axon)
what is the trigger zone ?
trigger action potential (depends on if threshold value is reached -55mV)
what is output zone ?
passes signal to next neutron by real leasing chemicals (synapse happening at axon terminal)
what is graded potential ?
depo / repo / hypo
what does depolarization mean ?
the cell becomes more positive than RMP
what does hyperpolarization mean ?
the cell becomes more negative than RMP
what does threshold mean ?
the minimum voltage to initiate action potential
where does Na move during depo ?
moves into the cell
where does Na move during repo ?
moves out of the cell (decreases in charge and becomes more negative)
what does amplitude mean ?
how high it goes
what is a graded potential ?
space that brings to threshold
during an AP what happens once hits +30mV ?
Na+ stops entering and K starts leaving neuron
what causes repolarization during AP to get back to RMP?
K+ leaving
what is the activation and inactivation gate at RMP ?
activation gate = closed
inactivation gate = open
what is the activation and inactivation gate during depolarization ?
activation gate = open
inactivation gate = closed
what is the activation and inactivation gate during repolarization ?
activation gate = open
inactivation gate = closed
what influences speed of propagation ?
membrane resistance to ion leak (myelination) and axon diameter
what is happening during multiple scelorosis ?
multiple neutrons are hardening
what happens when the action potential reaches the axon terminal ?
chemical synapse
what is the synaptic cleft ?
the space between the presynaptic neutron and the postsynaptic neuron
what element opens channels at synapses ?
calcium
