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What are nonpolar molecules; give 2 examples
nonpolar molecules have postiitve and negative charges uniformly distributed throughout the molecule; there isno net charge
Oxygen and isoflurane
They dissolve in lipids but not water
What are polar molecules; give 2 examples
polar molecules have no net charge, but they have a region iwth a cluster of positive charges and a region with a cluster of negative charges
They are water soluble
Gluces and Water are 2 examples
What types of molecules can cross the lipid bilayer (cell membrane)?
Hydrophilic, lipophobic, small, uncharged molecules
Examples: water, oxygen, CO2,
What is endocytosis?
Name 2 types and examples of when it occurs
this is the process in which ghte surface membrane of a cell invaginates, pinches off, and becomes an intracellular vesicle containing extracellular fluid.
There are 2 types: pinocytosis (occurs in the renal tubules to reabsorb protiens) and phagocytosis (macrophages do this to bacteria)
What is exocytosis?
Give an example of wehn this occurs in the body
This is when an intracellular vesicle "melts" into the surface membrane before opening to the extracellular space and extruding it contents
Nuerotransmitters are released from nerv terminals by this process
what type of receptor is at the neuromuscular junction?
Ligand -Gated Channel Receptor: when the ligand (Ach) attaches to the receptor (nicotinic receptor), the channel opens to allow Na  & Ca ions to diffuse in and K ions to diffuse out
what is the role of G proteins?
They relay messages from receptors (on the outside surface of the cell membrane) to enzymes (on the insude surface of cell membranes)
This converts an external signal to a cellular response
what is the goal of the Sodum-potasium Pump?
Keep intracellular K HIGH and intracellular Na LOW
Name 2 types of drugs that stimulate the NA-K pump
Insulin
and Beta2 Adrenergic agonists
by stimulating the NA-K pump, they both drive K into the cell and promote hypokalemia
What is the normal intracellular and extracellular concnetration of K? Na?
K 140 intracellular and 4 extracellular
Na 10 intracellular and 145 extracellular
*the resting membrane potential in excitable tissues (neurons, skeletal muscle, etc) is determined mostly by what ion???
Potassium
there are continuously leakiking potassium channels that allow the diffusion of K out, which leaves the negatively charged portiens inside.  this causes the outside fo the cell to become lined with positivley charged K ion and the inside to be lined with negatively charged proteins (Na and Ca stay in place b.c their channels are closed).
What happens to the resting potential of the cell membrane in Hyperkalemia?
the diffusion gradient is smaller (b.c the extracellular K concnentration is increased), so less K diffuses out of the cell, making the cell membrane less polarized.  so the resting potential is decreased from -70 to -60
What happens to the resting potential of the cell membrane in Hypokalemia
It become hyperpolarized (more likely  to
What process is used to release neurotransmitters from nerve terminals: exocytosis, pinocytosis, or phagocytosis?
Exocytosis
What is another name for pinocytosis?
"cell drinking"
it is a form of endocytosis (bringing something ito the cell)
protiens ar absorbed in the proximal tubule fo the kidney by this process
What are First Messangers at the cellular level?
they are the chemicals (also called ligands) that attach to receptors that are on the surface of cell membranes and initiate a transmembrane signialing process
explain the G protien signal transduction system....How does an etracellular signal get transfered to an internal signal using the G protien?
A First messenger attaches to its receptor (adrenergic agonist), this activates a G protien (either inhibitory or stimulatory).  The G protien then sends info to the enzyme adenylate cyclase.  Then, the second messenger cAMP is formed.  cAMP then triggers a biological response (for example: increased contractivlity)
If the G protien was inhibitoyr, it would stop adenylate cyclase from acting.
Can second messengers in cells produce different biological responses depending on the tissues they are in?
Yes,
cAMP in the heart increases Ca+=increased contractility
cAMp in the bronchial smooth muscle decreases Ca+ = smooth muscle relaxation
**second messenger action in tissue specific
Which side of the cell membrane is negative the inside or outside?
The inside of the cell is negatively charged (Protiens).  Resting potential is -70mv
an increase in myocardial contractility caused by Dobutamine involves wha signal tranduction system?
G Protein: G(s)
Enzyme: Adenylate Cyclase
Second Messenger: cAMP
What direction does Na move in during depolarization of the cell membrane and which direction does K move during repolarization of the cell membrane
Na move in during depolarization
K moves out during repolarization
Does Hyperkalemia cause hyperpolarization or hypopolarization of the cell membrane?
Hypopolarization (depolarization)
K in = 135
K out >4.5
so the gradient is not as strong to not as many K moving out
When the sodium channel is in hte inactivated state, the neuron is:
Absolutely refractory
Where in the spinal cord do Motor neurons originate
They originate in the Anterior/ventral horn of the spinal cord.
they carry efferent signals to skeletal muscles
Sensory neurons carry signals from skeletal muscle to what part of the spinal cord?
They carry Afferent signals to the Dorsal/posterior horn of the spinal cord
What type of receptors are found at the Neuromuscular junction?
Nicotinic Receptors are found in the presynaptic nerve terminal and in the postsynaptic motor end-plate
What chemical is released from the motor nerve terminal at the neuromuscular junction?
ACh Acetycholine
how many molecules of ACh are required to open a channel of the motor end-plate?
2
What chemical causes the release of ACh at the motor nerve terminal?
Calcium
when an action potential arrives at the nerve terminal, it depolarizes the terminal.  This causes the Ca gates to open and Ca moves into the nerve terminal (down a concentration gradient).  The Ca in the nerve terminal cuases vesicles filled wiht Ach to fuse wiht the cerve terminal membrane and ipen to the exterior, spilling ach into the synaptic cleft (exocytosis)
"Calcium comes into a nerve terminal and __________ goes out"
Neurotransmitter
(at the neurosmuscular junstion the neurotransmitter is ACh)
When 2 ACh are attached to a nicotinic receptor at motor end plate (postsynaptic membrane), what happens?
the channel opens and Ca and Na diffuse in and K diffuses out
Thsi causes the motor end plate to depolarize.....when threshold is reached, an action potential is initiated....this triggers muscle contraction
What is ACh broken down to?
Choline and Acetate
Broken down by acetylcholinesterase (true) cholinesterase
How does Hypocalcemia and Hypercalcemia affect the release of ACh at the nerve terminal?
Hypocalcemia causes less ACh (or any other neurotransmitter) to be released
Hypercalcemia cuases an increased amount of neurotransmitter to be released
Does Magnesium have an effect on neurtrasnmitter release in nerve terminals?
Yes, b/c Ca and Ma are antagonisitc at nerve terminals, so Increased Ma will decreased Neurotransmitter release and decreased Ma with increased Neurostransmitter release
With a nondepolarizing neuromuscular blokcer, do the channels at the neuromuscular end plate remain open or closed?
NDNBs competitively block the nicotinic recepors from ACh, they bind to the receptors, but they have no direct effect on the channel, so it remains closed
However while the NDNB are attached to the nicotinic receptors, ACh cannnot attach, so the membrane remains polarized and no depolarization (and action potential...and muscle contraction) can occur.
What are 3 names for the enzyme that metabolized succinylcholine?
  • Plasma cholinesterase
  • Pseudocholinesterase
  • Butyrocholinesterase
What is the basic chemical structure of all neuromuscular relaxants?
Quaternary ammonium Compounds
Ch3(3) - N+ - CH2 - R
How are atracuriom and cisatracurium eliminated from the body
metabolized by Hoffman Elimination
Atracurium is also metabolized by ester hydrolysis
What 2 muscle relaxants are eliminated by biliary excretion?
Rocuronium  and vecuronium
How is pancuronium eliminated from the body:
Biliary excretion, renal excretion, or metabolism
kidney excretion
metabolism (ie: pseudocholinesterase, hoffman elimination, etc.) is the primary route of eliminatioon of which 4 muscle relaxants>
Succinylcholine: pseudocholinesterases
mivacurium: pseudoshcolinesterases
Atracuriom: ester hydrolysis and Hoffman elimination
Cisatracurium: Hoffman elimination
what 2 factors are important in Hoffman elimination
pH and temperature
What is the main cardiovascular effect of succinylcholine?
Bradycardia: due to direct stimulation of the muscarinic receptors of the sinoatrial node (b/c it mimics ACh)
Which neuromuscular blocking agents cause the release of histamine?
Succinylcholine, Mivacurium, Atracurium, d-Tubocurarine, Metocurine
Which muscle relaxants produce significant hypotension?
Succinylcholine, d-tubocuraine, and metocurine
Which muscle relaxants can produce significant hypertension?
Pancuronium, and gallamine
List the Adverse Effects associated with succinylcholine
  • potassium release from cells
  • Muscle pains
  • bradycardia
  • AV conduction block
  • Increased intraocular pressure
  • Increased Intragastric pressure
  • Increased Intracranial pressure
  • Malignant Hyperthermia
  • Fasciculations
  • Myoglobinemia
  • Prolonged Resp. Depression
Which muscle relaxants have no cardiovascular effects?
atracurium (reflex tachycardia is p0ossbile if histamine is released)
Cisatracurium
Vecuronium (minimal)
Rocuronium
If you use a nerve stimulate on the right wrist of the patietn with right sided hemiplegia, will the twictch be less than, the same as, or greater than the twitch on the left?
The twitch will be greater on the right sied than on the left becuase the right side has Up-regulation; (there are more nicotinic receptors)
Name some conditions that can put pt at risk of hyperkalemia with succinylcholine use.
Burns
Paraplegia or hemiplegia
skeletal muscle injury
Upper motor neruon injury (head injury, CVA, parkinson's disease)
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