Neurophysiology Flashcards
Function of the myelin sheath
1) Covers the axon
2) Insulates the axon
3) Increases speed of nerve impulse
4) Protects the axon
Mitotic activity is lost in most neurons (Amitotic) except:
In the Hippocampus
How many different types of neurotransmitters can a single neuron release?
One
Most abundant neuron in the body
Multipolar neurons
Somatic motor and sensory nerves are __________ received.
Consciously
Visceral sensory and autonomic motor nerves are ___________ received.
Unconsciously
Somatic sensory nerves are found in what 4 locations?
Skin, skeletal muscles, bones, joints
Visceral sensory nerves are found where?
Visceral organs (abdomen) as well as thoracic and abdominal cavities
Somatic motor nerves control what?
Skeletal muscles
Autonomic motor nerves unconsciously control what 3 things?
Glands, cardiac muscle, smooth muscle (blood vessels and GI)
What division of autonomic motor nerves arouse the body to action?
Sympathetic
What division of the autonomic motor nerves have a calming effect?
Parasympathetic
What are the 2 types of nervous tissue?
Neurons and glial cells
Excitable nervous tissue cells are called?
Neurons
Name the 5 characteristics of Neurons
Excitable Conductivity Secretion of neurotransmitters (excitatory or inhibitory) Extreme longevity Amitotic (don’t divide)
A neuron cell body is called the _____ while the long arm that can be covered in myelin or not is called the _______ .
Soma, axon
What part of the neuron summates local potentials that, if added up to -55mV, stimulates an AP?
Axon Hillock
What is the outside and inside of a neuron called?
Axolemma and axoplasma respectively
Each neuron has one axon, but it can be divided into many branches, and each branch is called a _______ or __________ ____________.
Telodendrion or axon terminal
Each telodendrion or axon terminal ends at a __________ ____________, which forms a synapse with another neuron or cell of the target organ.
Synaptic knob
What are the 4 things myelin does for the axon?
Covers
Protects
Insulates
Increases speed of impulse
What structural classification of neuron has many processes that extend from the soma, one being an axon, the others being dendrites. Also the most abundant neuron in the body.
Multipolar
Inter neurons and motor neurons are examples of what structural classification of neuron?
Multipolar
What structural classification of neuron has two processes that extend from the soma, and where are they found in the body?
Bipolar
Eyes, ears, nose (special senses)
What structural classification of neuron is described as having a single, short neuron process that extends directly from the soma like an “on/off” ramp, with a peripheral process that brings information to the soma, and a central process that brings information to the spine (CNS)?
Unipolar neuron
Bonus: they are sensory and the ganglia are located in the ganglia!
All a. motor or b. sensory neuron cell bodies (somas) are in the ______ root ganglion?
Sensory
Dorsal
Unipolar sensory neurons with somas in the dorsal root ganglion synapse with what type of multipolar neuron inside the spine?
Inter neurons
Where is the body (soma) of a motor neuron located?
Within the spine
A cable-like bundle of parallel axons is called a _______ .
Nerve
A thick layer of dense irregular connective tissue that encloses the entire nerve, providing support and protection, is called the ____________.
Epineurium
The layer of dense irregular connective tissue that wraps bundles of axons and supports blood vessels by holding them to fascicles is known as the __________ .
Perineurium
A delicate layer of areolar connective tissue that separates and electrically insulates each axon and has capillaries that supply the axon is called the ________ .
Endoneurium
Cranial nerves extend from the ______ while spinal nerves extend from the ____ _____.
Brain
Spinal cord
Oligodendrocytes, astrocytes, ependymal cells, Schwann cells, satellite cells, and microglia are all ______ cells.
Glial
These glial cells are connected to the axons (CNS), providing support and insulation.
Oligodendrocytes
These glial cells are by far the fewest and seek out pathogens, acting as phagocytes that engulf/destroy microorganisms and cell debris.
Microglia
These glial cells are the most abundant glial cells that have processes which touch capillary walls, helping to form the blood-brain barrier that regulates the passage of substances into the brain. They also for the structural network and occupy the space of dying neurons.
Astrocytes
These glial cells line the ventricles of the brain and central canal of the spinal cord producing CSF
ependymal cells
These cells are flattened and wrap around axons (PNS) to form myelin
Schwann cells or neurolemmocytes
These cells are flattened and surround the soma in a ganglion, regulating the exchange of nutrients and wastes between neurons and their environment.
Satellite cells
Explain the RMP
K+ leaks out of cell down conc gradient through K+leak channels. K+ is major intracellular ion
K+ stays close to membrane bc it’s attracted to the negative ions inside the membrane
Net positive charge outside, net negative inside
Bilayer is tight to most ions and is tight to negatively charged ions, so they stay inside
Na+ leaks into cell down conc gradient through Na+ leak channels. Na+ is major extracellular ion
Na+ leak channels are very minor contributor to RMP bc they’re narrow
Na+/K+ pumps use ATP to maintain Na+ K+ conc gradient across membrane despite leak
Pump pushes 3Na+ out, then 2 K+ in, against conc gradient, make a -70mV RMP
K+ leak channel is most influential in establishing RMP
Graded or local potentials results from the permeability of neuron membrane determined by ________ gated ion channels.
Ligand
Action potentials result from the permeability of resting neuron membrane determined by _____ gated ion channels.
Voltage
Reduction in membrane potential inside the membrane, becoming less negative, from -70mV to +35mV is called?
Depolarization
Is when there is an increase of membrane potential inside the cell membrane, which becomes more negative.
Repolarization
The increase of membrane potential above RMP
Hyperpolarization
Explain the steps of an AP
Dendrite receives stimulus. Local potential occurs when voltage-gated ion channels open and allow Na+ to flood the membrane. This travels to the axon hillock, which holds a large amount of voltage gated ion channels. At the hillock, the local potentials are summed. If this summation results in depolarization from -70 to -55mV (threshold), and AP is formed. This triggers a conformation change in the voltage gated ion channels in axon hillock. Na+ rushes into cell through voltage gated ion channels down conc gradient. Inside fo cell becomes less negative (depolarization). Continues until +35mV. At zero (0), Na+ channels begin to close. At +35mV K+ voltage gated channels open, with K+ leaving the cell (repolarization), making the inside of the cell more negative. K+ channels are slower and allow excess in (hyperpolarization). ATPase reestablishes conc gradient RMP.
This division of the autonomic motor nerves has soma located in brain stem, exiting through CN III, VII, IX, and X, with a long preganglionic axon that meets another neuron in the ganglion close to or within the effector organ.
Parasympathetic
This division of the autonomic motor nerves has its soma located in the lateral horn of the spinal cord (T1 - L2) with a short, branching preganglionic axon and a long postganglionic axon.
Sympathetic division
Which cranial nerve parasympathetic fibers control contraction of pupils and ciliary muscle?
CN III
Which cranial nerves parasympathetic fibers stimulate the lacrimal (tears) gland and submandibular and sublingual salivary glands?
CN VII
Which cranial nerve’s parasympathetic fibers stimulate the parotid salivary glands in the back of the throat?
CN IX
Which cranial nerve’s parasympathetic fibers control lungs, heart, esophagus, liver, gallbladder, stomach, pancreas, spleen, kidneys, proximal ureters, small intestine, proximal large intestine, testis or ovaries?
CN X
Which sacral nerve parasympathetic fibers control the distal large intestine, distal ureters, urinary bladder, uterus, external genitalia, and accessory glands?
SN S1-S3
All sympathetic preganglionic neurons are cholinergic neurons that release ______ .
Acetylcholine
Sympathetic postganglionic neurons have some _________ receptors and some ______ receptors
Nicotinic & Muscarinic
Some sympathetic postganglionic neurons release Ach at their target organs, such as _______ ______, ______ ________, and _______ _________.
Sweat glands, blood vessels, and skeletal muscles
The sympathetic postganglionic neurons that release Ach are across from effector organ cells that have what type of receptor?
Muscarine or Muscarinic
Some sympathetic postganglionic neurons release Ach, while others release ___________.
Norepinehprine
The effector organ cells that receive norepinephrine have what type of receptors?
Adrenergic
A1 sympathetic adrenergic receptors cause vasoconstriction of ______ ________ going to the skin, GI, and kidneys.
Blood vessels
A1: think fight or flight, shunt blood from skin and GI
A2 adrenergic receptors inhibit ________ secretion from the pancreas and contract GI sphincters.
Insulin
B1 adrenergic receptors stimulate increased _______ _______ and contractility and stimulate ______ secretion from kidneys.
Heart rate
Renin
B2 adrenergic receptors cause vasodilation of blood vessels going to the ______, ______, and _________ _________, as well as ______________ of the lungs.
Heart, liver, skeletal muscles
Bronchodilation
Bonus: there are lots of B2 receptors in the bronchioles, heart, and skeletal muscles so blood can get there during sympathetic response.
Which adrenergic receptor dominates in vascular smooth muscle, A1 or A2?
A1
Which adrenergic receptor dominates at the heart, B1 or B2?
B1
Atenolol, metoprolol, and propranolol are all B1 or B2 adrenergic receptor blockers?
B1 (B1 is for heart rate and contractility; beta blockers affect B1 to lower BP)
B2 adrenergic receptors cause vasodilation in the heart, skeletal muscles, and ___________ in the lungs.
Vasodilation
Think about B2 for fight/flight: you want more blood going to the heart and skeletal muscles
Albuterol is an agonist of which adrenergic receptor? A1 A2 B1 B2
B2 (B2 bronchodilates, and albuterol makes that happen when it binds to B2 receptors)
Parasympathetic preganglionic and postganglionic neurons all release the same neurotransmitter,which is _______.
Ach (acetylcholine)
All parasympathetic postganglionic neurons secrete Ach, which binds with ____________ receptors on effector organ target cells?
Muscarinic
At low epinephrine concentrations, the A1 or B2 adrenergic receptor binds with epi because it has a higher affinity.
B2
At high epinephrine concentrations, both A1 and B2 adrenergic receptors will be occupied, but because there are so many more ______ receptors, the predominant effect at the high epi concentration is vascular smooth muscle ____________.
A1
Contraction
T/F: Somatic motor neurons go through a ganglion.
False. Somatic motor neurons go directly from the lateral horn to the effector organ (ie: skeletal muscles)
T/F: Autonomic motor neurons go through a ganglion where they synapse with postganglionic neurons.
True. Both sympathetic and parasympathetic neurons synapse in ganglia.
T/F: Sympathetic motor neurons have short preganglionic neurons that synapse in a ganglion.
True. Sympathetic motor neurons have short preganglionic neurons that synapse in the autonomic ganglia (sympathetic trunk or prevertebral). They have long postganglionic neurons
Soma of the sympathetic neurons are located where?
Lateral horn of spine
Soma of parasympathetic neurons are located where?
Brain stem and lateral gray matter of SN S2-4
Sympathetic neurons synapse in the autonomic ganglia. What are the 2 different types and where are they located?
Sympathetic trunk ganglia (aka paravertebral ganglia) which are on either side of the vertebral column.
Prevertebral ganglia, which are located anterior to the vertebral column
The exception to the sympathetic neurons passing through ganglia is the ______ ________, in which the preganglionic neurons have long axons that exit through SN T5-9 and directly synapse with the target organ.
Adrenal Medulla
sympathetic postganglionic neurons are long and release either _________, which binds to _________ receptors, or ____________, which binds to ____________ receptors.
Ach, muscarinic
NE (norepi), adrenergic
There are two types of sympathetic pathways. Both preganglionic neurons release Ach, which binds to nicotinic receptors on the postganglionic neurons, but one type of postganglionic neuron releases _________, which binds to _________ receptors (such as sweat glands, blood vessels, and skeletal muscle). The other postganglionic neuron releases __________, which binds to __________ receptors of most other body structures.
Ach, Muscarinic
NE (norepi), adrenergic
The sympathetic neuron pathway that releases Ach to muscarinic receptors effects which target organs/body parts?
Sweat glands, blood vessels, skeletal muscle
T/F: some of the sympathetic neurons of the ANS exit through the cranial nerves
False. No sympathetic neurons exit through cranial nerves
Parasympathetic neurons exit through which cranial nerves?
III, VII, IX, X
What does each parasympathetic neuron exiting cranial nerves III, VII, IX, and X do?
III: contracts pupil, contracts ciliary body making lens thicker for near vision
VII: activates lacrimal gland (tears) and submandibular and sublingual salivary glands
IX: activates parotid salivary gland
X: lungs, heart, liver, stomach, pancreas, spleen, kidneys, proximal ureters, small intestine, proximal large intestine, testis and ovaries
Parasympathetic neurons exit through which sacral nerves?
S1-3
parasympathetic neurons exiting SN S1-3 innervate what?
Distal large intestine Distal ureters Urinary bladder Uterus External genitalia Accessory glands
Sympathetic activation of the liver does what?
Glycogenolysis
Parasympathetic activation of the liver does what?
Glycogenesis
Sympathetic activation of adipose tissue does what?
Lipolysis
Alpha blockers bind alpha adrenergic receptors. What is an example of an alpha-1 adrenoreceptor antagonist that blocks the binding of NE at smooth muscle receptors?
Doxazosin or Prazosin
Alpha blockers bind alpha adrenergic receptors. What is an example of a non-selective alpha-1 and alpha-2 adrenoceptor antagonist that creates an irreversible blockade of postganglionic synapses in exocrine glands and smooth muscle?
Phenoxybenzamine
Do beta blockers, such as atenolol and metoprolol block beta-1 or beta-2 receptors?
Beta-1, which causes increased heart rate and force of contraction
Name a drug that is a beta-2 agonist used to for bronchodilation.
Albuterol
