Exam 2 Flashcards
Repolarization is
the return to Vrm from depolarized
If the fast Na channels are not allowed time to reset what will happen?
They cannot be used for future actional potentials or there will be a reduced amount
In the heart repolarization of which ion is important to the hearts function?
Calcium
During depolarization concentration & ___ play a role in the membrane potential
Permeability
An influx of Chloride has what kind of response in cell?
Hyperpolarizes as it a negative ion; makes it more difficult to excite
Propagation of V-G Na channels are an example of
Positive feedback
What type of receptors open chloride channels in neurons?
GABA
Depolarization typically opens which type of channels
Voltage-gated Na channels
Depolarization of Na channels is a ___ process
2-way
What is the difference between a two-way propagation & a one-way propagation?
- 2 way propagation spreads out in both directions increasing depolarization speed
- 1 way spreads from 1 end to another taking longer to activate membrane
A resetting wave would mimic the direction of
the initial depolarization wave
Neurons that communicate with skeletal muscles are called
Motor Neurons
What is used to communicate between motor neurons and skeletal muscles?
Neurotransmitters
The area where the Neuron communicates with the skeletal muslce is called the?
Neuromuscular Junction (NMJ)
What is the neurotransmitter receptor found on skeletal muscle
Nicotinic Acetylcholine receptors (nACh-R)
How many binding sites do the nACh-R have?
2
What is the neurotransmitter released from the motor neuron to contract the skeletal muscle?
Acetylcholine
What is something can stimulate the nACh-Receptors other than ACh?
Nicotine (can simulate Acetylcholine - shaky/tremors)
For the nACh receptors to be activated, how many acetylcholine molecules must bind?
Two must bind simultaneously
What is lined on the inside of a nACh-R protein?
negatively charged amino acids (repels negatively charged ions from entering)
What is majority of the current that enters through nACh-Receptors?
Na
What ions can enter/leave the cell upon the opening of nACh-Receptors?
K can leave cell & Ca can enter cell (very little of both move out/in)
The net influx of ions entering cell upon opening of nACh-Receptors are ___ charged
Positively
Influx of Na through nACh-Receptors activates what type of channels
Fast Na channels (leads to action potential)
Where do paralytics work?
Neuromuscular Junction (NMJ)
Hyperpolarization makes the cell more
Negative (suppresses activity)
Muscarinic acetylcholine receptors (mACh-R) have what type of function on the cardiac cell?
Regulate electrical activity of the heart by controlling how hyperpolarized the cells are
mACh-Receptors respond to which type of compound?
Muscarine
Where can mACh-Receptors be found?
Heart, lungs, smooth muscle
Where are mACh-Receptors found on the heart?
Pacing centers - SA node & AV node
How does an action potential spread in the heart?
SA node –> through atria –> AV node –> pass into ventricles
What is the nerve that comes in contact with the pacing structures of the heart?
Vagus nerve (Right vagus affects SA & Left vagus affects AV)
What is the neuro transmitter used to communicate between Vagus nerve & the nodes of the heart?
Acetylcholine
Muscarinic ACh-Receptors are which kind of receptors?
GPCR
When the a-subunit disassociates from the mACh-R (GPCR), it activates which channels in the heart?
K channels; opening of more K channels makes the heart more negative (Hyperpolarizes)
Acetylcholine being released from the vagus nerve has what effect on the heart?
Regulates heart by lowering Vrm & keeping its rhythm at an acceptable rate (72 bpm lecture ex.)
Stimulation of the Vagal nerve has what effect on the heart?
K permeability is INCREASED (this causes even greater hyperpolarization of the pacer nodes ultimately slowing down HR)
If mACh-Receptors are blocked, what effect will be seen on the heart?
K channels would close –> Increasing Vrm –> Increasing excitability –> Increasing HR
What is the MOA of Atropine?
It blocks the mACh-Receptors on the heart –> increasing HR
If the pacer nodes were not affect by the nervous system how many BPM might we see?
100-110 BPMs (there is a basal amount of acetylcholine affecting heart to keep it at a lower rate)
The starting point of each Action Potential is referred to as
Troughs (per daddy schmidt)
What are the two types of Receptors found on the heart?
m-ACh-Receptor & B-receptor (antagonize one another)
___ pressure can activate a neuron
Physical
Describe that process that takes place when pressure is sensed
Pressure is sensed –> widens Na channels —> more Na let in the sensor —>action potential –> nervous system
An increase in pressure increases what?
Na permeability –> action potential
Hypocalcemia has what affect on Na channels & Vrm?
less calcium –> increased Na permeability –> increasing Vrm
Hypercalcemia has what affect on Na channels & Vrm?
More calcium –> Decreased Na permeability –> decreasing Vrm
What is sub-threshold?
Depolarization but no AP
What is Threshold?
Point where depolarization leads to AP
What is Supra-threshold?
Stimulus strong enough to generate strong AP surpassing threshold
The extension of the action potential in the heart is due to? (Plateau)
Slow calcium channels
Sustained APs give the heart time to?
Contract & pump blood through the heart
Calcium is said to be __ & __ & tends to block Na leaky channels
Big & Clunky
Chloride channels in a cell make the cell more?
Negative (Hyperpolarize - found in neurons)
Which ion is considered the “Brakes” of the nervous system?
Chloride (if Cl- is taken away, cell would become very excitable leading to seizures)
Influx of Calcium leads to?
Massive Depolarization (huge concentration gradient & 2 positive charges)
Hyperkalemia has what affect on Vrm?
Increases Vrm (More positive)
In a pt with Hyperkalemia, what affect would giving Calcium have?
Hyperkalemia increases Vrm; a calcium bolus would block Na leaky channels hindering influx of Na into cell –> decreasing Vrm
Calcium does not have an effect on what type of Na channel?
Fast Na channels (calcium only hinders leaky channels)
Mg works similar to Ca in that a bolus would have what affect on a cell?
Mg bolus would block Na leaky channels hindering influx of Na into cell –> decreasing Vrm
What is Trousseau sign?
Carpopedal spasm caused by Hypercalcemia
What is Chvostek’s sign?
Twitching of facial muscles caused by Hypocalcemia
Ca & Mg have __ effect on neuronal & muscular cells by?
“Calming” effect ; decreasing cells electrical excitability
Rate of AP propagation is affected by?
- Length of nerve (shorter nerve = faster)
- Diameter of nerve (Wider = less resistance = faster)
- Insulation of nerve - Myelin sheath (More insulation = faster)
What is Myelin?
Myelin is an insulating compound derived from sphingomyelin in cell wall
What is a Schwann cell?
Myelinating cell that maintains myelin on Myelinated neurons
How does a Schwann cell work?
Wraps itself around neuron & squeezes out water leaving only a lipid compound –> provides protection, speed, & efficiency
The Na/K pump resets the cell after an AP by?
Maintaining the membrane polarity & chemical gradient
How does Myelin aid in the speed of an AP?
- Limits the amount of Na that comes out the cell & forces the Na forward (reduces energy required)
What can be found in the nodes of the Myelin sheath
Lots of Fast Sodium channels
What are the benefits of Myelination?
- Provides insulation
- Speeds up electrical propagations of APs
- More energy efficient cell (fewer Na channels have to open)
What are the spaces between the Myelin sheath called?
Nodes of Ranvier
Which neuron would require more local anesthetic to block, a myelinated or unmyelinated?
Myelinated
(d/t high density of fast Na channels located in Nodes - unmyelinated have more Fast Na channels but require more energy)
The movement from one node to another is referred to as (Jumping pattern)
Saltatory Conduction
(Na is not able leave cell forcing it towards next node)
What are Glial Cells?
Supporting cells in the CNS
What are the two types of Glial cells that produce myelin?
Schwann & Oligodendrocytes cells
What is the difference between Schwann & oligodendrocytes?
- Schwann cells produce myelin for the PNS & are able to repair Myelin
- Oligodendrocytes cells produce Myelin for the CNS & do NOT repair myelin post Adulthood
What were the three Demyelinating diseases discussed in class?
Multiple Sclerosis (MS), Optic Neuritis, & Guillain-Barre Syndrome
Why can demyelination lead to paralysis?
Underneath the myelin sheath there are no Fast Na channels to continue action potential & extra Na/K pumps send out Na
Describe Guillain-Barre Syndrome
Antibodies are produced and attack more than just the infection, attack nervous system (Seen after COVID) (reversible)
Describe MS
Demyelinating disease that affects motor neurons
What can repopulate once myelin sheath is removed?
Na/K pump
What can cause Demyelination?
Infection, Genetics, Autoimmune responses to vaccines
What are the ways one cell can talk to another?
Synapse or Gap Junction
A way to pass information through direct electrical synapses would be referred to as a?
Gap Junction
What are Gap Junctions composed of?
Connexons (2)
What are ConnexOns composed of?
6 connexin proteins assembled to resemble a cylinder
What is the advantage of a Gap Junction?
Allows for VERY fast way of transmitting AP by directly connecting to another cell
What is a disadvantage of a Gap Junction?
A rogue AP can directly cross over to another cell
What can travel through Gap Junctions?
Na
How does the number of Gap Junctions affect AP transmission?
- Fewer gap junctions –> more resistance –> increased difficulty of spreading AP
- More gap junctions –> less resistance –> increased speed of AP being spread
Describe a chemical synapse
- A close connection between two cells that allows for signal sending
The sending cell of a neuron is referred to as
The Presynaptic Terminal
The receiving cell of a neuron is referred to as
The Postsynaptic Terminal
In the heart, acetylcholine has what type of affect?
Inhibitory
In the smooth muscle, acetylcholine has what type of affect?
Excitatory
“A” neurons are
Heavy myelinated
“B” neurons are
Lightly myelinated
“C” neurons are
Non-myelinated
The larger the neurons the ___
faster the information can be sent (Motor Neurons - large & heavy myelinated)
The smaller the neurons the ___
slower the information is sent (tickle/cold/warm)
In order from largest to smallest, what are the neuron size sub-types
Alpha (largest) –> Beta –> Gamma –> Delta (smallest)
The cell body of a neuron is known as a
Soma
The receiving ends of Neurons are called
Dendrites (project from soma)
Some of the connections on the dendrites can either be __ or ___
Excitatory or Inhibitory
Excitatory areas of the dendrites are more
Positive than soma Vrm
Inhibitory areas of the dendrites are more
Negative than soma Vrm (hyperpolarization)
Neurons can have connections with
over 10,000 neighbors
A ___ neuron receives input from several different places then decides whether or not to send out an AP
decision making (multipolar)
The sending end of a neuron is
the Axon (most are myelinated)
The very beginning of the axon is?
The Axon Hillock
What type of connections can be found on the axon hillock?
Inhibitory
What is the common Neurotransmitter used at the axon hillock?
GABA
What affect does GABA have on the Axon hillock?
Increases permeability to Cl-
An influx of Cl- will have what affect on the neuron?
Hyperpolarize/inhibitory effect ; controls electrical activity of CNS
What would happen if all GABA was removed?
All inhibition would be removed & result in high electrical activity (seizures)
What affect does alcohol have on GABA receptors?
Alcohol is a GABA receptor agonist, eventually body will stop producing GABA & rely on alcohol
What would happen if you were to take alcohol away from an alcohol dependent GABA receptor?
Seizures & over activity in CNS
What is considered the “Brakes” of the CNS
GABA
The axon hillock functions as the cells
Decision-maker ; suppresses over activity of CNS
What are the 4 types of Glial cells?
Astrocytes, Ependymal, Oligodendrocytes/Schwann (all three are macroglia cells) & Microglia (smallest glial cell)
A brain tumor would most likely be what kind of brain cell?
Glial cell (can replicate unlike neurons)
Describe the Astrocyte & its function
Star-shaped; wraps itself around the true part of BBB & regulates electrolytes in CNS & pH –> supporting cell
Describe the function of Ependymal cells
Produce CSF & use cilia to move CSF
Describe the function of Microglia
Act as immune system of CNS ; macrophages & phagocytosis
What are the three types of Neurons?
Multipolar, Pseudounipolar, & Bipolar
Describe Multipolar neurons
Decision-making cells - receive input & decide whether or not to fire AP (motor neuron)
Describe Pseudounipolar neurons
Majority of sensory cells (near spinal cord)
Cell body only exists to build proteins maintain neuron
Describe Bipolar neurons
Used in special organs for specialized senses ; two projections - dendrite & axon (photoreceptors in retina - optic nerve)
Being able to consciously feel what is being sense is a
Somatic Sensation
Nociceptors are pain receptors that will always be
Free nerve endings (distributed in several places)
Pacinian & Meissner’s are
Pressure sensors
G-tendon apparatus is
a pressure/stretch sensor - gives feedback of skeletal muscles
Muscle spindles are
stretch sensors interwoven into skeletal muscles to tell us whether or not muscle has contracted
Mechanoreceptors are
receptors that take physical stimulus and turn it into an electrical signal to be relayed to body
What does the term “adaptation” mean in regards to sensory receptors?
The ability of receptors to reset or adjust to a new normal to blunt a response after a certain amount of time
Baroreceptors respond to what?
Stretch of arterial walls
- increased stretch (HTN) ; baroreceptors will tell brain to vasodilate
- Decreased stretch (Hypotension) ; baroreceptors will tell brain to vasoconstrict
Which type of receptor does not reset at all? (Reverse Adaptation)
Pain Receptors (the more painful the stimuli –> the more sensitized)
What is one way to prevent pain receptors from “ramping up”?
Nerve block - block one area of body from being able to sense pain –> no reverse adaptation or sensitization
Define Superior
Located higher in altitude (towards top of head)
Define Inferior
Lower in altitude (towards bottom of feet)
Define Dorsal/Posterior
Backside
Define Ventral/Anterior
Frontside
Define Lateral
Further to the side
Define Medial
More towards midline
Define Rostral
The front upper portion of body
- (ex. Beak of bird –> Rostral)
Define Caudal or Caudate
The lower and to the rear
- (ex. Tail of Bird –> Caudal/caudate)
Define Distal
further away from CNS
Define Superficial
close to skin (not deep)
Define Proximal
closer to CNS
Define Sagittal plane
separates left & rights sides of the body
Define Coronal plane
separates anterior from posterior part of the body
Define Deep
deep in tissue
Define Horizontal plane
separates superior from inferior
Define Oblique plane/section
goofy or add angle
What composes the CNS?
Brain, Brainstem, & Spinal cord
The brain is separated into how many parts & what are they?
2 parts - Telencephalon & Dienceplaon
What is the Telencephalon?
The outer upper part of the brain
- Cerebral hemispheres
What is the Diencephalon?
The inner area of the brain
- serves as connecting point between cerebral hemispheres & brain stem
What is housed the in Telencephalon?
Cerebral cortex
What is housed in the Diencephalon?
Thalamus & Hypothalamus (deep or underneath thalamus)
What is the main function of the Thalamus?
“Relay Center” - relay center between cerebral cortex, Brainstem & rest of body
What is the primary function of the Hypothalmus?
“Control center” & Sensory area (osmo receptors, Infection receptors, & body temp sensors)
Where is the Brainstem located?
underneath the Diencephalon
What composes the Brainstem?
- Midbrain or Mesencephalon (top part)
- Pons (Middle part - big olive shaped structure)
- Medulla Oblongata (Bottom part)
What is the term for a “groove”?
Sulcus
What is the term for a “really deep groove”?
Fissure
What is the term for a lump of tissue?
Gyrus (many gyrus = gyri)
What are the four major lobes of the Brain?
Frontal, Parietal, Occipital, & Temporal
What happens in the frontal lobe?
Most of our thinking
What happens in the Parietal lobe & where is it located?
- located behind frontal lobe
- primary somatosensory cortex (sensations processed here)
What happens in the Occipital lobe & where is it located?
- located Rear of Brain
- Vision is processed here
What happens in the Temporal lobe & where is it located?
- located on lateral sides of brain
- auditory sensations are processed here
What separates the frontal lobe from the parietal lobe?
Central Sulcus
What separates the Temporal lobe from the Parietal & Frontal lobe?
Temporal lateral fissure
(underneath central sulcus)
What separates the left & right hemispheres? (runs from front of brain to the back)
Longitudinal Fissure
What creates a boundary between the two sides of the brain?
Longitudinal Fissure
The bridge like area where both sides of the hemisphere can communicate is?
Corpus Callosum (not separated by longitudinal fissure)
The Corpus Callosum contains a heavy amount of __ neurons allowing for crosstalk
myelinated
What is the specific area of the brain where language comprehension is processed?
Wernicke’s Area
What is the specific area of the brain where the process of speaking takes place (motor function)?
Broca’s Area (controls voice box & respiratory system to speak - motor func.)
Thinking/planning an action first takes places in the
front of the frontal lobe
Where is the primary Motor Cortex located?
Anterior to Central Sulcus & most posterior part of frontal lobe
Actually executing movements takes place where?
Rear of Frontal lobe
What does the Precentral Gyrus do?
The Primary Motor Cortex (last strip of tissue at rear of frontal lobe)
What is the Postcentral Gyrus?
The Somatosensory area (anterior part of parietal lobe)
The emotional area of the brain is the?
Limbic system
How does the limbic system affect pain perception?
If emotions get involved while in pain the pain is perceived as much worse
The spinal cord is narrow, no wider than
the size of a quarter
What is the difference between Grey matter & White matter?
The presence of Myelin
Describe White matter
- lighter area
- white = myelin
- Transmits/Receives decisions made by grey matter
Describe Grey matter
- Darker area
- Grey = little to no Myelin
- Cell bodies are found here (decision makers)
- thinking portion of CNS
What type of decisions are typically made by decision maker cells in the spinal cord
Motor reflexes
Grey matter in the brain is?
Superficial to the white matter in the cerebral cortex
What is a benefit of Grey matter in the brain being superficial?
Blood vessels do not have to travel far to supply decision making centers
What is a disadvantage of Grey matter in the brain being superficial?
The possibility of head injury, a concussion can temporarily or permanently damage grey areas
How does the body protect grey matter in the cranium?
Brain is suspended in CSF (not a perfect system)
The front groove of the spinal cord is called?
The Anterior Median Fissure (wider than Posterior groove)
The back groove of the spinal cord is called?
The Posterior Median Fissure
The grey area where the possibility of crossover can take place is called?
Lamina X (10)
The white area where the possibility of crossover can take place is called?
Anterior White Connoisseur (AWC)
Information moving from one side to another is called?
Cross-over
Why is the Anterior Median Fissure wider than the Posterior Median Fissure?
A large arterial blood vessel is parked in it
The opening in the grey matter is called?
The Central canal
The butterfly projections are called?
Horns
What is the purpose of the Central Canal?
It uses ciliated cells to move CSF down the cord
What does the CSF surround?
Brain, Cerebellum, & Spinal cord
What are the horns located in the back of the cord called?
Dorsal Horns
What are the horns located in the front of the cord called?
Ventral horns (larger than dorsal)
What kind of information gets fed into the Dorsal Horn?
Sensory information
What comes out of the Ventral horns?
Motor function
Cell bodies at the rear of the spinal cord would have what type of function?
Sensory
Cell bodies at the front of the spinal cord would have what type of function?
Motor
Where would epidurals/spinals be administered & why?
The rear of the cord because that is where sensory input lies
Small projections that come out of the sides of the horn are called
Lateral or Intermediate Horns
Where do the feed vessels for spinal circulation come from?
Branches of our intercostal arteries that connect with spinal arteries & from vessels that come from top of cord, near brainstem & upper neck
Describe the Motor overview in Descending pathways
Brain –> Thalamus –> Brainstem –> pathways in cord –> Motor target
Where does the CNS end?
The spinal nerve
Structures immediately next to cords are
Rootlets
What are rootlets
individual strands of fibers that come in/out horizontally either carry sensory function or motor function
Sensory information coming into the dorsal horns would head up on
Ascending pathways to brain (white areas of the spinal cord)
Area where rootlets come together is known as
Root
Point where the Roots combine is called
The Spinal Nerve
Most spinal nerves will have a combination of ___ & ___ function
Sensory & Motor
The posterior root has a large lump called
Spinal Ganglion
What is the Spinal Ganglion composed of?
it is a collection of cell bodies from Pseudounipolar neurons
Why doesnt the Anterior root have a spinal ganglion?
The cell bodies of pseudounipolar neurons are found in the Ventral Horn
Descending pathways are primarily?
Motor
How many Vertebrae & spinal nerve pairs are located in the Cervical?
7 vertebrae & 8 pairs of spinal nerves
(SN1 starts right above C1 & SN2 right below C1)
How many Vertebrae & spinal nerves are located in the Thoracic?
12 vertebra & 12 pairs of spinal nerves
(SN1 starts below T1)
How many Vertebrae & spinal nerves are located in the Lumbar?
5 vertebrae & 5 pairs of spinal nerves
(SN1 starts just below L1)
What are dermatomes?
different regions of the body that are innervated by different spinal nerves (Dermatome Man)
How many Vertebrae & spinal nerves are located in the Sacral?
5 vertebrae at birth that fuse to form 1 & 5 pairs of spinal nerves
(SN1 starts just below S1)
How many Vertebrae & spinal nerves are located in the Coccygeal?
4 vertebrae at birth fuse to form 2 vertebrae & 1 pair of coccygeal vertebrae
the first couple spinal nerves out of C-spine innervate what?
top of the head/back of the head
The chest is innervated/sensed by?
Thoracic nerves
The legs are mostly innervated/sensed by?
Lumbar nerves
The rear legs/buttocks are sensed/innervated by?
Sacral nerves
The normal curve pattern of healthy individuals back is
S-shaped - provides a springy structure to absorb shock
The neck has what type of curvature?
Cervical Lordosis (anterior/convex curvature) –> comes towards front
The lumbar has what type of curvature
Lumbar lordosis (anterior/convex curvature)
The thoracic has what type of curvature?
Thoracic Kyphosis (posterior/concave curvature) –> going out towards back
The sacra has what type of curvature?
Sacral Kyphosis (posterior/concave curvature)
where is the most common type of abnormal curvature at?
Thoracic kyphosis –> hunchback
an abnormal lateral curvature is?
Scoliosis
What is Kyphoscoliosis?
most common combination curvature disease
- abnormal kyphotic + abnormal scoliotic curvature
At birth what is the only curvature we have?
Kyphotic curvature (thats why babies cant hold their neck up)
What is the weight supporting structure of the spine?
Vertebral body - where vertebral discs sit on (as you go up spine it gets smaller, as you go down spine it gets larger –> more weight to carry)
The U-shaped structure coming off vertebral body is called?
Vertebral arch
The opening in the vertebral arch is known as?
The Vertebral Foreman
What is housed in the vertebral foreman?
Spinal cord, spinal nerves & roots
The first part of the arch coming off the vertebral body is called?
Pedicle
The second part of the U, the circular part that connects the two pedicles is called?
Lamina
What are processes?
Bony extensions
The midline projection coming off the back of the vertebrae is called?
The Spinous process - easiest & most palpable
Processes that come off the sides are called?
Transverse processes (no real purpose)
Extending up from arch are two processes called?
Superior articular processes
Coming from out below the arch are two processes called?
Inferior articular processes
Articular means?
connecting one thing to another
The vertebral notch underneath the pedicle serves what purpose?
allows spinal nerve to exit
The point where the Inferior articular process & the superior articular process meet is called?
A Facet Joint
What is composed in the facet joint?
Cartilage - protects from bone on bone friction (wears down over time)
Which vertebrae bares the weight of the skull at the top of the neck?
C1 (Atlas)
A spinous process that has two projections is called a?
Bifid Spinous Process
Where are bifid spinous process found?
ONLY IN THE NECK
- C2 - C5 will have Bifid
- C6 50% will have Bifid
- C7 rarely will have bifid
An additional set of Foramen located in the Transverse process (Transverse Foramen) serve what purpose?
Arterial arteries run through here
In what vertebrae will you find Transverse Foramen?
C1-C7 BUT Vertebral arteries do not pass through C7
Transverse process with a sulcus (groove) allows for what?
Spinal nerves to lay in (act as protection)
What is a major difference between C1 and the rest of the vertebrae?
C1 does not have a vertebral body (it does not have to support a lot of weight)
What does the C1 have in lieu of vertebral body?
Anterior arch
What is the purpose of the anterior arch?
A pivot point that helps connect C1 & C2; allows for rotational axis
What are the components of the anterior arch?
Anterior tubercle & Facet of dens
Describe the anterior tubercle
little nub in front of the anterior arch
Describe the Facet dens
found on posterior side of anterior arch, where C2 connects with anterior arch of C1
The big bony projection that comes up from the top of C2 is called
Dens
(anterior side of C2)
In lieu of a spinous process, what does C1 have?
Posterior arch with a posterior tubercle
The superior articular processes of C1 connects to what?
Base of skull
The is the term for the opening of the base of the skull?
Foramen magnum
(Foramen = opening & Magnum = large)
Downward projections from the occipital bone found on the sides foramen magnum are called?
Occipital Condyles
The ligaments that connect the top of the spine through the foramen magnum are called? (2 of them)
Anterior Atlantooccipital ligament & Posterior Atlantooccipital ligament
Why is the atlantooccipital ligament named the way it is?
The ligament connects to the occipital bone of the skull & C1 (atlas)
The way the superior articular processes of C1 is curved & set up in the skull allows for?
Head movement (ability to nod)
The anterior articular facet of the dens connects to?
The posterior side of the anterior arch of C1
The transverse processes with transverse foramen allow for?
Spinal nerves to come out
The posterior articular facet of the dens connects to?
Ligaments of the neck
The joint between C1 & C2 created by the dens allows for?
Swivel head movement (side to side)
What is the ligament found in the front of the Vertebrae body called?
Anterior Longitudinal ligament
(runs entire anterior side of spine)
What is the ligament found in the back of the Vertebrae body called?
Posterior Longitudinal ligament
The ligament that links the tips of the transverse processes found on both sides is called?
Intertransverse ligament
The ligament that links the tips of the spinous processes is called?
Supraspinous ligament
Immediately deep the supraspinous ligament are ligaments that connect the bulk of the spinous process to each other called?
Interspinous ligament
The ligament that connects the anterior arches together is called?
Ligamentum flava
What is the difference between the composition of the ligamentum flava & the other ligaments?
other ligaments are made of rigid collagen vs. Ligamentum is elastic “stretchy”
When approaching the spine with a needle how will you know you have reached the Ligamentum flava?
A change in resistance (less resistant)
What issue can you come across by going midline in the posterior spine with a needle & how can you avoid this?
a lot of people do not have complete fusion of the ligamentum flava on both sides; becomes issue when trying to feel a change in resistance with needle (you will not feel it); to avoid this take a slightly off midline approach
What is the Nuchal Ligament
- extension of the interspinous ligaments
- fan-like expanded
The ligament that connects the arch of C1 to the posterior part of the opening of the foramen magnum is called?
Posterior Atlantooccipital ligament
The ligament that connects the arch of C1 to the anterior part of the opening of the foramen magnum is called?
Anterior Atlantooccipital ligament
The nub at the back of the skull where the Nuchal ligament & the supraspinous ligament connect with the skull is called?
External Occipital Protuberance
The bump on the back of the neck is referred to as?
Vertebral Prominens
(from spinal process of C7)
Although the vertebral prominens is said to be caused by the spinal process of C7, which vertebral spinal process may have more of an impact on the vertebral prominens?
T1 vertebrae spinal process
Which way are the Spinous processes in the thoracic spine angled?
Downward angled; making it difficult to come in midline with a needle
How many ribs in the body do we have?
12
Why do you rarely see T-spine injuries?
The T-spine is robust & stable due to all the attachments it has
Where do the ribs connect to on the T-spine vertebrae?
The connect to the T-spine at the vertebral body & transverse processes using Costal Facets
How do the last two ribs connection points differ from the other ribs?
They only have one connection point making them easily displaced
What are the three parts of the sternum?
- Top part –> Manubrium
- Middle part –> Body (larger part of bone)
- Inferior part –> Xiphoid process
How do the ribs connect to the sternum?
Cartilage
Why are the first 7 ribs called the TRUE ribs?
Connected to a piece of costal cartilage which connects to a piece of the sternum
What is the purpose of the flattened portion of the vertebral body on the thoracic vertebrae?
This provides room for the thoracic Aorta
Where do spinal nerves exit out of the vertebral foramen? What is directly above and below this exit site?
Spinal nerves exit out of the interveterbral foramen.
Directly above is the pedicle of the superior vertebrae
Below is the pedicle of the inferior vertebrae
What procedure makes access into the spinal column much more difficult?
Spinal fusion surgery.
What are two treatments for disc herniation? What is the problem with one of these?
Discectomy (less invasive)
Spinal Vertebral Fusion (last resort) more tension is placed on discs above and below, precluding them for the same problem later. Fusion usually has to be extended.
What is a really good, non-invasive way to treat back pain?
Physical Therapy
Strengthening of core muscles and hamstrings takes strain off of the vertebrae’s job in stabilizing the back.
What two functions does the CSF provide to the spinal cord?
Nutrient support (glucose and such)
Shock absorption
What are the 3 layers of the spinal meninges in order of superficial to deep? Is there any space in between these layers? If so, what inhabits this space?
Dura Mater
Arachnoid Mater
Pia Mater
There is the Arachnoid space in between the arachnoid mater and the pia mater for blood vessels and CSF.
Why are ribs 8, 9, & 10 called the FALSE ribs?
Connected to piece of costal cartilage that is connected to another costal cartilage of another rib (not directly connected to sternum)
What are the last two rib called?
Free floating ribs (not connected to any cartilage)
Which rib connects to the sternal angle?
Rib 2
How many sacral vertebra do we have at birth? How about as an adult?
5
1 – the sacrum
What is the purpose of rib cartilage?
Flexibility for breathing & shock absorption
What age do sacral vertebra fuse?
14-15 years old
What is the purpose of the flattened portion of Thoracic vertebral body on the left side of the body?
Provides room for the Aorta
What is the sacral foramina? What is it for? How many do we have?
Openings in the front/back of sacrum for nerves to exit - 4 pairs (8 total)
How many Coccyx vertebra do we have at birth? Which ones fuse by adulthood? How many do we have as an adult?
4
The last 3
2
The costal facets (unique to T-spine) have how many connection points for the ribs
3 - Inferior costal facet & superior costal facet (found on posterior side of vertebral body) & costal facet on transverse process
When is the medial sacral crest formed? Where is it located in relation to the lateral and median sacral crest?
Formed when superior/inferior articular processes fuse as sacrum is fused together by 14-15 y/o
Between them
Where do our long spinal ligaments end, and what path does it take to get there?
Coccyx - through the sacral hiatus
What is the costal tubercle
the neck of the rib comes in contact with transverse process
The shape of the T-spine vertebral body?
Heart shaped
What are the raised bumps on either side of the sacral hiatus?
Sacral cornu
By drawing a line midline to both Iliac crests, what vertebra would you end up at? Why is this important?
L4; Can be used as a marker for epidurals
What is the orientation of the L-spine spinous process?
straight back
What are the bumps you can see on someone’s low back with low rise pants?
Posterior superior iliac spine
How can the posterior superior iliac spine be used as a marker for anesthesia providers?
From posterior superior iliac spine
Drop 1cm
Go 1cm midline, will be a good approach to the S2 posterior sacral foramina
Can get drug to sacral foramina (maybe to shut down pain in the legs)
Why wouldn’t we try to get a drug to S1 over S2?
S1 is angled slightly and harder to reach, S2 is a clear shot
What is a promontory?
Flat area on medial superior sacrum - large disc sits here to support lumbar discs
How can you identify the inguinal ligament?
Leg/hip fold, especially in high BMI individuals
What is the anatomical difference between the pelvis of a man vs woman
Women have wider hips to accomodate babies
The lumbar spine is a popular site for?
Epidurals & spinals
Where do spinal nerves exit out of the intervertebral foramen? What is directly above & below this exit site?
- Spinal nerves exit out of the intervertebral foramen
- Directly above is the pedicle of superior vertebrae (inferior vertebral notch)
- below is the pedicle of the inferior vertebrae (superior vertebral notch)
What is good noninvasive way to treat back pain?
Physical therapy
- strengthening core muscles & hamstrings takes strain off of vertebrae’s job in stabilizing back
What are the 3 treatments for disc herniation?
- Discectomy
- Spinal vertebral fusion (more tension is placed on discs above & below leading to the spread of back pain & future spinal vertebral fusions
- laminectomy (removal of part of the bone)
The points of fusion on the sacrum are called?
Transverse lines (5)
the structure the intervertebral discs sit on top of at the sacrum is called
Promontory (weight supporting structure off the top of the sacrum)
What lumbar vertebra is the umbilicus at in a normal BMI patient?
L3-4
We have “two sets of hips.” What are these?
The lower set is the greater trochanter of the femur, the higher set is the iliac crests.
What are the intervertebral discs made of? How can we lose them?
Has a fibrous outside
-Anulus fibrosus
Gel like center
-Nucleus pulposus
Can lose discs through spinal fusion
What is the purpose of an intervertebral disc?
Shock absorption
Are we more likely to have a disc herniation anteriorly or posteriorly? Why?
Posteriorly. The anterior aspect of the disc is wrapped in a cross hatched fiber, providing a strong support. The posterior aspect has fibers running in the same direction, providing a weaker support structure and increasing risk of herniation.
What are two causes mentioned in class of disc herniation (nucleus pulposus leaking out of disc)?
Trauma
Bad genetics
Why is posterolateral herniation of the disc bad?
Spinal nerve compression
What can be done about posterolateral herniation of the disc?
Remove part of disc causing the problem
Discectomy**
Can try to stabilize the spine to prevent pulposa getting pushed out
Fuse vertebra to do this
Create more space so nerves were not compressed
Laminectomy
What is one common surgical complication of discectomies?
Postoperative pain
What is the longer lasting solution for a herniated disc?
Laminectomy (removes part of the bone causing compression)
How can the CRNA get more room between spinous processes of the lumbar spine when accessing the spine?
Have the patient lean forward
What layer of the spinal meninges is stuck to neurons/glial cells?
Pia matter
How is “Matter” pronounced?
“mot-ter” per daddy Schmidtty
What is above the Pia matter, but below the arachnoid matter?
Sub arachnoid space
(Spinal nerves, arteries, veins, CSF)
Where is the arachnoid matter?
Between the Pia matter and the dura matter; middle layer of spinal meninge
Is there anything between the arachnoid matter and dura matter?
No
What is the outer most layer of the spinal meninges?
Dura matter
If you need a laminectomy, discectomy, or fusion, what specialist should you see?
See a good neurosurgeon, NOT a orthopedic doctor
With tight hamstrings, what happens to the lumbar spine? What can you do to fix it 80% of the time?
The lumbar spine is compressed. This can be fixed through stretching and strengthening via PT.
In regards to pia mater, dura mater, etc, what does the internet say about the pronunciation of mater?
“mayter” - but that’s not right, per Schmidt. It’s pronounced “Mot-ter”
The opening at the top of the sacrum is called?
Sacral canal
the opening at the bottom of the sacrum is called?
Sacral hiatus
The combination of fused spinous processes from the original sacral vertebrae create
the median sacral crest (runs midline)
The fusion of the superior & inferior articular processes in the sacrum create
Medial sacral crest (run next to median crest on both sides)
The fusion of the transverse processes in the sacrum form
Lateral sacral crest (runs laterally on both sides)
How many total sacral foramina are there?
8 (4 on both sides)
The superior ridge on the sacrum is called
Iliac Crest
At the front of the pelvis there are raised nubs called
Tubercles
(raised bump that attaches something)
What does the Tubercle attach to?
Inguinal ligament
What does the inguinal ligament connect to?
Anterior superior iliac spine & Pubic tubercle
The ligament that connects transverse processes of (L4 & L5) to the rear part of the pelvis is called
Iliolumbar ligament
Pubic symphysis has what function?
connects the two front pieces of the pelvis
Gel filled center of Intervertebral disk is called?
Nucleus pulposus
fibers that wrap around nucleus pulposus are called?
Anulus fibrosus
What sandwiches the nucleus pulposus & the anulus fibrosus?
Hyaline cartilage end plate
What layer of the meninges is the CSF found?
Subarachnoid space
What sits above the pia layer but below the arachnoid layer? What is this space called?
All arteries & veins
Subarachnoid space
What cell is in charge of making CSF?
Ependymal cells
How do Ependymal cells make CSF?
They are the bridge between the CV system. They take sodium, chloride, and water through one side of the cell, and push it to the other side into the CSF system. Pushing sodium into the CSF uses ATP.
What is the normal volume of the CSF system?
150mL
How much CSF is created per day?
~500mL
Roughly how many times a day is CSF “refreshed?”
3 times a day
Where does CSF get “stale?” Why?
Dural sac — does not have a great way to make it back up the spinal column
Can anesthetics impact CSF production? If so, how?
Yes. Some anesthetics can impact CSF production by speeding up or slowing down sodium permeability into ependymal cells. This also impacts chloride and water, as they follow sodium. This changes the amount of CSF produced.
Activity of ependymal cells is changed by changing Na pump activity.
What is another name for a tissue made up of ependymal cells?
Choroid plexus
Where is the choroid plexus located?
Inside each of the four cerebral ventricles.
What cerebral ventricle is in similar shape to the hypothalamus? What is the shape? What is the name for the area of the brain that it is located?
3rd ventricle; triangle; diencephalon
Which cerebral ventricle is anterior to the cerebellum and right in the middle of the brain stem? What is the shape?
4th ventricle; triangle
Which two cerebral ventricles are the largest? Where are they located in the brain? Where are they in relation to the 3rd and 4th ventricle?
Lateral ventricles; encased in the cerebral hemispheres; superior and lateral to the 3rd and 4th ventricle
Do ependymal cells require energy?
Yes, they require ATP to move sodium OUT of the cell into the CSF.
Within the CSF, how are electrolytes managed?
Astrocytes act as a buffer within the CSF.
What is the opening between the 2nd and 3rd cerebral ventricle called?
Interventricular foramen (older name; Foramen of Monroe)
What is the area called where CSF drains from the 3rd to 4th ventricle?
Cerebral aqueduct (or older name; aqueduct of Sylvius)
What layer is just outside the dura?
Epidural space
What is found in the Epidural space?
Adipose tissue (fats) & venous veins
Where do the Meninges end?
Spinal nerves (end of CNS)
Why is the Epidural layer a popular layer for Epidurals?
Fat & venous bloods vessels
Lipophilic anesthetic drugs can be given here (take longer to activate & wear off d/t fat cells)
What is the lateral exit point of the 4th ventricle called? Is there more than one exit point?
There are two lateral exit points (one on the left, one on the right). It is called the the lateral aperture (or Foramen of Luschka)
Other than the lateral apertures, what is the third exit point of the 4th ventricle? Where is it located in relation to the ventricle?
Median aperture (foramen of Magendie).
It exits posteriorly.
If the CSF system is occluded, does CSF production stop?
No
What happens if the CSF system is clogged?
Pressure is put onto the brain/surrounding structures.
Where is the most common place to get a CSF blockage? What is the common cause per Schmidt? What is this pathway going between?
Cerebral aqueduct (aqueduct of Sylvius)
Tumor, maybe something lodged inside
Between the 3rd and 4th ventricle
What is a temporary fix when there is a CSF blockage to prevent ventricles from getting too big? What’s the downside?
Bolt/EVD; fairly invasive. “Can cause massive problems.”
Where are spinal procedures typically given?
Subarachnoid layer
(Risk of spinal cord puncture)
What term is used for “extra” CSF?
hydrocephalus
What are the two types of hydrocephalus, and what do they mean?
Noncommunicating hydrocephalus - Occlude any of the openings in ventricles (think, ventricles not connecting/communicating)
Communicating hydrocephalus - Problem where ventricular system is intact/open, but CSF is not being absorbed for whatever reason; leads to pressure increasing everywhere (think, ventricles are connecting/communicating)
Where is CSF reabsorbed? How does it work normally?
arachnoid granulations (pressure blowoff valves) - if pressure rises, valve opens to send some CSF to CV system, relieving pressure of CSF.
The point where the spinal cord ends is called?
Conus Medullaris (L1)
Where are arachnoid granulations located mostly?
Infoldings found at top of brain midline with longitudinal fissure
What is normal ICP as described in class?
10mmHg
Other than the infoldings at the top of the brain, where else is CSF reabsorbed?
Very little in the spinal cord.
What is the “horse tail” of the spine?
Cauda Equina (L3-S5)
(Area below spinal cord where it is just a bunch of spinal nerves)
What kind of hydrocephalus would a stroke that occluded arachnoid granulations be called?
Communicating hydrocephalus - no blockage between ventricles, just no way to dispose of csf
What does the cerebellum do, and where is it located?
Inferior/posterior brain.
The part of brain responsible for coordinating complex tasks such as walking down the street. We need muscles to activate in a complex sequence requiring coordinated movements.
The cerebrum is an important part of the motor system of the body.
Why is the cauda equina good area to do spinal procedures?
There is no spinal cord to damage only spinal nerves, giving the spinal nerves room to get out of the way if the spinal is put in too deep
While the lateral apertures empty into the spinal cord, where does the median aperture empty into?
cerebellomedullary cistern (old name cisterna magna (pool of csf))
Which has a faster onset, epidurals or spinals?
Spinals - deeper but more risk
Epidurals - superficial taking longer to activate but safer
What are the two enlargements where there are extra neurons are placed for innervation & sensory in the spine?
- Cervical enlargement (C3 - C6)
- Lumbar enlargement (T11-L1)
If absolutely needed, where can fresh CSF be sampled?
The foramen magnum–> cerebellomedullary cistern - very risky
When describing a venous system, what does sinus mean?
Big vein that has structure to it
Describe the venous blood flow of the cranium back to the CV system.
- The Superior sagittal sinus meets the Inferior sagittal sinus at the sinus confluence, which is a T shape.
- The point that the inferior sagittal sinus straightens out prior to the sinus confluence is called the straight sinus.
- From the sinus confluence (the point where all the sinuses connect), the blood flows laterally through the transverse sinus.
- From the transverse sinus, there is a “hairpin turn” of the vein called the sigmoid sinus.
- The cavernous sinus (venous collecting pool in the front of the brain; also includes blood runoff from the face etc)
- From the cavernous sinus, blood goes to the sigmoid sinus to the internal jugular veins down the neck.
**need to edit 5&6
What is the connective tissue between superior/inferior sagittal sinus called? What is the general descriptor Schmidt used? What does it separate?
falx cerebri
“Fan-Like”
Separates left and right hemispheres
The structure the Cervical enlargement feeds into is?
The Brachial Plexus
What connective tissue does the occipital lobe sit on? How is it formed?
Tentorium cerebelli
The falx cerebri extends down to form a “floor” of connective tissue for the brain
The Lumbar enlargement feeds into what?
Sciatic nerve & Lumbar Plexus
The connective tissue that is an extension of pia mater that anchor the cord in the spinal canal are?
Filum Terminale
- Filum Teriminale Internum: End of cord to dural sac
- Filum terminale Externum: Dural sac to sacral hiatus
What part of the brain is inferior to the tentorium cerebelli?
Cerebellum
Where does the blood in the external jugular vein come from in comparison to the internal jugular vein?
External - external structures on the side of the head
Internal - Internal structures (other than face, which drains into the sinus confluence)
How many arteries do we have going to the head? what are they called?
5
2x vertebral artery
2x internal carotid arteries
1x external carotid artery
What is the Dural sac composed of?
CSF
What is the Dural sac?
Extension of the meninges layer below conus medullaris, also called Lumbar Cistern
How far down does the Dural sac extends?
Extends to S2 Vertebrae
Where does the Conus medullaris end in the Adult & in a new born?
Adult - L1
Newborn - L3
(Bone grows faster than cord develops)
Does the vertebral artery supply blood to the front or the back of the brain?
Back of the brain
What portion of the brain do the internal carotid arteries supply?
Anterior portions of the brain
What portion of the head does the external carotid artery supply?
Superficial areas
What is the normal brain blood flow?
750mL/min
If brain blood flow was calculated with brain tissue, what would that look like?
50mL/min/100g tissue
What is the normal cardiac output per Schmidt?
5L/min
What % of CO is brain blood flow?
15%
What % of bodyweight is the brain?
2-3%
Given the large amount of perfusion per % of body weight of the brain, the perfusion is considered what?
Lopsided
What % of brain blood flow goes to the gray matter? Why is this important?
80%
Decisions/actions are happening here in terms of managing electrolyte levels (i.e. action potentials; excitatory/inhibitory signals)
How should CSF look on a scan?
Black
What % of brain blood flow goes to the white matter?
20%
Why does the white matter require less blood flow than the gray matter?
White matter is efficient due to myelin - much less energy required to send a signal due to nodes of ranvier
What is a downside to the Dural sac?
CSF can get stale as it is far from production –> great place to get sample however it will not be fresh or completely accurate
The most common locations to draw spinal sample are?
L3 to L4 interspace
&
L4 to L5 interspace
A rarely used access point to plant a needle posteriorly be?
Sacral Hiatus
What is the degree suggested for the off midline approach?
15 degrees
Describe the CSF compositions of pH, Cl, Na, K, Mg, and glucose
- pH 7.31
- Cl concentration is very similar to Na
- K is 40% less than normal plasma
- Mg is 40% higher than plasma
- Glucose is 60 mEq/dL
Arterial bleeds in the brain are typically from which layer of the Meninges?
Epidural (arteries in skull) & Subarachnoid (contains arteries)
Venous bleeds in the brain are typically from which layer of the Meninges?
Subdural
The space between the arachnoid layer and the pia mater is held up by what?
Arachnoid Trabeculae
Why is the pH in the CSF lower than the pH in the blood?
The CSF has its own buffer system that buffers CO2 using HCO3- however bicarb in the CSF is lower
What is the normal glucose in plasma?
90mg/dL
Without auto regulation of CPP, what happens?
Elevated BP would result in elevated CPP.
Decreased BP would result in decreased CPP.
In an auto regulation graph, what are the points where auto regulation fails?
LLA - lower limit auto regulation
ULA - upper limit auto regulation
If your BP was 150/x for two months, what would happen to auto regulation of CPP?
There would be a “new normal,” i.e. in class he mentioned 100 would be the new baseline BP rather than 50.
What is the normal range of BP for auto regulation of CPP?
50-150
What is the adjustment of a system called?
i.e. BP elevated for a long time, auto regulation adjusts with new normal range
Adaptation
Other than CPP auto regulation, what example did Dr. Schmidt give us in class regarding adaptation?
baroreceptors
When our blood pressure rises, what happens to the vessels in the brain?
Constrict to limit flow
When our blood pressure drops, what happens to the vessels in the brain?
Dilate to enhance flow
What physical characteristics do blood vessels develop with chronic hypertension? What are the implications?
What other disease could cause this, per Schmidt?
Thick, tough, not able to dilate/stretch as easily. If BP drops, the vessels would not dilate, meaning CPP would drop and auto regulation would not be as effective.
Autoregulation would be effective at say 80, instead of 50 bp.
Diabetes
In reference to DM/HTN, what do they do to our blood vessels over time?
“zap them” per Schmitty
What do we look at to gauge blood vessel health? Why?
How well do they dilate and contract?
The better they can do that, the better off the patient will be.
In a healthy person, what structure helps a person “not even know they had a heart attack?”
What coronary artery is the exception to this?
Collateral blood flow (connecting vessels to one another limiting the chance of ischemia in the event of a clot, etc.)
LAD
Why do diseases such as DM/HTN lead to more severe MI/CVA events?
Lack of stretch/dilation of blood vessels leads to poor autoregulatory function
What drugs can impact auto regulation?
Volatile anesthetics
On an auto regulation graph, how would a volatile anesthetic change the shape?
Slanted rather than straight
If a drug is more effective at shutting off auto regulation, would the graph be more or less slanted?
More slanted
What are error bars?
Bars placed on auto regulation graphs to determine whether a drug affects auto regulation in a statistically significant way.
What does it mean if a drugs auto regulation line is out of the error bar?
If the drugs auto regulation line is out of the error bar, it is statistically significant.
In the axon of a motor neuron, what channels are present? What purpose do they serve?
Fast Na+ channels (for action potential)
K+ channels (to help reset)
Na-Kase pump (helps reset neuron; uses ATP; 3Na+ out, 2K+ in, net 1- charge)
On the presynaptic terminal of an axon, what channels are present?
Voltage sensitive P-Type Ca++ channels
Ca++ ion channels
V-G K channels
Ca++ dependent K channels
How does a Voltage sensitive P-Type Ca++ channel work? When is it open?
The axon sends an action potential from fast Na+ channels.
Rise in Vrm leads to P-Type Ca++ channels opening during depolarization, allowing Ca to flood into the cell.
These Ca++ ions find ACh storage vesicles and signal them to exit via exocytosis (stimulus to release neurotransmitter) into the neuromuscular junction.
Finally, it also opens Ca++ dependent K+ channels to reset the cell.
What type of neuron is a motor neuron?
Multipolar
What are the two types of vesicles discussed in class in the motor neuron presynaptic terminal? What makes them different?
Vesicular pool ACh storage vesicles
(VP-1)
(VP-2)
VP-1 is a vesicle that is either not full of neurotransmitter yet and still being filled, or has not made it to the right positioning. “It isn’t ready yet.”
VP-2 are storage vesicles filled with ACh that are ready to exit the cell via exocytosis when acted on by Ca++
Which are in greater abundance; VP-1, or VP-2?
VP-1
How do the Ca++ ion channels in the presynaptic terminal work?
Ca++ exits the cell via ATP usage to help reset the cell after depolarization.
How do Voltage Gated K+ channels work in the presynaptic terminal?
They help reset the neuron to baseline Vrm after depolarization.
How do Ca++ dependent K+ channels work in the presynaptic terminal?
Ca++ enters the presynaptic terminal via P-Type Ca++ channels, act on VP-1, release ACh via exocytosis, and the charge from Ca++ helps open the Ca++ dependent K+ channel to help reset the cell.
If the neuron doesn’t reset to baseline Vrm, can another action potential be fired?
Nada
At the motor end plate, what receptor is present? How many?
Nicotinic Acetylcholine Receptors
Millions per Schmidt
How many nACh-R need to be activated to cause an action potential at the motor end plate?
Around 500,000
How many ACh need to bind to the nACh receptor to open it?
2
What ion(s) flow through the nACh receptor once open?
Na+ floods into the cell
A few K+ can exit the cell
A few Ca++ can enter the cell
Once Na+ comes into the skeletal muscle, what other channels open due to rise in Vrm?
Fast Na+ channels (end plate potential causes these to open along the length of muscle)
What do we call the depolarization of skeletal muscle at the motor end plate?
End plate potential
Is an end plate potential guaranteed if nACh receptors open? Why?
Yes - we have “tons of extra receptors and Acetylcholine.”
Once fast Na+ channels open on skeletal muscle, what happens?
Contraction
Although the Sinuses are large veins, they are an extension of what?
Dural Meninges layer making them thick and robust
What dictates brain blood flow?
Metabolic activity
- Coma –> low blood flow
- Highly active –> High blood flow
A ring of arteries that connects the brains anterior & posterior circulation is called?
Circle Of Willis
What is the benefit of the Circle of Willis?
It ensures collateral circulation, if one were to be blocked the others would be able to feed the blocked vessels
Which two arteries connect in middle of the Circle of Willis and feed into it?
Internal Carotid Arteries (2)
Which two arteries combine to form the Basilar Artery?
Vertebral Artery (2 left & right)
Where does the Basilar Artery lay?
Inferior to the pons (runs underneath it)
Where does the Basilar artery connect with Circle of Willis?
The posterior midline area of the Circle of Willis
Of the three large arteries that compose of the Circle of Willis, which one is the largest?
Middle Cerebral artery
- perfuses a large part of the brain –> if injured it is catastrophic
What areas of the brain do the Circle of Willis cover?
- Anterior cerebral artery cover the front part of the brain
- Middle cerebral artery covers temporal & lateral sides of the brain
- Posterior cerebral artery covers back side of the brain and far lateral lower sides
The part of the anterior cerebral artery that is involved in the Circle of Willis is called? (early part)
Pre-communicating part of Anterior Cerebral Artery or A1
The part of the anterior cerebral artery that extends from the Circle of Willis is called the? (late portion)
Post-communicating part of the Anterior Cerebral Artery or A2
The small artery that connects the left & right anterior cerebral arteries is called?
Anterior communicating artery
Once the internal carotid arteries become apart of the Circle of Willis, what does their name become?
Middle Cerebral Artery
The posterior artery that is apart of the Circle of Willis is called?
Pre-communicating part of the Posterior Cerebral artery or P1
The part of the posterior artery that extends from the Circle of Willis is called?
Post-communicating part of the Posterior Cerebral Artery or P2
The artery that connects the Middle cerebral artery to the posterior cerebral artery is called?
Posterior Communicating Artery
The artery that covers the front and top of the cerebellum is called?
Superior Cerebellar Artery
The artery that covers the middle of the cerebellum is called?
Anterior-inferior cerebellar artery
The artery that cover the lower and back of the cerebellum is called?
Posterior-inferior cerebellar artery
The Superior cerebellar & anterior-inferior cerebellar arteries arise from which Major artery?
Basilar Artery
The Posterior-inferior cerebellar artery arises from which artery?
Vertebral artery
Epidural hematomas are usually are a result of
Trauma/skull fracture
Why are subdural hematomas typically slow to develop?
Subdural hematomas are typically venous leaks
What is something sinuses lack that typical veins have?
Valves
(daddy schmit said this when that one guy who always asks questions, asked a question)
What are subarachnoid hemorrhages typically caused by?
Rupture of an aneurysm
Why are subarachnoid hemorrhages much more difficult to deal with?
They are deeper in the brain and infiltrate glial and neural cells
What is the most common type of Hemorrhagic stroke?
Subarachnoid hemorrhage
What are the typical causes for Subarachnoid hemorrhages?
Genetics or lifestyle
- alcoholism
- uncontrolled HTN
What does alcohol do to blood vessel?
Thins them out making them susceptible to bleeds
What can uncontrolled HTN do to an aneurysm?
Cause it to rupture
What is the main by product of the brain?
CO2
- since it is the main byproduct body uses this to gauge metabolic requirement
What is the system used to maintain constant blood flow in the brain?
Autoregulation
If blood pressure were to increase, what would the healthy brain blood vessels do?
Brain blood vessels should constrict (increase in vascular resistance) to limit over perfusion
If blood pressure were to decrease, what would the healthy brain blood vessels do?
Brain blood vessels would dilate (decrease in vascular resistance) to maintain a healthy amount of blood pressure in the brain
What would happen if the brain did not have autoregulation?
- unchecked overperfusion would cause aneurysm to pop
- unchecked under perfusion would lead to cell death
Vast majority of skeletal muscles are innervated by how many motor neurons?
One motor neuron
Give an example of skeletal muscle that is innervated by more than one motor neuron
Ocular muscles in the eye socket
Where are the motor neuron cell bodies located?
Anterior horn of grey matter in spinal cord
What are the two ways a motor neurons can be activated?
Descending pathways originating from brain or reflex arcs
What are the two contractile elements within skeletal muscle?
Actin & Myosin (arranged in tube like structures)
What is fiber another term for?
Cells in skeletal muscles
The specialized version of the endoplasmic reticulum found in skeletal muscle is?
Sarcoplasmic Reticulum
Calcium used for contraction in skeletal muscle is utilized from outside or inside the cell?
Inside (calcium is stored in SR and released during AP)
After contraction what pumps the calcium back into the SR?
Sarcoplasmic Reticulum Calcium ATPase pumps (SERCA pumps) –> utilizes ATP
What is the specialized structure that helps carry the AP deep into the muscle cell?
Transverse tubule
Where can the NMJ typically be found on a skeletal muscle?
In the middle
What drives actin/myosin cross bridging?
Calcium
Why does a skeletal muscle have a cross hatch zebra type of pattern?
Actin & Myosin filaments
The in-folding at the NMJ of the skeletal muscle is called?
Cleft (primary if is has one in-folding, further in-folding in the cleft is called secondary cleft)
How & what does Acetylcholinesterase break Acetylcholine into?
Breaks down ACh via Hydrolysis into –> Acetate + choline
What organelle produces Acetate within the motor neuron?
Mitochondria
Which cell produces AChE?
Skeletal muscle (attaches it to cell wall near cleft at NMJ)
About how many ACh-Receptors can be found at the NMJ?
5 Million
About how many ACh-Receptors are activated by typical pre-synaptic message?
500,000 (10%)
What is the bare minimum requirement of ACh to be release by Presynaptic terminal in order for a response to occur?
1 million (each n-ACH-Receptor requires 2 ACh to bind to it in order to be activated)
How much ACh is typically released by motor neuron?
2 million
How does the paralytic Curare work?
it is a receptor antagonist, it blocks nACh-receptor (it only needs to block one nACh-R ; it is the model for most of the non-polarizing paralytics)
How many subunits does a nACh-Receptor have, how many are for ACh?
it has 5 subunits, and 2 of them are for ACh
What sets up the release of ACh through the presynaptic terminal?
Calcium
What are “voltage sensors” and what is their function?
DHP receptors found on cell wall and T-tubules , “sense” AP –> open Calcium Release Channels located on SR
What does DHP stand for? and what drugs can be used against this receptor?
Dihydropyridine ; Dihydropyridine calcium channel blockers, block these receptors
Does the DHP receptor allow for calcium influx into cell?
very little calcium comes in through DHP receptor, DHP receptor is tethered to Calcium Release Channel & when activated pulls on Calcium release channel releasing Ca from SR into the skeletal muscle
What is the other name for the Calcium Release Channel?
Ryanodine receptor (RyR) –> it is sensitive a chemical called ryanodine
Describe the process of AP from a motor neuron down to skeletal muscle contraction
Motor neuron depolarizes –> AP spreads along neuron to the end of NMJ –> Calcium will influx into motor neuron through P-Type Ca channels –> calcium ions cause ACh storage vesicles to fuse to presynaptic wall –> ACh is secreted into NMJ –> ACh interacts with nACh-Rs –> nACh-Receptors open & Na floods in & generates EPP –> AP will spread & be sensed by DHP receptors –> DHP receptors will pull on Ryanodine receptors –> calcium will be released from SR into sarcoplasm –> SERCA pumps will tuck Ca back into SR after contraction
What is an End plate potential?
Local depolarization in skeletal muscle caused by influx of Na through nACh-R
How is Choline recycled back into cell?
2 Ways:
- ATPase pump –> uses ATP to shove choline back into motor neuron
- Secondary active transport moves choline & Na into motor neuron
What can store choline in the cell wall?
Phosphatidylcholine
What is the benefit of the T-tubule?
it is a way for an AP to spread deep into a muscle
What is the condition where the pt’s body produces antibodies to nACh-Rs?
Myasthenia Gravis (MG)
(antibodies attach to nACh-R & elicit immune response destroys receptor)
As the nACH-Rs are being destroyed, what gets put in the clefts?
Scar Tissue
What is typically responsible for MG?
Thymus gland
What happens over the course of the day with MG?
In the morning pts are okay but as the day goes on the more tired/greater dysfunction they have
What are treatments for MG?
- Removal of the Thymus gland
- Plasmapheresis
- Drugs - “stigmine”
What is the MOA of “-stigmine”
inhibits AChE –> increasing ACh at NMJ –> increases the chances of ACh binding to nACh-R
What is the disease where antibodies attack P-type calcium channels?
Lambert Eaton Myasthenic Syndrome (L.E.M.S) or E.L.M.S
What is L.E.M.S?
a paraneoplastic syndrome (caused by cancer –> especially lung cancer)
P-type calcium channels are ___ ___ specific
Motor function
Would AChE inhibitors be affective against L.E.M.S?
NO, AChE inhibitors are affective against POST-synaptic therapy, L.E.M.S. is a PRE-synaptic disease
What affect does destroying P-type calcium channels have on neurotransmitter transmission?
The destruction of P-type calcium channels reduces the amount of calcium influx into the terminal end plate, reducing the amount of ACh being released into the synapse
What are treatments for L.E.M.S?
- Plasmapheresis
- Lung tumor removal
- drugs
Why are drug treatments typically a last resort for L.E.M.S.?
They work by blocking V-G Potassium channels prolonging depolarization & are very good at it making them extremely cardio toxic
- Tea & Four-five diaminopyridine are two examples
What are the two types of Paralytics?
Non-depolarizing muscle relaxant & depolarizing muscle relaxant
How do NDMRs work?
Block one the two ACh binding sites on nACh-Rs inhibiting receptor activation
Which nACh-R blocker are all others derived from?
Curare
How do Depolarizing paralytics work?
They bind to nACh-Rs and cause a depolarization and keep the nACh-Rs open
What is a popular Depolarizing paralytic?
Succinylcholine (Succs)
What is succs comprised of?
2 AChs attached to each other
Is Succs broken down by AChE?
No, it does breaks down ester bond that links Acetate & Choline, but Succs is two ACh attached together making it difficult for AChE to break it down
What happens to the fast sodium channels with Prolonged nACh-R activation caused by succs?
Fast Na channels near NMJ cannot reset, however, fast Na channels away from NMJ can reset
What happens to potassium with prolonged activation of nACh-Rs?
The continuous influx of Na will eventually begin to push out K causing a spike in serum K
How much does serum K increase with a normal dose of succs?
Serum K increases by 0.5 mEq/L in healthy pts
In a pt with a stroke or unhealthy skeletal muscle, how would this affect succs administration?
In pts with unhealthy skeletal muscle or lack of use the cell will attach more nACh-Rs at the cell wall to increase the chance of activity, this creates an issue with succs administration as more nACh-Rs open means –> greater influx of Na –> leading to greater increase of K efflux –> greater hyperkalemia
