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