Exam 1 Flashcards
What are the 4 basic parts of a neuron?
The cell body (soma), axon, dendrite, & axon terminal
What is the relationship between a dendritic spine and an axon terminal?
Dendritic spines connect with axon terminals to communicate between the pre-synaptic and post-synaptic cells
What are the two types of neurons and which system do they belong to?
Multipolar neurons belong to the CNS (typical neuron)
Pseudounipolar neurons belong to the PNS (soma and two extending arms)
What occurs in the axon?
Axon transports materials for NTs
What are the two types of axonal transport?
Anterograde - cell body to axon terminal
Retrograde - axon terminal to cell body
What do glial cells do?
Glial cells play a supportive role to ensure neurons stay healthy
What are the glial cells of the CNS?
Astrocytes
Oligodendrocytes
Microglia
What are the functions of astrocytes?
Provide structural support
Secrete growth factors
Forms conduit between cell and other parts
Acts as a filter that tries to eliminate bad things from entering neuron
Modulates synaptic activity by releasing glutamate
Buffers pH & ionic environment in extracellular space
Removes excess potassium from action potentials & transports it to perivascular spaces
Absorbs nutrients from blood and brings it to neuron
What are the functions of oligodendrocytes?
Cover axon in myelin in order to increase conduction speed
What are the functions of microglia?
Immune cells that protect neurons & glial cells
Phagocytic scavengers, release neurotoxins
What are the glial cells of the PNS?
Satellite cells
Schwann cells
Macrophages
Which CNS glial cells match the PNS glial cells?
Astrocytes - Satellite cells
Oligodendrocytes - Schwann cells
Microglia - Macrophages
What is the main difference between oligodendrocytes and Schwann cells?
Oligodendrocytes has projections that cover axon while Schwann cells have units that wrap around axon
Describe the process of action potential progression.
- NTs in vesicles mobilize towards axon terminal with the help of calcium
- NTs release from pre-synaptic cell
- NTs will hopefully bind to receptor and let sodium or chloride into post-synaptic cell
What can happen to the neurotransmitter in the second stage of action potential progression?
- Inactivated (broken down) by enzymes
- Undergo reuptake (go back where they came from)
- Cross synapse and bind to receptor
What are the differences between sodium and chloride?
Sodium is excitatory and causes depolarization
Chloride is inhibitory and causes hyperpolarization
Describe the two ways of summation of post-synaptic potentials.
- Spatial - many inputs result in firing
- Temporal - one pre-synaptic neuron results in firing
How does charge build in the summation of post-synaptic potentials?
The charge builds with sodium ions
How is the charge read?
The charge is read with the axon hillock
Describe the two ways a transmitter-receptor interaction can occur.
- Single Messenger Synapses
- Second Messenger Synapses
voltage changes
What are the differences between the 2 transmitter-receptor interactions?
Single messenger synapses cause momentary voltage changes and is simple
Second messenger synapses cause longer-lasting voltage changes and is more complex
Describe the process of a single messenger synapse interaction.
- NT binds to receptor
- Receptor opens channel
- Channel allows ions in
Think as lock and key process
Describe the process of a second messenger synapse interaction.
- Second messengers (G-proteins) bind to receptor and activate adenylyl cyclase that turns ATP into cAMP
- cAMP results in downstream cellular response in nucles
- Positive loop is created as a result, where more 2nd messengers are made
Think of the positive loop process
What does cAMP stand for?
cAMP stands for cyclic adenosine monophosphate
What 2 things help change the excitability of the post-synaptic cell?
Receptors & channels help to change post-synaptic cell excitability
What are the six common neurotransmitters covered in lecture? Which are the two most important in this context?
1. Glutamate
2. GABA
3. Dopamine
4. Acetylcholine
5. Serotonin
6. Norepinephrine
What does GABA stand for?
GABA stands for gamma amino butyric acid
What is the criteria for a neurotransmitter? What do they mean?
- Localization - must be found in the pre-synaptic terminal
- Release - must be released when pre-synaptic cell activates
- Specificity - must have a unique and specific effect on the post-synaptic cell voltage
What are the 2 categories of neurotransmitters?
- Neuropeptides
- Small molecule messengers (SMMs)
Describe the differences between neuropeptides & SMMs.
Neuropeptides are big and have long-term effects on post-synaptic potential.
SMMs are small and have short-term effects on post-synaptic potential.
Define receptor antagonists & agonists. Provide an example for each.
Antagonist - helps receptor activation
Agonist - prevents receptor activation
An example is the use of heroine (agonist) & naloxone (antagonist).
What are the four types of receptor regulation?
- Desensitization
- Down regulation
- Sensitization
- Up Regulation
Describe the differences between (de)sensitization & up/down regulation.
Desensitization - receptors will not open because of NT influx
Down Regulation - number of receptors will lessen because of NT influx
Sensitization - receptors will open because of NT scarcity
Up Regulation - number of receptors will increase because of NT scarcity
Remember DEsensitization & DOWN regulation!!
What are the three factors that make a neuron more likely to fire?
Changes in voltage
Neurotransmitters
Mechanical Pressure
Define bi-lipid membranes and how are they important to action potentials.
Bi-lipid membranes are a type of membrane that have a hydrophilic head outside of the cell & a hydrophobic tail inside of the cell.
This is important because this helps receptos (which also have hydrophilic/phobic parts) embed themselves in the post-synaptic cell.
Describe the concentration differences in an ionic gradient.
On the outside of the cell, there are high concentrations of sodium & chloride.
On the inside of the cell, there are high concentrations of potassium.
What do Sodium-Potassium pumps do?
They help neurons maintain resting membrane potential
Why do cells become slightly negative?
They become slightly negative due to the uneven amount of sodium ions and potassium ions. 3 sodium ions exit as 2 potassium ions enter.
What is diffusion potential?
Diffusion potential is the potential energy that can occur if ion channels flowed OR the energy created by concentration differences
What is equilibrium potential?
Equilibrium potential is the voltage required to stop flow of ions OR when diffusion stops
What is the equation for equilibrium potential?
Nernst equation is used to calculate equilibrium potential
At how many millivolts would everything stopped if all channels opened?
+55 mV
What is the equation for membrane potential?
Goldman-Hodgkins-Katz (GHK) equation is used to calculate membrane potential
At how many millivolts will a neuron be at resting membrane potential?
-70 mV
What are the membrane potentials for potassium,, chloride, & sodium?
Potassium potential = -80 mV
Chloride potential = -60 mV
Sodium potential = +55 mV
equilibrium values
What is the importance of these values?
The potassium & sodium values are the most important because the lowest an activation threshold can reach is -80 mV while the highest if +55 mV.
Voltage relies on what two things?
Membrane integrity & ion permeability
What happens if sodium channels open?
Increased membrane potential
Increased current flow for sodium ions
Flow of sodium into cell
Moves membrane potential closer to +55 mV
What happens if chloride channels open?
Decreased membrane potential
Increased current flow for chloride ions
Flow of chloride into cell
Moves membrane potential closer to -80 mV
Describe the process of how an action potential occurs/is initiated.
- Voltage-gated sodium & potassium channels are triggered at -55 mV
- Sodium rushes in (depolarization)
- Sodium channel closes at +30 mV
- Potassium channel opens slower then potassium rushes out (repolarization)
- Membrane potential dips below resting then returns to resting state at -70 mV
What gates keep ions in & out?
Activation & Inactivation gates
Define refractory periods.
A refractory period is a period where another action potential cannot occur
What are the 2 types of refractory periods?
Absolute - no action potential can occur & is helped by activation gates
Relative - action potential can rarely occur, but there must be a massive amount of sodium injected into post-syn. neuron; helped by some sodium channels returning to rest
Ion flows because of what 2 properties?
- Passive Electrical Property
- Active Electrical Property
Describe passive electrical property & its relationship with charge.
Passive electrical property allows charge to flow slowly down the axon & the charge will gradually lessen the farther it goes.
eg) a water hose
Describe active electrical property & its relationship with charge
Active electrical property consists of nodes of Ranvier that help push charge down the axon
eg) mini action potentials
What is the importance of the nodes of Ranvier? Where are they found?
The nodes of Ranvier are found in the small gaps in between the myelin of the axon. The nodes help to propel charge forward
What is another name for the passive/active process of electricity?
Saltatory conduction
What unit are muscles made of?
Muscle fibers
Describe the differences between an insertion and origin point.
An insertion point is the tendon connected to movable bone.
An origin point is the tendon connected to immovable bone.
Muscle fibers are covered in what type of non-contractile tissue?
Sarcolemma
What is a motor unit as discussed in lecture?
Motor units consists of a motor neuron and all of the muscle fibers it innervates
What is the significance of the relationship between motor neurons and muscle fibers?
One motor neuron can innervate many muscle fibers. but each fiber is only innervated by one motor neuron.
eg) a parent and multiple kids
What is the neuromuscular junction?
The NMJ is a synaptic connection between the axon terminal of a motor neuron and a muscle.
Describe an endplate potential (EPP) and its relationship with sarcolemma.
EPPs are a localized change in voltage in a muscle fiber that occurs when neurotransmitters bind to the muscle’s postsynaptic membrane.
It is important because it works with sarcolemma to spread the signal across the muscle, rather than in one localized spot.
Name the 2 characteristics of a muscle fiber.
- T-Tubules
- Sarcoplasmic Reticulum (SPR)
What are the functions of T-Tubules?
T-Tubules, or transverse tubules, allow EPPs to travel to SPR & deeper within the muscle fiber.
They will also change shape to allow Calcium to leave SPR.
What are the functions of the SPR?
The sarcoplasmic reticulum stores and releases Calcium.
What are myofibrils and why are they important to discuss?
Myofibrils are the next smallest component of a muscle after muscle fibers. Muscle fibers consist of myofibrils, and they are important because they are the main muscle component that is contracting.
How are sarcomeres related to myofibrils?
Myofibrils are divided into sarcomeres, which are units of contraction
Name the two filaments inside of a myofibril.
Myosin & Actin
Why are myosin & actin filaments significant?
They are important because they are directly responsible for actual contraction because they pull on one another.
What is the ratio of myosin to actin & vcice-versa?
For every 1 myosin, there are 6 actin surrounding it.
For every 1 actin, there are 3 myosin surrounding it.
Describe the anatomy of a sarcomere.
A sarcomere is bordered by 2 Z-discs. The middle of the sarcomere is called the M-line. Thin actin filaments are attached to the Z-discs, and between every actin filament, is a thicker myosin filament.
Describe the anatomy of a myosin molecule.
A myosin molecule has two heads with intertwining body (twizzler-like) and a tail.
Name the 3 important characteristics of a myosin molecule.
- Actin-binding sites on top of the heads
- ATP/ADP/PI-binding sites on the lateral heads
- Flexible hinge region
Describe the anatomy of an actin filament.
An actin filaments has chains of actin intertwined with each other, with threads of tropomyosin blocking off the myosin receptors. Troponin is also there in order to remove tropomyosin.
Name the 3 important characteristics of an actin filament and their functions.
- Actin - receives and binds to myosin
- Tropomyosin - blocks off myosin receptors when muscles are at rest
- Troponin - pulls tropomyosin to expose actin for binding
What role does calcium play in the actin filament, thus in muscle contraction?
Calcium helps to expose the myosin binding sites for filament attachment.
The cycle covering a single muscle contraction is called…
The cross-bridge cycle
Where is calcium attached for the entirety of muscle contraction?
Calcium is attached to troponin.
What are the 4 steps of the cross-bridge cycle?
- CB Formation
- The Power Stroke
- CB Detachment
- Myosin Head Reactivation
Describe what happens in the first step of the CB Cycle.
CB Formation is where the myosin head attaches to the actin filament. Here, ADP & PI attach to the myosin head.
What does ADP & PI stand for?
ADP = adenosine phosphate
PI = inorganic phosphate
Describe what happens in the second step of the CB Cycle.
The Power Stroke is where ADP & PI will fly off of the myosin, and the myosin head will stay in a bent position to pull actin closer to the M-line
Describe what happens in the third step of the CB Cycle.
CB Detachment is where the myosin head will detach from the actin, and here, ATP will attach to the myosin head
Describe what happens in the fourth step of the CB Cycle.
Myosin Head Reactivation/Elevation is where ATP will hydrolyze back into ADP & PI and the head will return back to its original position in stage 1. After this stage, the cycle will continue until contraction is ended.
What happens to calcium if muscle contraction ends?
Calcium will detach from troponin and return to the sarcoplasmic reticulum
What couples excitation & contraction?
Calcium couples excitation & ccontraction
How do you relate muscle length & muscle contraction?
How much actin & myosin overlap
What contributes to muscle contraction?
- Degree of muscle stretch
- Number of stimulated muscle fibers
- Size of muscle fibers - the bigger the size, the more the overlap
- Frequency of stimulation - faster firing, more calcium, more contraction
What are the two types of contractions? Which is more important?
1. Concentric
2. Eccentric
Define a reflex.
An obligatory, uncontrollable response to stimulus
Define an efferent nerve.
A nerve that exits the CNS
Define an Alpha motor neuron.
A motor neuron that excites extrafusal muscles and causes contraction
What are intrafusal motor fibers?
Sensory parts of the muscle, specifically sensing stretch
Define an afferent nerve?
A nerve that senses muscle spindle changes and sends it to the spinal cord
What is a gamma motor neuron?
A gamma MN is a neuron that innervates the intrafusal fibers
Define the two types of nerves that innervate the intrafusal muscles and their differences.
- Type 1A - has anulospiral endings that wrap around intrafusal fibers; receptors pick up degree and rate of stretch
- Type 2 - has flower-spray endings that pull on the ends of intrafusal fibers when activated; receptors pick up only degree of stretch
What are the 3 nerves associated with intrafusal muscles?
- Efferent gamma motor neurons
- Type 1A Nerve
- Type 2 Nerve
Compare the intrafusal and extrafusal muscle fibers.
Intrafusal fibers are found deep within the muscle and are innervated by the gamma motor neurons, type 1A & type 2 neurons. There are only sarcomeres on the ends of the fibers, so the middle is made of non-contractile tissue.
Extrafusal fibers are found on the external side (typically what we think of as a muscle) & have sarcomeres throughout. These are innervated by alpha motor neurons.
Name the 5 components of a reflex.
- Receptor - senses change
- Sensory Neuron
- Integration Center - where sensory information is processed in spinal cord
- Alpha motor neuron activates
- Effector - muscle being affected
What are the 2 types of reflexes involved the patellar reflex?
- Stretch Reflex
- Reciprocal Inhibition
What is the primary inhibitory neurotransmitter in the brain?
GABA (gamma amino butyric acid)
Action potentials are generated when enough excitatory potentials have been summated in the _______.
Axon hillock
What is the name of the electrical impulse in a neuron?
Action potential
Which types of muscle spindle nuclei are aligned in a single row in the center of the fiber?
Nuclear Chain Fibers
What happens when voltage gated sodium channels open?
Action potential
The repolarization of the neuronal membrane occurs with ______.
the closing of the sodium channels and opening of the potassium channels
Describe how the stretch reflex & reciprocal inhibition are used in the patellar reflex.
When a doctor hits a reflex hammer against the patella, it activates the sensory neuron that sends information to the spinal cord. It activates the motor neurons attached to the quads and hamstrings. The stretch reflex is activated by the alpha motor neuron attached to the quads, while the reciprocal inhibition is activated by the motor neuron attached to the hamstrings. The reciprocal inhibition is activated by the excited inhibitory interneuron in the spinal cord.
How are muscle spindles and spatial awareness related?
Spindles help the body know where it is in space
What are the three muscle spindle types?
1) Dynamic nuclear
2) Static nuclear
3) Nuclear chain
What muscle spindle is only innervated by the Type 1A & Gamma motor neuron?
Dynamic nuclear
Name the three muscle spindle reflexes.
Internal Stretch
External Stretch
Voluntary Contraction
What does the external stretch aid?
It helps to stabilize your arm in order to counteract forces
Name the difference between internal & external stretch and provide an example of each.
Internal stretch is triggered by something within the body & external stretch is triggered by something outside of the body. An example of internal is shivering & an example of external is reaching a plate for food.
Name the three types of muscle spindle activities discussed in lecture.
1) External stretch
2) Alpha motor neuron stimulation
3) Voluntary contraction
Describe how sensory information travels in the three different spindle activities
External stretch - sensory information is sent with 1A firing
Alpha stimulation - sensory information is reduced because 1A is not firing as fast (spindle is not stretched)
Voluntary contraction - sensory information is sent with 1A firing
Name the one muscle spindle activity where the gamma motor neuron is activated.
Voluntary contraction
Define the Golgi Tendon Organ and what nerve it is afferent to.
a receptor located in the tendon of a muscle & it is afferent to the Type 1B Nerve
What does the golgi tendon organ do (what effect does it have)?
It produces an inhibitory effect in the same muscle
What are the main differences between the muscle spindles & GTOs?
Location
Response to Forces
Sensory Information
Afference
Name the location, forces, sensory feedback, & afference of muscle spindles.
Location – muscle
Forces – dynamic & static
Sensory feedback - picks up degree & rate of stretch
Afference – Type 1A & 2
Name the location, forces, sensory feedback, & afference of GTOs.
Location - tendon
Forces - static
Sensory feedback - picks up degree of stretch
Afference - Type 1B
Describe the effects of the stretch reflex, reciprocal inhibition, & the GTO reflex.
Stretch reflex is the excitation of the alpha motor neuron in a closed-loop.
Reciprocal inhibition is the activation of the motor neuron to lower excitation of the antagonistic muscle
GTO Reflex produces an inhibitory effect in the same muscle in a closed-loop.
How many pairs of nerves exit the spinal cord & what are the 5 divisions?
31 pairs exit the spinal cord in the cervical, thoracic, lumbar, sacral, & coccygeal regions.
How many vertebrae are in each section of the spinal cord?
Cervical 5
Thoracic 12
Lumbar 5
Sacral 5
Coccygeal 1
How are the first 7 nerves different from the remaining nerves?
The first 7 nerves exit the vertebrae superiorly (over vertebrae)
Name and define the two types of roots of the spinal nerve.
Ventral root - carries sensory info to the spinal cord
Dorsal root - carries motor signals to muscles
What are dermatomes?
Divisions of the skin where sensory enter the spinal cord
Define a plexus.
A network of nerves that contain motor & sensory neurons from the spinal cord
Describe the important nerves and roots of the cervical plexus.
The cervical plexus originates from C1 to C5, and the important nerve is the phrenic nerve. If there is damage to the phrenic nerve, the diaphragm will be affected and possibly result in respiratory arrest.
Describe the important nerves & roots of the brachial plexus.
The brachial plexus originates from C4 to T1, and the important nerves are the axillary, musculocutaneous, median, radial, & ulnar nerves.
What area of the body does the brachial plexus innervate?
Brachial plexus innervates the chest, arm, and shoulder
What are the divisions of the brachial plexus? (Roots, trunks, etc.)
6 roots
3 trunks (upper, middle, lower)
3 cords (lateral, posterior, & medial)
2 divisions (anterior & posterior)
What do the brachial plexus nerves innervate?
Axillary - deltoids
MusculoQ - biceps/brachialis
Median - thumb
Ulnar - hand
Radial - extensors
Describe how the median nerve is a common injury site.
The median nerve is usually associated with carpal tunnel syndrome due to nerve impingement or pressure, which can result in numbness and difficulty doing pincer movements.
What does the lumbar plexus innervate?
Lumbar plexus innervates the thighs, abdominal wall, & psoas muscles
Describe the important nerves & roots of the lumbar plexus
Lumbar plexus roots are L1 to L5, and the important nerves are the femoral and obturator nerves.
What do the lumbar plexus nerves innervate?
Obturator - adductor muscles
Femoral - quads
Describe the important nerves & roots of the sacral plexus
Sacral plexus roots are L4 to S3, and the important nerve is the sciatic nerve.
What does the sacral plexus innervate?
Sacral plexus innervates glutes, lower limbs, pelvic structures, & perineum
What does the sciatic nerve innervate?
Composed of tibular & common fibular nerves, it innervates hamstrings
Where do the intercostal nerves originate from?
T1 to T11
Describe Common Pattern Generators (CPGs).
CPGs make things simpler because they do not require much brain input (eg. walking)
Name the statistics of back pain populations and why it occurs.
Back pain affects 60% - 90% of people aged 35-55. It occurs because of disc herniation in L5 to S2
Name the four abdominal muscles and discussed in lecture.
External Oblique
Internal Oblique
Rectus Abdominis
Transversus Abdominis
Name the characteristics of the four abdominal muscles. Which is the most superficial and most deep?
External Oblique - most superficial; runs inferomedial (pockets)
Internal Oblique - runs superomedial (Armpits)
Rectus abdominis - 6-pack shape
Transversus abdominis - most deep
What is the function of the rectus abdominis?
Depresses ribs & stabilizes pelvis during walking
Hip flexion, Forward flexion, Brings pelvis to sternum
What is the function of the external obliques?
Lateral spine flexion/hinging
What is the mnemonic related to oblique rotation?
Internal oblique will coincide with rotation direction & external oblique will be opposite
Rotate left, Left internal & Right external
Describe the relationship of centrum and spinous processes to the vertebral column.
Centrum get larger as you go down column
Processes get smaller as you go down column
Why is posture important?
To maintain health of intervertebral discs
What is the main function of intervertebral discs?
Absorb shock & provide spine flexibility
Describe the anatomy of an intervertebral disc.
Nucleus pupolsus is gelatinous and gives disc its flexibility.
Annulus Fibrosis contains nucleus pulposus
What are the different types of disc problems?
Degeneration - normal with aging; wear tear of annulus
* can occur with osteophyte formations
Bulging - intact annulus, but nucleus bulges out
Herniation - escape of nucleus, broken annulus
Thinning - normal with aging
What are the three ligaments that unite the vertebral column?
Anterior longitudinal ligament (covers centrum)
Posterior longitudinal ligament (covers centrum)
Short ligaments (covers spinous processes)
What are the muscles that stabilize the vertebral column, and what is their function?
Help in balance and stabilizing vertebral column
* Rotatores
* Multifidus
* Interspinales
Name the characteristics of the rotatores muscle
Smallest
Found in T1 - T12
Spans 1 to 2 segments
Name the characteristics of the multifidus muscle
Found in the cervical/thoracic regions
Spans 2 to 4 segments
Name the characteristics of the interspinales muscle
Longest
Found in cervical/thoracic regions
Spans up to 6 segments
What is the bone marking on the rib discussed in lecture?
Articular facet that fits into different vertebral segments
What are the features of the sacrum & coccyx?
Foramina: holes for nerves and blood vessels
Alae: gives sacrum its wing-like appearance
What are the muscles flex the head?
Sternocleidomastoid, scalenes, & sternohyoid
What muscles extend the head?
Traps, levator scapulae, splenius, longissimus capitis, semispinalis capitis, & semispinalis cervicis
What muscles extend the spine?
Erector spinae, semispinalis thoracis, & quadratus lumborum
