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Neuroscience > Midterm #1 Main Topics (also look at diagrams on D2L) > Flashcards

Midterm #1 Main Topics (also look at diagrams on D2L) Flashcards

1
Q

Directions

A

Medial:
Horizontal, moving towards the middle

Lateral:
Horizontal, moving away from the middle

Dorsal: above

Ventral: below

Anterior: front

Posterior: behind

Proximal: close to body

Distal: further from body

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2
Q

Horizontal vs. Frontal vs. Sagittal

A

Frontal (aka Coronal): separates the front from the rest

Sagittal: Separates the left and right

Horizontal: x- axis

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3
Q

Directions/Orientation

A

Contralateral: opposite side

Ipsilateral: Same side

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4
Q

Major Divisions of Nervous System

A

Central Nervous System (CNS)
- brain and spinal cord

Peripheral Nervous System (PNS)
- nerves

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5
Q

Protection for CNS

A

Bone: skull and spinal cord

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6
Q

3 Meninges

A

Dura mater: outermost, tough membrane.

Arachnoid layer: web-like

Pia mater : innermost layer of protection,
attached to the brain

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7
Q

Cerebrospinal fluid (CSF)

A

Supports or ‘cushions’ the brain.

Found in sub-arachnoid layer and 4 ventricles

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8
Q

Ventricles

A

Ventricles are filled CSF

Central Aqueduct transports CSF across the ventricles

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9
Q

Peripheral Nervous System Separates Into…

A

Autonomic:
- regulates internal organs and involuntary organs

Somatic:
- controls voluntary movements and interacts with external environment

Autonomic Separates into…
- Sympathetic: fight or flight
- Parasympathetic: rest and digest

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10
Q

Efferent vs Afferent nerves

A

Efferent: information exiting the NS

Afferent: information to the NS

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11
Q

12 Cranial Nerves

A

Olfactory - smell

Oculomotor - eye movement and pupil reflex

Trigeminal - face sensation and chewing

Facial - face movement and taste

Glossopharyngeal - throat sensation, taste, and swallowing

Accessory - neck movement

Optic - vision

Trochlear - eye movement

Abducens - eye movement

Vestibulocochlear - hearing and balance

Vagus - movement, sensation, and abdominal organs

Hypoglossal - movement, sensation, and abdominal organs

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12
Q

Major Brain Divisions

A

Developing:

Telencephalon and Diencephalon ➡️ Forebrain (matured)

Mesencephalon ➡️ Midbrain (matured)

Metencephalon and Myelencephalon ➡️ Hindbrain (matured)

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13
Q

More Detailed Divisions

A

Forebrain (major division):

  • Lateral
    (ventricle)
  • Telencephalon
    (subdivision)
  • Cerebral cortex, Basal ganglia, Limbic system
    (principle structures)
  • Third
    (ventricle)
  • Diencephalon
    (subdivision)
  • Thalamus, Hypothalamus
    (principle structures)

Midbrain (major division):

  • Cerebral aqueduct
    (ventricle)
  • Mesencephalon
    (subdivision)
  • Tectum tegmentum
    (principle structures)

Hindbrain (major division):

  • Fourth
    (ventricle)
  • Metencephalon
    (subdivision)
  • Myelencephalon
    (subdivision)
  • Cerebellum, Pons, Medulla oblongata
    (principle structures)
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14
Q

Hindbrain Divisions

A

Myelencephalon:

  • medulla ➡️ life support functions ➡️ damage = death
  • reticular formation ➡️ ‘gate keeper’; can admit or block sensory info

Metencephalon:

  • pons ➡️ ‘bridge’; main connection b/w cortex and cerebellum, role in sleep, dreaming
  • cerebellum ➡️ ‘little brain’
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15
Q

Midbrain Divisions

A

Mesencephalon:

Tectum (dorsal surface):
- superior colliculus ➡️ vision
- inferior colliculus ➡️ audition

Tegmentum (ventral surface):
- 3 colourful structures
- periaqueductal gray ➡️ analgesia
- substantia nigra ➡️ sensorimotor
- red nucleus ➡️ sensorimotor

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16
Q

Forebrain Divisions

A

Diencephalon:

Thalamus
- relay centre from senses to the cortex.
- all senses stop here except for olfaction.

Hypothalamus
- located below thalamus
- homeostasis: internal balance

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17
Q

Cerebral Cortex

A

The very top of the brain

It has many foldings and convolutions to increase surface area

Sulci: small grooves
Fissures: larger sulci
Gyri: bumps/ bulges

Longitudinal fissure – a groove that
separates right and left hemisphere

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18
Q

Parts of the Neuron

A

Soma: cell body of the neuron, contains the nucleus

Dendrites: branch-like structure that receives messages from other neurons

Axon Hillock: located between cell body and axon. Integration site before signal
goes down the axon

Axon: The long, thin cylindrical structure that conveys information from the soma
of a neuron to its terminal button

Node of Ranvier: gaps between section of myelin

Terminal buttons: The bud at the end of a branch of an axon

Synapse: A junction between the terminal button of an axon and the body/dendrites of another neuron

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19
Q

Cytoskeleton

A

(helps give a neuron its shape: Scaffolding)

Microtubules: Long ‘pipes’ running down the axon

Neurofilament:
- consists of wound rope-like subunits
- very strong

Microfilaments:
- most densely found in the neurites (axons and dendrites)
- plays a role in changing shapes of a cell (actin)

20
Q

Glia Cells

A

Support & nourish neurons

Outnumbers neurons 10:1

Four types: Oligodendrocytes, Schwann Cells, Astrocytes, Microglia

21
Q

Oligodendrocytes

A

Produce myelin: the fatty sheath that covers the axon

Can myelinate multiple axons in Central Nervous System (CNS).

Can produce up to 50 segments of myelin.

Not all axons are myelinated

22
Q

Schwann Cells

A

Produce myelin in peripheral nervous system (PNS)

Only myelinates a single nerve.

Digest dead axons and provide process for regrowth.

23
Q

Astrocytes

A

Largest glia, star-shaped

Many functions:

  • surround neurons and contact blood vessels via end-feet.
  • provides physical support.
  • provides nourishment
24
Q

Microglia

A

Involved in response to injury or disease

Protect the brain from invading micro-organisms

25
Q

Membrane Structure

A

Phospholipids are the molecules that make up the cell membrane.

They have three sections.

2 hydrophobic tails: will not dissolve in water

1 hydrophilic head: will dissolve in water

Phospholipid Bilayer
Cell membrane is semi-permeable

26
Q

Protein Synthesis

A

DNA→ mRNA: Transcription
RNA→ Protein: Translation

Amino acids are the building blocks of proteins

27
Q

Ion distribution creates Resting Membrane
Potential

A

Ions, charged particles, are unevenly distributed

4 Ions Contributing:

  • Sodium (Na+)
  • Chloride (Cl- )
  • Potassium (K+)
  • Negatively charged proteins: synthesized within the neuron found primarily within the neuron
28
Q

Factor of Resting Potential - Random Motion

A

Particles move down their concentration gradient

From areas of high concentration to area of low concentration

Even distribution

29
Q

Factor of Resting Potential - Electrostatic Pressure

A

Like forces repel, opposites attract

Even distribution

30
Q

Factor of Resting Potential - Selective Permeability

A

Some ions can pass through others cannot

Uneven distribution

31
Q

Factor of Resting Potential - Sodium-Potassium Pump

A

Moves 3 Na+ out for every 2K+ in

Uneven distribution

32
Q

Neuron Equilibrium Equations

A

To calculate the equilibrium of one ion -> Nerst equation

All relevant ions -> Goldman equation

Resting membrane potential: -70mV

33
Q

Action Potential

A

“All or nothing”

Mechanical or chemical (neurotransmitter) input causes depolarization of the cytoplasm when sodium enters the cell (stretching of ion channels, or gated ion channels)

Lots of sodium outside, not as much inside – it floods in and makes the inside more positive in charge

If the potential reaches –55mV, an AP is triggered

Na+ is concentrated outside the cell

Depolarization caused by Na+
influx when channels open (voltage-gated)

K+ is concentrated inside the cell, so moves outward. It takes longer for K+ channels to open compared to Na+ channels!

Refractory period caused by efflux of K+ (because delay in channel opening) - cell becomes temporarily hyperpolarized

33
Q

Refractory Periods

A

Absolute refractory period:

sodium channels inactivate when the membrane becomes strongly depolarized. They cannot be activated again, and another action potential cannot be generated until the polarization becomes low enough

Relative refractory period:

the membrane potential stays hyperpolarized until the voltage-gated potassium channels close. An action potential can be generated but requires a stronger depolarization to do so

34
Q

Saltatory Conduction

A

Ions cannot flow in and out of the cell across fatty tissues, and so they flow directly towards the next node without activating ion channels until they reach
an “open space” (which takes time)

Myelin allows current to spread further between nodes, and speeds up AP conduction

35
Q

Chemical Messengers

A

Electrical and chemical synapses

Neurotransmitter families
- Cholinergic, catecholaminergic, serotonergic, amino acids

Receptor families
- G-proteins, transmitter-gated channels

Pharmaceuticals
- Agonists, antagonists

36
Q

Types of Synapses

A

Electrical

  • Occur at specialized sites called gap junctions
  • Membranes of two cells are very close together (3nm); the gap contains proteins called connexins
  • Allow direct transfer of ionic current from one cell to the other (very fast)

Chemical

  • Presynaptic and postsynaptic membranes are separated by a 20- 50nm cleft (10x the width of gap junctions)
  • Many specialized components on both sides help to convert chemicals (i.e., neurotransmitters) from the presynaptic neuron into electrical signals on the postsynaptic side (a much slower process)
37
Q

Electrical Synapses

A

6 connexins = 1 connexon

2 connexons = 1 gap junction channel

Each gap junction channel bridges the cytoplasm of two cells. Ions and small molecules can travel in both directions.

Many gap junction channels create one “gap junction”

Fast and reliable! Cells connected this way are “electrically coupled”

PSPs generated at a single gap junction are very small, but neurons form gap junctions with many cells – many PSPs generated at the same time can add together to generate an AP

38
Q

Chemical Synapses

A

The cleft is filled with fibrous proteins that act as a “glue” to hold the two cells together

Presynaptic side:

  • Site of release is called an active zone
  • Contains many synaptic vesicles that hold neurotransmitters (produced in the cell body and then transported to the presynaptic site)
  • Contains voltage-gated calcium channels

Postsynaptic side:

  • Protein clusters known as postsynaptic density contain neurotransmitter receptors
  • This is where the chemicals (neurotransmitters) bind and become translated into a change in membrane
    potential (electricity)
  • The postsynaptic response varies depending on what kind of receptor is activated (ionotropic vs metabotropic)
39
Q

Chemical Synapses: Presynaptic Activity

A

Action potential arrives at the presynaptic terminal

Voltage-gated calcium channels are opened in response to changing cell potential – calcium enters the presynaptic cell rapidly

Calcium influx triggers synaptic vesicle exocytosis

Vesicles are recycled back into the cell via endocytosis

40
Q

Chemical Synapses: Postsynaptic Activity

A

Neurotransmitters are like a “key in a lock” - you need the right key to activate each receptor

Transmitter-Gated Ion Channels:
- Transmitters trigger conformational change that opens a pore between subunits
- Consequences depend on which ions can pass through the channel
- Not as selective as voltage-gated channels (e.g., ACh activated channels allow passage of both Na+ and K+)

G-protein Coupled Receptors:
- Slower and longer-lasting effects than transmitter-gated ion channels
- More steps involved
- Receptors activate g-proteins
- G-proteins activate effector proteins
(ion channels or enzymes)

41
Q

Ionotropic Receptors: EPSP/IPSP

A

Excitatory Postsynaptic Potential (EPSP):

  • If the open channels are permeable to Na+ then the net effect is to depolarize the postsynaptic cell (i.e., take the cell closer to triggering an action potential)

Examples: ACh-hated and glutamate-gated ion channels

Inhibitory Postsynaptic Action Potential (IPSP):

  • If the open channels are permeable to Cl then the net effect is to hyperpolarize the
    postsynaptic cell (i.e., take the cell further from triggering an action potential)

Examples: GABA and glycine-gated ion channels

42
Q

EPSP Summation

A

Not every EPSP triggers an action potential. Most EPSPs are very small (A)

Spatial summation (B) occurs when many nearby synapses each generate an EPSP to generate a larger depolarization when added together

Temporal summation (C) occurs when a synapse fires multiple times in short succession (before the cell has time to repolarize)

43
Q

IPSP Shunting

A

If the resting membrane potential is already - 65mV, no IPSP will be visible (membrane potential already = reversal potential for Cl)

So what effect is the IPSP having on cell signaling?

When an EPSP depolarizes the cell membrane and the current flows towards the soma, the current may pass by an active inhibitory synapse

Positive current here will flow out of the cell,
redirecting the excitatory potential away from the soma

The inhibitory synapse acts as a “shunt” and prevents an action potential from being generated

44
Q

Neurotransmitter Families

A

Cholinergic:
- Present at neuromuscular junction
- Produced by all motor neurons in the spine and brainstem
- Examples: Acetylcholine

Catecholaminergic:
- Tyrosine is the precursor of all catecholaminergic neurotransmitters
- Regulate movement, mood, attention, and visceral function
- Examples: dopamine, norepinephrine, epinephrine

Serotonergic:
- Tryptophan is the precursor of
serotonergic neurotransmitters
- Plays a role in regulating mood, emotional behaviour, and sleep
- Examples: serotonin

Amino Acid:
- Literally amino acids (building blocks of proteins)
- Very small
- Examples: glutamate (excitatory), glycine, GABA (inhibitory

Other:

ATP
- excitatory

Endocannabinoids
- retrograde messengers

Nitric Oxide
- gaseous, membrane permeable

45
Q

Receptor Agonists vs. Antagonists

A

Like neurotransmitters, many drugs bind to receptors to exert an effect on the nervous system

Agonists
- Bind to receptors and imitate the actions of neurotransmitters
- Effect looks similar to response to naturally-occurring neurotransmitter release
- Example: nicotine (binds to ACh receptors, mimics ACh function – muscle activation)

Antagonists
- Binds to receptors and inhibits (antagonizes) their function
- Blocks the action of naturally-occurring
neurotransmitters
- Example: curare (binds to ACh receptors, prevents ACh function at the neuromuscular junction – paralysis)

Neuroscience (5 decks)

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