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Nervous System Flashcards

1
Q

What is the nervous systems function?

A

The Nervous system allows us to sense and respond to conditions inside and outside the body.

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2
Q

What germ layer does the nervous system develop from?

A

The nervous system develops from the ectoderm

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3
Q

What does the CNS consist of?

A

The Central Nervous System consists of the brain and spinal cord.

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4
Q

What does the PNS consist of?

A

The Peripheral Nervous System consists of cranial nerves, spinal nerves, and associated ganglia.

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5
Q

What is a cranial nerve and how many are there?

A

A cranial nerve connects the brain to organs mainly in the upper head / body.

There are 12 pairs of cranial nerves.

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6
Q

What are the spinal nerves and how many are there?

A

The spinal nerves connect the spinal cord to parts of the body below the head.

There are 31 pairs of spinal nerves.

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7
Q

What are the two subdivisions of the PNS?

A

The Peripheral nervous system consists of two subdivisions:

  • Somatic Nervous System: Voluntary. Will carry impulses to skeletal muscles, tendons, and skin
  • Autonomic Nervous System: Involuntary. Impulses are carried to cardiac muscle, smooth muscle, or glands.
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8
Q

What are the three subdivisions of the autonomic nervous system?

A

The three subdivisions of the autonomic nervous system are:

  • sympathetic: Fight or Flight, energy generation. (increased heart rate, tense muscles, blood vessels constrict, all digestion stops)
  • parasympathetic: Rest and Digest, calmness. (decreased heart rate, dilated blood vessels, digestion)
  • Enteric: controls the secretory and motile functions of the digestive tract
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9
Q

What is a motor neuron?

A

Also known as efferent, a motor neuron relays signals from the brain or spinal cord to muscle or gland cells.

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10
Q

What is a sensory neuron?

A

Also known as afferent, a sensory neuron relays signals from the internal and external environment to the CNS.

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11
Q

What is the Pneumonic for Motor and Sensory neurons?

A

SAME
Sensory - afferent
Motor - efferent

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12
Q

What is a ganglion?

A

A ganglion is a mass of neuron cell bodies usually found outside the CNS

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13
Q

What is a Neuron composed of?

A

A neuron is the basic unit of nervous tissue, it is a nerve cell including cell body (soma), axon, and dendrites

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14
Q

What is the difference between an axon and a dendrite?

A

An axon conducts neural impulses away from the cell body (soma)

A dendrite conduct neural impulses toward the cell body (soma)

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15
Q

How many neurons are in the body?

A

There are over 100 billion neurons in the body.

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16
Q

How do neurons reproduce?

A
  • THEY DON’T!
  • They are so specialized that they are incapable of reproducing themselves.
  • Replacing old neurons with new neurons would literally “erase” our memory away, thus there is no mitosis in these cells.
  • There ability for regeneration is very poor.
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17
Q

Describe the nucleus and organelles of the neuron

A

The neuron has the following organelles:

  • Nissl bodies ( A specialized neural cell organelle that is essentially a large complex of rough ER and ribosomes)
  • mitochondria
  • ribosomes
  • golgi apparatus
  • lysosomes
  • The nucleus is large
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18
Q

What are nissl bodies?

A

Nissl bodies are specialized organelles in the neuron that are composed of large branching Rough ER and ribosomes.

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19
Q

Describe the brains relationship to glycogen

A
  • Glycogen is stored in the brain, but not at the same levels as the liver or skeletal muscle.
  • Glycogen is stored in specialized non-neuronal cells called astrocytes.
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20
Q

What are glial cells?

A

Glial cells surround neurons and provide support and protection for them. Glial cells represent the most abundant cell in the CNS. They include:

  • Astrocytes
  • Oligodendrocytes
  • Schwann Cells
  • Microglia
  • Satellite cells,
  • Ependymal cells
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21
Q

What is an Axon?

A
  • An axon is an extension of a neuron that carries nerve impulses away from the cell body (soma) to target cells such as the nerve, muscle, or gland cells.
  • No neuron has more than a single axon.
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22
Q

What is a Dendrite?

A

A dendrites are highly branched neuronal extensions that bring nerve impulses toward the cell body (soma)

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23
Q

Where are mitochondria located in the neuron?

A

Mitochondria are found scattered all over the cytoplasm of the cell body, axon, and dendrites, but it is most abundant at the axon terminals

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24
Q

What are axon terminals?

A

Axon terminals are the end of the axon where neurotransmitters get released into the synapse

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25
Q

What are astrocytes?

A

Astrocytes are star shaped cells found in the brain.

  • most numerous glial cell
  • regulate electrical impulses
  • provide neurons with lactate for nutrients
  • contain channels for K+ transport
  • regulates blood flow
  • takes part in neural repair
  • stores glycogen
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26
Q

What are oligodendrocytes?

A

Oligodendrocytes make myelin in the CNS

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27
Q

What are schwann cells?

A

Schwann cells make myelin in the PNS

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28
Q

What is the blood brain barrier?

A

The blood brain barrier consists of high density endothelial cells that prevent the passage of pathogens, antibiotics, and chemicals into the brain.

  • Some molecules such as CO2, O2, water, glucose, and amino acids can cross.
  • Bottom line: It protects the brain from toxic substances and pathogens
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29
Q

What is multiple sclerosis?

A

Multiple Sclerosis is an auto-immune disease

  • A part of the blood brain barrier breaks down allowing T-lymphocytes to cross over and attach the myelin sheath.
  • It results in communication issues with your brain and the rest of the body.
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30
Q

What is epilepsy

A

Epilepsy is uncontrolled seizures.

- Also shown to be caused by failures of the blood brain barrier.

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31
Q

What happens when the sympathetic nervous system is stimulated?

A

When the sympathetic nervous system is stimulated it:

  • Increases heart rate
  • Increases blood pressure
  • Increases respiration
  • Increases blood flow to skeletal muscles
  • Pupil Dilation
  • Stimulates adrenal medulla (epinephrine and norepinephrine)
  • Stimulates glycogenolysis
  • Slows intestinal and stomach movements
  • Salivary gland secretion decreases
  • Decreases urine production
  • Relaxes urinary bladder (takes away urge to pee)
  • Fight or Flight
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32
Q

What happens when the parasympathetic nervous system is stimulated?

A

When the parasympathetic nervous system is stimulated:

  • Decreases heart rate
  • Decreases blood pressure
  • Decreases blood flow to skeletal muscles
  • Pupil constriction
  • Stimulates intestinal and stomach movements
  • Salivary gland secretions increase
  • Increases urinary production
  • Tenses urinary bladder (makes you want to pee)
  • Rest and digest
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33
Q

What is the enteric nervous system?

A

The enteric nervous system is part of the autonomic nervous system.

  • It extends the entire length of the alimentary tract (esophagus to anus)
  • It controls the secretory and motile functions of the digestive tract
  • Contains a large number of neurons (100 million), that’s more than the spinal cord.
  • Sometimes dubbed the second brain, it can work independent of parasympathetic or sympathetic systems, or in tandem with them.
  • Makes over 30 neurotransmitters
  • 90% of our serotonin and a good percentage of our dopamine is made here.
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34
Q

What is the myelin sheath?

A

The Myelin sheath is a fatty substance surrounding some axons that increase the speed of impulse along the axon

  • Electrically insulating
  • needed for proper functioning
  • made up of cholesterol, lipids, and about 20% proteins
  • Made by schwann cells in the PNS
  • Made by oligodendrocytes in the CNS
  • Unmyelinated fibers have slower impulse speed
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35
Q

Where are myelinated axons found in the brain?

A

In the brain:

  • Grey matter: consists of mainly unmyelinated axons
  • White matter: consists of mainly myelinated axons
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36
Q

What is the axolemma

A

The axolemma is the cell membrane surrounding the axon.

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37
Q

What are the nodes of Ranvier?

A

The nodes of ranvier are gaps between adjacent schwann cells.

  • At these nodes, the axolemma is especially permeable to Na+ and K+.
  • These nodes are only present when the axon is myelinated
  • Action potentials can jump between these nodes in what is called saltatory conduction.
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38
Q

What is saltatory conduction?

A

As the neural impulse travels down the axon, it starts to lose some of its strength. At the nodes of ranvier, the impulse of the axon triggers the release of more action potential effectively boosting the signal of the impulse. This perpetual boosting of the signal through the myelinated axon increases the speed dramatically vs an unmyelinated axon.

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39
Q

What is the difference in speed between a myelinated and unmyelinated neuron?

A
  • A Myelinated neuron can transmit an impulse at 120 m/s

- An unmyelinated neuron can transmit an impulse at less than 1 m/s

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40
Q

What is the cerebrum?

A

The cerebrum is:

  • The largest part of the mature brain (80%)
  • Consists of two hemispheres connected by a deep bridge of nerve fibers called the corpus callosum
  • Each hemisphere is surrounded by an outer covering of grey matter called the cerebral cortex
  • The inner portion of the cerebrum consists of white myelinated matter that acts as the communication portion of the brain.
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41
Q

What is the corpus callosum?

A

The corpus callosum is a deep bridge of nerve fibers that connects the two hemispheres of the brain.

  • It is composed of white matter for quick communication between hemispheres
  • It is the largest white matter structure in the brain
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42
Q

What is the cerebral cortex?

A

The cerebral cortex is the outer covering of grey matter that surrounds the cerebrum.
- Cortex means outermost layer. Cerebral means of the cerebrum

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43
Q

What does the brain’s gray matter consist of?

A

The gray matter consists of:

  • Unmyelinated portions of axons
  • cell bodies
  • glial cells
  • dendrites

Most of the brain’s neuronal cell bodies are here.

They gray matter includes regions of the brain involved with seeing, hearing, memory, speech, emotion, and decision making, among others

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44
Q

What does the brain do to pack more gray matter in a smaller space?

A

The cortex is wrinkled to allow more gray matter to fit into the small amount of space in our skull. The wrinkles are called covolutions or gyri, which are separated into two categories:

  • Shallow groove: sulcus
  • Deep groove: Fissure
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45
Q

What are the four lobes of the brain?

A

The four lobes of the brain include:

  • Front
  • Parietal
  • Occipital
  • Temporal

This is sufficient for the DAT

46
Q

What does the brain’s white matter consist of?

A

The brain’s white matter:

  • connects various areas of gray matter to each other and carry impulses between neurons.
  • Bundles of nerve fibers are called tracts.
  • Tracts are used to describe the myelinated axons of the white matter
  • Bottom Line: White matter is a relay and communication region of the brain.
47
Q

What is the basal ganglia?

A

The basal ganglia:

  • located in the deep white matter
  • Allows us to feel the passage of time.
  • Helps us select the behaviors associated with decisions
48
Q

What is the meninges

A

The meninges are three membranes that envelope the brain and the spinal cord.

  • Dura Mater:
    • Outermost layer
    • Many Nerves and blood vessels
    • Tough and Fibrous
  • Arachnoid Mater
    • Middle Layer
    • No blood vessels
    • Thin delicate layer
  • Pia Mater
    • Innermost Layer
    • Very Vascular
    • Intimately attached to the brain and spinal cord
49
Q

Where is CNS located in the meninges?

A

CNS is located between the Arachnoid Mater and the Pia Mater in the meninges.

50
Q

What is inflammation of the Meninges called?

A

Inflammation of the meninges is called Meningitis

  • It can be bacterial or viral
  • It will usually involve the arachnoid and pia maters
51
Q

What part of the body does the right and left hemisphere of the brain control?

A

The right hemisphere of the brain controls the left side of your body and vice versa

52
Q

What is the cerebellum?

A

The cerebellum

  • is involved with balance and muscle coordination
  • fine motor movement (ex: moving your finger tip)
  • equilibrium
  • posture
  • motor learning
53
Q

What parts of the brain control fine motor movement?

A

The parts of the brain that control fine motor movement are:

  • The cerebellum
  • The basal ganglia, which includes
    • Caudate nucleus
    • Putamen
    • Globus Pallidus
54
Q

What is the hypothalamus?

A

The Hypothalamus is:

  • the link between the endocrine and the nervous system
  • part of what is called the limbic system, dealing with emotions, motivation, behavior, and is still very unknown.
  • Makes ADH and oxytocin and releasing hormones.
  • Involved with a range of bodily functions including:
    • fluid balance
    • blood pressure
    • body temperature
    • maintaining homeostasis
    • emotions
    • sex drive
    • thirst
    • production of digestive juices
  • Main take away: Link between nervous system and endocrine system
55
Q

What makes up the limbic system?

A

The limbic system, is a complex system that deals with emotions, motivation, memory, and behavior. It’s still very unknown. It’s made up of the:

  • Hypothalamus
  • amygdala
  • hippocampus
  • thalamus

The Hippocampus is associated with long term memory. The rest we don’t need to know in any more detail

56
Q

What is the Medulla Oblongata?

A

The Medulla Oblongata:

  • Helps regulate functions such as breathing, heart rate, swallowing, and digestion
  • Center for respiration and circulation
  • Involved with involuntary functions
  • Contains both myelinated and unmyelinated fibers
  • Cardiac, respiratory, sneezing, and vomiting centers are located here.
  • Chemoreceptors can tell whether the blood is acidic or not. Chemoreceptors send signals to the medulla which can respond by increasing breathing rate
  • This part of the brain was very early to develop. It’s found fully developed in Agnathans (jawless fish, the first fish, hagfish and lampreys)
57
Q

What are Agnathans?

A

Agnathans are the first fish to have developed in the world.

  • Include: Hagfish and lampreys
  • They are jawless
  • Posses a fully developed medulla
58
Q

What is the Thalamus?

A

The Thalamus is:

- A relay station in the brain. It relays sensory information to the proper areas of the brain.

59
Q

What is Tay-Sach’s disease?

A

Tay-Sach’s disease is a disease that is caused from a deficient lysosomal enzyme that’s involved with lipid breakdown.

  • Neurons are destroyed in the brain and spinal cord
  • The ganglioside (type of lipid) content of the brain is elevates in an infant.
  • The disease is usually fatal by the age of 3
60
Q

What is the cerebrospinal fluid?

A

The cerebrospinal fluid bathes, nourishes, and protects the brain and spinal cord from injury

61
Q

What is the choroid plexus?

A

The choroid plexus is a network of cells that produce cerebrospinal fluid.

  • Found in the ventricles of the brain
  • The plexus consists of cells called ependymal cells.
  • Also involved with removing waste, excess neurotransmitter, and foreign substances from the cerebrospinal fluid.
  • Four Ventricles are involved, within these cavities you find the choroid plexus
62
Q

What are Microglia?

A

Microglia are phagocytic cells located in the CNS. They account for 5% of the glial cells

63
Q

What is a stroke?

A

A stroke is when blood flow is shut off to a certain area of the brain. Deprivation of O2 causes cell death. Symptoms include:

  • Trouble with speaking
  • numbness of the arm, leg, or face
  • visual problems
  • headache
  • trouble walking
64
Q

What is TIA?

A

TIA is a transient ischemic attack (mini stroke). It occurs when a clot or debris blocks the flow of blood to your brain.

65
Q

What are the three classes of neurons?

A

The three classes of nuerons are:

  • Sensory (afferent)
  • Interneuron
  • Motor (efferent)
66
Q

What is a sensory neuron

A

Sensory (afferent) neurons are closely related with receptor cells.
- They respond to external stimuli or internal conditions and relay them to brain and spinal cord.

67
Q

What is an interneuron?

A

An interneuron is located between sensory and motor neurons

  • Integrates sensory input and motor output
  • Acts as a relay station for impulses between sensory and motor neurons
68
Q

What is a motor neuron?

A

A motor neuron (efferent) carries impulses out from the brain or spinal cord to effectors such as muscles or glands

69
Q

What are mixed nerves?

A

Most nerves are mixed nerves, a mixture of sensory and motor fibers

70
Q

What is an axon hillock?

A

An axon hillock is the part of the cell body that connects to the axon.
- This is where action potentials originate

71
Q

What is a synapse?

A

A synapse is the junction where one neuron communicates with another neuron.
- Neurotransmitters diffuse across here.

72
Q

What is a pre-synaptic cell?

A

A pre-synaptic cell stores the neurotransmitters like acetylcholine in vesicles.
- Can be a muscle, neuron, or even a gland.

73
Q

What is a post-synaptic cell?

A

A post-synaptic cell is the cell that has receptors that bind to specific neurotransmitters

74
Q

What is the synaptic cleft?

A

The synaptic cleft is the space between the pre-synaptic and post-synaptic membrane

75
Q

What is the default resting state charge of a neuron?

A

A neuron is negative at its resting state.

  • A sodium-potassium pump is actively pumping 3 Na+ ions out for every 2 K+ ions in against their gradient to maintain this negative resting potential.
  • There are large negatively charged proteins in the neuron that don’t move outside the membrane.
  • There also exists Cl- ions that generally reside in the neuron as well.
76
Q

Explain how Na+ and K+ contribute to a negative resting neuron potential

A
  • At a neuron’s resting potential, there is a high concentration of K+ ions inside the cell, and a high concentration of Na+ ions outside the cell.
  • Both want to travel down their gradient to either get out of the cell (K+), or get into the cell (Na+).
    There also exists an electrical gradient. Both K+ and Na+ want to get into the cell since from an electrical gradient perspective, since the cell is more negative.
  • If K+ could flow impeded out of the cell without Na+ moving, there would be a net negative increase in potential
  • If Na+ could flow impeded into the cell, there would be a net positive increase in potential.
  • The sum of the electrical and concentration gradients, as well as the active pumping of 3 Na+ ions out for every 2 K+ ions in by the sodium-potassium pump against their gradient, makes it so there is a net negative charge across the cell membrane.
77
Q

What happens when there is a nerve impulse?

A
  • A nerve impulse will open up the Na+ ion channels which cause Na+ to flow into the neuron.
  • This brings the potential to a positive value.
  • As this happens we see a large change in the membrane voltage. This is action potential.
  • If the potential is high enough, it will carry the impulse along the axon.
78
Q

What is depolarization?

A

Depolarization occurs when Na+ ion channels open and the membrane potential swings to positive.
- We can see a swing of -70 mV to +40 mV during a nerve impulse.

79
Q

What is hyperpolarization?

A

Hyperpolarization occurs when K+ ion channels open and the cell becomes more negative.
- This is an inhibitory stimulus

80
Q

What is a voltage gated channel?

A

A voltage gated channel is a class of transmembrane proteins that form channels that can open or close due to a voltage.

  • They are usually ion specific.
  • We see voltage gated channels for Na+, K+, Cl-, and Ca++.
81
Q

What is a neuron threshold?

A

A nueron cell must reach a certain voltage before it can trigger.

  • For most mammalian neurons, the voltage must increase to -55 mV for an action potential to occur and the neuron to trigger.
  • These can be additive. If multiple dendrites are sending signals to open positive Na+ channels, then their combined effect can increase to the threshold amount where a single one would have failed.
82
Q

What is the refractory period?

A

After a neuron has generated an action potential, there is a short refractory period before it can trigger again. There are two parts:

  • Absolute Refractory Period: No stimulus, no matter how strong can generate another action potential. This is due to the Na+ pumps deactivating for a short time after it hits its max voltage.
  • Relative Refractory Period: The Na+ pumps are active, but a hyperpolarization has occurred that makes the cell more negative than usual. Therefore, a very strong stimulus would be needed to generate an action potential.
83
Q

How does the strength of the stimulus affect the strength of the nerve impulse along the axon?

A

IT DOESN’T

  • Speed is constant along the axon once an action potential is generated.
  • A stronger impulse can generate more action potentials, but it won’t affect the speed of the impulse down the axon.
84
Q

Are neurons bidirectional, unidirectional, or multidirectional?

A

Neurons are unidirectional.

Pre-synaptic cell -> Synaptic Cleft -> Post-synaptic Dendrite -> Cell body -> Axon Hillock -> Axon -> Presynaptic Cleft.

85
Q

How do dental injections prevent pain from occuring?

A

Dental injections block Na+ channels from opening up at pain receptors, thus blocking the action potential from generating.

86
Q

How is the diameter of the axon related to its speed?

A

The larger the diameter, the faster the impulse can move along the axon.

-NB: Know for the DAT

87
Q

Describe how a pre-synaptic neuron releases neurotransmitters into the synaptic cleft.

A

A pre-synaptic neuron releases neurotransmitters through the following process:

  • Neurotransmitters exist in the cell inside vesicles bound to membrane proteins on the inside of the cell membrane.
  • When the action potential arrives, Ca++ voltage gated channels open and Ca++ moves into the cell across its concentration gradient.
  • Ca++ binds to the membrane proteins, causing the proteins to undergo a conformational change that fuses the vesicle into the membrane and exocytoses the neurotransmitter into the synaptic cleft
  • The neurotransmitter then binds to the post-synaptic cell membrane’s receptors.
  • The receptors can be inhibitory or excitatory. If it’s inhibitory, it will cause K+ to flood into the neuron. If it’s excitatory, it will cause Na+ to flood into the neuron.
88
Q

What happens to the neurotransmitters after they have bound to the receptors?

A

After neurotransmitters bind to the receptors, they can:

  • Diffuse away
  • Be broken down by enzymes
  • Be taken up by the synaptic terminal
89
Q

What is acetylcholine?

A

Acetylcholine is a neurotransmitter involved with learning and memory enhancement.
- It also is the chief neurotransmitter of the parasympathetic nervous system

90
Q

What is Dopamine?

A

Dopamine is a neurotransmitter involved with keeping focused, paying attention, and promoting feelings of pleasure

  • It is a catecholamine like epinephrine and norepinephrine
  • It’s classified as only a neurotransmitter, but there’s debate as to whether it should be classified as a hormone as well.
91
Q

What is Serotonin?

A

Serotonin is a nuerotransmitter that is involved with keeping you happy. Depression can occur with deficiency

92
Q

What is norepinephrine?

A

Norepinephrine is both a hormone and a neurotransmitter involved with mental alertness and memory

93
Q

What is GABA?

A

GABA is the body’s inhibitory neurotransmitter. It keeps you calm and without anxiety.
- Alcohol is thought to mimic the effect of GABA in the brain, decreasing anxiety and inhibitions.

94
Q

What is Glycine?

A

Glycine is a neurotransmitter that works with GABA to help decrease anxiety among other functions

95
Q

What are the chief neurotransmitters of the sympathetic and parasympathetic nervous systems?

A
  • The chief neurotransmitters of the sympathetic nervous system are norepinephrine and epinephrine.
  • The chief neurotransmitter of the parasympathetic nervous system is acetylcholine
96
Q

What are neuropeptides?

A

Neuropeptides are small peptide molecules that can be used as neurotransmitters by nerve cells for communication.

  • These small molecules can bind to cell surface receptors.
  • Example: Substance P is made up of 11 amino acid residues and is involved with pain and inflammation.
97
Q

What are endorphins?

A

Endorphins are our bodies natural analgesics that decrease our perception of pain.

  • These are a type of neuropeptide
  • They also produce a euphoric or happy feeling in us.
  • Laughing and running are activities that increase endorphins. This is what the runners high is.
98
Q

What are nerves like in cnidaria?

A

Cnidaria include hydra and sea anemones.
- They contain a loose mesh of nerve cells called a nerve net. These nerves can interact with sensory and contractile cells.

99
Q

What are nerves like in arthropods?

A

Arthropods have a small, but intricate nervous system that allows them to detect and respond to the world around them.

  • They posses a brain and a ventral nerve cord.
  • Despite their small size, many insects have axons bigger than what is seen in humans. Thus their fast speed.
100
Q

What are nerves like in flat worms?

A

Flatworm nerves

  • Contain nerve net
  • Also have long nerve cords connected to cerebral ganglia in the head region.
  • Have bilateral nervous system, with long nerves running along the lengths of both sides, with transverse nerves connecting the two.
  • Earthworms have all of this, as well as a brain and ganglia.
101
Q

What are nerves like in Echinoderms?

A

Echinoderms (sea stars, sea urchins, sea cucumbers, and sand dollars)

  • Do not have brains
  • have nerves running along the mouth down each arm.
102
Q

What are nerves like in sponges?

A

They don’t have any!

  • Only multi-nucleated animal that lacks a nervous system
  • No nerve or sensory cells
103
Q

What is a reflex?

A

A reflex is an automatic, unconscious response to certain stimuli
- Helps to protect the body from harm

104
Q

What is a reflex arc?

A

A reflex arc is the pathway in which are reflexes occur. The path is as follows:

  1. Receptor (dendrite)
  2. Sensory neuron (relays impulse to CNS)
  3. Reflex center (composed of interneurons) makes arc
  4. Motor neuron conducts impulse to effector
  5. Effector (muscle or gland) reacts.

Example:

  • You touch a hot stove.
  • Pain receptors in your skin are stimulated and the message is sent to the the sensory neuron
  • The message is then sent to the spinal cord. (no decision by the brain is needed. The body just reacts involuntarily to the pain.)
  • At the reflex center in the spinal cord, interneurons transmit impulses to the motor neuron
  • The motor neuron transmits impulses to the effector.
  • The muscles contract and you move your hand, all without brain power!
105
Q

What is the structure of the spinal cord?

A

The spinal cord is made up of:

  • Gray matter (neurons found here): Looks like a butterfly.
  • White matter (axons found here): contains the spinal tracts, sensory, and motor
106
Q

Describe the two roots of the spinal cord

A

A spinal cord has two roots that emerge

  • Dorsal root: Transmits sensory information (sensory root)
  • Ventral root: This is the motor root and it carries information towards the limbs and organs.

Sucky DMV (Sensory Dorsal, Motor Ventral)

107
Q

How does a hyperpolarization occur in a neuron?

A

Hyperpolarization occurs either from the movement of K+ ions out of the neuron, or Cl- ions into the neuron.

  • This can be caused by inhibitory impulses or after an action potential has been reached, to repolarize the membrane
  • This hyperpolarization either completely prevents a new stimulus from being received by the neuron, or dramatically increases the threshold needed.
  • Eventually, the Sodium Potassium pump reestablishes the resting potential.
108
Q

What is EPSP?

A

EPSP is Excitatory Post-synaptic potential

- It’s an event that causes the release of Na+ ions into the neuron to increase depolarization

109
Q

What is IPSP

A

IPSP is Inhibitory Post-Synaptic Potential
- It’s an event that causes the release of K+ ions out of the cell, increasing the negative charge of the cell and causing hyperpolarization.

110
Q

How do EPSPs and IPSPs work together?

A

Many neurons in the CNS have both inhibitory and excitatory synapses

  • Neurotransmitters can be either excitatory or inhibitory.
  • Based on the effect of both EPSPs and IPSPs, the cell may or may not reach the action potential needed for the Na++ ion voltage gated channels to open at the axon hillock.
111
Q

What is temporal summation?

A

Temporal Summation involves a SINGLE synapse.

- EPSPs occur one after another and are added together where they overlap in charge

112
Q

What is spatial summation?

A

Spatial summation involves multiple synapses - EPSPs occur at the same time.

DAT Bio (46 decks)

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