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Anatomy & Physiology > Nervous System > Flashcards

Nervous System Flashcards

1
Q

Describe the structure of the peripheral NS

A
  • 12 pairs of cranial nerves
  • 13 spinal nerves
  • ganglion
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2
Q

Define a ganglion

A

a knot-like swelling in a nerve where neurone cell bodies are concentrated

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3
Q

What makes up the central nervous system ?

A

brain & spinal cord

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4
Q

What are the 2 types of cells in the nervous system ?

A
  • neurons
  • supporting cells
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5
Q

What makes up the autonomic division of the peripheral NS?

A
  • Sympathetic & parasympathetic
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6
Q

Describe a neuron

A
  • functional unit of the NS
  • properties = excitability, conductivity & secretions
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7
Q

Describe the cell body of nervous tissue

A
  • contains a nucleus surrounded by cytoplasm
  • contains typical cellular organelles
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8
Q

What are neurofibrils ?

A
  • composed of bundles of intermediate filaments
  • provides the cell shape & support
  • also made up one microtubules which asset in moving material between the cell body & axon
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9
Q

Describe Lipofuscin

A

a pigment that occurs as clumps of yellowish brown granules in the cytoplasm

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10
Q

What are Nissl Bodies ?

A

free ribosomes and prominent closures of RER in the neuronal cell bodies

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11
Q

What are the variations of neuron structure ?

A
  • multipolar
  • unipolar
  • bipolar
  • anaxonic
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12
Q

What are the 3 functional classes of neurones ?

A
  • sensory (PNS)
  • motor (PNS)
  • interneurons (CNS)
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13
Q

What are the supportive cells in the nervous system ?

A
  • astrocytes
  • oligodendrocytes-myelin (CNS)
  • Ependymal cells
  • microglial cells
  • Schwann & Satellite cells (only PNS)
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14
Q

What are the 2 types of astrocytes ?

A

protoplasmic & fibrous

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15
Q

Define protoplasmic astrocytes

A

have many short branching processes and are found in grey matter

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16
Q

Describe fibrous astrocytes

A

they have many long unbranched processes and are located mainly in the white matter

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17
Q

Describe astrocytes

A
  • contain microfilaments that give them considerable strength, allowing them to support neurons
  • regulates the extracellular space & ion conc.
  • may play a role in learning and memory by influence the formation of neural synapses
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18
Q

Describe microglia

A
  • function as phagocytes - removes microbes & damaged nervous tissue
  • they remove cellular debris formed during normal development of the NS
  • 10% of total brain cell population
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19
Q

Describe oligodendrocytes

A
  • looks similar to astrocytes due to their projections
  • involved in forming & maintain the myelin sheath around CNS axons
  • a single oligodendrocyte myelinates several axons
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20
Q

Describe Ependymal cells

A
  • these cells line the ventricles of the brain & central canal of the spinal cord
  • cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia
  • produce & assist in the circulation of cerebrospinal fluid
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21
Q

Describe Schwann Cells

A
  • they encircle the PNS axons, form the myelin sheath around the axons
  • 1 Schwann cells myelinates 1 axon
  • participates in axon regeneration
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22
Q

Describe satellite cells

A
  • flat cells that surround the cell Bodie of neurons of PNS ganglia
  • provides structural support
  • regulates the exchanges of materials between neuronal cells bodies and interstitial fluid
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23
Q

What are the gaps in the myelin sheath called ?

A

nodes of ranvier

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24
Q

Define graded potentials

A

used for short distance communication only

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24
Q

What are the steps in sensory transduction ?

A
  • stimulus
  • receptor
  • change in ionic permeability or afferent nerve
  • generation of action potential
  • propagation of action potential
  • integration of information by CNS
25
Q

Define action potentials

A

allows communication over long distance within the body

26
Q

What is the electrical potential difference termed ?

A

resting membrane potential

27
Q

Describe Ion channels

A
  • allows the diffusion of ions like K+ & Na+
  • some ion channel are gated = they only allow flow following certain stimuli
  • maintains the resting membrane potential of the cell
28
Q

Describe a ligand-gated channel

A

Opens & closes in repose to a specific chemical stimulus, such as acetylcholine/neurotransmitters/hormones

29
Q

Describe a mechanically gated channel

A

It opens/closed in response to mechanical stimulation in the form of vibration, touch, pressure or tissue stretching
- the force distorts the channel from its resting position, opening the gate

30
Q

Describe a voltage-gated channel

A

Opens in response to a change in membrane potential
- voltage-gated channels participate in the generation & conduction of action potentials

31
Q

Why does the resting membrane potential exist ?

A

because of a small build-up of negative ions in the cytosol along the inside of the membrane, and an equal build-up of positive ions in the extracellular fluid on the outside surface of the membrane

32
Q

The resting membrane potential arises from what 3 major factors ?

A
  1. unequal distribution of ions in the ECF & cytosol
  2. inability of most anions to leave the cell
  3. electrogenic nature of the Na/K ATPases
33
Q

Describe the unequal distribution of ions in the ECF & cytosol

A
  • extracellular fluid is rich in Na+ and chloride ions (Cl-)
  • in cytosol the main cation is K+ and the 2 dominant anions are phosphates attached to molecules, such as 3 phosphates in ATP, and amino acids in proteins
34
Q

Describe the inability of most anions to leave the cell

A
  • most anions inside the cell are not free to leave
  • they cannot flow the K+ out of the cell because they’re attached to non-diffusible molecules such as ATP & large proteins
35
Q

Describe the electrogenic nature of the Na/K ATPases

A
  • small inward leak of Na+ and outward leak of K+ is offset by the Na+/K+ ATPases (sodium-potassium pumps)
  • these pumps remove more positive charges from the cell than they bring it
  • they are electrogenic = they contribute to the negativity of the resting membrane potential
36
Q

Describe a graded potential

A
  • small devotion from the membrane potential that makes the membrane either more polarised or less polarised
37
Q

Define hyperpolarising graded potential

A
  • when a response makes the membrane more polarised (inside is more negative)
38
Q

Define a depolarising graded potential

A

when a repose makes the membrane less polarised (inside is less negative)

39
Q

When do graded potentials occur ?

A

when a stimulus causes mechanically gated or ligand-gated channels to open or close in an excitable cell’s plasma membrane

40
Q

What does the amplitude of a graded potential depend on?

A
  • stimulus strength
  • the greater the stimuli strength, the larger the amplitude of the graded potential
41
Q

Define an action potential

A

A sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restored it to the resting state

42
Q

What are the 2 main phases of an action potential ?

A
  1. depolarising
  2. depolarising
43
Q

What occurs in the depolarising phase ?

A
  • when the membrane potential of axon reaches threshold, the Na+ channel activation gates open
  • As Na+ ions move through these changes into the neuron, a build up of positive charges form along inside surface of membrane and the membrane becomes depolarised
44
Q

What occurs during the repolarisation phase ?

A
  • Na+ channel inactivation gates close and the K+ channels open
  • the membrane starts to become repolarised as some K+ ions leave the neuron and a few negative charges begin to build-up along the inside surface of the membrane
  • K+ outflow continues, more negative charge builds along the inside surface of the membrane
  • K+ outflow eventually restores the resting potential
  • Na+ channel inactivation gates open
  • returns to resting state when K+ gates close
45
Q

What occurs during the resting state ?

A
  • all voltage-gated Na+ and K+ channels are closed
  • the axon plasma membrane is at resting membrane potential
  • small build-up of negative charges along the inside surface of the membrane, and an equal build-up of positive charges along the outside surface of the membrane
46
Q

Define Propagation

A
  • conduction of action potentials across larger distances in the body
47
Q

Describe what occurs at a chemical synapse

A
  • nerve impulse arrives at a synaptic end build of a presynaptic axon
  • depolarising phase opens voltage-gated Ca2+ channels
  • Ca2+ flows inward through the opened channels
  • increase in Ca2+ inside presynaptic neuron triggers exocytosis of the vesicles
  • neurotransmitters diffuse across cleft & bind to receptors on postsynaptic neuron plasma membrane
  • binding triggers opening of ligand-gated channels
  • ions flow through opened channels chaining the voltage –> post synaptic potential
48
Q

Describe a excitatory postsynaptic potential

A
  • a neurotransmitter that depolarises the post synaptic membrane is excitatory as it brings the membrane closer to threshold
49
Q

Describe an inhibitory postsynaptic potential

A

a neurotransmitter that causes hyper polarisation is inhibitory
- generation of action potential is more difficult as the membrane potential is more negative and thus even further from threshold

50
Q

What are the 3 layers of the meninges ?

A

Dura mater, arachnoid & pia mater

51
Q

What are the 5 lobes of the cerebellum ?

A

frontal, insula, parietal, occipital, temporal

52
Q

What are the key functions of the frontal lobe ?

A
  • abstract thought
  • mood
  • explicit memory
  • decision making
53
Q

What are the key features of the insular lobe ?

A
  • taste
  • pain
  • visceral sensation
  • consciousness
54
Q

What are the key functions of the parietal lobe?

A
  • somatic sensation
  • sensory integration
  • language processing
55
Q

What are the key functions of the Occipital lobe ?

A

visual awareness & processing

56
Q

What are the key functions of the temporal lobe ?

A
  • hearing
  • smell
  • emotion
  • learning
  • verbal memory
57
Q

What is the homunculus ?

A

a cortical homunculus is a distorted representation of the human body, based on the neurological ‘map’ of areas and proportions of the brain dedicated to processing motor functions and/or sensory functions

58
Q

Left hemisphere functions

A
  • specialised for spoken & written language
  • sequential & analytical reasoning
  • breaks info into fragments & analyses
59
Q

Right hemisphere functions

A
  • perceives information in a more integrated way
  • seat of imagination & insight
  • musical & artistic skill
  • comparison of sights, sounds, smells and tastes
60
Q

What are the functions of the spinal cord ?

A

conduction, neural integration, locomotion, reflexes

61
Q

Describe the role of the cerebellum in motor control

A
  • maintains muscel tone & posture
  • coordinates eye & body movements
  • coordinates motions of different joints with each other
  • aids in learning motor skills
  • lesions on the cerebellum can cause ataxia (clumsy gait)

Anatomy & Physiology (15 decks)

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