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Anatomy > Nervous System > Flashcards

Nervous System Flashcards

1
Q

Central Nervous System (CNS)

A
  • Command centre
  • Brain + spinal cord
  • Processes + integrates information
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2
Q

Peripheral Nervous System (PNS)

A
  • Consists of:
    1) Cranial nerves - to/from brain
    2) Spinal nerves to/from spinal cord
  • 2 divisions of PNS:
    1) Sensory/afferent division
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3
Q

Peripheral Nervous System Divisions

A

1) Sensory/afferent division
- Has sensory receptors that detect stimuli (changes in the internal or external environments)
- Nerves convey impulses TOWARD CNS
2) Motor/Efferent division
- Nerves convey impulses AWAY from CNS
- Innervates (supplies nerves to) effectors = muscles + glands (endocrine or exocrine)

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4
Q

Relationship between CNS and PNS

A

Look at diagram

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5
Q

Nervous System Organization

A

Diagram

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6
Q

Neurons (Nerve cell type)

A
  • Conduct impulses
  • Make up CNS + PNS
  • Mostly amitotic (irreplaceable) exceptions = taste, olfaction, memory
  • Structures:
    1) Cell body
    2) Processes from cell body
    a) Dendrites
    b) Axon
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7
Q

Cell body (Neurons)

A
  • Typical organelles
  • RER called Nissl bodies
  • Groups/clusters in CNS = nuclei (grey matter)
  • Groups/clusters in PNS = ganglia
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8
Q

Dendrites (Neurons)

A

Receive incoming messages + relay to cell body

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9
Q

Axon (Neurons)

A
  • Carries impulses away from cell body
  • Axon hillock - where axon meets cell body
  • Axon terminal - typically branched with synaptic end bulbs (enlarged tips)
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10
Q

Myelinated Axon

A
  • Myelinated - wrapped in many layers of cell membrane from Schwann cells (PNS) or oligodendrocytes (CNS)
  • Electrical insulation
  • Gaps in myelin sheath are called nodes of Ranvier
  • Myelinated axon bundles in:
    1) CNS = tracts (white matter)
    2) PNS = nerves (know the difference)
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11
Q

Unmyelinated Axon

A

No myelin

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12
Q

Neuroglia (Glial cells) (Nerve Cell Type)

A
  • Support neurons = can undergo mitosis (prone to cancer - brain tumour)
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13
Q

CNS Neuroglia

A

1) Oligodendrocytes
2) Microglia
3) Astrocytes
4) Ependymal Cells

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14
Q

Oligodendrocytes (CNS neuroglia)

A

Produce myelin around axon

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15
Q

Microglia (CNS neuroglia)

A
  • Protective – become phagocytic if detect infected, dead or damaged neurons (because immune cells can’t enter CNS)
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16
Q

Astrocytes (CNS neuroglia)

A
  • Surrounded blood capillaries to form part of blood brain barrier (BBB)
  • Help control capillary permeability
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17
Q

Ependymal Cells (CNS neuroglia)

A
  • Neural epithelium
  • Line brain ventricles + central canal of spinal cord
  • Secrete cerebrospinal fluid (CSF) + circulate it (cilia)
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18
Q

PNS Neuroglia

A

1) Schwann Cells
- Form myelin around axons in PNS
2) Satellite Cells
- Surround neuron cell bodies ganglia
- Protection and support

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19
Q

Neuron Classification

A

1) Structural/ Anatomical Types:
- Based on number of processes coming off cell body
a) Unipolar
b) Bipolar
c) Multipolar
2) Functional Types:
- Based on direction of impulse conduction
a) Sensory/Afferent neurons
b) Interneurons
c) Motor/Efferent neurons

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20
Q

Unipolar

A
  • 1 process the divides into two: central + peripheral
  • Peripheral end has dendrites = sensory receptors (pain, touch, etc) - reminder is axon
  • Always sensory
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21
Q

Bipolar

A
  • 2 processes: 1 axon, 1 process with dendrites

- Sensory = retina, nose (olfaction)

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22
Q

Multipolar

A
  • 3 or more processes: 1 axon, many dendrites

- All interneurons + motor neurons

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23
Q

Sensory/Afferent Neurons

A
  • Mostly unipolar

- From sensory receptors to CNS

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24
Q

Interneurons

A
  • Within CNS (between sensory + motor)

- 99% of neurons (mostly multipolar)

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25
Q

Motor/Efferent Neurons

A
  • CNS to effectors (all multipolar)
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26
Q

Neuronal Junctions (Synapses)

A

1) Neuronal Junction:
- Neuron to Neuron
- Can be chemical (use neurotransmitters) or electrical (ions)
2) Neuromuscular Junction:
- Motor neuron to skeletal muscle cell
3) Neuroglandular Junction:
- Motor neuron to smooth or cardiac muscle, or a gland

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27
Q

Chemical Neuronal Synapses

A
  • Most common
  • Structures:
    1) Presynaptic Neuron
  • Neuron bringing impulse
  • Has axon terminal with synaptic end bulbs
  • Inside end bulb = synaptic vesicles containing neurotransmitter (nt)
  • Presynaptic membrane (cell membrane facing space)
    2) Synaptic Cleft
  • Space between neurons
    3) Postsynaptic Neuron
  • Receives the signal
  • Has postsynaptic membrane = cell membrane of dendrites or cell body with receptors for nt
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28
Q

Central Nervous System: Protective Features

A

1) Bone
2) Meninges
3) Cerebrospinal Fluid (CSF)
4) Blood-Brain Barrier (BBB)
5) Cerebral Arterial Circle

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29
Q

Bone

A
  • Skull and vertebral column
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30
Q

Meninges

A
  • CT around brain + spinal cord
  • Layers:
    1) Dura Mater
    2) Arachnoid Mater
    3) Pia Mater
  • Meningitis = inflammation of meninges
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31
Q

Dura Mater (Outer)

A
  • Brain = 2 fused layers - separated in some places to form spaces = venous (dural) sinuses - contain blood
  • Spinal cord - 1 layer
  • Deep to dura mater = subdural space - filled with ISF
  • Superficial to dura mater = epidural space (spinal cord only) - filled with fat, blood vessels, CT, etc
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32
Q

Arachnoid Mater (Middle)

A
  • Avascular
  • Subarachnoid space:
    ~contains cerebrospinal fluid (CSF)
    ~ Web-like strands of CT secure it to Pia mater (below)
  • Has arachnoid granulations (brain only)
    ~ Projections into dural sinuses
    ~ CSF enters granulations to return to blood
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33
Q

Pia Mater (Inner)

A
  • On surface of CNS (brain and spinal cord)

- Vascular

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34
Q

Cerebrospinal Fluid (CSF)

A
  • Surrounds brain + spinal cord
  • In brain ventricles + central canal of spinal cord
  • Ventricles:
    ~ Spaces inside brain (filled with CSF)
    ~ 2 lateral ventricles (1st and 2nd) - in cerebrum
    ~ 3rd ventricle - in diencephalon
    ~4th ventricle - surrounded by pons, medulla oblongata, cerebellum
  • Central canal:
    ~ Space in spinal cord
  • Cushions CNS - brain buoyant
  • Formed from blood plasma (similar composition)
  • Produced by choroid plexuses (blood capillaries) found in each ventricle
  • Circulation: LOOK AT DIAGRAM
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35
Q

Blood-Brain Barrier (BBB)

A
  • 2 cell types:
    1) Endothelial cells (of capillaries) with tight junctions
    2) Astrocytes - foot processes wrap around endothelial cells
  • Selectively Permeable
  • Allows: glucose, fat soluble material to cross
  • Not toxins, antibiotics etc
  • In most parts of brain except:
    Posterior pituitary, hypothalamus, vomiting centre
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36
Q

Cerebral Arterial Circle

A

Cerebral arteries form circle at base of forebrain

  • Circles pituitary gland and optic chiasma (where optic nerves cross)
  • Unites the 2 major blood supplies to the brain (anterior and posterior)
  • Provides an alternate toute for blood if vessels blocked
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37
Q

Blood flow to Brain

A

Diagram

38
Q

Blood Return From The Brain

A 
Cerebral Arteries
Capillaries
Cerebral Veins
Dural Sinuses
Superior Vena Cava
39
Q

Cerebrum (Forebrain)

A

= right and left cerebral hemispheres

  • Lobes (named after overlying bones)
    1) Frontal
    2) Temporal
    3) Parietal
    4) Occipital
    5) Insula - deep to temporal lobe
40
Q

Structure Features of the Cerebrum

A

1) Fissures = deep groves
2) Gyri = ridges
3) Sulci = Shallow Grooves (separate gyri)

41
Q

Fissures

A

1) Longitudinal Fissure
- Separates right and left hemispheres
2) Transverse Fissure
- Separates cerebellum + cerebrum
3) Lateral Fissure
- Separates temporal lobe from rest of cerebrum

42
Q

Gyri

A

Examples:

  • Postcentral gyrus in parietal lobe
  • Precentral gyrusin frontal lobe
43
Q

Sulci

A

Example:

- Central sulcus - between frontal and parietal lobes

44
Q

Layers to the Cerebrum

A

1) Cerebral Cortex
2) Tracts (white matter)
3) Basal Nuclei

45
Q

Cerebral Cortex

A
  • 2-4 mm thick, grey matter
  • Has functional areas:
    1) Motor Areas
    2) Sensory Areas
    3) Association Areas
    4) Others
46
Q

Motor Areas (Cerebral Cortex)

A
  • All in frontal lobe
  • Control skeletal muscle movement
  • 3 regions:
    1) Primary motor area (pre central gyrus)
    2) Premotor Area
    3) Broca’s - language
47
Q

Sensory Areas (Cerebral Cortex)

A

1) General sensory area (pain, temp, touch, pressure)
- Postcentral gyrus in parietal lobe
2) Vision
- Occipital lobe
3) Auditory + Olfaction
- Temporal lobe
4) Taste + Visceral Sensation (e.g. full bladder)
- Insula

48
Q

Association Areas (Cerebral Cortex)

A

Recognize into from memories - parietal, occipital, temporal lobes

49
Q

Others (Cerebral Cortex)

A
  • Memory - Temporal lobes
  • Conscious intellect (personality, learning, ideas, judgement etc)
  • Prefrontal cortex
50
Q

Tracts (white matter)

A

1) Association Tracts
- Form gyrus to gyrus in same hemisphere
2) Commissural Tracts
- Form gyrus to gyrus in opposite hemispheres
- E.g. corpus callosum
3) Projection Tracts - run vertically (brain to spinal cord/ spinal cord to brain)

51
Q

Basal Nuclei

A
  • Paired masses of grey matter (within the white matter)

- Involved in control of skeletal muscle movement

52
Q

Diencephalon

A
  • All gray matter
    1) Thalamus
  • 2 lobes connected by intermediate mass (bridge of grey matter across 3rd ventricle)
  • Relay station for most sensory impulses to cortex
    2) Hypothalamus
  • Inferior to thalamus, above pituitary
  • Major regulator of the internal environment (visceral control)
  • e.g. blood pressure, heart rate
53
Q

Midbrain

A
  • Connects pons + diencephalon
  • Contains cerebral aqueduct
  • Anterior portion = cerebral peduncles (projection tracts)
  • Posterior portion = 4 nuclei = corpora quadrigemina
    ~ 2 superior colliculi - visual reflexes
    ~ 2 inferior colliculi - hearing + auditory reflexes
54
Q

Hindbrain

A 
Includes:
1) Pons
2) Medulla Oblongata
3) Cerebellum
NOTE: Brain Stem = midbrain, pons, medulla
55
Q

Pons (Hindbrain)

A
  • Anterior to cerebellum
  • Contains:
    Tratcs between brain + spinal cord + tracts to/from cerebellum
    Pontine respiratory centres
56
Q

Medulla Oblongata (Hindbrain)

A
  • Inferior to pons
  • Ends at foramen magnum
  • 2 bulges called pyramids = large motor tracts (= part of corticospinal tracts)
  • Just above spinal cord = decussation of pyramids (tracts cross over)
  • 3 vital centres (nuclei) in medulla:
    1) Cardiac
    2) Vasomotor (blood vessels)
    3) Respiratory
  • Several non-vital centres - for swallowing, sneezing, vomiting
57
Q

Cerebellum (Hindbrain)

A
  • Posterior to pons, medulla
  • Has folds similar to gyri = folia - cortex (grey matter(
  • Arbor vitae (deep to cortex, anterior cerebellum) = white matter
  • Coordinates skeletal muscle contraction - posture, balance
58
Q

Limbic System (Functional Systems)

A
  • Nuclei in cerebrum + diencephalon
  • Regulates emotions + emotional behaviours (laughing, crying etc)
  • Contains areas involved in memory (memories evoke emotional responses)
59
Q

Reticular Formation (Functional Systems)

A
  • Nuclei in brain stem
  • Cortex, thalamus + hypothalamus involved - together form RAS = Reticular Activating System
  • Regulates alertness + attention - filters stimuli + only sends new/unusual signals to other brain areas
  • Sleep results when inhibited
  • If damaged = coma
60
Q

Spinal Cord (Structure Overview)

A
  • Foramen magnum to level of lumbar vertebrae L1?l2 (conus medullar is)
  • Nerves continue down from spinal cord through vertebral foramina as caudal equina (“horse’s tail”) - exit at intervertebral foramina
  • Filum terminale
    ~ CT= extension of Pia mater - anchors conus medullar is of spinal cord to coccyx
    ~ Location where CSF samples taken
61
Q

Spinal Cord (Cross-sectional Structure)

A

1) Anterior median fissure + posterior median sulcus
2) Central Canal
3) Gray Matter
4) White Matter

62
Q

Anterior Median Fissure + Posterior Median Sulcus

A
  • Separate cord into right and left halves
63
Q

Central Canal

A
  • Contains CSF
64
Q

Gray Matter

A
  • Cell bodies + dendrites of motor neurons, interneurons
  • H-shaped
    ~ Cross bar = gray commissure
    ~ Horns
    1) Dorsal Horn = sensory
    2) Lateral Horn = motor
    3) Ventral Horn = motor
65
Q

White Matter

A
  • Myelinated axons = ascending (sensory) and descending (motor) tracts
  • Forms columns:
    1) Dorsal Column
    2) Lateral Column
    3) Ventral Column
66
Q

Spinal Cord Function in the CNS

A
  • Carries sensory and motor impulses

- Produces reflexes - Fas, predictable, automatic responses to changes in the environment (E.g. withdrawal reflex)

67
Q

Cranial Nerves (PNS) Pairs)

A 
- 12 pairs in total 
I. Olfactory 
II. Optic
III. Oculomotor 
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglassal
68
Q

Cranial Nerves are associated with the following brain regions:

A 
-Forebrain:
Olfactory, Optic
- Midbrain
Oculomotor, Trochlear
- Pons: 
Trigeminal, Abducens, Facial, Vestibulocochlear
- Medulla Oblongata
Glossopharyngeal, Vagus, Accessory, Hypoglossal
69
Q

Cranial Nerves Extra info

A

1) 2 pairs = only sensory neurons
- I + II
2) 1 pair = mainly sensory
- VIII
3) 9 pairs = mixed nerves
- Carry both sensory + motor neurons
- Motor neurons = cell bodies in brainstem nuclei
- Sensory neurons = cells bodies in ganglia of PNS
- E.g. Trigeminal (V)
Motor function = chewing
Sensory function = conveys general sensations (touch, pressure, pain, temperature etc) from face to CNS

70
Q

Spinal Nerves (PNS)

A
  • 31 pairs = all mixed nerves
    8 cervical
    12 thoracic
    5 Lumbar
    5 Sacral
    1 Coccygeal
  • Exit via intervertebral foramina (except 1st - between atlas + occipital bone)
  • Each has 2 points of attachment to spinal cord: 1) Dorsal Root and 2) Ventral Root
  • Spinal Nerves = joining of dorsal + ventral roots - immediately divides into branches = rami: 1) Dorsal Ramus 2) Ventral Ramus 3) Rami Communicantes
71
Q

Dorsal Root

A
  • Sensory; cell bodies in dorsal root ganglion (Have diagram)
72
Q

Ventral Root

A
  • Autonomic and somatic motor neurons; cell bodies in ventral or lateral horn
73
Q

Dorsal Ramus

A

Innervates skin + muscles of back

74
Q

Ventral Ramus

A
  • Forms thoracic nerves (t2-T12) OR further branch + join up forming nerves plexuses (= nerve networks)
75
Q

Rami Communicantes

A
  • Connect ventral ramps to sympathetic trunk

- Contain autonomic nerve fibres (neurons)

76
Q

Cervical Nerve Plexus

A
  • Formed by spinal nerves C1-C5

- Important nerves arising - Phrenic (innervates diaphragm)

77
Q

Brachial Nerve Plexus

A
  • Formed by spinal nerves C5-C8, T1

- Important nerves arising -Axillary, Radial, Ulnar median, Musculocutaneous

78
Q

Lumbar

A
  • Formed by spinal nerves L1-L4

- Important nerves arising: -Femoral

79
Q

Sacral

A
  • Formed by spinal nerves L4-S4

- Important nerves arising: - Sciatic = divides into tibial + common fibular

80
Q

Cross-section of a Nerve (PNS)

A

1) Nerve = Epineurium - around whole nerve (CT)
2) Axon = Perineurium - around fascicles (CT)
3) Fascicle = Endoneurium - around axon + myelin (CT)

81
Q

Peripheral Nervous System: Sensory (Afferent) Division

A

Consists of:

1) Receptors
a) Location
b) Type of stimulus
c) Structure of Receptor
2) First Order Neurons = sensory neurons

82
Q

Receptors of Sensory Division

A
  • Detect changes in environment
  • Classified by:
    a) Location
    b) Type of Stimulus Received
    c) Structure of Receptor
83
Q

Exteroceptors (Location)

A
  • Stimulus in external environment = receptors at body surface e.g. Touch, most special senses
84
Q

Interceptors (Location)

A
  • Stimulus in internal environment (in viscera, blood vessels etc.)
85
Q

Proprioceptors (Location)

A
  • Located in joints, skeletal muscles etc.

- Monitor body position (stretch receptors, muscle spindles) - balance + movement

86
Q

Mechanoreceptors (Type of Stimulus Received)

A
  • Mechanical stimuli (e.g. pressure, touch, hearing)
87
Q

Thermoreceptors (Type of Stimulus Received)

A

-Temperature

88
Q

Chemoreceptors (Type of Stimulus Received)

A
  • Chemical
89
Q

Photoreceptors (Type of Stimulus Received)

A
  • Light
90
Q

Nociceptors

A
  • Pain
91
Q

Structure of Receptor (General Senses Only)

A

1) Free Nerve Endings
- Terminal dendrites of unipolar sensory neurons
- E.g. pain, root hair plexus
2) Encapsulated nerve endings
- Terminal dendrites enclosed in CT
- E.g. Messiner’s + Pacinian Corpuscles

92
Q

First Order Neurons = Sensory Neurons

A
  • Unipolar neurons attached to or associated with receptor
  • Axon located in cranial/ spinal nerves to CNS
  • Cell bodies in:
    a) sensory ganglia of cranial nerves
    b) Dorsal root ganglia of spinal cord
  • Axon terminals nuclei
    a) Brain nuclei
    b) Dorsal horn of spinal cord

Anatomy (16 decks)

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