Chapter 9 Flashcards

1
Q

CNS protected by

A

Glial cells
Bone- Skull, Vertebrae column
Connective tissue- meninges
Cerebrospinal fluid

100 billion neurons and 100 trillion synapses in CNS

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2
Q

Glial cells types

A

Schwann cells
Oligodendrocytes
Microglia
Astrocytes (most abundant)

Release growth factors

90% of CNS

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3
Q

Astrocytes

A

Form a link between neurons and non nervous tissue and ECF
develop neurons and synapses
regenerate damaged axons
Maintain homeostasis in EC envir (K+ levels)
Remove Glutamate (toxic) and biogenic amines from synapses
Synthesize and store molecules
Protect from toxins with microglia
Protect from oxidative stress and remove cellular debris

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4
Q

Microglia

A

Protect CNS from foreign matter, bacteria or dead cells using phagocytosis or cytokines

Protect against oxidative stress

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5
Q

Physical support of CNS

A

Cranium (Skull)
Vertebral column
Meninges
Cerebrospinal fluid

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6
Q

Meninges

A

3 connective tissue membranes:
Dura Mater- outermost, tough like leather
Arachnoid Mater- middle layer, weblike and joined with dura
Pia Mater-right above neurons, subarachnoid space filled with cerebrospinal fluid

*Subarachnoid space- between pia Mater and arachnoid Mater filled with CSF

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7
Q

Cerebrospinal fluid

A

Surrounds CNS and fills ventricles within brain and spinal cord, provides nutrients and remove waste, Maintains ionic composition

Total volume: 125-150mL recycled 3x a day
Choroid plexus produces 400-500mL/Day

Reabsorbed into venous blood in the subarachnoid space by arachnoid villi

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8
Q

Brain cavities (4)

A

Two C shaped lateral ventricles, connected to the third ventricle by inter-ventricular foramen.

The cerebral aqueduct connects the third ventricle to the fourth ventricle

*Ependymal cells line ventricles and central canal to help circulate CSF

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9
Q

Central canal

A

Long thin cylindrical cavity that runs the length of spinal cord, lined with ependymal cells

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10
Q

Choroid plexus

A

The choroid plexus is a plexus of cells that produces the cerebrospinal fluid in the ventricles of the brain. The choroid plexus consists of modified ependymal cells, pia Mater, and capillaries

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11
Q

CNS Blood Supply

A

Receives 15% of the body’s blood
High demand for glucose and oxygen 20%
Accounts for 50% of all glucose consumed

During starvation or diabetes mellitus, Ketones can supply energy

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12
Q

Blood brain barrier

A

Hydrophobic molecules diffuses easily (alcohol, gases)

Hydrophilic molecules rely on transport proteins (ions, catecholamines, amino acids)

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13
Q

Glucose (blood brain barrier)

A

Glucose transports across barrier using GLUT-1 Carriers

Receptors for insulin are located on certain CNS neurons to regulate food intake

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14
Q

Cannot penetrate blood brain barrier

A
Catecholamines
Inorganic ions (H+)
Several drugs (Antibiotics)

No transport carrier for these molecules

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15
Q

Gray matter (cerebral cortex)

A

40% of CNS, site of synaptic communication and neural integration

Makes up external surface of brain and beneath spinal cord

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16
Q

White matter

A

60% of CNS, white due to Myelinated axons

Below cerebral cortex, consist of areas of gray matter called subcritical nuclei

Organized into bundles or tracts that connect different regions of gray matter

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17
Q

Projection fibers

A

Tracts conncet the cerebral cortex with more levels of the brain or spinal cord

Fibers connect one region of gray to another

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18
Q

Association fibers

A

Connect one area of cerebral cortex to another on the same side of the brain

Arcuate fasciculus- connects broca and wernicks area

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19
Q

Commissural fibers

A

Connect cortical regions on one side of the brain with corresponding cortical regions on the other side

Located in bands of tissue called corpus callosum which connects the cerebral hemispheres

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20
Q

Spinal nerves

A

Nerves that branch of spinal cord, 31 pairs that exits the vertebral column between to adjacent vertebrae

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21
Q

Cervical nerves

A

There are 8 pair (C1-C8) emerge from neck region

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22
Q

Thoracic nerves

A

12 pairs (T1-12) emerge from chest region

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23
Q

Lumbar nerves

A

5 pairs (L1-L5) emerge from lower back

Conus medullaris: terminal end of the spinal cord which ends around L1-L2

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24
Q

Sacral nerves

A

5 pairs (S1-S5) emerge from tailbone or coccyx

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25
Coccygeal nerve
1 nerve (C0) emerges from tip of coccyx
26
Spinal cord gray matter (Butterfly shaped)
Contains interneurons, cell bodies and dendrites of efferent neurons, and axon terminals of afferent neurons Dorsal horn- posterior half of gray matter on either side, where afferent neurons terminate Ventral horn- anterior half of spinal cord Lateral horn- between dorsal and ventral horns, origin of efferent neurons Intermediolateral cell column-between dorsal and ventral horns, efferent neurons originate from autonomic sys
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Dorsal root ganglia
Consist of the cell bodies of afferent fibers outside the spinal cord in clusters
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Efferent neurons
Located in spinal cord, originate in ventral horn and travel to periphery to form synapses with skeletal muscles
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Dorsal roots
Contain afferent axons, come together to form with Ventral roots to form spinal nerves
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Ventral roots
Contain efferent axons, come together to form with Dorsal roots to form spinal nerves called mixed nerves
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White matter of spinal cord
Surrounds outer region of cord, tracts provide communication at diff lvls in spinal cord or between brain and spinal cord Ascending tracts- Carry sensory info to the brain (with three neurons), from receptor to the somatosensory cortex. Consist of: Posterior (Dorsal) Column, Spinothalamic Tracts, and Spinocerebellar Tracts. Descending tracts- Upper motor neurons (that originate in brain) descend through tracts in spinal cord to synapse in the lateral and ventral horns of gray matter to lower motor neurons. Consist of: Pyramidal System and Extrapyramidal System. *found on both sides of spinal cord, link peripheral nerves to brain
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Ipsilateral
When a sensory or Motor pathway remains on the same side as it’s origin
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Contralateral
When a sensory or motor pathway crosses to the side opposite of it origin
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Brain main parts
Forebrain- superior part of brain, hemispheres, consists of cerebrum and diencephalon (hypothalamus) Cerebellum- Motor coordination, balance Brainstem- connect forebrain and cerebellum to spinal cord
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Brainstem (3 regions)
3 regions: Midbrain: Connects forebrain Pons: middle portion, connects cerebellum Medulla oblongata: connects to spinal cord Reticular formation: diffuse network of nuclei that regulates sleep wake cycles, arousal of cerebral cortex, and consciousness Processing center for 10 of the 12 pairs of cranial nerves, regulates involuntary functions
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Cerebral cortex
Carries out the highest level of neural processing. Consist of grooves called sulci and ridges called gyri 1.5mm to 4nm thick Cortex arranged in 6 layers
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Organization or cerebral cortex
Frontal lobe Parietal lobe Occipital lobe- visual cortex Temporal lobe- auditory cortex Frontal and parietal separated by central sulcus Occipital and temporal lobe separated by lateral sulcus
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Parietal lobe
Primary somatosensory cortex- processes somatic sensory info associated with somesthetic sensations (tough, itch, pain) and proprioception (awareness of muscle tension)
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Frontal lobe
Primary motor cortex, voluntary movement, language, planning and personality Motor homunculus- neural circuits for movement Sensory homunculus- neural circuits for sensory
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topographical organization
Body parts are mapped onto cortical surface which they correspond to called motor or sensory homunculus Size of body part relative to cortical area devoted to it
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Association areas
Involved in more complex processing that requires integrating different types of information
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Brain latetization
Certain brain functions are dominant on one side of the brain relative to the other, 2 hemispheres *Not for every person on same side
43
Right brain abilities
Movement of left side Sensory perception of stimuli (left side) Spatial orientation Creativity Face recognition Music Dream imagery Philosophy Intuition
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Left brain abilities
Right side of body Sensory perception of stimuli (right side) Logic Analytical processing Strong language capabilities Math skills
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Subcortical nuclei
Regions of gray matter located within the cerebrum
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Basal nuclei (basal ganglia)
Notable for their role in modifying movement Caudate nucleus Globus Pallidus Putamen
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Diencephalon
Inferior to cerebrum Thalamus and hypothalamus
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Thalamus
Cluster of nuclei that functions as relay center before being transmitted to the cortex Important in directing attention Relays info from cerebellum and basal ganglia to the motor cortex to provide feedback in controlling movement
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Hypothalamus
Located inferior to the thalamus, regulates homeostasis. Link between endocrine and nervous system Released hormones, hunger and thirst center, thermoregulatory, and behavior Communicates with autonomic system direct and indirectly
50
Suprachiasmatic nucleus of hypothalamus
Generates and regulates the circadian rhythm (melatonin)
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Limbic system
Brain areas associated with autonomic functions, motivation, memory and emotions Amygdala, hippocampus, fornix, cingulate, and parahippocampal gyri of cerebral cortex, portions of the prefrontal cortex, thalamus and hypothalamus
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Reflex arcs
Neural pathways for reflexes 5 components: sensory receptor, afferent neuron, integration center, efferent neuron, detects a stimulus Receptor to CNS via afferent neuron to efferent One single neuron if network of neurons
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Reflex groups (5)
Spinal or cranial Somatic or autonomic Innate or conditioned Monosynaptic or polysynaptic
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Muscle spindle stretch
Monosynaptic reflex in the human body Knee jerk reflex- stimulated by patella tendon; contraction of quadriceps inhibits the hamstring by interneurons
55
Withdrawal reflex
When subjected to painful stimulus and withdraw from it To occur, The muscles that cause withdrawal should be excited muscles that oppose withdrawal should be inhibited Info is processed in the brain before the withdrawal and reflex occurs
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Pupillary light reflex
Autonomic cranial reflex Light enters eye->Activate photoreceptors->Activate afferent neurons->info goes to midbrain of brainstem->Efferent neurons smooth muscles of the eye->pupillary constriction
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Crossed extensor reflex
When a painful stimulus triggers the withdrawal reflex (steps on tack) Nociceptor stimulated->excite afferent neuron->excite interneuron->efferent neuron contracts hamstrings and inhibits/relax quadriceps (withdrawal)->activates crossed extensor reflex on opposite leg (interneurons)-> on opp leg-> causing contraction of quadriceps and inhibit hamstring
58
Voluntary motor tasks components
Developing the idea to move Putting together a program of motor commands to carry out the movement Executing the movement by activating the correct muscles at the correct time Constant feedback to ensure that the movement is carried out smoothly and successfully
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Association areas for movement
Prefrontal cortex, cerebral cortex, basal nuclei, limbic system Based on sensory input, memories, emotions, or other motivating factors
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Lower motor neurons or motor neurons
The afferent neurons that control skeletal muscles originate in the ventral horn of the spinal cord Lateral pathways or ventromedial pathways
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Pyramidal tracts
Direct pathways from the primary motor cortex to the spinal cord. Control movement of distal extremities Most axons cross over to the opposite side of the CNS in an area of the medulla called the medullary pyramids Forearms, hands, and fingers, smaller groups of muscles
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Upper motor neurons
The axon of neurons from pyramidal tracts that terminates in the ventral horn of the spinal cord
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Rubrospinal tracts
Direct pathways from the primary motor cortex to the spinal cord. Originate in the red nuclei of the midbrain Axons of these tracts decussate and join axons of the pyramidal tract
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Ventromedial pathways
Indirect connections between the brain and spinal cord These neurons do not form synapses on motor neurons Influence large groups of muscles, trunk, neck, and proximal portions of the limbs
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Vestibulospinal tracts
Originate in the vestibular nuclei of the medulla Receives info from inner ear regarding movement of the head Controls head, neck, and lumbar muscles to maintain posture and balance
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Tectospinal tracts
Originate in superior colliculi of the midbrain Receives input from the eyes, somewhat the skin and ears Control head and eye movement/focus
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Reticulospinsl tracts
Originate in reticular formation of pons or medulla Important for balance
68
Cerebellum muscle coordination
To operate the cerebellum must both receive information from the cortex regarding planned woodlands and be continually updated about performance Receives input from sensorimotor areas of cortex, the basal nuclei, brainstem, spinal cord, sensors from all over body Sends to cortex to adjust planned movement
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Basal nuclei motor control
Provide feedback to the cortex for the development of Moter strategies and smoothing out of movements Necessary for automatic performance of learned repetitive motions Receive input from cortex and send output back to the cortex via thalamus Initiates purposeful movement, inhibits unwanted movement Huntingsons Chorea – lethal genetic disease that causes loss of motor coordination and decline of cognitive f(x) until dementia, twitching face
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Wernickes area
Located in the posterior and superior portion of the Temporel lobe and the inferior parietal lobe Involved in language comprehension Sound, written words, or hand signals
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Broca’s area
Located in frontal lobe Involved in language expression our ability to speak or right
72
Kinds of sleep
Slow wave sleep (SWS)- multiple stages of low frequency waves in EEG REM sleep- hit frequency waves in EEG and periodic episodes of rapid eye movement
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Ascending reticular activating system (ARAS)
Critical in maintaining alert wakefulness Send info to cortex thru thalamus, hypothalamus, and forebrain Neurotransmitters: acetylcholine, norepinephrine, and dopamine Nicotine, orexin, histamine amphetamines and cocaine
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Wake and alert
EEG shows high frequency low amplitude Beta waves
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Awake but resting
EEG of lower frequency and higher amplitude Alpha waves (greater synchronization among neurons vs beta)
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SWS stages
Stage 1: drowsey period (asleep and awake) Stage 2: light sleep Stage 3: moderate sleep Stage 4: deep sleep
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Cortisol
Helps the body adjust to stress by mobilizing energy stores, even at the expense of breaking down so proteins to amino acids
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Emotions
Cerebral cortex, limbic system, and hypothalamus (anger, aggression), Amygdala (Fear, anxiety) Triggered by sensory input or memories Autonomic, Motor, and hormonal changes Left brain: positive emotion Right brain: negative emotion
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Procedural memory (implicit memory)
Memory of motor skills and behaviors Includes cerebellum, basal nuclei, and pons Ex. Learning to ride a bike, you never forget
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Declarative memory (explicit memory)
The memory of learned experiences Ex. facts and events
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Plasticity
The ability to alter the nervous systems anatomy and function in response to changes in it’s activity patterns Synapses can be developed and altered New neurons in areas of memory
82
Long term potentiation
Repetitive stimulation of a particular synapse leading to increased and the strength of that connection. Better able to trigger a action potential in the postsynaptic cell caused by an increase in the size of EPSPs Hippo campus and occurs at preexisted synapsis
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Multiple sclerosis
Autoimmune disorder, stops neural signals, muscle weakness and balance problems Treatment: corticosteroids, interferons, immunosuppressants
84
Alzheimer’s disease
Decrease in the #of cholinergic neurons, microglia and astrocytes release inflammatory chem, causes memory loss and confusion, Motor dysf, loss of cognitive f(x) Treatment: antioxidants, acetylcholinesterase inhibitors, Antidepressants
85
Parkinson’s Disease
Decrease in dopaminergic neurons in the substantia Niagra, causes movement disorders Treatment: Levodopa, COMT inhibitors, Surgery
86
Analysis of CSF
Tested by extracting between L3 and L4 Cloudy CSF: Bacterial meningitis, Viral meningitis, Fungal meningitis(HIV), Tuberculosis meningitis, neurosyphilis, neoplasm (growth) Red CSF: intracranial hemorrhage Analyzed: Glucose, protein, leukocytes, RBCs, Pressure
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Flow of CSF
1) Lateral ventricle 2) Interventricular Foramen 3) Third Ventricle 4) Central aqueduct 5) Forth Ventricle 6) through foramen of luschka (lateral hole) 7) Up cross cerebral hemisphere and down spinal cord 8) enters subarachnoid space is reabsorbed in arachnoid villi —> then taken to heart via jugular vein
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Intracranial hypotension
CSF Leakage caused by tear in Dura by head brain or spinal injury, bad placement of tubes ex. Epidural, spinal tap (lumbar puncture) Symptoms: runny nose, ear leak, bad headache when sitting up Testing: MRI, X Ray with contrast
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Assessing brain death
1) Pupillary reflex 2) Response to pain 3) Respond to sound 4) Ability to breathe w/o the ventilator
90
Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease)
Neurons die Causing muscle weakness, paralyzed body, breathing and swallowing affected first, does not affect special senses Symptoms begin age 50 Stephen Hawking
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Control of Posture
Extrapyramidal tracts – include all motor control pathways outside the pyramidal system. Indirect conections b/w the brain and spinal cord. Involuntary control of posture: Muscles constantly adjust changes in posture standing still or moving. •Postural control, Brain uses info from sensory, propioceptors in muscles and joints and receptors in the vestibular system (inner ear that detect motion of the head). •Brain also uses info from eyes and ears.