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Neuroscience 4
4th exam
111
Other
04/23/2008

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Term
What is a motor unit?
Definition
Motor neuron + innervated muscles
Term
Why does the motor unit vary in different muscles?
Definition
Varies based on size; stapedius will have 2-3 muscles/motor neuron and gastrognemius will have ~1000 muscles/motor neuron
Term
What are the three types of muscle fibers? What size neurons are associated with them?
Definition
Red (slow twitch - small motor neuron), intermediate (fast twitch fatigue resistant - intermediate size motor neuron), and white (fast twitch, fatigable - large motor neuron)
Term
What is the size principal upon which recuriting muscle fibers during contraction is based?
Definition
Smallest neurons are recruited first
Term
T or F a single motor unit has only one type of muscle
Definition
T
Term
T or F Individual muscles are composed of only one type of muscle fiber
Definition
F Individual muscles are composed of all three fiber types
Term
What are the three types of receptors that are sending information about the state of the muscle to the CNS?
Definition

Primary, secondary, and Golgi

Every muscle, w/ few exceptions, contains all three types 

Term
What do spindle organs and Golgi tendon receptors detect?
Definition

Spindle organs - muscle length and rate of change of muscle length

Golgi tendon receptors - muscle tension and rate of change of tension 

Term
Where do the primary and secondary muscle spindle receptors and Golgi tendon organs feed into?
Definition
The spinal cord
Term
From where do the primary and secondary afferent muscle spindle stretch receptors arise from?
Definition
The muscle spindle
Term
What motor neurons comprise the motor neuron pool?
Definition
Alpha and gamma
Term
What do the alpha motor neurons do?
Definition
Innerate the contractile muscle fibers including slow, fast-twitch fatigue resistant, and fast-twitch
Term
What do gamma motor neurons do?
Definition
Innervate the muscles of stretch receptors and are of two types: fusimotor and dynamic fusimotor
Term
Are alpha or gamma motor neurons larger?
Definition
Alpha
Term
What fibers are the sensory basis of the stretch receptor refelexes of the spinal cord?
Definition
The 1a afferent fibers
Term
Where does sensory innervation of the spindle come from?
Definition
Group 1a and group 2
Term
A single muscle stretch receptor is made of of two types of fibers. What are they?
Definition
Nuclear bag and nuclear chain fibers
Term
To which afferents and fusimotor efferents are the neuclear bag fibers and the nuclear chain fibers associated?
Definition

Nuclear bag: Group 1a afferents and dynamic fusimotor efferents

Nuclear chain: Group II afferents and static efferents

Term
What does a stretch of muscle reveal about the components of primary (1a) and secondary (Group II) fibers?
Definition

Primary (1a) - dynamic and static components

Secondary (Group II) - static only (muscle length) 

Term
Which fiber responds best to a brief stretch?
Definition
the 1a fibers (Group II is minimally affected)
Term
Tendon tap reflexes are initiated by which spindle stretch receptors?
Definition
1a
Term
Definition
Term
What does the limbic system control?
Definition
Motivation, memory and movement
Term
Why is the limbic system difficult to study in the lab?
Definition
Because its structures are interconnected and it is difficult tomeasure emotions
Term
What are the elements of the limbic system?
Definition

Amygdala, hippocampus, cingulate gyrus, prefrontal cortex, septal nuclei, anterior nucleus of the thalamus, mammillary bodies

Term
What is the Papez circuit?
Definition
Circuitry of the limbic system
Term
Where are the amygdala and the hippocampus?
Definition
Temporal lobe
Term
What is the Fornix?
Definition
Axons coming from the hippocampus to mammillary bodies and to the septal nucleus
Term
What is the mammillothalamic tract?
Definition
Axons from the mammillary bodies to the anterior nucleus of thalamus
Term
What three pathways make up the Papez circuit?
Definition
  1. Fornix - axons from hippocampus to mammillary bodies or septal nucleus
  2. Mammilothalamic tract -mammillary bodies to anterior nucleus of thalamus
  3. Thalamus to prefrontal cortex and singulate gyrus
Term
What organ is always involved in the lymbic system?
Definition
Hypothalamus
Term
What type of innervation do the limbic areas receive?
Definition
Monoaminergic (norepi, dopa, seratonin) and cholinergic (ACh)
Term
Where are the cell bodies making NE located?
Definition
The pons in the locus cerulius
Term
Where are the cell bodies making serotonin located?
Definition
In the raphe nuclei from pons to midbrain
Term
What is the monoamine hypothesis of depression?
Definition
In people with depression there is a decrease in NE, serotonin, or in the receptor activity for NE or serotonin
Term
What are the therapies used for treating the monoamine hypothesis of depression?
Definition
  1. MAO inhibitor - Decrease monoamine oxidase (which metabolizes NE and 5HT)
  2. Tricyclic antidepressants - block reuptake of NE and 5HT to increase them in the synaptic cleft
  3. SSRIs - specific seratonin reuptake inhibitor, ie Prozac
Term
What is the dopamine hypothesis of schizophrenia?
Definition
It is caused by an increase in dopamine or dopamine receptor activity?
Term
What is the strategy for treating schizophrenia?
Definition
Block DA receptors (halperidol for ex)
Term
What is the etiology of Alzheimers?
Definition
Neurodegeneration that includes limbic structures (hippocampus) and loss of ACh
Term
Where are the cell bodies releasing ACh found?
Definition
Septal nucleus and nucleus basalis
Term
To what organ do septal nucleus and nucleus basalis project?
Definition
Hippocampus
Term
The mesolimbic system is the center for what:
Definition
motivation and positive reinforcement
Term
Where is the mesolimbic system located?
Definition
Ventrotegmental area
Term
What NT is made in the VTA?
Definition
Dopamine
Term
To where does the VTA project to release dopamine?
Definition
Septal nucleus, cingulate nucleus, and nucleus accumbins
Term
How does addiction work (ie cocaine and amphetamines)?
Definition
Increase DA in synapse by blocking DA reuptake
Term
What happens when the VTA is lesioned?
Definition
There is a decrease in addictive behavior
Term
The amygdala is the center of what?
Definition
Fear conditioning
Term
What is urback-Wieth disease?
Definition
Bilateral amygdala lesions causing the patient to not show fear conditioning
Term
Continual electric shocking of the amygdala paired with a neurtal tone will cause what?
Definition
Conditioned fear to the tone causing inc HR and freezing behavior
Term
What happens to fear that is already conditioned if the amygdala is lesioned?
Definition
Rapid extinction
Term
What happened to HM?
Definition
Couldn't form new memories after surgery to temporal lobe (esp declarative memory ie facts)
Term
For what is the hippocampus important?
Definition
Memory consolidation
Term
A lesion in the hippocampus results in what?
Definition
Loss of declarative memory
Term
What is Korsakoff's syndrome?
Definition
Disorder of immediate memory causing disorientation and confabulation and inability to form new memories
Term
What is the etiology of Korsakoff's syndrome?
Definition
Lesion in anterior nucles of thalamus and/or mammillary body
Term
Korsakoff's syndrome is primarily found in who?
Definition
Alcoholics - deficiency in the vitamin thiamin due to inadequate diet
Term
What are the symptoms of Kluver Bucy Syndrome?
Definition
Oral tendencies, changes in emotions, hypersexuality, visual agnosia (inability to discriminate visual stimuli)
Term
What is the etiology of Kluver Bucy Syndrome?
Definition
Damage to temporal cortex including amygdala and hippocampus
Term
What are the progressivesymptoms of Alzheimers?
Definition
  1. Loss of memory
  2. Anxiety and/or depression
  3. Loss of motor fucntion
  4. Complete loss of cognitive function
Term
A loss of prefrontal cortex (Phineas Gage) results in:
Definition
  1. More impulsive behavior
  2. Loss of planning
  3. Inc in profanity
  4. Dec in social responsibility
Term
Definition
Term
What system maintains homeostasis?
Definition
Hypothalamic-pituitary
Term
The hypothalamus integrates what to control what?
Definition
Integrates info from peripheral and central receptors to control ANS, limbic system and pitutiary gland
Term
What is the median eminence (infundibulum)?
Definition
Where the hypothalamus and pituitary intersect
Term
Is the anterior or posterior pituitary a true endocrine gland?
Definition
Anterior, releases directly into blood stream
Term
Where are oxytocin and vasopressin synthesized?
Definition
Magnocellular neurons in the supraoptic and paraventricular nuclei
Term
How are the post pit hormones transported?
Definition
Via axons through the median eminence to the post pit. where they are released into the blood stream
Term
What are the stimuli and effects of vasopressin?
Definition

Inc in blood osmolarity or dec in volume or pressure

Inc in water retention or vasoconstriction 

Term
What are the stimuli and effects for oxytocin?
Definition

uterine stimulation --> uterine contraction

Suckling --> Milk ejection from mammary gland

Genital stimulation leading to orgasm --> contractile elements in genitalia 

Term
What are the somatomammotropins?
Definition
Growth hormone and prolactin
Term
Stimuli and effects of growth hormone?
Definition
Exercise, stress, slow wave sleep --> growth of tissues and metabolism
Term
Stimuli and effects of prolactin?
Definition
Suckling and stress --> Cause milk production
Term
What are the glycoproteins?
Definition
TSH, FSH, LH
Term
Stimuli and effects on TSH?
Definition
Cold temperature --> synthesis and secretion of thyroid hormone
Term
What are the effects of FSH?
Definition
spermatogenesis and ovarian development
Term
What are the effects of LH?
Definition

Stimulation of testosterone

Ovulation and inc stim of progesterone 

Term
What is pro-opiomelanocortin (POMC)?
Definition
The common precursor to ACTH and Beta-endorphin
Term
What are the opiomelanocortin peptides?
Definition
ACTH and B endorphin
Term
Stimuli and effects of ACTH?
Definition
Stress and inc. secretion of adrenal corticol hormone: cortisol
Term
Stimuli and effects of B-endorphin?
Definition

Stimuli: stress

Effect: opiate-like peptide --> analgesia 

Term
TRH, GnRH, CRH (corticotropin rel hormone), and GHRH cause increases in what?
Definition

TRH --> TSH

GnRH --> FSH LH

CRH --> ACTH and B endorphin

GHRH --> GH 

Term
Where are hypothalamic releasing factors synthesized?
Definition
In the parvocellular neurons
Term
Where do axons transporting hypothalamic releaasing factors terminate?
Definition
Median eminence
Term
Where are hypophyseal releasing factors released?
Definition
Into the hypophyseal portal blood system
Term
What is the junction between the parvocellular neurons (1st capillary bed) and 2nd capillary bed?
Definition
Median eminence
Term
Where is somatostatin released from? What is its affect?
Definition
Hypothalamus; its inhibitory and causes decrease in GH
Term
What is the only hormone with both inhibitory and excitatory inputs? Is this net excitatory or inhibitory?
Definition
GH; net excitatory
Term
What is the affect of dopamine?
Definition
Dec in prolactin
Term
What is only hormone under net inhibitory control?
Definition
Prolactin
Term
Loss of secretion of what hormone occurs in diabetes insipidus? What are the symptoms? Treatment?
Definition

Vasopressin

Polyuria, excesive urination, polydipsia

Give analog of vasopressin (antidiuretic w/o vasoconstriction) 

Term
What is the etiology of diabetes insipidus?
Definition

Head trauma resulting in pit stalk section losing connection between magnocellular neurons and post. pit.

OR

Autoimmune loss of magnocellular neurons 

Term
Hyperprolactinemia causes:
Definition
inc in prolactin in blood causing decrease in FSH and LH causing cessation of menstruation and inappropriate lactation
Term
What is the etiology and tx of hyperprolatinemia?
Definition

Etiology: Pit. microadenoma and inc secretion of prolactin

Tx: give dopamine or dopamine receptor agonist 

Term
Definition
Term
What is the general concept of hypothalamic control systems?
Definition
  • Measured by feedback detectors
  • Compare to set point (desired value)
  • Integrator or error detector generates error signal
  • Error signal drives controlling elements to correct
Term
As temperature decreases what happens to core and shell?
Definition
Core shrinks and shell increases in size
Term
What are the primary and secondary sites of heat loss?
Definition

Primary - skin

Secondary - lung 

Term
What are the primary and secondary efferent mechanisms for regulating heat loss or production?
Definition
  • Primary
    • Vasomotor
    • Behavior
  • Secondary
    • Sweating
    • Inc cellular metabolis
    • Shivering-induced thermogenesis
    • Non-shivering thermogenesis
Term
How does the vasomotor mechanism regulate heat loss?
Definition
Changes blood flow to the skin; inc vasodilation to lose heat and dec vasodialtion to retain heat
Term
What causes vasoconstriction and vasodilation to control body temp?
Definition

Vasoconstriction --> Norepi from postganglionic sympathetic nn.

Vasodilation: VIP (vasoactive intestinopeptide) from postgang symp nn (ACh also released but doesnt act directly on vasodilation only a cotransmitter)

Term
What is the sympathetic effector of sweating?
Definition
ACh from sympathetic post-gang. ACh
Term
What are the effectors to increase cellular metabolism?
Definition
Inc thyroid hormone to inc cellular metabolism and inc heat production
Term
What is the mechanism and effector for shivering induced thermogenesis?
Definition

Asynchronous skeletal muscle contraction (stim extensors and flexors together w/o movement)

ACh is effector 

Term
What is the mechanism and effector for nonshivering thermogenesis?
Definition

BAT - has a protein that uncouples glucose oxidation from formation of ATP to generate heat instead

Effectors are: NE and thyroid hormone 

Term
What are the hot and cold receptors in the skin? What tract do they make up?
Definition

Cold: A delta

Warm: C fibers

Spinothalamic tract 

Term
What is in the anterior hypothalamic - preoptic area?
Definition
Central thermal receptors responding to inc in warming and cooling
Term
How is fever produced?
Definition
Through endogenous pyrogens
Term
Where do endogenous pyrogens come from?
Definition
Macrophages in response to bacterial or viral particles (lipopolysaccharides ofthe wall of bacteria/virus)
Term
Where do enodgenous pyrogens (cytokines) act? What is the result?
Definition
????Act on neurons in the AH/POA (anterior hypothalamic-preoptic area) resulting in a decreased firing rate of warm-sensitive neurons and inc. firing rate of cold-sensitive neurons
??????????
Term
Definition