ch 2 brain functioning and development

Question 1

Nervous system -composed of two parts:

1. Peripheral nervous system

Answer 1

PNS lies outside the brain and spinal cord and composed of 12 pairs of cranial nerves and 31 pairs of spinal nerves. It’s main NT is acetylcholine. The pns has two divisions:

 a. Somatic -neurons sends stimuli to skin, muscles, joints. Provide info to brain regarding position, perception, pressure, environment.
 b. Autonomic - neurons send stimuli to internal organs, blood vessels, and glands. Influenced by cerebral cortex, amygdala, RAS, and most strongly the hypothalamus.  It regulates temp, pulse, bp, water, and food intake. Functions without conscious thought. Includes 3 systems:
    i. Sympathetic - response of body to emergencies, main NT are epi and norepi. Redistributes blood to vital organs, dilates pupils. 
    ii. Parasympathetic- conserves body resources and restores homeostasis, slows hr, stimulates digestion, causes bladder to contract, constricts pupils.
   iii. Enteric - neural system controlling transportation and digestion of food.

Question 2

Brains structure-

1. Cerebral cortex

Answer 2

• largest, is a thick layer covering both hemispheres composed of gray and white matter. Info is process and interpreted here, plans made and evaluated, mvmt control, behaviors selected, memory recall, planning, goal directed behavior.
  a. made up of into 4 lobes (pg 45) per hemisphere, parietal, temporal, frontal, occipital and limbic system, and insular cortex.
  i. cingulate cortex and insular cortex involved in response to pain.
  ii. Insular - processes tactile information called stereognosis, also info about cold, hunger, thirst, cravings, disgust.
  iii. Limbic - involved in learning, memory, emotions, aggression, submission. consists of 5 parts:
  a. hypothalamus - receives stimuli from brainstems and spinal cord, regulates autonomic systems and hormone secretion.
  b. thalamus - gaits intro and relays info, wakefulness, sleep, pain perception.
  c. hippocampus - memory and learning, cognitive maps
  d. amygdala - fear and anger, emotional memories, seeks attachments indiscriminately.
  e. septal nuclei - attachment and reward, dampens rage responses, socialization, sexual pleasure.
  (Other structures :
  -RAS - arousal and sleep,
  -Dorsal raphe - produces serotonin,
  sleep/wake cycles, Locus ceruleus -
  produces norepi, activity maintains
  arousa, inactivity allows sleep,
  -Brainstem - regulates autonomic,
  parasympathetic.,
  -Nucleus accumbens - modulates limbic
  system, reward and pleasure city,
  -Cingulate gyrus - integrates emotional
  info, assigns emotional value to stimuli)

Hemispheres - connected by corpus callosum allowing both hem. to communicate.
A. Right hemisphere - encodes and recalls nonverbal memories and negative memories, involved in avoidance behaviors.
1. endusers survival, emotions, recognition of faces, body image, music, visual imagery, daydreams.
2. Deficits due to damage may lead to speech interpretation problems, flat, monotone speech, not recognize nonverbal cues, inability to sing, visuospatial, pain, and perceptual disfunction, reading problems, memory deficits, mania or mood lability, pressured speech, ideas of reference, irritability, euphoria, impulsivity, or promiscuity.
3. temporal parietal damage then inability to understand or produce emotional speech, if damage to right frontal area, then confabulation, excessive speech, and tangentiality.

B. Left Hemisphere - encodes and recalls verbal memories and positive memories, cheerfulness, approach behavior. Is factual.

1. left frontal is Broca’s area (production of speech), expressive aphasia, problems writing or performing 3 step commands, may become depressed or irritated.
2. Damage to left frontal and medial appear apathetic, hypoactive, and poorly motivated. Anomia - problems word finding.
3. Wernickes areas - temporal lobe posterior damage involved with language comprehension, speech lacking content.

C.corpus callosum - no memory before age 3 due to hippocampus not matured sufficiently. Damage here manifested by inability to transfer information between hemispheres. Associated with dev delays, intellectual disabilities, and neurological deficits.

Question 3

Neurotransmission

Answer 3

1. Involves electrical impulses or action potentials
   2.Involves release of neurochemicas
2. Invovles receptors to receive message
3. Involves termination of NT
   Spark, spray, slide, scoop up of NT.

A. Receptors -

1. ion gated- ionotropic, activatedby gaba and glutamate. Rapid transmission.
2. g protein receptors - cosntitute 80% of recap., regulate “second messengers” changes shape. DA, Norepi, Serotonin, cannabinoids, and enkephalins receptors. Longer transmission.
3. tyrosine kinases and phosphatase receptors - used by growth factors, cytokines.
4. Nuclear receptors - regulate gene expression in response to steroid hormones.

B. Neutrotransmitters
1. Monoamines - include cathecholamines (DA, NE, epinephrine), indoleamines (serotonin, melatonin) and histamine. Influenced by antidepressants,antipsychotics, and stimulants. Mainly found in frontal lobes, and limbic system, involved in higher brain function. (see individual cards)

2. AA - i.e. glutamate excitatory, aspartate exitatory, GABA inibitory , glycine inhibitory, adenosine. Most widely used NT in brain.

a. Glutamate - work horse. found in cortex, hippo, thalamus, striatum, cerebellum, spinal cord, Calcium channel regular. Plays role in plasticity, learning, memory. Assoc with epilepsy and schizophrenia. Trauma, ischemia, and severe stress increase glutamate in hippo.Excess glutamate is excitotoxin. ALS.
glutamate receptors:
i. AMPA - stimulated by glutamate, fast excitatory signal, drugs of abuse alter receptors in ventral segmental area and causes permanent changes of brain in response to drugs.
ii. NMDA - opened by glutamate and glycine together involved in memory storage. hippo, cerebellum, spinal cord. Excessive receptor activity leads to ^ Ca influx and possible neuronal death.
iii. kainite - synaptic plasticity, regulation of mood, risk-taking behaviors, mania behaviors. Increased levels assoc with ALS.

b. Aspartate - exictatory, found in spinal cord.

c. GABA - major inhibitory NT, located throughout brain. Glutamate is precursor for GABA and require Vit B6. Reduces aggression, anxiety, working memory, sleep, muscle relaxation.
i. Inhibits action potentials.
ii. Guards to prevent glutamate from excessive stimulation of neurons.
iii. Gaba agonists like BENZOS, also induce inflow of chloride.
iv. Without inhibitory action, increase in excitatory neurons > rapid thoughts, excessive anxiety, seizure activity.
v. GaBA transmission in prefrontal cortex is increased by serotonin. Therefore SSRIs help with anxiety.
vi. Vulnerable to stress related cortisol and excitotoxicity from glutamate.

d. Glycine - inhibitory, barinstem and spinal cord, inhib its neuronal firing by gating chloride channels. Can change NMDA functioning. NMDA agonists improve cognition, decrease negative symptoms in schizophrenia.
e. Adenosine or ATP - neromodulation through Na - K ion regulation. Reuptake of glutamate. If not working, ^ glutamate and therefore excitotoxicity. Action is blocked by caffeine.

3. Cholinergic - acetylcholine - produced by choline et needs lecithin. Primary NT in PNS. Prepares for action or defensive behaviors, attention, learning, memory. control salivation, GI motility, pupil size, mucus secretion. Found in hippo, thalamus, cerebellum, limbic, cerebral cortex. Thalamus and hippo densely innervated by cholinergic neurons.
   i. balance dopamine input in striatum > coordinate EP motor control. If dopamine blocking > EPS, therefore use anticholinergic to restore acethylcholine and dopamine balance.
   ii. Action terminated byenzyme. Imapirment of acetylcholine systems assoc with alzheimers and othe dementias.
   iii. Alz meds inhibit cholinesterase action to ^ acetylcholine availability.

Recepctors:
i Muscarinic - g protein coupled, regulate ion channels, esp Ca or K ion, or linked by second messenger systems. assoc with attention, learning, memory, cardiac, GY, salivary functioning. Meds that block receptors (atropine) cause memory problems, confusion, dry mouth, constipation, blurred vision.
ii. Nicotinic - ionotropic recap involved in epilsepsy, Alz, Parkinsons, schizophrenia.

4. Neuropepetides - insulin, somatostain, ACTH, neurostatin. Regulate body homeostatic behvaiors such as food, water, consumption, sex, sleep , body temp. Invovled in depression, dementia schizophrenia. Inhibit or excite.
5. Neurohormones - cortisol. Organizaional effect prenatal, activational effect postnatal. Stimulate changes in gene expression. Also act on NT. Alrer effectiveness of glutamate or GABA transmission.
   i. cortisol - stress hormone, elevated blood glucose, suppresses inflammatory response, increases gastric secretion, catabolism, breaks down adipose tissue, skin, and bones to produce energy. Stimulates urge for comfort foods.
   ii. TRH - stimlates T3 and T4 release. Its regulated by Acetycholine, NE, DA, Serotonin. Blunting occurs with depression, alcohol, BPD.
   iii. Prolactin - from anterior pit gland. Hypo controls secretion, GABA controls its regulation. ^prolactin > anxiety, irritability, depression, libido loss, difficulty tolerating stress.

Question 4

Nervous system made up of 2 parts:

2. Central NS

Answer 4

2. Central nervous system - encased in bone, cerebrum, cerebellum, brainstem, and spinal cord. There are neurons and glial cells in brain. Glial cells protect neurons by nourishing, removing debris, and support.
   a. neurons - receive, process, transmit info to other neurons, muscles, and to secretary cells.
   A. Each cell:
   
   1. membranes have receptors, ion channels, andreuptake pumps.
   2. cell body contains nucleus which has DNA. neuron is made up of body, axon, axon terminals, and dendrites.
   3. cells do not touch, synapses in between (cleft).
      B. Glial cells:
   4. oligodendrocytes produce myelin to insulate neurons in brain.
   5. Schwann cell, also produce myeline to coat PNS neurons.
   6. astrocytes scaffold neurons during brain development, nourish, and form BBB.
3. microglia remove debris after injury.
4. Gliomas arise from astrocytes.

Question 5

Brain structure

2. Basal ganglia

Answer 5

2. Basal ganglia - integrates emotion, executive function, motivation, and motor activity, located below cortex and is involved in mvmt and motor control. Structures are caudate nucleus, putamen, and globes pallidus.

Question 6

NT - DA

Answer 6

a. DA- made in substantia nigra from AA tyrosine>L-dopa>DA.Not widespread as NE or Serotonin. Involved in thinking, decision making, reward seeking behaviors, integration of thoughts and emotions, fine muscle movements. Dopamine pathways:
i. mesolimbic - reward, neruons in ventral tegmental area, mood d/o, psychoses, and drug abuse, positive symptoms.
ii. nigrostriatal dopamine - largest, vol/invol mvmt, decision about actions, goal directed activities, bipolar.
iii. mesocortical - stress, cognition, planning, modulating behavior, negative symptoms.
iv. tuberoinfundibular - hypothalamus and pituitary, prolactin, if dopamine interrupted >prolactenemia.

• DA receptors - D1-D5
  i. D1 - includes D5 receptors, frontal cortex and EP system, higher cognition, antipsychotic effect of meds. More prevalent.
  ii. D5 - prefrontal region, hippocampus, limbic system, nuc accumbens. TEn times affinity for DA.
  iii. D2 - includes D2-4. Caudate nut, putamen, NA, ventral tegmental, sub nigra. Positive symptoms, target of atnipsychotic meds. D3 limbic region, D4- cortical, thoughts process. Clozapine affinity for D4.

Question 7

NT NE

Answer 7

b. NE and Epinephrine - part of noradrenergic NT system.
i. Epi - monoamine prevalent in PNS, not brain.
ii. NE - prevalent in brain, alertness, arousal, learning, memory formation, foci attention, orientation, retrieves traumatic memories. fight or flight.
iii. Made in locus cerulus by tyrosine>L dopa > DA > NE.

• NE Receptors:
  a1 , b1 - g protein mediated second messenger systems in cerebrum, thalamus and hypothalamus. Less NE> ^a1, b1 receptor sites. Longterm antidep use > down regulation of a1, b1 receptor sites. NE a2 receptors stimulation decreases NE release. Therefore, a1 antagonists increase NE availability. Assoc with mood d/o, gen anxiety, panic d/o, PTSD>

Question 8

NT serotonin

Answer 8

c. Serotonin receptors 5HT1-7. Made in raphe nucleus of brainstem from AA tryptophan > enzyme > serotnonin. Involves limbic, hypothalamus, thalamus. Inhibits activity and behavior. Increases sleep time, decreased aggression and secual activity. Mediates eating, mood, pain perception, function and release of proaction and ACTH.
Alterations of serotonin - irritability, hostility, sleep dysregulation, loss of sex interest and appetite, Anxiety d/o, OCD, depression, suicidality.

i. 5ht1- high concentrations in limbic area, reduced functioning assoc with depression. Subtype 5ht1a - body temp, eating, sex, depression, and anxiety. Antagonists of 5HT1a prevent feedback that shuts off serotonin > ^ availability.
subtype 5ht1b - movement d/o, anxiety, food intake, sex, aggressive behavior.
Subtype 5ht1d - motor action, vasoconstriction, migraine, appeitte.

ii. 5HT 2 - hypo, thalamus, cortex, sitratum, Nuc accumbens, olfac, hippo. emotion, cognition, mvmt, reward, memory, smell reactions.
Subtype 5ht2a - smooth msucle contraction, hormaone, release, sex, sleep regulation, motor behaviors. Epilepsy, migraines, anxiety, depression, schizophrenia, hallucinations.
Subtype 5ht2b - smooth muscle contraction and cognition.
Subtype 5ht2c - produces csf. wt gain, appetite. Clozapine binds to 5ht2 rceptors, fewers eps and sex.

iii. 5HT3 - intestines, GI distress. Remeron used for IBS. In brainstem, receptors assoc with vomiting. Ondanseron antagonize.
iv. 5HT4 - located basal ganlis, hippo, neocortex. Involved in cardiac, adrenal, bladder, Gi tract actitivy. Modlate GABa release.
v. 5HT5 - hypo,hippo, corpus callosum, ventricles. High affinity for LSD.
vi. 5HT6 - in cerebral cortex, and limbic. HIgh affinity for tricyclic.
vii. 5HT 7 - cerebral cortex, hippo, thalamus, caudate nuc. Smooth muscle relaxation, sensory processes, circadian rhythms, mood behaviors.
d. HIstamine - regulate brain function, immune response, gastric secretions, ACTH prolactin/oxytocin release.