Lec 16 - brain and protective structures
describe the flow of CSF from Choroid Plexus to the Venous System
choroid plexus --> lateral ventricle --> interventricular foramen --> 3rd ventricle --> 4th ventricle --> cerebral aqueduct --> subarachnoid space --> arachnoid granulations --> superior sagittal sinus --> venous blood system
Identify the 5 functional groups of THALAMIC NUCLEI
Anterior Group = apart of limbic system (mem and emotion)
Posterior Group
- Lateral Geniculate Nucleus: visual signals to occipital lobe
- Medial Geniculate Nucleus: auditory signals to temporal lobe
Medial Group = emotions
Lateral Group = somatosensory output to association areas
Ventral Group = somatosensory output to association areas
Identify the molecules that act as NTs
Amino Acids
Monoamines
Nueropeptides
AAs
- glycine, gaba, glutamate, ACh
Monoamines
- catecholamines, histamine, serotonin
Neuropeptides
- Substance P, opioids
Describe the AWAKE brain waves, SLEEP brainwaves, and REM sleep
Awake
- beta waves = performing a task
- alpha waves = awake but resting
Sleep
- theta waves = common in children, represent drowsiness/sleepiness in adults
- delta waves = deep sleep in adults; when RR and HR slow a lot
REM = dream sleep
- vitals in ECG represent a wakeful state
- REM atonia = muscle paralysis to prevent self injury/sleep walking
- rapid eye mvmt, pupil constriction, erection
describe the differences between the SNS and the PNS
FUNCTIONAL
ORIGIN IN CNS
LENGTH OF GANGLIONIC FIBERS
LOCATION OF GANGLION
WORKING NTS
DEGREE OF PREGANGLIONIC BRANCHING
SNS
Function: fight or flight
Origin
- paravertebral ganglia
- thoracolumbar division
Pre&Post-ganglionic axons
- short pre
- long post
Galglion Location
- close to CNS
NTs
- catecholamines
Degree of Branching
- extensive branching = widespread effects
PNS
-
Function: rest and digest
Origin
- craniosacral division
Pre&Post-ganglionic axons
- long pre
-short post
Galglion Location
- close to effector organs
NTs
- ACh
Degree of Branching
- some branching = selctive stimulation on target organ
Contrast the Blood-Brain Barrier and the Blood-CSF Barrier
Blood-CSF
- capillaries of choroid plexus, fenestrated endothelial cells, ependymal cells, CSF
Blood-Brain
- everywhere in brain, nonfenestrated (=selevtively permeable) endothelial cells, astrocytes & pericytes
Identify the 6 HYPOTHALAMIC NUCLEI and their functions
suprachiasmatic = circadian rhythm/clock
mammillary nucleus = memory formation
dorsomedial nucleus = rage and other emotions
lateral hypothalamic nuclei = feeding center
ventromedial nuclei = satiety center
arcuate nucleus = regulates VM and LHT nuclei!!! (receives signals from GI tract and adipose tissue)
describe three ways for concluding synaptic transmission and give examples
enzymatic degredation
- COMT & MAOa, Acetylcholinesterase
diffusion
- ACh
Reuptake (by transporter protein)
- SERT = serotonin transporter
describe the Pineal Gland and the SCN (suprachiasmatic nucleus)
SCN
- receives direct input from the eyes to sync body rhythms with rhythms of night and day like sleep, body temp, urination, hormone secretion
Pineal Gland
- melatonin in dark phase for sleep, energy balance
- orexin inn light phase for wakefulness, food intake
Describe the 3 routes that the sympathetic fibers can follow after entering sympathetic chain ganglia
1) spinal nerve route
- synapse in trunk ganglion at same level
- pre-ganglionic white ramus communicans
- post-ganglionic gray ramus communicans
2) sympathetic nerve route
- travels up and down sympathetic trunk; synapse in trunk ganglion at a higher or lower level
3) splanchnic nerve route
- pass thru sympathetic trunk and synapse in collateral ganglia
- past ganglia preganglionic fibers are splanchnic nerves
- collateral ganglia lie btwn sympathetic chain and organ of supply
- celiac ganglia, superior & inferior mesenteric ganglion
describe these structures of the MIDBRAIN
- Cerebral Peduncles (hint: what do the two colliculi do?)
- the Tectum, Tegmentum, Substantia Nigra, and Crus Cebri
- superior colliculi = visual reflexes
- inferior colliculi = auditory reflexes
Tectum?
Tegmentun = red nuclei (subcortical motor centers)
Sunstantia Nigra - dopamine (motor control!!!)
Crus Cerebri = corticospinal (motor tract!!!)
Describe the 3 WHITE MATTER TRACTS of brain and give EXAMPLES
association tracts: connect diff. regions w/in same hemisphere (intrahemispheric tracts)
- cingulum
projection tracts: run vertically btwn high and low centers of brain
- corona radiata (fibers of the internal capsule), fornix
commissural tracts: cross from one hemisphere to another
- corpus callosum, anterior commisure
Describe the 4 DOPAMINERGIC PATHWAYS
Nigrostriatal
- substantia niagra + striatum
- too much dopamine = hyperkinetic (huntingtons)
- too little dopamine = hypokinetic (parkinsons)
Mesolimbic
- VTA (midbrain) + limbic system
- motivation & reward
- positive schizo. (hallucinations) = increased dopamine signaling
Mesocortical
- VTA (midbrain) + prefrontal cortex
- emotion & affect, judgement & planning
- negative schizo. (cognitive) = dereased dopamine signaling
Tuberoinfundibular
- arcuate nucleus (infundibular nucleus) + pituitary
- dopamine inhibits prolactin release
describe the FIVE structures involved in the limbic system and their functions
Prefrontal Cortex = decision-making, emotional regulation, social behavior
Amygdala = fear, anger, pleasure, stress, appetite, sexual pleasure
Hypothalamus = physiological changes associated w stress like increased HR, BP
Basal Ganglia/Striatum = avoidance of stimula
Hippocampus = memory storage of emotional events
Are these effects sympathetic or parasympathetic?
bronchodilation
bladder contarction
increased GI motility
pupil dilation
increased heart rate
glycogenolysis
- SNS
- PNS
- PNS
- SNS
- SNS
- SNS
describe the structures and functions of the MEDULLA OBLONGATA
Overall function: control RR, HR, BP, cough, vomit
Anatomy
- Pons = helps w respiration
- Pyramids = descending corticospinal tracts (pyramidal tracts!!!)
Describe the functions and associated impairments of CRANIAL NERVES 1-6
Olfactory: sensory, smell, anosmia
Optic: sensory, visual signals, blindness
Oculomotor: motor, controls extraocular muscles (pupil constriction & lens focusing) and upper eyelid, impairment of normal vision
Trochlear: motor, superior oblique muscle & allows down and right gaze, double vision
Abducens: motor, lateral rectus muscle & lateral vision, double vision?
Explain the changes that occur in Short Term Memory & Long Term Memory
STM = temp potentiation by
- increased NTs
- increased postsynaptic receptors
- altering how much electrical current flows through ion channel (synaptic strength)
LTM = lifetime potentiation by strong, sustained activities
- structural: new dendritic spines, changes cortical area, enlargement
- functional: neurons adopt new function
Describe the PRIMARY motor and somatosensory areas and the ASSOCIATION motor and sensory areas of the cortex
PRIMARY Motor
- precentral gyrus
- controls voluntary mvmt
PRIMARY somatosensory
- postcentral gyrus
- receives somatosensory stimuli and provides awareness of it
- general senses like temp, pain, pressure
ASSOCIATION motor
- premotor cortex in frontal lobe
- motor/mvmt planning
ASSOCIATION somatosensory
- parietal association area in roof of lateral sulcus
- makes cognitive sense (gives meaning and association to) of somatosensory stimuli
describe ALPHA RECEPTORS, BETA RECEPTORS, MUSCARINIC RECEPTORS, and NICOTINIC RECEPTORS
Alpha-1 Rs
- VC of blood vessels
- Urinary retention via CONTRACTION of sphincters
- Glycogenolysis
- Pupil Dilation
Beta-1 Rs
INCREASES HR, Contractility, AV Conduction
INCREASES BP (w help of RENIN from KIDNEYS)
Beta-2 Rs
- Bronchodilation
- VD
- Decreased GI motility, Increased insulin
B-3 Rs
- Lipolysis
- RELAX bladder
Nicotinic Rs
- NMJ; initiate skeletal muscle contraction
Muscarinic Rs
- M2 = decreases HR and contractility
- M3 = smooth muscle contraction & glandular secretions
Describe the location and function of RAS and the Cerebellum
- length of brainstem
- maintains consciousness & regulates muscle activity & habituation
Cerebellum
- hind brain
- arbor vitae (white matter)
- coordination and balance
Describe the functions and associated impairments of CRANIAL NERVES 7-12
Facial: mixed, facial muscles and sensory for taste, loss of sensation in effected facial regions
Vestibulocochlear: sensory, hearing and equilibrium, deafness & nystagmus
Glossopharyngeal: mixed, innervates pharynx and tongue, difficult swallowing & loss of nitter/sour taste sensations
Vagus: mixed, most extensive branching (cardiac, pulmonary, digestive, urinary functions), damage can be fatal
Accessory Spinal: motor, from upper spinal cord & controls swallowing and neck and shoulder muscles, shoulder pain
Hypoglossal: motor, controls tongue movement, ?
Contrast LTD and LTP, and outline the 4 STEPS involved in the possible mechanism of LTP in hippocampus by Glutamate & NMDA-AMPA receptors
LTD = use it or lose it
LTP = persistent strengthening of a connection by high-frequency signals and repeated stimulation
LTP mechanism
1) glutamate activates AMPA receptor -> NA
2) NA influx -> depolarization -> Mg releaseea from NMDA receptor -> allow Ca
3) Ca influx -> new AMPA receptors
4) bc of more AMPA receptors postsynaptic cell is more sensitive to glutamate! Ca also promotes new dendritic spines
Describe the CORTICOSPINAL TRACT
Prefrontal Cortex (alpha motor neurons)
Corona Radiata
Internal Capsule
Midbrain (Crus Cebri/Cerebral Peduncles)
Pons
Medulla
Spinal Cord = pyramidal decussation, where lateral and anterior corticospinal tract fibers cross over, creating the pyramidal tracts of medulla!
Lower Motor Neuron
How are sweat glands and blood vessels exceptions to dual innervation?
- eccrine sweat glands = thermoreg. BUT they release ACh to a musacrinic R
- apocrine sweat glands = stress sweat = NE to a alpha-1 R
Blood Vessels (symp. innervation)
- vasomotor tone! continual SNS input maintains partial and constant tension in vessel