CNS Structure And Function

Question 1

Acetylcholine

Answer 1

Secreted by: 
-pyrimidal cells in the cerebral cortex
-some in the basal nuclei
-alpha motor neurons
-preganglionic neurons of ANS 
Postganglionic neurons of PNS
-some sympathetic system post-gang neurons 

Excitatory

Question 2

Norepinephrine

Answer 2

Secreted by many neurons in the brain stem and hypothalamus, some in the pons and most sympathetic neurons

Either excitatoy or inhibitory

Question 3

Dopamine

Answer 3

Secreted by neurons in the substantia nigra

Usually inhibitory

Question 4

Glycine

Answer 4

Secreted by synapses in the spinal cord

Always inhibitory

Question 5

GABA

Answer 5

Screted by many areas of the spinal cord and cerebral cortex

Always inhibitory

Question 6

Glutamate

Answer 6

Secreted by many sensory pathways entering the CNS
Many areas of the cerebral cortex

Always excitatory

Question 7

What is characteriistic of potentials created on the membranes of dendrites? Why is this so?

Answer 7

Decremental conduction
-a gradual loss of the potential as the depolariztion spreads from the site of initiation and becomes weaker.

The membranes are thin and are partially permeable to potassium and chloride ions and results in the loss of potential

Few voltage gated channels and high thresholds

Question 8

What is electronic conduction?

Answer 8

On dendrites, a direct spread of electrical current by ion conduction in dendritic fluids without generating an action potential

Happens because of dendrite characteristics: little voltage-gated sodium channel and high thresholds

Question 9

What is the excitatory state?

Answer 9

The summated degree of excitatory drive to the neuron

More excitation than inhibition
Or
More inhibition that excitation

Question 10

What is the firing rate of a neuron? What factors does it depend on?

Answer 10

The neuron will fire repeatedly if it remains above the threshold of excitation

Rate depends on normal excitatory rate and the changes in the exciitory rate due to more or less signals

Question 11

What is synaptic delay? What is the miminal synaptic delay? What does synaptic delay depend on?

Answer 11

Refers to the time it takes to transmit a signal from presynaptic neuron to a post synaptic neuron

Miminal time is 0.5 msec

• time it takes to release neurotransmitter from the presynaptic neuron
• time it takes for the neurotransmitter to diffuse across the synaptic cleft
• how the neurotrmitter acts on the postsynaptic mem
• time it take for the recieving receptor to increase mem permeability
• time for inward diffusion of Na+

Question 12

What are the compenents oof the telencephalon?

Answer 12

Cerebral hemispheres 
-gyri and sulci
-left and right, 5 (6?) lobes
-80% of brain mass 
Olfactory bulb 

Basal nuclei
-corpus striatum (in cerebrum)

Question 13

What are the functions of the occipital lobe?

Answer 13

Integration of eye focusing movements

Correlates visual images with visial memory

Conscious perception of. Vision

Seperated from the parietal lobe by the parietoccipital sulcus

Question 14

Parietal lobe

Answer 14

Somatesthetic interpretation
-postentral gyrus

Understanding speech

• wernickes area
• auditory association cortex

Formulation words to express thoughts and emotions

Central sulcus is the landmark

Question 15

Frontal lobe

Answer 15

Voluntary motor control: precentral gyrus

Motivation 
Aggression
Mood 
Personality
Cognitive processess
Verbal communication - Broca's area

Question 16

Temporal lobe

Answer 16

Receives/interprets olfactory and audition sensation

Responsible for storage of memory related to auditory and visual experiences

Question 17

Insula

Answer 17

Involed with memory

Psychic cortex with highest level of brain function

• abstract thought
• judgement

Question 18

Corpus Striatum

Answer 18

Component of the telecephalon, cerebrum.

Functions:

Subconscious movements of skeletal muscles - caudate nucleus, putamen

Globus pallidus - regulation of meuscle tone

Question 19

What are the components of the Diencephalon?

Answer 19

Epithalamus with Habenular nuclei and Pineal Body

Question 20

What are the two sources of blood to the brain?

Answer 20

Internal Carotids and vertebral arteries

Question 21

Compare and conrast the functions of the magnocelluar and parvocellular zones of the RAS and the raphi nuclei

Answer 21

.parvocellular: lateral reticular formation- small cells
Noradreneric pathway from this zone going to the hypothalamus and other limbic structures
Regulat blood flow in the brain

Question 22

Components of the circle of willis

Answer 22

Posterior cerebral arteries

Posterior communicating arteries

Internal carotids

Anterior cerebral arteries

Anterior communicating artery (unpaired)

Question 23

Functions of the Reticular Activating System (RAS)

Answer 23

Modulates sensation of pain

Modulates some postural reflexes and muscle tone

Helps control heartbeat and breathing

Regulates level of brain arousal and consciousness

Two zones: magnocellular and parvocellular

Question 24

What effects do caffeine, theophyllin, theobromine, strychnine and anesthetics on synaptic transmission?

Answer 24

Caffiene, theophylin and theobromine all increase excitability of neurons by decreasing the thershold for excitation

Strychnine also increases excitabliity but by inhibiting inhibitory neurotransmitters

Anesthetics decrease synaptic transmission by increases the threshold for excitation