Nervous System Part 2

Question 1

What do axon terminals contain?

Answer 1

• synaptic vesicles filled with NT
• mitochondria
• active zone: specialized proteins that control exocytosis of vesicles, voltage gated ion channels

Question 2

How do synaptic vesicles get released into the synapse?

Answer 2

The membrane depolarize and ALOT of Ca2+ goes into the cell, and then interacts with proteins to trigger the vescicles to fuse with active site plasma membrane

Question 3

How does the axon terminal make new synaptic vescicles?

Answer 3

It has proteins inside it that can generate

Question 4

How is acetylcholine re-uptaken into the axon terminal? What is another way that it can be recycled?

Answer 4

• Broken apart by AChE and returned into the axon terminal

- transporter proteins or astrocytes

Question 5

How does cocaine affect the dopamine transporter protein?

Answer 5

It is an inhibitor

Question 6

How do SSRI’s work?

Answer 6

They block the function of the transporter protein for a related NT — serotonin—

Question 7

What is an excitatory post synaptic potential? What is an inhibitory post-synaptic potential?

Answer 7

Excitatory: make a neuron more likely to fire an AP (an EPSP depolarizes the membrane and is usually generated by the opening of channels that are permeable to Na+)
Inhibitory: make a neuron less likely to fire an AP (an IPSP is generated by the opening of channels that are permeable to K+, or channels permeable to Cl- and often hyperpolarizes)

Question 8

What is an agonist?

Answer 8

A drug that mimics the action of an endogenous NT

Question 9

What is an antagonist?

Answer 9

The drug that blocks the activation of an NT receptor (the NT can’t bind so cellular activity is blocked)

Question 10

Is alcohol an agonist or an antagonist? What about caffiene?

Answer 10

Both are antagonists

Question 11

What is the effect on a graded potential when SSRI’s cause serotonin to stay in the cleft for a long time?

Answer 11

• the graded potential increases because there is more serotonin taken up into the cell

Question 12

What is graded potential summation?

Answer 12

Two ESPs can add together and create a larger depolarization, or an IPSP can subtract from EPSPs and move the potential further from the threshold

Question 13

What is spatial summation?

Answer 13

Overlap of two graded potentials generated by two different presynaptic neurons

Question 14

What is temporal summation?

Answer 14

The overlap of 2 graded potentials generated by 2 APs of the same presynaptic neuron at different times

Question 15

What are metabotrophic receptors?

Answer 15

Receptors that signal through G proteins

Question 16

What is convergence, divergence and parallel processing?

Answer 16

Convergence: 1 post synaptic neuron receives many inputs
Divergence: 1 pre synaptic neuron shares its outputs with more than one neuron
Parallel processing: many post synaptic neurons receive and pass on the same information to different places

Question 17

What is serial processing, recurrence and recurrent inhibition?

Answer 17

• sequential post synaptic neurons receive and filter the information at each stage
• postsynaptic neuron synapses back on the presynaptic partner
• the recurrence is blocked by an inhibitor

Question 18

What are the steps of a spinal reflex?

Answer 18

1. Stimulation of a receptor
2. Activation of sensory neuron
3. Information processing in the CNS
4. Activation of motor neuron
5. Response of peripheral effector

Question 19

What are the steps of a stretch reflex?

Answer 19

• begins at the muscle spindle (intrafusal muscle fibres)
  1. Tapping the tendon stretches the muscle
  2. Stretch activates mechanoreceptor channels in the sensory neuron GP, then AP
  3. Sensory neuron synapses directly on the muscle’s alpha motor neurons, triggering EPSPs
  4. Action potentials cause the extrafusal muscle fibres to contract, causing a movement

Question 20

How are stretch reflexes enhanced?

Answer 20

Divergence: stretch receptor sensory neuron activates interneurons and the muscle’s motor neuron

Question 21

What are the steps of the withdrawal reflex?

Answer 21

1. Free nerve endings within the epidermis/dermis detect potential damage
2. Sensory neuron synapses on the interneurons
3. Synapses lead to sending signals to the brain, contracting the agonist muscle and relaxing the antagonist muscle

Question 22

What are the steps of the crossed extensor reflex?

Answer 22

1. Sensory neuron sends signal to spinal cord and synapses on interneuron
2. Sends signal to brain, and diverges to send signals to both legs
3. Ipsilateral side: flexors contract to lift the foot
4. Contralateral side: extensors contract so it can support the weight of the body

Question 23

What do the somatic and visceral nervous systems control

Answer 23

Somatic: skeletal muscle
Visceral: everything that’s not skeletal muscle

Question 24

What are the three layers of the meninges?

Answer 24

1. Dura mater: dense irregular connective tissue associated with periosteum
2. Arachnoid mater: elastic connective tissue with extensive trabeculae, and a simple squamous epithelium
3. Pia mater: areolar connective tissue and simple squamous epithelium

Question 25

What is the structure of the BBB?

Answer 25

Endothelial cells in CNS capillaries are connected by tight junctions, limiting the movement of water and hydrophilic molecules

Question 26

How is cerebral spinal fluid circulated? How is it reabsorbed into the circulatory system?

Answer 26

• circulates from ventricles to the subarachnoid space, pumped through CNS tissue
• CSF is absorbed back into the circulatory system via arachnoid granulations that penetrate through dura into sinuses

Question 27

What is the glymphatic system?

Answer 27

Astrocytes that push CSF through the CNS tissue and filter wastes. Especially active during sleep

Question 28

What is white matter made of? What is grey matter made of?

Answer 28

White: myelinated axons (white because myelin contains fat)
Gray: glia, neuronal cell bodies, dendrites and axon terminals

Question 29

What does S, L, Th and C stand for in the dorsal column?

Answer 29

Sacral, lumbar, thoracic and cervical

Question 30

What are the three divisions of the telencephalon?

Answer 30

Limbic system, basal ganglia, cerebral cortex

Question 31

What are the primary sensory cortices? What are primary motor cortices?

Answer 31

Sensory: first cortical region to receive sensory information (from the thalamus)
Cortical: last cortical region to process motor information, and projects directly to the spinal cord

Question 32

What does the accurate fasciculus do?

Answer 32

Connects an auditory association area involved in comprehending language to a promoter area involved in speech productions (Broca’s to Wernicke’s)

Question 33

What is the longitudinal fasciculi?

Answer 33

Tracts of white matter that connect frontal lobe to other parts of the forebrain

Question 34

What does the corpus callosum do?

Answer 34

Enables coordination of movement between the hemispheres

Question 35

What are the four different types of brain waves in an EEG?

Answer 35

Alpha, beta, theta and delta

Question 36

What causes a seizure?

Answer 36

Often a piece of scar tissue sets off neuronal activity— lots of graded potentials firing action potentials
- become too synchronized

Question 37

How is the resting potential of any cell created and maintained?

Answer 37

K+-ATPase pumps Na+ out and K+ in, setting up a K+ gradient. The K+ leaks out of the membrane through the K+ leak channel. There are a large number of negatively charged proteins in the cytoplasm that cannot leak out. When the K+ leaks out there is a separation of charge that causes the inside to be negative (due to the proteins) with respect to the outside