Neurophys block 5

Question 1

What are the 3 meninges?

Answer 1

1. Dura matter
2. Arachnoid
3. Pia Matter

Question 2

Dura matter

Answer 2

• outmost layer
• fused w inner skull
• thicker, protects the CNS

Question 3

Arachnoid

Answer 3

• web like appearance, trabeculae
• Thin, loose CT
• Subarachnoid space between arachnoid and pia matter

Question 4

What is the function of the subarachnoid space?

Answer 4

Traps CSF, CSF is absorbed

Question 5

Pia matter

Answer 5

Innermost layer

Adheres to surface of CNS, covers CSF

Question 6

What is the major source of CSF?

Answer 6

Choroid plexus

Question 7

Ventricular system

Answer 7

1. Lateral ventricle
2. 3rd ventricle
3. 4th ventricle

One of the places where the CSF is produced

Question 8

Interstitial capillaries

Answer 8

Provides O2 + substances consumed in large amounts

Macronutrients

Question 9

Absorption of CSF

Answer 9

From subarachnoid space into venous sinuses through

1. Arachnoid villus
2. Dorsal Sagittal sinus
3. Veins

PRESSURE DEPENDENT + UNIDIRECTIONAL

Question 10

Functional types of synapses

Answer 10

1. Chemical
2. Electrical

Question 11

Chemical synapses

Answer 11

• most common, unidirectional
• presynaptic neuron secretes neurotransmitter and acts on receptor proteins in post synaptic membrane

EXCITATORY + INHIBITORY

Ex: AcH @ NMJ

Question 12

Electrical synapses

Answer 12

Adjacent cells directly connected by clusters of ion channels called GAP JUNCTIONS

BIDIRECTIONAL

interacts w chemical synapses, promotes synchronous firing

Question 13

Ionotropic Receptors

Answer 13

• Cation channels opened by excitatory neurotransmitters
• Induces depol +++

Ex: Na+ channel

Question 14

Metabotropic receptors

Answer 14

• acts thru secondary messengers
• GPCR’s open ion channels thru post synaptic membrane

Activates cAMP, intracellular enzymes, or gen transcription

Question 15

Types of summation in graded potentials

Answer 15

1. Spatial summation
2. Temporal summation

Question 16

Excitatory Postsynaptic Potentials (EPSP)

Answer 16

Ligand gated

• Depolarizes graded potentials
• Drives mp to threshold
• excitatory synapses, opens cation channels

Question 17

Speed of conduction

Answer 17

Depends on axon diameter and degree of myelination

Question 18

How does saltatory conduction work?

Answer 18

1. Na flows in cell (DEPOL)
2. Electrical current flows thru axoplasm and in axon (Passive and decremental Na+ current)
3. Impulse sent from node to node
4. Changes voltage on next node to open Na channels
5. When next node is done depolarizing the previous one is repolarizing (AP regenerated)

Question 19

Spatial summation

Answer 19

graded potential induced by different synapses, summates in post synaptic neuron

simultaneous summation of EPSP + IPSP’s

Question 20

Temporal summation

Answer 20

succesive discharges from a single presynaptic terminal, summates in post synaptic neuron

IF RAPID ENOUGH

Question 21

Inhibitory Post Synaptic Potentials (IPSP)

Answer 21

Hyperpolarizing graded potentials

Drives mp away from threshold so AP is less likely

Inhibitory synapses, opens anion channels

Question 22

Functional classification of sensory neurons

Answer 22

1. Mechanoreceptors
2. Thermoreceptors
3. Nociceptors
4. Photoreceptors
5. Chemoreceptors

Question 23

Mechanoreceptors

Answer 23

1. Skin tactile sensibilities
2. Deep tissue sensibilities
3. Hearing
4. Equillibrium/ balance
5. Arterial Receptors

Question 24

Chemoreceptors

Answer 24

Receptors for
- taste
- smell
- arterial O2
- osmolality
- Blood CO2
- BG, AA, FA

Question 25

Nocireceptors

Answer 25

receptors for pain! free nerve endings

Question 26

Primary/ 1st order neuron

Answer 26

PNS to CNS primary afferent

Question 27

Secondary/ 2nd order neuron

Answer 27

in CNS, crossing over spinal cord or brainstem to thalamus

Question 28

Tertiary/ 3rd order neuron

Answer 28

in CNS thalamus to primary somatosensory cortex

Question 29

4th order neuron

Answer 29

in CNS sensory area of cerebral cortex

Question 30

Types of adaptation

Answer 30

1. Slow adapting receptors= tonic 2. Fast adapting receptors= phasic

Question 31

The BBB is highly permeable to?

Answer 31

H2O, CO2, O2 and lipid soluble molecules

Question 32

What is the BBB impermeable to?

Answer 32

plasma proteins and non lipid soluble large organic molecules

Question 33

The BBB is slightly permeable to?

Answer 33

Na+, K+, Cl-

Question 34

Arachnoid villi

Answer 34

finger like projections of arachnoid membrane that pokes through dura matter in lumen on venous sinuses helps drain CSF

Question 35

Functions of the CSF

Answer 35

1. Protect brain + spinal cord 2. Waste control, removes harmful metabolites 3. Brain distribution system for peptide hormones and growth factors 4. Maintains microenvironment for neurons and glia (micronutrients)