Lecture 1: Intro to Neuroscience Flashcards Preview

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1

What is the general function of our nervous system?

-control
-regulate
-communicate

2

What are the components of the CNS?

brain and spinal cord

3

What are the components of the PNS?

Somatic:
-cranial and spinal nerves
Autonomic:
-Parasympathetic, Sympathetic, Enteric

4

What are the main components of the neuron?

-dendrites
-soma (cell body)
-axon hillock
-axon
-terminal branches
-synapse

5

Dendrite function

receives signals

6

Soma function

-interpret info from dendrite
-determine if there is going to be an AP
-contains nucleus and organelles

7

Axon hillock function

signal becomes an AP --> elicits response

8

Axon function

-where the AP travels
-contains Myelin Sheath and Nodes of Ranvier

9

Terminal branches function

-at the very end right before synapse
-sends out NTs into synapse

10

Synapse function

specialized point of functional contact between neurons, or between a neuron and a target organ

11

What are the 3 types of neurons that can be found in the nervous system? Structural and Functional

Structural:
-multipolar
-bipolar
-unipolar
Functional:
-sensory (afferent)
-motor (efferent)
-interneuron

12

Multipolar neuron

most common, several dendrites and axons

13

Bipolar neuron

rare, single dendrite and single axon arising from a cell body, for special sensory organs (sight and smell)

14

Unipolar neuron

in PNS, axon and dendrite arise from a single process
arising from a soma

15

Main role of sensory (afferent) neurons and types

-Afferent= arrive
-signals from receptors to CNS
-special sensory:
i. vision
ii. auditory
iii. equilibrium
iv. gustatory (taste)
-viscerosensory: unconscious
-somatosensory: conscious

16

Main role of motor (efferent) neurons and types

-efferent=exit (response)
-signals from CNS to effectors
-somatomotor: voluntary; CNS--> skeletal muscle
-autonomic motor: involuntary; connects vital structures to CNS; smooth muscle, cardiac glands

17

What is the function of interneurons/associative neurons?

-local integration center
-comprised of brain and spinal cord
-connect sensory to motor

18

Define a reflex

-unidirectional rapid, predictable, and involuntary response to a stimulus
-NO cortical involvement

19

Define a reflex arc

neural pathway that controls a reflex
-sensory receptor --> sensory neuron --> interneuron --> motor neuron --> effector

20

Types of reflexes in human body

-somatic: skeletal muscle (ex: knee jerk)
-autonomic: smooth muscle, cardiac, and glands (ex: salivary reflex)

21

Explain the steps of the myotatic reflex, starting from the hit of the hammer to the leg kicking outwards.

-“knee jerk”
-hammer hit → extensor muscle → muscle sensory receptor → sensory neuron/ motor neuron in spinal cord/ interneuron synapse inhibits motor neuron in flexor muscles → motor neuron sends AP to extensor muscle to contract/ flexor relaxes due to inhibition of motor neuron

22

Explain the steps of the Flexor Withdrawal Reflex. When does this reflex come into play in function?

-flexor reflex + crossed extension reflex
i. flexor reflex: painful stimulus → afferent neuron → interneurons → efferent neurons → excitation of flexors, inhibition of extensors
ii. crossed extension: painful stimulus → afferent neuron → interneurons cross midline → efferent neurons → excitation of extensors, inhibition of flexors

23

Function of astrocytes and PNS equivalent

-are glial cells
-support cells
-maintain BBB
-tissue repair
-1/2 of CNS neural tissue
PNS equivalent= satellite cells

24

Function of ependymal cells and where they are found

-they produce and facilitate exchange of CSF
-line ventricle and central canal walls, forming choroid plexus

25

Function of microglia

"macrophages of the CNS"
-remove foreign bodies
-protect against infection

26

Oligodendrocytes

-CNS myelin creation
one cell can myelinate multiple axons

27

Shwann cells

-PNS myelin creation
-multiple cells required to myelinate one axon

28

Role and anatomy of Myelin

-speed up AP
-AP jumps node to node
-insulate strength/integrity of AP
-mixture of proteins and phospholipids → white matter

29

Nodes of Ranvier

-spaces between myelin sheath
-enables regeneration of AP
-saltatory transmission--> AP jumping from node to node

30

Where is a synapse found? Main components?

-found between a neuron and target cell/organ
-components are the presynaptic terminal (first neuron that starts the info and sends it down), synaptic cleft (chemical signals/NTs), and postsynaptic element (dictates type of synapse)

31

Different synapse types:

Axodendritic
Axosomatic
Axoaxonix
Dendrodendritic

32

Axodendritic

most common, axons of pre communicate with dendrites of post

33

Axosomatic

axons of pre go to cell body/soma of post

34

Axoaxonix

axon to axon, mediators (inhibit or facilitate)

35

Dendrodendritic

dendrite to dendrite, mainly found in vision/smell, uncommon

36

Electrical Synapse

-directly connected via gap junctions
-fast communication (1 ms)
-bi-directional
-latent period very short
-most typically seen in hypothalamus
-pro: quick
-con: not selective

37

Chemical Synapse

-slower process
-take up to a minute
-increased magnitude
-larger distance between neurons
-stronger and last longer
-these are the majority

38

Resting Membrane Potential

- neg. 70 mV
-intracellular K+
-extracellular Na+, Cl-
-maintained by the sodium-potassium pump and ion channels

39

Ionotropic receptors

"Ligand-gated channels"
-NT binds, channel opens, ions flow across membrane

40

Metabotropic receptors

"G-protein coupled receptors"
-NT binds, G-protein is activated, G-protein subunits or intracellular messengers modulate ion channels, ions flow across membrane, ion channels open

41

Agonists

same effect as the NT

42

Antagonists

block the effect of the NT

43

Inverse Agonists

opposite effect of NT

44

Neuromodulators

affect the likelihood that the NT will bind

45

Excitatory postsynaptic potentials (EPSP)

-causes depolarization of the cell
-increase Na permeability into cell
-increase likelihood of postsynaptic AP

46

Inhibitory postsynaptic potentials (IPSP)

-cause hyperpolarization of cell
-increase Cl permeability
-decrease likelihood of postsynaptic AP

47

Temporal summation

several impulses from one neuron at a time

48

Spatial summation

several impulses from several neurons at the same time

49

Continuous vs Saltatory conduction

Continuous is unmyelinated and saltatory is myelinated so it is faster

50

Conduction velocity is dependent on:

1. Fiber diameter
2. Presence of myelin
3. Thickness of myelin
4. PNS: fiber classification