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Neurophys Exam II > Cells of the nervous system > Flashcards

Flashcards in Cells of the nervous system Deck (47)
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1
Q

Nearly how many neurons are within the human brain?

A

~90billion

2
Q

How many neurons are estimated to be in the neocortex?

A

~30billion

3
Q

What type of neurons compromise approximately 25% of the human cortex?

A

Stellate neurons

4
Q

How many synapses do stellate neurons contain per neuron?

A

~10,000

5
Q

What type of neurons comprise the rest of the 75% of the cortex?

A

pyramidal neurons

6
Q

How many synapses do pyramidal neurons contain per neuron?

A

~18,000

7
Q

What are the two main classes of cells that are present in the nervous system?

A

Neurons and Neuroglial cells

8
Q

What are neurons?

A

specialized cells for rapid communication through the conduction of nerve impulses and exchanging information with other neurons

9
Q

What are neuroglia?

A

non-neuronal cells that perform various important functions

10
Q

What is the ratio of neuroglia to neurons?

A

10 to 1

11
Q

What were glial cells originally thought to do?

A

originally thought to be supportive, inactive connective tissue

12
Q

What are the neuroglia of the CNS?

A

Oligodendrocytes
Astrocytes
Microglial cells

13
Q

What are oligodendrocytes?

A

Send out proteoplastic processes that make contact with nearby axons and form myelin sheaths around them

14
Q

What does myelin consist of?

A

long sheet of oligodendrocyte plasma membrane that wraps in a spiral fashion around an axon

15
Q

What is the bare portion at the end of each myelin sheath?

A

Node of Ranvier

16
Q

What is the purpose of myelin sheaths?

A

has certain insulating properties that allow APs to jump from node to node, therefore does not need to be continuous along the entire length of the axon

17
Q

What is the name for the jumping of node to node during APs?

A

Saltatory conduction

18
Q

What are astrocytes?

A

star-shaped (or stellate) glial cells that contain multiple processes extending form their somas
- Have a wide range of function

19
Q

What are the functions of astrocytes?

A
  • Produce ECM proteins and adhesion molecules that guide the migration of neurons during development
  • Secrete growth factors that regulate the morphology, differentiation, proliferation, and even survival of neurons
  • Aid in the formation of the blood-brain barrier by inducing and maintaining the tight junctions in endothelial cells that form the barrier
  • Regulate neurotransmitter removal form the synaptic cleft via uptake
  • Intracellular signaling and potentially even intercellular signaling through the generation of intracellular Ca waves which can travel to adjacent cells
20
Q

Which cells detoxify the CNS by sequestering metals and other neuroactive (and potentially harmful) substances?

A

Astrocytes

21
Q

Which glial cell mediates astrogliosis and recruitment in response to neural injury or disease in attempt to reduce neural damage, often results in glial scar formation?

A

Astrocytes

22
Q

What are microglial cells?

A

cells with small somas and numerous processes, they mediate the majority of immune reactions within the CNS
- retain the ability to divide

23
Q

What do microglial cells do? during development?

A

Phagocytose degenerating cells that are undergoing apoptosis

- During development, they aid in fiber tract development, gliogenesis, and angiogenesis by secreting growth factors

24
Q

Which glial cell is involved in presenting antigens to T lymphocytes?

A

microglial cells

25
Q

Which glial cell becomes reactive and phagocytic during pathological circumstances in the adult CNS?

A

microglial cells

26
Q

What are the glial cells of the PNS?

A

Schwann cells

27
Q

What do Schwann cells produce?

A

myelin

28
Q

What makes Schwann cells different from oligodendrocytes of the CNS?

A

They only myelinate one axon at a time

29
Q

What makes the neural triad?

A

Neurons, Glia and Vasculature

- integral functional and structural components of the CNS

30
Q

What is the function of Cerebral vasculature in the neural triad?

A

supports brain development and function both during embyogenesis into adulthood

  • Contributes to neurogenesis
  • Transports O2 and nutrients into the brain while removing metabolic waste and carbon dioxide
31
Q

What do endothelial cells of the cerebral vasculature interact with? and what do they form?

A

Glial cells of the CNS and form the blood-brain barrier (BBB)

32
Q

What restricts the passage of molecules between the brain and the systemic circulation?

A

The endothelial cells that interact with glial cells of the CNS which work together forming the BBB

33
Q

What does the tripartite synapse consist of?

A

Astrocyte processes that make contact with pre and postsynaptic neurons

34
Q

How do astrocytes produce signals?

A

by exhibiting a form of non-electrical hyperexcitability that utilizes Ca

35
Q

Calcium signaling in astrocytes

A

Release of Ca from intracellular stores in response to metabotropic r/c activation –> initiates a signal transduction pathway (STP) that prompts the release of stored Ca within the astrocyte
- Slight changes in intracellular [Ca] can lead to Ca-dependent release of NT molecules

36
Q

What are gliotransmitters

A

release of NT molecules in response to changes in intracellular Ca (in astrocytes)
- affects the nearby astrocytes and neurons

37
Q

Do Ca signalling within astrocytes diplay all-or-none features?

A

No they do not, they increase in intracellular Ca only in a portion of the astrocyte process
- may or may not spread to other parts of the astrocyte

38
Q

What are the Gliotransmitters?

A

ATP
Glutamate
D-serine

39
Q

Target of ATP

A

glia to glia

40
Q

Receptor of ATP

A

metabotropic

41
Q

Function/ action of ATP

A

Decreases glial cell calcium levels

42
Q

GLU target

A

neurons and glia

43
Q

GLU r/c

A

Neuron: Ionotropic (AMPAR’s & NMDAR’s)
Astrocyte: metabotropic

44
Q

Function/Action of GLU

A
  • Enhances NT release
  • Enhances EPSPs
  • Modulates glial Ca levels (can increase or decrease)
45
Q

Target of D-serine

A

postsynaptic neuron

46
Q

Receptor of D-serine

A

Ionotropic (NMDAR’s)

47
Q

Funcition/Action of D-serine

A

Enhances EPSPs