Biology lecture 2

?
  • Created by: The Shrew
  • Created on: 17-02-16 14:53
Number of neurones and synapses
86 billion neurones/ one hundred trillion synapses (10 to the power 17)
1 of 66
Each neurone connected to
10,000 synapses
2 of 66
Hercelano-Houzel et al
each brain cell has 1 nucleus/ nuclei: brain cell= 1:1/ in whole brain (of 4 dead men) neurone: glia= 1:1
3 of 66
Ratio differs from area to area
cortex= more glia/ cerebellum= more neurones
4 of 66
Cortex need more because
Fairly new to humans- glia supports neurones and helps them work better
5 of 66
More evolved animals
More glia
6 of 66
Brain developing
glia makes scaffold and makes pathways for neurones to follow- directs migration- prevents neurological abnormality
7 of 66
Greek
Glia= glue
8 of 66
Glia reproduce
This is what tumours are made of
9 of 66
Astrocytes
Do most of glials functions
10 of 66
Oligodendrocytes
wrap axons in the CNS in an insulating mylin- nourishes axons
11 of 66
Swann cells
produce mylin in peripheral nervous system (outside brain/ spinal chord)
12 of 66
Microglia
Immune system- destroy pathogenic cells and infected neurons- eat dead material/ inflammation/ pruning
13 of 66
Macroglia include
Astrocytes, Schwann cells, Oligodendrocytes, NG2 glia
14 of 66
9 types of astrocyte (7 examples)
Scaffolding, scavengers, neurotransmitter reuptake, guide migrating neurones and direct outgrowth of axons, regulate properties of presynaptic terminal, help from blood-brain barrier, Release growth factors
15 of 66
Einstein
more glial cells than average
16 of 66
Communicate
Chemically, can't generate action potentials
17 of 66
Receptors for same chemical messengers used by neurones
Can communicate with neurones, can eavesdrop and strengthen messages
18 of 66
Neurones from rodents
few synapses, little synaptic activity until surrounded by astrocytes
19 of 66
With astrocytes
Synaptic activity enlarged by 10 times
20 of 66
Neurodegenerative diseases
Abormal pruning of healthy synapses
21 of 66
One rodent astrocyte
associate with 300-600 neuronal dendrites and 100,000 individual synapses
22 of 66
Humans
one astrocyte 30 times the size, associates ith 2,000,000 synapses
23 of 66
Olygodendrocytes
one cell wraps around several axons, each branch around one segment
24 of 66
Schwann cells
the cell is the wrap- one cell around one segment
25 of 66
Multiple sclerosis
Failure of remyelination by oligodendrocytes/ unnecessary pruning
26 of 66
Degenerative diseases- amyotropic lateral sclerosis/ Parkinson's disease
Mutant proteins act in glia and release toxic compounds or reduce support activities
27 of 66
Neuropathic pain
Schwann cells, microglia and astrocytes in complex temporal and spatial pattern
28 of 66
Mood disorders
Post mortem findings- reduction in glial cell numbers in some brain regions
29 of 66
Major depressive disorder
Reductions in olygodendrocytes in the amygdala
30 of 66
Bipolar disorder
Microglial alterations
31 of 66
Rats with destroyed astrocytes in the prefrontal cortex
Depressive behaviour in behavioural tests
32 of 66
Antidepressants
Reverse reduction in astroglial density
33 of 66
When not doing anything brain uses
20% of energy
34 of 66
Things that can get through lipid bilayer
H2O, O2, CO2, Ethanol
35 of 66
Can't get through
Ions, amino acids, glucose
36 of 66
Cholesterol
Makes membranes stronger
37 of 66
Extracellular matrix proteins
Attach cells to other structures
38 of 66
Cytosketeton
Anchors- attach membrane to actual cell/ connect to protein filaments- inner membrane
39 of 66
Other use of proteins
Identify cells- rejected transplants
40 of 66
Integral proteins
Receptor on outside sends signals inside
41 of 66
Ions gradients inside and out
*
42 of 66
Diffusional force on ions
Moving from high conc to low conc (don't need energy- through protein with a hole in the middle)
43 of 66
Electrical force on ions
Positive ions attracted to negative and vice versa
44 of 66
Leak channels and ligand gated channels
Channel only opens with right key (eg potassium)
45 of 66
Voltage gated
change in charge of membrane opens or closes
46 of 66
Mechanically gated ion channels
Stress activated (eg sounds)
47 of 66
Pump requires energy to
Put ions where they don't want to go
48 of 66
Facilitated diffusion
follow conc or electrical gradient- no energy required
49 of 66
Primary active transport
against gradient- Energy= ATP
50 of 66
Secondary active transport
Uses energy from primary active transport to push in amino acids/ glucose
51 of 66
Selective permeability
Keeps cell functioning- keep in wanted molecules and let out unwanted- essential for nervous system
52 of 66
Inside of cell overall
Negatively charged(-60), outside positively charged= resting potential
53 of 66
Comes from
leaky K+/ Na- channels
54 of 66
Depolarize/ Hyperpolerize
Go towards 0/ Go away from 0
55 of 66
External stimuli causes
Neurotransmitters to open ligand-gated sodium channels- inside more positive
56 of 66
Threshold of excitation, hyperpolarisation, squid axon
Action potential blah blah blah
57 of 66
6 stages
Sodium channel opens, potassium channels open, sodium channels become refractory- no more sodium, potassium continues to leave cell, potassium channels close and sodium channels reset, extra potassium outside diffuses away
58 of 66
Action potentials generated in the
hillock
59 of 66
Speed of propagation depends on
Presence of myelin/ thickness of axon
60 of 66
Neurons not in the hillock produce
Postsynaptic potentials not actinon potentials
61 of 66
Action potentials always depolarizing
Postsynaptic potentials can be both
62 of 66
AP amplitude all or none
PP amplitude proportional to strength of stimulus
63 of 66
AP large amplitude 100mV
PP- amplitude generally small
64 of 66
AP- amplitude does not diminish along neuronal projections (non-decremental)
PP- amplitude diminishes (decremental)
65 of 66
Axon of motor neurones is 10,000 times as long as a cell body is wide
Need axon potentials to keep energy
66 of 66

Other cards in this set

Card 2

Front

Each neurone connected to

Back

10,000 synapses

Card 3

Front

Hercelano-Houzel et al

Back

Preview of the front of card 3

Card 4

Front

Ratio differs from area to area

Back

Preview of the front of card 4

Card 5

Front

Cortex need more because

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all Biological Psychology resources »