1
Q
Stages of Information Processing
A
- sensory input
- integration
3 motor output
2
Q
Sensory Neuron
A
- detect light, sound, etc
- dendrites connect directly to axon
- cell body located in middle of axon
3
Q
Interneuron
A
- central nervous system (spine & brain)
- collect info into cell body
axons take to more cells - one axon takes info into complex dendrite tree
4
Q
Motor Neuron
A
- dendrites collect info into cell body
- no synapse
- one axon from nervous system to muscle tissue
5
Q
Astrocytes
A
- gila cells
- central nervous system
- provide support
- regulate extracellular concentration of ions and neurotransmitters
- formation of blood brain barrier
- compound must be VERY lipidphilic to enter brain
6
Q
Oligodendrocytes and Schwann Cells
A
- oligodendrocytes = CNS
- schwann cells = PNS
- form myelin sheaths around axons
- node of ranvier (Exposed axon) causes action potential
- lipid membranes –> insulator
- defective insulator makes electrical signals stop before end of neuron
7
Q
Resting Membrane Potential
A
resting potential is negative
-70 mV
8
Q
Ion Gradient / ATPase Pump
A
- Na+/K+ Atpase pumps 3 Na+ out of cell and 2 K+ into cell
- results in neg charge inside cell
- against concentration –> uses transporter for energy
- electrogenic pump (neg charge inside cell)
OUTSIDE
5mM K+, 150mM Na+, 120mM Cl-
INSIDE
140mM K+, 15mM Na+, 100mM A-
9
Q
Hyperpolarisation
A
- inside of membrane becomes more negative
- opening of VG K+ channels
- K+ out
- increase membrane potential
- slower
- closed open
10
Q
Depolarisation
A
- inside of membrane becomes more positive
- opening of coltage gated Na+ channels
- Na+ in
- decrease membrane potential
- fast
- closed –> open –> inactivated –> closed…
11
Q
Action Potential Graph
A
- resting stage - VG ion channels closed
- Stimulus - causes a few Na+ channels to open, Na+ in
- Depolarisation - if threshold reached, lots of Na+ channels open
- Hyperpolarisation - K+ channels open & K+ out. Na+ channels inactivate
- Undershoot - small hyperpolarisation. Also need ATPase to restore ion concentrations
12
Q
Refractory Period
A
- VG Na+ channels inactivated during repolarisation
- during absolute refractory period (peak), no AP can be generated
- during trlative refractory period (undershoot), AP only if large stimulus
- some Na+ channels closed again
- limits firing frequency of neuson
- local anaesthetics don’t allow channels to go from inactivated –> closed, no pain signals
13
Q
Factors Affecting Conduction Speed
A
Axon diameter
- increase diameter –
> decrease resistance = faster
Temperature
- chemical reactions occur faster at higher temps
- more kinetic energy
Degree of Myelination
- myelin insulates axon membrane = faster
- affected more by myelin than diameter
- AP only generated at nodes of ranvier (saltatory conduction)
14
Q
Neurotransmitter Release at Chemical Synapse
A
- chemical stored in synaptic vesicle (not metabolised)
- exocytosis occurs
- axon signal passes through ligand gated ion channel
- allows Ca2+ to enter presynaptic neuron via VG Ca2+ channels
- Ca2+ causes fusion of vesicle and membrane –> release of neurotransmitters
- depolarisation —> excitatory post synaptic potential
- hyperpolarisation —> inhibitory post synaptic potential
15
Q
Temporal Summation
A
- several EPSPs from same synapse just after each other
- can reach threshold at axon hillock —> axon potential
16
Q
Spatial Summation
A
- two or more EPSPs from different synapses
- EPSP + IPSP = unlikely to reach AP
17
Q
Potentials: Postsynaptic vs Action
A
Postsynaptic
- EPSP or IPSP
- graded
- local
- at cell body or dendrites
Action
- depolarisation
- “all or nothing”
- EPSPs add up to cause AP
- generated at axon hillock
18
Q
Direct Synaptic Transmission
A
- fastest (ms)
- neurotransmitters open ion channels on postsynaptic membrane
- action via ligand gated ion channels (opened via neurotransmitter binding)
19
Q
Indirect Synaptic Transmission
A
- neurotransmitter binds to receptor on postsynaptic membrane
- activates a signal transduction pathway
- involves a second messenger (GPCR)
- slower (s)
20
Q
Removal of Neurotransmitters From Synaptic Cleft
A
- must be quick
- can be lost to diffusion or enzymes
- can be recycled by transporters back into neuron
21
Q
Peripheral Nervous System
A
- 12 pairs of cranial nerves
- 31 pairs of spinal nerves
- both PNS and CNS contain sensory and motor neurons
- contains ganglia (segmentally arranged clusters of neurons)
- contains somatic nervours system (voluntary) and automatic nervous system (involuntary)
22
Q
Dorsal/Posterior
A
back of body
23
Q
Automatic Nervous System
A
- sympathetic division
- parasympathetic division
- entric division (intestines)
24
Q
Parasympathetic Division
A
- from cervical & sacral region
- long pre ganglionic fibre
- short post ganglionic fibre
- “rest & digest”
- calming
- often opposite response to sympathetic division
25
Sympathetic Division
- from thoracic and lumbar region
- short pre ganglionic fibre
- long post ganglionic fibre
- "fight or flight"
- bronchi dilate
- increase heart rate
- glycogen to glucose
- adrenaline secretion
- digestion inhibited
26
Central Nervous System
brain and spinal cord
27
The Brain
- Forebrain: cerebrum and diencephalon
- Midbrain: part of brainstem
- Hindbrain: part of brainstem and cerebellum
- grey matter outside, white matter inside
28
Cerebrospinal Fluid
- protects CNS
- clear fluid
- subarachnoid space (b/w skull and cortex)
- 4 ventricles and central canal
- supplies nutrients and horomones
- removes waste
- blocked flow in hydrocephalus
29
Spinal Cord
white matter outside
grey matter inside
30
Brainstem
- oldest part
- basic functions
- homeostasis, movement
- transfers info to rest of brain
- made of three parts: pons, midbrain, medulla oblongata
- reticular formation --> selectivity filter than determines arousal and sleep
31
Cerebellum
- coordination
- motor function
- cognitive and perceptual function
32
Diencephalon
Epithalamus:
- connects limbic system (emotional) to rest of brain
- pineal gland --> melatonin (sleep)
Thalamus:
- input from sensory neurons
- output via motor neurons
Hypothalamus:
- homeostasis regulation
- biological clock
- temp regulation
- survival (hunger, thirst, etc)
33
Ventral/Anterior
front of body
34
Cerebrum / Cerebral Cortex
- neocortex
- left and right hemisphere connected via corpus callosum
- basal nuclei: deep in tissue and important for movement
- four lobes
- frontal, temporal, parietal, occipital
35
Frontal Lobe
- prefrontal cortex = decision making, planning
- motor cortex = control of skeletal muscle
- Broca's area = forming speech
36
Temporal Lobe
- auditory cortex = hearing
| - Warnicke's area = comprehending language
37
Parietal Lobe
- somasensory cortex (touch)
| - sensory integration cortex (integration of sensory info)
38
Occipital Lobe
- visual cortex = processing visual stimuli, pattern recognition
- visual association cortex = combining images and object recognition
39
Limbic System
- thalamus
- hypothalamus
- olfactory bulb
- hippocampus (memory)
- amygdala (fear)
40
Long-term Potentiation
- high frequency transmission
- results in increase size of postsynaptic potentials at synapse
- fundamental process for storing memories ---> learning
