Behavioural Neuroscience Flashcards
The Peripheral Nervous system consists of what two systems?
Somatic System
Autonomic System
The Central Nervous system consists of what two systems?
The brain
Spinal Cord
What is the Somatic System made of?
Peripheral nerve fibers —sends sensory info—> CNS
—-> Motor Nerve fibers (project to skeletal muscle)
What does the Autonomic System do?
Controls muscle of the internal organs (viscera) and glands
What is the brain made of?
100 BILLION nerve cells (neurons) and trillions of support cells (glia)
How long is the spinal cord?
43cm long in adult women
45cm long in adult men
Note: Weights about 35-40 grams
What do Glia cells do?
Provide Support
Provide Nutrition
Provide “housekeeping”
Provide insulation
How are Neurons similar to other cells in the body?
Neurons are surrounded by a cell membrane
They have a nucleus that contains genes
Neurons contain cytoplasm, mitochondria, and other shit
Neurons carry out basic cellular processes like protein synthesis and energy production
How do Neurons differ from other cells in the body?
Neurons have speciliased extensions called dendrites and axons
Dendrites bring information to the cell body
Axons take info away (A for Away ;)
Neurons communicate with each other through an electrochemical process
Neurons contain specialised structures like synapses and chemicals like neurotransmitters
Describe what happens in the transfer of an Action Potential
Sodium and potassium channels in nerve cells are voltage-gated, meaning they can open and close depending on the voltage across the membrane
In response to a signal at a sensory receptor or dendrite, sodium channels open and sodium enters the neuron passively
The influx of sodium (Na+ in) causes the membrane potential to become positive (depolarisation)
If a sufficient change in membrane potential is achieved (threshold potential), adjacent voltage-gated sodium channels open, generating a wave of depolarisation (action potential) that spreads down the axon
The change in membrane potential also activates voltage-gated potassium channels, causing potassium to exit the neuron passively
The efflux of potassium (K+ out) causes the membrane potential to become negative again (repolarisation)
Before the neuron can fire again, the original distribution of ions (Na+ out, K+ in) must be re-established by the Na+/K+ pump
The inability to propagate another action potential during this time (refractory period) ensures nerve impulses only travel in one direction
How is a resting potential generated?
The sodium-potassium pump (Na+/K+ pump) maintains the electrochemical gradient of the resting potential (-70 mV)
It is a transmembrane protein that uses active transport to exchange Na+ and K+ ions across the membrane (antiport mechanism)
It expels 3 Na+ ions for every 2 K+ ions admitted (in addition, some of the K+ ions will leak back out of the cell)
This makes the inside of the membrane relatively negative when compared to the outside (-70 mV = resting potential)
How does a synaptic transfer occur?
When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels
Calcium ions (Ca2+) diffuse into the cell and promote the fusion of vesicles (containing neurotransmitters) with the plasma membrane
The neurotransmitters are released from the axon terminal by exocytosis and cross the synaptic cleft
Neurotransmitters bind to appropriate neuroreceptors on the post-synaptic membrane, opening ligand-gated channels
Excitatory neurotransmitters (e.g. noradrenaline) open ligand-gated sodium channels (depolarisation)
Inhibitory neurotransmitters (e.g. GABA) open ligand-gated potassium or chlorine channels (hyperpolarisation)
The combination of chemical messengers received by dendrites determines whether the threshold is reached for an action potential in the post-synaptic neuron
Neurotransmitter molecules released into the synapse are either recycled (by reuptake pumps) or degraded (by enzymatic activity)
