Brain Basics Flashcards
Formaldehyde
Used to preserve brains and organs.
Weight of the human brain
3lbs, 2-3% of body weight
Amount of energy the brain consumes
The brain consumes 20% of our body’s energy.
Amount of neurons the brain has, and where most are located
The brain has <100 billion neurons, more than 50% of these are located in the cerebellum.
Neurogenesis
The process of formation of new neurons within the brain. Most neurogenesis happens within the womb, after we are born it happens in very small amounts only.
When we are born, we have the maximum amount of neurons we will ever have.
Neuron
Nerve cells that process and communicate messages and changes throughout the body.
Flow of a neuron signal
The path a neuron signal travels (4 parts of a neuron)
Dendrite → soma → axon → terminals
Dendrite
Parts of a neuron that receive information from other neurons.
Soma
The body of a neuron. Also contains the nucleus of the neuron.
Axon
The part of a neuron that sends neurotransmitters to other neurons.
Synapse
Components that make up the connection between neurons. Includes the axon terminals and synaptic cleft.
Synaptic Cleft
The gap between a pre- and post-synaptic neuron. Neurotransmitters travel along this gap.
Axon Terminals
Release neurotransmitters into the synaptic cleft to relay signals.
Nodes of Ranvier
Little gaps in between the myelin sheaths on an axon. They contain sodium that generates action potentials.
Projection Neurons
Neurons that extend from the neuronal cell body within the CNS to 1 or more distant regions of the CNS. Typically have a longer axon and fewer inputs/outputs than an interneuron.
Interneurons
Interneurons act as a bridge of communication between the CNS and PNS, transferring signals between the two. Help with synchronization of signals as well as timing of signals (eg. for motor skills). Can also help supress sensory information by inhibiting certain signals from sensory neurons.
Afferent Nerves/Neurons
Nerves/neurons that arrive at the CNS. They deliver sensory information to the brain. (A for arriving)
Efferent Nerves/Neurons
Nerves/neurons that deliver info from the CNS to muscles (in other words, they deliver motor signals). (E for exiting)
Glia
Non-neuronal cells in the central and peripheral nervous system (CNS & PNS).
Glia play a key role in brain function. However, Prof. Tomm noted we will hardly talk about them throughout the course.
Macroglia
Schwann cells, oligodendrocytes, astrocytes. Maintain CNS homeostasis.
Microglia
Part of the brain’s immune response. Microglia surveil brain cells. When they sense foreign bodies, they go into a prime state.
Microglia
Prime state
The state when microglia sense a foreign body. They grow large and digest/”swallow” the foreign bodies.
Schwann Cells
Schwann cells create myelin sheaths that speed up action potentials’ travels along the axon (PNS only).
Oligodendrocytes
Myelin creating cells (CNS only). Myelinate several different axons. Myelin speeds up the travel of action potentials.
Astrocytes
Glial cells that stablize the blood-brain barrier. They provide neurons with oxygen, glucose, and other nutrients. They can buffer ions in axons, adding/removing them in gap junctions. They can influence neurons at the synapse, increasing or reducing standard transmission.
Summary: Astrocytes are part of the blood brain barrier, provide neurons nutrients and influence neurons and ions.
Tripartite synapse
Refers to the communication between three parts of the synapse (“A conversation of three”). Astrocytes shape synaptic conditions/wrap around the synapse & the pre- and postsynaptic terminals communicate. Astrocytes regulate neurotransmitter levels, modulate synaptic transmission, etc.
Astrocytes also can promote formation and stability of synapses, play a role in synaptic pruning, respond to brain injury, and help with calcium signalling.
Grey matter
Where cell bodies of neurons are as well as where the dendrites are. Grey matter is where info is being sent and received & processes sensory information.
Grey matter makes up the outer layer of the brain.
White matter
Contains myelinated axons. The myelin is what gives white matter its colour.
White matter is found in the inner layers (subcortical tissues) of the brain.