Brain Background Flashcards
Weight of the human brain
3lbs, 2-3% of body weight
Cerebellum
little brain; extremely dense and has more than half of our neurons
Do we produce new neurons in adulthood
No
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.
Gray matter
Pale parts in the scan
Cell bodies of neuron; found in the outer cortex
Small neurons that don’t have a certain substance– unmyelinated axons
White matter
Myelinated axons connecting areas; found near the center of the brain
Two basic cell types
- Neuron
- Glia
Neuron
Extreme fast signal because of action potential; reaction time is in milliseconds
Nerve cells that process and communicate messages and changes throughout the body.
Glia
Glue, acts as support, provides nutrition
Ex: Astrocyte and oligodendrocyte
Different types of neurons
Pyramidal- cerebral cortex
Stellate- star shape; cerebellum
Purkinje- cerebellum
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.
Spiny neurons- pyramidal, glutamate neurons (they release glutamate)
Non-spiny neurons- specifically referring to GABA 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.
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 the timing of signals (eg. for motor skills).
local processing and communications within a specific brain region
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)
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).
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
Astrocytes stabilize the BBB that is actively working
- Mediate all the nutrition your brain and neurons need
- A key role of keeping the environment what it should be
- Buffers out sodium if it is too much or buffers in potassium if it’s too little
- All astrocyte works together = glial network
Oligodendrocytes
Myelin creating cells (CNS only). Myelinate several different axons. Myelin speeds up the travel of action potentials.
Nissl-stain
Stains cell bodies in the brain, shows gray matter
Fibre stain
Stains glial cells, see where white matter in the brain is
Blood Brain Barrier (BBB)
Tightly packed astrocytes wrapped around tightly packed capillaries, protects the brain from foreign entities.
Challenges of studying humans before
neuroscience methods are either invasive or require postmortem tissue
Golgi stain
reveal cell type, show cell body and all its branches
Central dogma of molecular biology
The theory that genetic information flows only in one direction: From DNA, to RNA, to protein (or from RNA directly to protein).
Synapse
Components that make up the connection between neurons. Includes the axon terminals and synaptic cleft.
Effect of an increase or decrease in dendrites
Decrease in dendrites can lead to schizophrenia
An increase in dendrites can mean on the spectrum of autism
Peripheral Nervous System (PNS)
Somatic Nervous System
Sends voluntary motor signals from the CNS to muscles in the body. Collects sensory information from the body and sends it to the CNS.
Synaptic cleft
a
The gap between a pre- and post-synaptic neuron. Neurotransmitters travel along this gap.
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.
Peripheral Nervous System (PNS)
Autonomic Nervous System
Controls involuntary bodily functions. Heavily oriented towards internal organs/the internal bodily system
Subsystems in Autonomic Nervous System (ANS)
Sympathetic Nervous System
Activate’s the body’s “fight or flight” response. Stimulates secretion of adrenaline (epinephrine) and norepinephrine.
Shuts down the digestive system so the energy can be used elsewhere.
Elevates one’s heartbeat, and stimulates glucose production/release.
Subsystems in Autonomic Nervous System (ANS)
Parasympathetic Nervous System
Activates the “rest and digest” aspects of the nervous system. Conserves energy, slows one’s heart rate, and stimulates digestion.
Gyrus/gyri
The bumps/ridges in the brain.
Sulcus/sulci
The dips/valleys in the brain.
Blood-brain barrier (BBB)
Tightly packed astrocytes wrapped around tightly packed capillaries, protects the brain from foreign entities.
