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.
Nissl-stain
Stains cell bodies in the brain a bluish-purple.
Fibre stain
Stains glial cells, so one can see where white matter in the brain is.
Thyroxine hydroxylase
Enzyme involved in dopamine synthesis. Used as a marker for dopamine-related neurons in the brain when brain staining.
Neuraxis
The spine-to-brain path.
Anterior
Towards the front of the brain.
Posterior
Towards the back of the brain.
Superior
Higher/above in the brain.
Inferior
Lower/below in the brain.
Rostral
Towards the front of the brain in humans and animals. Points up the spinal curvature in humans.
Caudal
Towards the “tail” (so for animals, towards the back of the brain, but for humans is both referring to towards the back of the brain and downwards on the axis of the brainstem/spinal cord).
Dorsal
Towards the back. To humans, points to the top of our brain, but points sideways on our back. If a human had a fins like a fish, those would be visual indicators of the dorsal directions.
Ventral
Towards the belly. In humans, points to the bottom of the brain and to the belly on the spinal axis.
Medial
Towards the middle (of the brain).
Lateral
Towards the edge (of the brain).
Coronal Plane
Vertical plane that divides anterior and posterior sections of the brain.
Sagittal Plane
Vertical plane that divides the brain into left and right sections. Is called a midsagittal plane if it divides the brain directly in half.
Horizontal Plane
Divides the brain into superior (upper) and inferior (lower) sections.
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.
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.
Related to Subsystems in Autonomic Nervous System (ANS)
Sympathomimetic drugs
Drugs that act on the sympathetic nervous system by mimicking its endogenous agonists. Essentially, these drugs activate the same bodily functions as our “fight or flight” response: Raised blood pressure, heart rate, and so on.
Ganglion
A cluster of neurons in the PNS.
Gyrus/gyri
The bumps/ridges in the brain.
Sulcus/sulci
The dips/valleys in the brain.
Longitudinal fissure
This fissure separates the left and right hemispheres.
Sylvian (lateral) fissure
This fissure separates the temporal lobe from frontal lobe and parietal lobes.
Forebrain
Where complex cognitive activities are performed. Very large in humans.
Hypothalamus
An older part of forebrain, regulates sleep, body temperature, heart rate, hunger, sex drive, and thirst. Also regulates the endocrine system.
Limbic system
Forms a barrier around cortical/non-cortical structures.
Nucleus accumbens
Play an important role in addiction. Play a key role in our reward system overall.
Hindbrain
Controls our vital survival functions (the medulla in the hindbrain controls breathing & heart rate, for example).
Lots of lethal drugs have effects on the hindbrain.
Basal ganglia
Composed of caudate nucleus and putamen. Are part of controlling voluntary movement.
Which arteries supply blood to the brain?
Four arteries supply blood to the brain. The left and right carotid arteries, and the vertebral arteries.
If an artery is blocked, that blood flow is gone and cannot reach the brain by any other route. This is part of why strokes are so harmful.
Blood-brain barrier (BBB)
Tightly packed astrocytes wrapped around tightly packed capillaries, protects the brain from foreign entities.
Meninges
Three layers of membranes that protect the brain and spinal cord.
Pia mater, arachnoid mater, dura mater
4 total, including the skull
Layers that protect the brain and spinal cord
Skull -> Dura Mater -> Arachnoid mater -> Pia mater
Cerebrospinal fluid (CSF)
Fluid that flows in and around the hollow/empty spaces of the brain and spinal cord. The brain produces CSF for nutrients, to remove waste, etc. but also is like an “airbag” in case we bump our heads.
Polymorphisms
The presence of multiple variant forms of a specific DNA sequence among individuals/populations.
Epigenetics
Enviromental factors that affect how genes work/express themselves. Can be passed down multiple generations, but epigenetic changes do not change the DNA sequence, just how it is expressed.
Genes
Transgenic Animals
Animal whose genome has been altered to carry genes from a different species.
Genes
Knockout Animals
Animals that have been genetically modified to lack a specific gene.
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).
