Week 5 - Neurons Flashcards
Camillo Golgi (1843)
- reticular theory, which was an idea that the nervous tissue was one continuous net-like structure.
- developed the ‘Golgi staining technique’, which colours the cell bodies of the neurons, easier to see the branch-like structures.
- discover the Golgi apparatus, an organelle in cells.
Santiago Ramón Y Cajal (1852)
- using Golgi’s method, investigated neural tissue, to create technical illustrations of human and animal samples.
- discovered that neural tissue was made up of individual cells, which are distinguishable processing units rather than continuous structures.
soma
central part, contains the nucleus, which holds genetic information, and directs protein synthesis and provides the energy for cells to function.
Dendrites
how the cells receive inputs. On them are dendritic spines, which are protrusions that form synapses with terminal buttons of the presynaptic axon.
axon
the primary output. It extends off of the soma, splitting several times to connect with other neurons. There are numerous branches to allow it to connect with other cells.
action potential
“all or nothing” electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation. It allows messages to be sent from one area of the brain to another.
When the signal propagates all the way down the axon, it reaches the synapse.
synapse
junctions between the presynaptic terminal button of one neuron and the dendrite, axon, or soma of another postsynaptic neuron.
myelin sheath
substance surrounding the axon that serves as insulation, allowing the action potential to conduct rapidly.
nodes of Ranvier
small gaps between myelin sheath of insulation, to speed up electrical currents
intracellular fluid
slightly negatively charged relative to the outside of the cell, which forms the resting membrane potential.
Ion channels
proteins that span the cell membrane, forming channels that specific ions can flow through between the intra and extracellular space.
action potential
electrostatic pressure repels anions such as Chloride (Cl-) and attracts cations such as Potassium (K+). The differences in concentration of molecules can cause ions to either be pushed out of or into the cell, in a process known as diffusion.
Anions
negatively charged ions in high concentration within cells.
Potassium (K+)
high concentration inside cells. The cell membrane is highly permeable to K+.
Chloride (Cl-)
high concentration outside cells. The cell membrane is highly permeable to Cl-.
Sodium (Na+)
high concentration outside cells. The cell membrane is not very permeable to Na+.
resting membrane potential
-70mV, result of the interactions between these molecules and the subsequent difference in charge between the inside and outside
sodium-potassium pump
ion channel that uses the neuron’s energy (adenosine triphosphate, ATP) to pump three Na+ ions outside the cell in exchange for bringing two K+ ions inside the cell.
Excitatory postsynaptic potential (EPSPs)
depolarizing current that causes the membrane to become more positive and closer to the threshold of excitation.
Inhibitory postsynaptic potential (IPSPs)
hyperpolarizing current that causes the membrane to become more negative and further from the threshold of excitation.
threshold is met
Voltage-dependent sodium (Na+) channels are opened.
Na+ rushes inward due to electrostatic pressure and diffusion pushing it inside the cell, making it highly depolarized.
Because the inside of the cell is positive, voltage-gated potassium (K+) channels are opened.
K+ rushes outside of the cell due to diffusion and electrostatic pressure.
Na+ channels close as the cell becomes more negative, due to the potassium quickly decreasing. This combines with the sodium-potassium pump and the K+ channels gradually closing to cause the charge to drop lower than the resting membrane potential.
This slight drop below the resting membrane potential leads to a short refractory period. A higher increase in charge is required to reach the threshold of excitation during this period.
saltatory conduction
action potential travels down the axon, the myelin sheath protects it from losing significant cellular energy, this allows it to quickly travel
synaptic vesicles
presynaptic terminal button, package together groups of chemicals called neurotransmitters
motor neurons
to initiate movement and behaviour
interneurons
process the sensory input from our environment in order to be represented, and to plan and execute behavioural responses.
Unipolar neurons
one axon and no dendrites; they relay information forward, such as communicating body temperature through the spinal cord to the brain.
Bipolar neurons
one axon and one dendrite; they are involved in sensory perception and allow for the acquisition and passing of information.
Multipolar neurons
most common, with one axon and many dendrites allowing for communication with other neurons; they communicate sensory and motor information in the brain.
Glial cells
forming myelin sheaths, digesting debris of dead neurons, carrying nutrients from the blood to neurons, etc. They support the neurons but do not communicate between cells.
electrochemical action
electrical conduction of dendritic input to the initiation of an action potential within a neuron, and chemical transmission across the synaptic gap to the postsynaptic neuron.
Diffusion
force on molecules to move from areas of high concentration to low concentration.
Diffusion
force on molecules to move from areas of high concentration to low concentration.
Electrostatic pressure
force on two ions with similar charges to repel each other, and with opposite charges to attract one another.
depolarization
change in the charge or potential of the cell from its resting membrane potential (-70 mV) in a more positive direction.
threshold of excitation
-50mV, specific membrane potential that the neuron must reach to initiate an action potential
Behavioural endocrinology
scientific study of the interaction between hormones and behaviour. This interaction is bidirectional.
Hormones are chemical messengers that influence the nervous system to regulate behaviours (released by specialized endocrine glands through the bloodstream, and can travel over great distances and temporal ranges)
Psychopharmacology
study of how drugs affect behaviour (psychoactive or psychotropic drugs)
- change the way you feel do this by altering how neurons communicate with each other.
- all psychoactive drugs interfere or alter the process of neurotransmission.
- can either increase activity at the synapse (agonists) or reduce activity at the synapse (antagonists).
- have effects on other neurotransmitters
Acetylcholine (ACh)
related to learning and memory, as well as muscle movement in the peripheral nervous system and Alzheimer’s disease.
Dopamine (DA)
related to our brain’s reward circuits, and Schizophrenia.
Norepinephrine (NE)
related to arousal and depression.
Serotonin (5HT)
related to depression and aggression, as well as Schizophrenia.
Glutamate (GLU)
related to learning. It is the major excitatory neurotransmitter in the brain.
GABA (GABA)
related to anxiety disorders and epilepsy. It is the major inhibitory neurotransmitter in the brain.
Endorphins
related to pain, reward, and analgesia (loss in a sensation of pain).
Pharmacokinetics
how the body handles a drug that we take.
-Psychoactive drugs alter neuronal communication in the brain, by traveling in the blood.
-ADME is used to describe this process:
Absorption, Distribution, Metabolism, Excretion.
Motor Neurons
Allow us to initiate movement and behaviour.
Found in the cerebrum.
brain stem
Regulates basic behaviours such as breathing, circulation, digestion.
Sorts information going up and down (motor and sensory).
Attached to the spinal cord.
cerebellum
Controls motor function, balance, and motion memory (remembering to ride a bike).
Small lobe at the back of the brain, behind the brain stem.
thalamus
Acts as a router, sorting and sending information to where it needs to go.
In the middle of the forebrain, sitting on top of the brain stem.
hypothalamus
Maintains homeostasis; Body temperature, appetite, circadian rhythm, etc.
Sits just below the thalamus, right above the roof of the mouth.
pituitary gland
Sends out hormones to maintain hormone balance.
Hangs below the hypothalamus.
cerebrum
Integration - making sense of all of the data and information which is received.
The large, upper portion of the brain.
right hemisphere
Facial recognition, expression.
The right side of the cerebrum.
left hemisphere
Mathematical reasoning, logic.
The left side of the cerebrum.
corpus callosum
A connection of nerves between the two hemispheres, allowing them to communicate.
Connects the two hemispheres of the cerebrum.
basal ganglia
Made up of nuclei (groups of neurons that have the same function). Regulates our motor control.
Directly below the corpus callosum.
cerebral cortex
Makes up 80% of the brain. Controls the functions of the cerebrum.
Makes up 80% of the brain. Is the main portion of the cerebrum.
frontal lobe
Controls executive function and emotional control. Damage to the frontal lobe can cause large emotional swings.
Front of the cerebrum.
parietal lobe
Dealing with and reacting to environments; lots of neurons bringing sensory input.
Upper-back of the cerebrum.
occipital lobe
Primarily controls vision.
Back of the cerebrum.
temporal lobe
Language, hearing, and memory.
Lower sides of the cerebrum.
somatosensory cortex
Where sensory information is coming into the brain. There are large areas devoted to primary sensory tools, such as the fingers and the tongue.
Inside the parietal lobe, bordering the frontal lobe.
motor cortex
Where motor output is released from the brain.
Inside the frontal lobe, bordering the parietal lobe.
