PS1090 - Understanding Neuroscience Flashcards
What happens when neurons connect to other neurons?
- Can stimulate other neurons (excitatory synapses/ neurons)
- Can inhibit other neurons (inhibitory synapses/neurons)
- Can receive input from many neurons
- Can send output to many neurons
What are dendrites?
Dendrites are protrusions where neurons collect information from other neurons, it integrates that information and makes a ‘decision’ about whether to pass information through the axon, it conducts signals through the axon.
What happens at axon terminals?
At the axon terminals, the neuron connects to other neurons, it can stimulate other neurons and either excite them and make them likely to fire a signal or inhibit them from sending a signal. Each neuron can receive information from many other neurons and also send output to other neurons.
What are glia or glial cells?
Glia or glial cells are non-neuronal cells in the central nervous system – brain & spinal cord
How can the shape of neurons indicate function?
if they have a very widespread dendritic tree, it could mean that they receive input from lots of neurons. If they have a widespread axon terminal ending, it could mean it connects with many other neurons.
What do neurons do?
They receive, process and transmit information.
What’s a simple reflex arc?
A receptor (neuron that detects the stretch of a muscle) connects to a motor neuron (neuron that controls muscles in the spinal cord) and that neuron then causes the muscle to contract.
How do neurons connect to make networks?
In the brain, there are complex patterns of convergence and divergence. There are neurons in one area passing on information to other areas. They spread out their information to multiple neurons (divergence) Each neuron will receive input from multiple neurons (convergence).
What does the function of a neural circuit depend on?
- How the neurons are connected
- How strong are the connections (synapses)? They can be very strong and pass signals easily or be weak and only pass a signal if there’s a lot of stimulation.
- Whether the connections (synapses) are excitatory (EPSP) or inhibitory (IPSP)
How can the function of a neural circuit change?
The function of a neural circuit can change through changes in synaptic strength – for example, memory!
What are the functions/characteristics of glial cells?
Supportive function
Protective function
Metabolic function - help clean up metabolites
Unlike neurons they divide throughout life
What are glial cells?
Glia, also called glial cells or neuroglia, are non-neuronal cells in the central nervous system and the peripheral nervous system that do not produce electrical impulses.
What are the most abundant type of cell in the central nervous system?
Glial cells are the most abundant cell types in the central nervous system.
What are the 4 types of glia?
• Astrocytes: star shaped (most common)
• Oligodendrocytes: few extensions, have a very specific function (only found in the CNS)
• Schwann cells (PNS – peripheral NS: found outside the brain)
Very similar to Oligodendrocytes but they’re outside the central nervous system.
• Microglia: smaller than the rest
How do astrocytes provide a scaffold by connecting neurons to blood vessels?
- They attach to blood and neurons
- Provide physical support
- Help control blood flow
How do astrocytes help to control blood flow?
How is this the basis of neuroimaging techniques?
They react to active neurones by controlling blood flow. They cause the capillaries (that they are attached to) to dilate when neurons around them are active. Bringing oxygen and nutrients to the neurones.
When neurons are active, blood flow increases and that’s caused by the astrocytes – this is the basis of neuroimaging techniques.
Apart from being a physical support and controlling blood flow, what are the other functions of astrocytes?
- Separate synapses (astrocytes maintain the gap between synapses which is important for neuronal communication.)
- Clean up debris that is generated by neuronal signalling (when one neuron communicates with another, it does so by excreting transmitter substances – small molecules that have to be cleaned up after each firing session)
Briefly bullet point the 5 functions of astrocytes.
- Attach to blood and neurons
- Provide physical support
- Help control blood flow
- Separate synapses
- Clean up debris that is generated by neuronal signalling
Where are oligodendrocytes found?
In the central nervous system
What are oligodendrocytes called in the peripheral nervous system (PNS)?
Schwann cells
Briefly bullet point the function of oligodendrocytes.
- Support axons
* Insulate axons and speed up information transmission
How do oligodendrocytes speed up information transmission.
They have a round shape and extend these sheath-like growths around the axon and surround each axon with a layer of fatty substance known as myelin which insulates them.
They provide electrical insulation which underlies the ability of neurons to send signals from one place to another really fast.
Explain what happens to the immune system of Multiple Sclerosis patients.
• It’s a demyelinating disease
• Induces numerous scars (multiple scleroses) in the brain
• Immune system attacks the myelin produced by oligodendrocytes
• Inflammation of CNS nerves
• Affects insulating layer of axons
• As the insulation becomes degraded, neurons can’t communicate as fast with one another. This causes problems for M.S. patients. • • First, they get problems with movement and motor control and then starts affecting cognition.
This is a very debilitating disease but fortunately the treatment for it is getting better.
What are microglia?
• Aren’t really glia • Precursors of blood cells • Part of the brain’s immune system • Related to macrophages Eat up debris and hostile bits
Why doesn’t the normal immune system work in the brain?
There’s a blood brain barrier, so there’s a very tight control of what comes into the brain. The normal immune system doesn’t work in the brain as the cells and large molecules that mediate immune functions can’t penetrate the blood brain barrier. The microglia work inside the brain and do a similar role.
What is included in the CNS?
- Brain
* Spinal cord
What is included in the PNS?
All nerves and neurons that reside outside, or extend beyond the CNS
What is a nerve?
A nerve is an enclosed bundle of axons.
What are the structural subdivisions of the PNS?
- Cranial nerves - nerves that emanates from the brain directly
- Spinal nerves – nerves that emanate from the spinal cord
What are cranial nerves?
The cranial nerves are a group of 12 nerves (bundles of axons) controlling muscles in the neck and head. Ten of the twelve cranial nerves originate in the brainstem while the remaining two originate in the cerebral cortex (the olfactory and optic nerves I and II respectively). They are unique because they have very specific functions.
What are the functional subdivisions of the PNS?
- Somatic nervous system
- Spinal nerves:
- Sympathetic nervous system
- Parasympathetic nervous system
What does each spinal nerve have?
Ventral (toward front) root
• Contains efferent fibres = projecting away from the CNS and towards the stomach.
Dorsal (toward back) root
• Contains (toward back) root = projecting towards the CNS
What is the somatic nervous system?
• Part of the PNS that controls voluntary body movements and conducts sensory information
• The elements of the PNS that aren’t part of the autonomic nervous system
This is what allows us to make any movement and to also receive physical sensations from the body. Pain, touch heat etc. Every nerve that controls movement is part of the somatic nervous system.
What does ‘soma’ and ‘somatic nervous system’?
Soma means body so somatic nervous system means the bodily nervous system.
What is the autonomic nervous system?
- Was thought to be independent
- Part of the PNS that controls homeostasis
- In charge of circulation, breathing, digestion, sexual function
- Usually not subject to voluntary control
- Made up of the sympathetic nervous system and parasympathetic nervous system
What does the autonomic nervous system regulate?
It regulates body functions, what we call homeostasis, maintaining the body in a functional state. You can’t control it with a lot of training. This is what controls our breathing, heartbeat, digestion, sexual function etc.
What is the autonomic nervous system made up of?
The autonomic nervous system is divided into two sections – sympathetic and parasympathetic.
What is the sympathetic nervous system?
The sympathetic division is anatomically distinct it’s driven by a chain of swellings (ganglia) that sit outside the spinal cord and it connects to lots of different organs in the body such as the heart, liver, kidneys, digestive system, genitals etc.
When it’s activated it stops you from salivating, dilates pupils, stops digestion, constricts blood vessels in the skin and it releases adrenaline or epinephrine. It puts the body in a mode of alertness.
What is the parasympathetic nervous system?
The parasympathetic system does the exact opposite. It constricts the pupil, makes the heart beat slower, increases digestion, dilates blood vessels. This could kick in after a big meal. This may explain why after a big meal you don’t feel like going for a run.
What is the brain and spinal cord protected by?
Cushioned by fluid, protected by bone
Brain: skull
Spinal cord: vertebra
What membranes cover the inside of the skull and spinal column?
Pia mater
Arachnoid mater
Dura mater
Describe each layer of membrane and their function.
The membranes have a protective and nutritious function. The pia mater is a soft matter, outside this there is the arachnoid mater, which is spider-like as it consists of lots of blood vessels which give a spiderweb like appearance. Then you have the dura mater which is a hard casing which serves a protective function. These cover the inside of the skull and the inside of the spinal column.
What is cerebrospinal fluid and its function.
It’s a watery cushion that allows the CNS to float.
Functions:
Protection - If you make any sudden movements, e.g. hitting your head, the hard impact isn’t immediately translated to your brain. The cerebrospinal fluid cushions and protects it.
Nutrition - It picks up excess neurotransmitters and metabolites from the brain and recirculates them.
What are ventricles? How many are there inside the CNS?
The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF). There are 4 ventricles, the 2 lateral ventricles are the large ones.
What happens to the ventricles in schizophrenia patients?
In some individuals, these ventricles get larger for instance in patients with schizophrenia.
What is grey matter and what parts of the spine and brain are made of grey matter.
Grey matter contains the cell bodies of neurons
It includes??? look this up
• Cortex (rind, bark)
• Nuclei (Kernels – if embedded in white matter)
• Inner part of spinal cord
What is white matter and what parts of the spine and brain are made of grey matter.
White matter: axons of neurons It includes??? look this up • Fibre tracts • Corpus callosum • Outer part of the spinal cord
Why are axons white?
They are surrounded by a fatty insulating sheath: myelin
What does lateral mean?
To the side
What does medial mean?
To the middle
What does Ipsi- mean e.g. ipsilateral.
Ipsi- means the same.
E.g. ipsilateral means belonging to or occurring on the same side of the body.
What does Contra- mean e.g. contralateral.
Contra- means opposite.
E.g. contralateral means belonging to or occurring on the same side of the body.
What does ipsilateral mean?
On the same side
What does contralateral mean?
On the opposite side
What does bilateral mean?
On both sides
What does superior mean?
To the top
