Week 1 Flashcards
What are the major divisions that make up the nervous system?
https://qbi.uq.edu.au/brain/brain-anatomy
CNS - Spinal Cord and Brain
PNS
1) SNS (afferent nerves arrive and efferent nerves exit)
2) ANS - (1) SymNS and (2) ParaNS - (afferent nerves arrive and efferent nerves exit)
What does the Somatic Nervous System do?
Primary purpose of SNS is to connect the CNS to the skeletal muscles to control voluntary movement.
Initiating and controlling movement in the body.
Hearing, touch and sight.
Afferent nerves (sensory neurons) carry signals from the body, like the skin and muscles to the CNS.
Efferent nerves (motor neurons) carry motor signals from the CNS to the skeletal muscles.
What does the Autonomic Nervous System do?
Primary purpose of ANS is involuntary body functions. Such as heartbeat, blood flow, breathing, body temperature and emotional response.
Made up of two parts, parasympathetic and sympathetic nervous system.
What does the Parasympathetic Nervous System do?
The parasympathetic nervous system controls things when you are at rest and relaxed.
Salvation and eyes to tear, slows the heart rate.
What does the Sympathetic Nervous System do?
The sympathetic nervous system is our flight, fight or freeze response.
Receiving information from parts of the brain such as the brain stem and hypothalamus, amygdala.
Activated in stressful or high-arousal situations.
Increase heart rate, dilate pupils, increase sweat glands increase lungs capacity, digestion constricts.
What are Cranial Nerves?
Nerves which fire from the brain. There are 12 cranial nerves with the longest being the Vagus nerve which runs from the gut to the brain. Which transmits motor and sensory information directly to the brain.
What are the meninges and what role do they play?
The meninges are three protective membranes of the brain.
(1) Dura Mater (tough mother) - tough fibrous layer,
(2) Arachnoid Membrane - delicate, spider web like structure,
(3) Pia Mater (gentle mother)- inner most meninx, also delicate and fibrous
Subarachnoid Space - filled with cerebrospinal fluid and blood vessels.
Where is cerebrospinal fluid (CSF) produced and located? And what is its function?
CSF also plays a role in protecting the CNS by cushioning the brain.
CSF is produced by the choroid (core roid) plexus. This is a network of capillaries that project pia matter into the ventricles of the brain.
The cerebral ventricles are a set of 4 interconnected cavities within the brain.
CSF is a clear fluid found in the brain and spinal cord.
What is the blood-brain barrier and its function?
Forms as a barrier between the circulating blood and the brain. Only allowing certain molecules such as glucose to pass through the barrier for fuel for the brain.
What are the major features of a neuron?
Dendrites Cell Body (soma) Nucleus Axon Hillock Axon Myelin Sheath / Schwann Cells Nodes of Ranvier Axon terminals / Buttons Synapse
Action Potential
The Synapse is…
The gap between two neurons where nerve impulses are transmitted via chemical signals.
This internal feature of the neuron is involved in synthesising proteins.
Ribosomes
These membranes store neurotransmitter molecules that are released at the synapse.
Synaptic Vesicles
Transport of materials within the neuron is done by these internal features.
Microtubules
These internal features of the neuron generate large quantities of energy through an aerobic (oxygen-consuming) process.
Mitochondria
This internal structure of the neuron contains DNA
Nucleus
The gaps between sections of myelin are known as…
Nodes of Ranvier
The long slender projection of a neuron that carries nerve impulses
Axon
The lipid bilayer of the cell membrane contains these two kinds of protein
Channel Proteins and Signal Proteins
Myelin
This external feature of a neuron provides a protective, fatty insulating covering around many axons.
What are the differences between the four different classifications of neuron?
MMUB
Multipolar Neuron - more than 2 projections from the cell body (most common)
Multipolar Interneuron - short of no axon
Unipolar Neuron - 1 projections from the cell body
Bipolar Neuron - 2 projections from the cell body
Clusters of cell bodies in the CNS are called
Nuclei
Clusters of cell bodies in the PNS are called
Ganglia
Clusters of axons in the CNS
Tracts
Clusters of axons in the PNS
Nerves
Oligodendrocytes (oh-lego-den-dro-sites) (CNS)
Provides supports to neurons by wrapping myelin sheath around the neuron to help the signals travel through the axon.
Microglia (CNS)
Smallest glial cells
Protect against injury and disease by creating a inflammation response
also help synapses, regulation of cell death
Astrocytes (CNS)
Star like shape, largest glial cell
Cover the outside of blood vessels, block blood brain barrier, also allow molecules to flow through the BBB
increase blood flow to brain
Schwann Cells (PNS)
Like Oligodendrocytes, they create a myelin sheath protection over the axon to speed up and protect the projection through an axon. Unlike Oligodendrocytes, Schwann cells can help repair damaged axons in the PNS.
Horizontal Plane
Frontal (coronal) Plane
Saggital Plane
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Mike’s Method Messes with Distinguished Theories
Myelencephalon Metencephalon Mesencephalon Diencephalon Telencephalon - made up of the cerebral hemispheres - experiences the most growth
(Encephalon which means ‘within the head’)
Gray Matter
Cell bodies and unmyelinated neurons what back up the H part of the spinal cord.
White Matter
Myelinated neurons that make up the area surrounding the gray matter area of the spinal cord.
Dorsal and Ventral Horns
Arms extending from the gray matter from the dorsal and ventral areas of the spine.
Dorsal and Ventral Roots
Spinal nerve axons are joined to the spinal cord via these.
Dorsal Roots are unipolar neurons (1)
Ventral Roots are multipolar neurons (2+)
Dorsal Ganglia Roots
Cell bodies on the Dorsal roots
Brain Stem
The collective term for the 4 divisions of the brain.
- Myelencephalon / Medulla (hindbrain)
- Metencephalon (Hindbrain)
- Mesencephalon (midbrain)
- Diencephalon (forebrain)
Myelencephalon
Medulla Oblongata (hindbrain)The most posterior part of the brain.
Includes the reticular formation - net Mainly composted of tracts (axons of the CNS) which send messages between the brain and the body. Plays many varied roles such as: - sleep - attention - movement - cardiovascular control - swallowing
Metencephalon
Hindbrain, made up of the pons (ventral) and cerebellum (dorsal of the brain stem)
Tracts make up the pons which sends signals from and to the brain and body.
Cerebellum - highly folded section of the brain.
- coordination
- motor control
- Sensorimotor functions such as precise movement.
If the Cerebellum is damaged it also impacts language and thinking/decision making.
Part of the reticular formation sits within the metencephalon
Mesencephalon
Midbrain - movement and auditory
(1) Tectum - dorsal
(2) Tegmentum - ventral
Tectum
Made up of two pairs of bumps
(1) Superior colliculi - movement and auditory
(2) Inferior colliculi - auditory
Tegmentum
Contains tracts and the reticular formation.
Contains the cerebral aqueduct - 3rd and 4th ventricles in the brain.
Periaqueduct Gray - Gray matter which surrounds this duct.
Functioning of the sensorimotor system:
- Red Nucleus
- Substantia Nigra
Diencephalon
Forebrain
Thalamus
Hypothalamus
Thalamus
Sensory rely station, all the thing that you see, hear, touch, taste, - all these sense you have come through your nerves and end up in your thalamus.
Emotions are very contingent on these senses, and the thalamus will send signals to other functions of the cortex.
Smell bypasses the thalamus
Made up of two lobes which sit at the top of the brain stem, joined by the massa intermedia.
Mainly made up of gray matter, part of the diencephalon.
- sensory and motor signals
- circadian rhythm
- memory and learning
Relay center for the signals passing from the lower centers to the higher centers of the brain.
The thalamus is made up of nuclei that receives information from the cortex and then sends information to other areas of the cortex.
Sits dorsal to the hypothalamus
It is a prime processing centre for sensory information, as it links up the relevant parts of the cerebral cortex with the spinal cord and other areas of the brain important for our senses. The thalamus also controls sleep.
Lateral Geniculate Nuclei (thalamus)
visual
sensory relay nuclei
Medial Geniculate Nuclei (thalamus)
auditory
sensory relay nuclei
Ventral Posterior Nuclei (thalamus)
somatosensory information
sensory relay nuclei
Hypothalamus
Sits posterior to the thalamus
Regulates motivation behaviors such as eating, sleep and sex. It does this through the pituitary gland - this releases hormones into the bloodstream.
It is involved in some hormonal activity and connects the hormonal and nervous systems. The hypothalamus also works to regulate things like our blood pressure, body temperature, and overall homeostasis.
Below the Thalamus, tiny structure, less than 1% of the brain.
Regulating functions in the body, autonomic nervous system.
Fight and flight VS Rest and Digest
Releases hormones into the bloodstream e.g. adrenalin.
Telencephalon
Forebrain, Cerebrum and cerebral cortex. Makes up 85% of the brain.
Limbic System
Basal Ganglia
Made up of mainly gray matter and split into two hemispheres.
4 lobes FPOT. Beneath the cerebral cortex, there are large knots of neurons called basal ganglia, they are fundamental in our motor function. When disease attacks the basal ganglia we see diseases such as Parkinson’s disease.
Cerebrum (Motor)
The cerebrum is composed of two hemispheres.
The major function of the cerebrum is to control the voluntary muscular movements of the body.
The cerebrum is where most of the important brain functions happen, such as thinking, planning, reasoning, language processing, and interpreting and processing inputs from our senses, such as vision, touch, hearing, taste and smell.
Corpus Collosum
Joins the two hemispheres of the brain
Gyrus
The ridges and grooves on the surface of the cerebral cortex. Gyri is the plural. Gyrus is a single one.
Sulci (Sulcus)
Groove in the cerebral cortex.
Fissures
Larger grooves in the cerebral cortex that divide it into lobes.
Longitudinal fissures divides the brain into 2 hemispheres.
Frontal Lobe
Voluntary motor Prefrontal - thinking, decisions, emotions Broca's area - speech Executive functioning Problem solving, planning
Parietal Lobe
Somatosensory cortex (feelings hot, soft, heavy), spatial manipulation. Sensing, fullness
Occipital Lobe
Vision
Temporal Lobe
Sound and Wernicke’s area language
Neocortex
New brain
Stellate and pyramidal cells
6 layers
90% of the brain
Amygdala
Plays a central role in our emotional responses, including feelings like pleasure, fear, anxiety and anger
The amygdala also attaches emotional content to our memories, so plays an important role in determining how robustly those memories are stored
it also plays a key role in forming new memories specifically related to fear. Fearful memories are able to be formed after only a few repetitions. This makes ‘fear learning’ a popular way to investigate the mechanisms of memory formation, consolidation and recall.
Hippocampus
Forming new memories
Short-term memory into your long term memory
Which can evoke memories
Limbic System
H - Hypothalamus
A - Amygdala (emotion) also part of the basal ganglia
T - Thalamus (rely center)
Hippo - Hippocampus (Memory)
Involved in motivated behaviors The 4 f's Fleeing Flighting Feeding Sexual behavior
Cerebral cortex (sensory)
The cerebral cortex is composed of four lobes: frontal lobe, parietal lobe, temporal lobe, and occipital lobe.
The cerebral cortex is mainly involved in the consciousness.
Basal ganglia
Subcortical system
Coordination of movement and decision making - linked to the thalamus
A group of structures linked to the thalamus (rely center of the brain) and is involved with movement and decision making.
Beneath the surface of the hemispheres are large knots of neurons called basal ganglia, which specialise in programming and executing our motor functions. When basal ganglia are affected by diseases such as Parkinson’s, patients have tremors and uncontrolled movements.
Substantia nigra
Tegmentum - (metencephalon)
Dopamine is a neurotransmitter that is produced in the substantia nigra, ventral tegmental area, and hypothalamus
Projects onto the striatum (basal ganglia)
https://www.khanacademy.org/test-prep/mcat/behavior
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Sensorimotor system
Association Cortex (CEO’s) stays out of the weeds, it gives direction.
The higher levels of the sensorimotor system are left to perform more complex functions.
AC can exert control over other levels of the system e.g. blinking when trying to insert a contact lens.
Information flows down
Secondary Motor Cortex
Primary Motor Cortex
Brain stem motor nuclei
Fornix
Major tract of the limbic system
Cingulate gyrus
Sit above corpus callosum
Involved in processing emotions and behavior
Caudate Tail / body
From the posterior of the amygdala form a semi circle - it forms the striatum with the putamen
Putamen
Centre of the BG, is connected to the caudate via fiber bridges and forms the striatum with the caudate
Striatum
Made up of the caudate and putamen - striped
Globus Pallidus
Pale globe,
Nucleus accumbens
Rewarding effects of drugs
BG
Membrane Potential
The difference in electrical charge between the inside and the outside of a cell
Polarized membrane
Has a positive electrical charge on one side and a negative charge on another side - this creates the resting potential (-70 mv)
Transporter
Sodium-potassium pump
Extracellular space
Outside the cell - sodium ions
Intracellular space
Inside the cell - potassium ions
Electrostatic pressure
Drive Na into the cell - Opposite charges attract the positive sodium ions
Concentration Gradient
Drive Na into the cell because of the overall lower concentration of Na inside the cell - Particles moving at random will tend to move from a high concentration to one of a low concentration. Outside of the cell is a higher concentration of sodium ions then inside
Hyperpolarise
Increases the polarisation of the membrane
Inhibitory postsynaptic potential (IPSP) - decreases probability of neuron firing
Depolarise
Reduces or removes polarization of the membrane
Excitatory Postsynaptic Potentials (EPSPs) - increases probability of neuron firing / action potential
Resting Potential
-70mV
Threshold of excitation
- 65mV
Postsynaptic Potential 3 principles
1) Graded response - weak- strong - spectrum every variation in between
2) They are so fast - they are instantaneous
3) Decremental - they loose amplitude like a sound wave.
Action Potential
-70mV - 30 50 mV All or none responses on or off - there is no inbetween PSP as a gradient They don't loose their amplitude - decremental Its slower - not instantaneous
Integration
Combining incoming signals into one overall signal
Spatial Summation
When local postsynaptic potentials produced simultaneously on different parts of the membrane sum to form a greater postsynaptic potential or to cancel each other out
Temporal Summation
When postsynaptic potentials formed in rapid succession at the same synapse sum to form a greater signal.
Voltage-activated ion channel
Channels that open and close in response to changes to the level of membrane potential - this is where you find nodes of Ranvier
Absolute Refractory period
Hyperpolarization
1-2 ms where an action potential is impossible
Relative Refractory Period
An action potential is possible, but requires a higher than normal level of stimulation
Antidromic conduction
axon conduction opposite of the normal direction - button up to the cell body
Orthodromic conduction
Axonal conduction in the normal direction
Saltatory Conduction
Transmission of an action potential in myelinated neurons
Neuropeptide
Large neurotransmitter - chains of amino acid
Exocytosis
The process of neurotransmitter release
Receptor
Binds to a ligand (molecule that binds to another) and produce signals in postsynaptic neurons
The sensorimotor system
Association Cortex Secondary motor cortex primary motor cortex Brain stem motor nuclei Spinal motor circuits
