Unit 1 Flashcards
Santiago Ramon y Cajal
Suggested neurons are the units of the brained he noted the important of neurons in the late 1900s
Brains are …
Metabolically expensive taking up 20% of the oxygen and nutrients of the body but only contributing to 2% of the body weight
The complexity of the brain allows for …
Higher intelligence, coordination and function of the body to enhance reproduction and survival rates - complexity of higher executive function, information processing, problem solving for adapting environments to our way of living, communication abilities and movement (bipedalism and specificity of movement)
Divisions of the nervous system
Central and peripheral nervous system
CNS
Brain + spinal cord
Peripheral nervous system
Spinal nerves, autonomic nervous system, (most) cranial nerves
Pineal gland alternative name
Pine cone gland
Formix alternative name
Arch
Cortex alternative name
Bark
Cingulate gyrus alternative name
The belt
Corpus callosum alternative name
Hard body
Septum pellucidum alternative name
Translucent wall
Pituitary gland alternative name
Slime gland
Mammillary bodies alternative name
Breast-like things
Pons alternative name
Bridge
Medulla Oblongata alternative name
Long-ish marrow
Thalamus alternative name
Inner chamber
Cerebellum alternative name
Little brain
Vermis alternative name
The worm
Lingual gyrus alternative name
The tongue
Cuncus alternative name
The wedge
Lamina Quadragemina alternative name
Layer of the four twins
Medial / medius
Towards the midline
Lateral
Towards the side
Anterior
Front or near to the head
Posterior
Back
Ventral
Front, towards the abdominal
Dorsal
Back, towards the back of the body
Dorsal of the brain
Top
Ventral of the brain
Bottom
Dorsal of the spine
Back
Ventral of the spine
Front
Rostral
Towards the nose
Caudal
Towards the tail
Interspecies differences of the brain
Increased size of the cortex with the more advanced / complex species (greater in humans, chimpanzees and dolphins than in rats), larger olfactory bulbs in animals that rely more on smell (rats), larger cortex increases capacity of executive functioning
Dorsal view of the brain
Viewing from the top of the brain downward
Ventral view of the brain
Viewing from the bottom of the brain upward
Lateral view of the brain
Looking at the sides of the brain
Medial (midsagittal) view of the brain
Looking at the middle of the brain
Frontal plane, coronal cut
Anterior and posterior
Sagittal plane
Lateral sides, midsagittal if it is in the middle
Horizontal plane, horizontal cut
Diving into dorsal and ventral
Coronal cut
Through the brain from left to right
Meninges
Membranes that surround the brain and spinal cord
Dura Mater
Most outside of the three layers (the most external), known as the hard mother
Arachnoid
Has wispy connections with the pia mater, fibrous area
Pia mater
Tender mother, sticks right to the brain, follows the curves of the cortex, cannot be separated
Subarachnoid space
Between the arachnoid layer (dorsal) and pia mater (ventral), this is where the CSF is found
CSF
Cerebrospinal fluid bathes the brain to keep it buoyant and have proper ion concentration to function properly, the fluid of the ventricles has similar density to the brain (while air would be very different), therefore it is able to absorb some of the shock to protect the brain
Meningitis
Bacterial, viral or fungal infection of the meninges
Ventricles
Four ventricles - two lateral ventricles, third and fourth ventricles, CSF is found in the subarachnoid space and is stored within the ventricles. The ventricles are fluid-filled cavities within the brain
Lateral ventricles
Found within the two hemispheres of the brain
Orientation of the ventricles within the brain
Third ventricles more dorsal than the fourth, but ventral (below) to the lateral ventricles
Cerebral Aqueduct
Acts as a water channel connecting the third and fourth ventricles, pathway for CSF
Central Canal
Continuation of the fourth ventricle down within the middle of the spinal cord
Potential problem with CSF production
CSF is constantly being produced, no nervous or hormonal control on the level of production, just keeps going (no tap). Problem - could be making too much or not enough
Hydrocephalus
Accumulation of CSF, buildup causes blockage in the drainage system, ventricles swell and head can become enlarged. Pressure buildup must be released with shunt to drain out excess fluid. Not much room for the brain to swell with the cranium’s restriction
Obstruction of CSF flow in hydrocephalus often at ..
Cerebral Aqueduct
Blood vessels of the brain
Most of the blood goes up the neck through the circle of Willis from the internal carotid and then divides into three main branches - anterior, middle and posterior cerebral arteries. Basilar artery goes posterior as the two posterior cerebral arteries join together
Problems with blood vessels of the brain - strokes
A stroke is a disruption of blood flow to the brain, the brain needs a constant supply of oxygen and glucose. If this disruption lasts too long there can be defects in cognitive function depending on where the infarct occurs (necrotic tissue accumulation point) or death may result
What’s an infarct
Accumulation of necrotic tissue in the brain due to hypoxia
Ischemic stroke
Blood supply is reduced due to a thrombus (local clot at site of development) or embolus (breaks off and causes obstruction somewhere else). Thrombus and embolus caused by accumulation of plaque. Anything downstream will be cut off from blood with complete obstruction
Hemorrhagic stroke
Caused by the bursting of a blood vessel and therefore blood begins to leak out into the surrounding area. Often caused by aneurysms which are little pouches in the vessels, as they grow, the stretched tissue becomes thin and can rupture. Toxins in the blood that leaks can damage tissue around it and delivery of blood is diminished
Hemorrhagic strokes can be caused by …
Due to high blood pressure of a congenital defect (aneurysms, arteriovenous malformation AVM)
High risk area of blood vessels for hemorrhagic strokes
Tangles of blood vessels
Symptoms of anterior cerebral artery infarction
Aggression, personality change, aphasia, motor weakness, sensory changes and apraxia (frontal lobe affected)
Symptoms of middle cerebral artery infarction
Hemiparesis (muscle weakness) on the opposite side of the body to the infarct. Right MCA stroke - left hemiparesis. Left MCA stroke - right hemiparesis and aphasia (difficulty speaking or understanding language)
What is aphasia?
Difficulty speaking or understanding language, contralateral function
What is hemiparesis?
Weakness of the muscle, contralateral function
TIA
Transient ischemic attack - mini stroke, may feel dizzy, loose some vision, just feel off. Warning sign for major stroke. Not full blockage, but diminished blood flow to area
Symptoms of strokes
B.E.F.A.S.T
B - balance E - eyes F - face A - arms S - speech T - time
Neuron
One of the main cells of the nervous system. Able to make different connections depending on the type of neuron
Dendrites
The arms of the neurons that spread and make connections
Cell bodies of the neurons
Can be located in the spinal cord and the terminal axons can go all the way to the tips of the phalanges
Axo-Somatic connection
Going from the axon to the cell body
Axo-dendritic connection
Going from the axon to the dendrites
Glia Cells
Majority of the cells in the brain, they are support cells important in immune function, communication between neurons and blood vessels and act as insulation to the neurons (myelination to propagate signalling between Schwann cells)
Unmyelinated neurons
Axons are still covered with glia cells but just not to the same extent
Glioblasts
In the development to become glia
What can go wrong with glia?
The glia cells are constantly being renewed and therefor at a quite high risk for cancer development because cells are constantly going through the cell cycle in growth and division
Glioblastoma
Glioblasts are cells that develop into glia
MS
Multiple sclerosis is an autoimmune disease where the body attacks the myelinated sheath (glia cells) surrounding the axon of the neurons, particularly the motor neurons. This causes slowed movement and poor muscle coordination and function
Divisions of the brain in development
The nervous system begins as a neural tube going along the body, then from this tube there is differentiation into the different structures
The neural tube has four major divisions through development …
Forebrain, midbrain, hindbrain and spinal cord
Brainstem basics
Everything above the spinal cord, excluding the cerebellum and cerebrum, the brainstem contains basic, evolutionary function (primal functions)
Brainstem functions
Breathing, digestion and circulation. A lot of nerves pass through this region to relay information between the spinal cord and the brain to control functions
Brainstem location and parts
The brainstem contains the midbrain between the parietal and frontal lobes, the pons and the medulla oblongata
Cerebellum
Involved in movement prediction, found at the inferior aspect of the occipital lobe. It is involved in muscle coordination and balance (helps with controlled motion). The cerebellum has ipsilateral control (same side)
Cerebrum
Evolutionarily new systems and functions, is the central hemisphere, outermost portion of the forebrain includes grey and white matter and the two hemispheres
Cerebral cortex
Refers mainly to grey matter
White matter
Glia cells surround the axons, and glia cells contain a lot of fat which gives them to the appearance of being white in colour (fatty axons = white matter)
White and grey matter distribution in the CNS
Brain - white on the inside (axons in the middle) and grey on the outside
Spinal cord - grey in the middle and white on the outside as it stretches outward to give up the nerves
White matter tracks
Allows axons of a neuron to go across different areas of the brain - including the corpus callosum that goes between the two hemispheres
Corona Radiata
White matter track that goes between the spinal cord and brain stem
Basal ganglia
Ganglion (mass of grey matter)
New imaging technique of diffusion
Diffusion of water used to figure out which was the water is diffusing - diffuses along the direction of the fibres to construct these white matter tracks
Coup concussions
Damage to the brain at the location of the trauma
Contrecoupe concussions
Damage to the brain at the location of the trauma plus to the side opposite (bounce back of the brain to the other side)
Sheering of tissue from concussions
Sheering of tissue - fibres are damaged by sheering and twisting motion of the brain during the trauma. Sheering can lead to the death of the neurons. Accumulation of necrotic tissue leads to area specific symptoms and can lead to CTE with early dementia
4 lobes of the brain
Frontal, occipital, parietal and temporal
Insula
Gap between the frontal and parietal, just above the temporal lobe, tissue insulated by the other lobes deep within
Gyrus
Outward bulge of the brain (the hill) (convexity)
Convexity
Gyrus
Sulcus
Indentations, the valleys of the brain (concavity)
Concavity
Sulcus
Fissure
Deep sulcus (deep concavity)
Longitudinal fissure
Interhemispheric fissure
Sylvian fissure
Huge deep, mostly horizontal, insult is buried within it, separates temporal lobe from parietal and frontal lobe
What is the insula hidden i?
The sylvian fissure