CNS I Flashcards
How much does an adult human brain typically weigh?
1400g
Approximately how many neurones does a brain contain?
~10^12 neurons
How many synaptic contacts does each neurone receive?
200,000 synaptic contacts
What are 2 other facts
-The brain is a predicting machine, responds to it’s environment based
on what it’s learned in the past
- Specific areas are responsible for certain tasks
What kind of networks do simple organisms have and and, the benefit of it? (What is the evolution of the nervous system?)
-Simple organisms (e.g. jellyfish)
- neural networks
- allow them to sense their environment but have no central integrating centre or brain
What kind of neurones do higher organisms have?
(What is the evolution of the nervous system for higher organisms?)
-Higher organisms (e.g. Snails, flatworms)
-possess collection of neurones in the head - cephalic ganglion - a
rudimentary brain
-In higher animals the cephalic ganglia become segmented
into regions, each with a defined function
What does the cerebrum show?
-Shows the most dramatic change during development.
-In man it is the most distinctive part of the brain
What are central pattern generators, and what are they responsible for in humans ?
- Circuits that give rise to rhythmic motor activity
- Once activated, they create spontaneous, repetitive movement
- In humans this is responsible for locomotion and breathing, among other
things
How are tissues referred to in the brain ?
- The colour it appears
What are the 3 facts of the gray matter?
-Neuronal cell bodies
-Often clearly organised in layers within certain brain regions
-In other areas of the brain they are grouped together into nuclei and identified by
specific names
What are 2 facts of the white matter ?
- Mostly axons
- Appear white due to myelination (fatty tissue)
What does ‘rostral’ mean ?
- towards the front
What does ‘caudal’ mean ?
- towards the tail
What does ‘dorsal’ mean ?
- towards the back
What does ‘ventral’ mean ?
towards the stomach
What does ‘sagittal’ mean ?
- parallel to the midline
What does ‘coronal’ mean ?
- divides NS into anterior and posterior parts
What does horizontal (transverse) mean ?
- divides NS into dorsal and ventral parts
What is the ‘nucleus’ ?
- collection of nerve cells visible under the microscope as a distinct structure
What are neurones ?
- excitable cells of the brain
What are the type of glia cells ?
- Astrocytes
- Microglia
- Ependymal cells
- Oligodendrocytes: myelin sheath
What are ‘Astrocytes’ ?
- Glia cells that is responsible for mechanical support, growth factors, some forms of plasticity
What is ‘Microglia’ ?
- c.f. macrophages
What are ‘Ependymal cells’ ?
- lining of the ventricles
What are ‘Oligodendrocytes’ ?
-myelin sheath
What are glial cells ?
( 8 facts)
- 10-50 times more abundant than neurons
- contribute to brain function by supporting neurons
- structural support
- Schwann cells provide myelin
- Act as scavengers
- Buffer potassium and uptake of neurotransmitters
- Guide migration of neurons in development
- Impermeable tight junctions, blood brain barrier
Can neurones function without glial cells ?
No
What 2 types of protection does the brain have ?
- physical:
*brain coverings
-chemical:
* blood brain barrier
* cerebrospinal fluid (CSF)
What are the 3 types of brain meninges ?
- Dura mater: tough outer covering - leathery and inelastic
- Arachnoid membrane: web-like consistency - separates dura from pia
- Pia mater: the thin membrane that gently adheres to the surface of the brain
What is the blood brain barrier (BBB) ?
- Protects the brain from blood borne substances (including [K+]O)
which may compromise its function
What is the physical structure of the blood brain barrier (BBB) ?
- Physical structure consists of: astrocytes and capillary endothelium.
- astrocytes which wrap around the capillaries
- capillary endothelium which line the capillaries
How do substances cross the blood brain barrier (BBB) ?
If they are lipid soluble or substrates for a specific transport mechanism
What are the 3 type of cells blood brain barrier (BBB) have ?
- Astrocytes
-Endothelial cells
- Pericyte cells
also has neutron
What are astrocytes responsible for ?
- Morphology and circuit connectivity
-Mitochondrial function
-Dopamine and ATP release
-ApoE and GLUT1 expression levels
-Glucose BBB transport
What are endothelial cells responsible for ?
-Vaso-regulation
-Potential role in tight junction structure
-Independent of insulin transport
-Regional CNS insulin signalling
-AB transport
What are pericyte cells responsible for?
-Proliferation
-Not involved in glucose uptake
-Hyperpolarization
- Protects endothelial cells
-Neuronal insulin sensitivity
-Responsible for regulating angiogenesis (Vascular development
Why is the neutron responsible for ?
- Peripheral metabolism
- Dopamine signaling
- Mitochondrial function
- Synapse density
- Supports cognition
- Tau phosphorylation
- IDE expression
- AB interaction
What is between the frontal lobe and the parietal lobe ?
The central sulcus
What is located between the frontal lobe and the temporal lobe ?
The lateral sulcus
What are the 3 planes that the brain can be sliced ?
- Midsagittal
-Horizontal
- Coronal
GROSS EXTERNAL STRUCTURE OF CNS
Where is the cerebrum and cerebellum located ?
Located at the top of the brainstem
GROSS EXTERNAL STRUCTURE OF CNS
What does the cerebral hemisphere control ?
Each cerebral hemisphere controls the opposite side of the body
GROSS EXTERNAL STRUCTURE OF CNS
Why is the brainstem important ?
The brainstem is an important relay between the cerebrum, cerebellum, and the spinal cord
GROSS EXTERNAL STRUCTURE OF CNS
Where are the vital functions mediated?
By the brainstem
Where does the cerebrospinal fluid (CSF) flow ?
CSF flows from the lateral
ventricles into the 3rd and 4th ventricles and then into the subarachnoid space.
What is the cerebral ventricle filled with ?
- Fluid filled spaces within the brain
What is the cerebrospinal fluid ?
- Fluid which fills the ventricles
- Composition similar to extracellular fluid
- Secreted by choroid plexus (capillaries within the ventricles)
- The CSF acts as a shock absorber for the brain
