Lectures 2 & 4 - Neuro Flashcards
What is the difference between the CNS and the PNS?
CNS: The brain and spinal chord; that which is encased in bone.
PNS: Anything outside of the brain and spinal chord; that which is not encased in bone.
How does the neuraxis change in humans compared to quadrupeds?
The neuraxis is essentially vertical in humans but is rotated anteriorly at the rostral end.
What are the three layers of meninges, from outside to inside?
Dura mater, arachnoid mater, pia mater.
What is between the arachnoid mater and the pia mater?
The subarachnoid space
What is contained within the subarachnoid space?
CSF, arachnoid trabeculae, and blood vessels.
What are the two layers of dura mater, from outer to inner?
Periosteal and meningeal
What is the name of the structure in the brain into which CSF and venous blood drain?
Sinuses, including the superior sagittal sinus.
How does venous blood drain from the subarachnoid space?
Through arachnoid villi.
Where does CSF come from and how is it produced?
It is primarily produced by ependymal cells (modified endothelium) of the choroid plexus in the ventricles.
How many ventricles are there?
Two lateral, third, and fourth
What is the relationship between the ventricles and the subarachnoid space? What does this relationship allow the CSF to do?
The ventricles are continuous with the subarachnoid space, thus allowing the CSF to communicate from the ventricles to the subarachnoid space.
What happens if the CSF does not return to circulation?
Hydrocephalus: Oedema, causing increased intracranial pressure.
How can hydrocephalus be resolved?
A catheter draining CSF from the ventricles into the peritoneal cavity.
What type of blood fills a subdural and epidural hematoma?
Subdural: venous blood
Epidural: arterial blood
What is a pathological difference between an epidural and a subdural hematoma?
An epidural hematoma will peel the dura off of the skull.
What are the two cellular components of the nervous system?
Glia and neurons.
How is information conveyed by the nervous system?
Electrically receives, integrates, and outputs electrical information along the processes of excitable cells called neurons.
Transmission within a single neuron is electrical. What type of transmission occurs between neurons (most often)?
Chemical transmission via neurotransmitters.
Where does transmission between neurons take place?
At synapses.
What are the two types of insulating glia in the nervous system? In which part of the nervous system is each, respectively?
Oligodendrocytes in the CNS, Schwann cells in the PNS.
Why are tracts in the CNS system called ‘white matter’?
The oligodendrocytes insulate the axons of neurons with lipid bilayer.
Why are axons insulated?
To increase speed of transmission without increasing the size of the axon.
Axons in the periphery cluster together to form what?
Nerves
What is the outer protective layer of a nerve called?
Epineurium.
Within the nerve, axons are sub-grouped into fascicles surrounded by what structure?
Perineurium sheath
Each individual nerve fibre is protected by what?
Endoneurium.
What is the role of astroglia/astrocytes?
Numerous functions including recycling of neurotransmitters and maintaining the ionic composition of the extracellular fluid.
What is the blood brain barrier?
A property of CNS endothelial cells conferred by astrocytes that controls the influx of material to the CNS.
How many spinal segments and pairs of spinal nerves are there?
31
What are the two nerves plexuses?
Brachial and lumbosacral plexus
How many pairs of cranial nerves are there?
12
Where do most of the cranial nerves connect to the CNS?
The brainstem
Through what part of the spinal cord do sensory nerves enter?
Dorsal root
Through what part of the spinal cord do motor nerves exit?
Ventral root
What is the role of the autonomic nervous system?
Unconscious homeostatic control of the body’s physiology.
What is the effect of the parasympathetic and sympathetic divisions of the ANS on TPR and cardiac output?
TPR: parasympathetic has no effect; sympathetic increases TPR
CO: parasympathetic decreases CO; sympathetic increases CO
Cell bodies of the parasympathetic nervous system are located in which part of the CNS?
Craniosacral - sacrum and brainstem
Cell bodies of the sympathetic nervous system are located in which part of the CNS?
Thoracolumbar - sympathetic ganglia run along the length of the thoracic and lumbar spinal cord.
Sympathetic innervation of viscera runs through what structure?
Prevertebral ganglion.
Sympathetic innervation of blood vessels and skin loops through what structure?
Sympathetic axon synapses in the sympathetic trunk via the white communicating rami. The peripheral axon then exits the trunk via the grey communicating rami to the periphery in the peripheral nerve.
What are the three divisions of the ANS?
enteric, sympathetic, and parasympathetic nervous systems
What are the four main divisions of the CNS?
Cerebrum, dienchephalon (thalamus and hypothalamus), cerebellum, brainstem (midbrain, pons, medulla oblongata), spinal cord.
Which cranial nerves are contained within the brainstem?
3-12
How does the cerebellum join to the brainstem?
By cerebellar peduncles
What are the three main functions of the brainstem?
- Contains integrative centres of vital functions (cardiovascular and respiratory control);
- All tracts to and from the spinal cord pasthrough it.
- Contains several small nuclei with hugely divergent projections to the rest of the brain that determine conscious state.
Describe the location of the diencephalon.
Situated between brainstem and cerebrum - closely associated with the third ventricle
What is the role of the thalamus?
Gateway for ipsilateral traffic to and from the cerebral cortex
What is the role of the hypothalamus?
Controls endocrine functions of the pituitary gland and engenders mental states and behavioral patterns associated with homeostatic drives.
What is the role of the cerebrum?
Associated with formulating voluntary movements, conscious perception, thought, language, social cognition and other higher functions
What is the name of the fold of meningial dura mater between the two hemispheres, above which the superior sagittal sinus sits?
The falx cerebri
What does ‘excitable’ mean when neurons are said to be excitable cells?
Cells that generate bioelectrical events across their membrane.
What function are neurons specialized for?
Information processing: reception, integration, and output
How can you tell the difference between a tract in the CNS and a nerve in the PNS?
Nerves in the PNC have connective tissue around them, especially collagen, whereas tracts in the CNS do not have connective tissue around them. IE, axons in the PNS need protection but CNS axons are already protected by bone.
What is the biggest challenge for pharmacologists designing drugs for the CNS?
Overcoming the blood brain barrier.
What are the two roots of the spinal cord?
Ventral and dorsal.
Fill in the blank: the _____________ has the cell bodies of the sensory neurons in the periphery.
Dorsal root ganglion
