Flashcards in Unit 2 Deck (38):
What are some protective and support structures of the CNS? (x3)
The cranium, the meninges and the cerebrospinal fluid
What are the three layers of the meninges?
The outermost layer is the dura mater, middle is the arachnoid mater and the innermost layer is the pia mater
What is the second largest structure in the brain after development?
When is there the most brain development during gestation? When does brain folding occur?
Most development occurs in the end of the first trimester. The folding of the cerebrum occurs way later, just before birth
In what layer of the meninges are there blood vessels? What occurs if there is a break in one of these arteries? Why is this so dangerous?
There are blood vessels in the arachnoid mater. If there is a break here there is a "brain bleed/hematoma/subdural hematoma". This is so dangerous because in this section of the brain, there is point of exit and the blood stays within the arachnoid space and there is an increase in ICP
What is the choroid plexus? What types of cells are these?
These are the cells within each ventricles that secrete CSF. They are a type of glial cells within the brain
What is indicative of blood cells or elevated proteins in the CSF (via lumbar puncture sampling of fluid in the subarachnoid space)? How does it do this?
Suggests infection. You can see this as the sample will be cloudy or there is blood
What are the glial cells in the CNS? What are their functions?
Oligodendrocytes (form myelin sheath within the CNS), Microglia (innumerable cells), Astrocytes (regulate ECF) Ependymal Cells (barrier cells within compartments, epidermal derivation)
How is CSF reabsorbed back into the venous blood?
Via Arachnoid villi
What is the circulation of CSF?
Lateral ventricles > Third ventricles > fourth ventricle . subarachnoid space . arachnoid villi > superior/dural sagittal sinus > venous return
What are the cells that create a barrier around the capillaries in the brain? They secrete what type of factor? What does this do?
Astrocytes put out foot processes that encircle the capillaries. They secrete paracrine factor that on the endothelial cells of the capillaries that control the permeability of the vessel by promoting tight junction formation.
What types of molecules can and cannot cross the BBB?
Lipid soluble molecules cross readily (ethanol). Hydrophilic substances will only cross if there are the proper transporters present. Hydrophobic molecules have trouble crossing.
What type of cell (oxygen requirement) are neurons? How does oxygen cross the BBB?
They are obligate aerobes. Oxygen crosses the barrier readily
How much of the body's glucose does the brain need?
The brain is responsible for about 50% of the body's glucose consumption.
What are the divisions of the spinal cord?
The four divisions are the cervical (neck), thoracic, lumbar and sacral.
What. is the most important parasympathetic nerve? Why? what organs does it innervate? (x6)
The vagus nerve. It innervates almost all the organs and sphincters of the abdomen. It innervates the lungs, liver, gall bladder, small intestine, large intestine and the pancreas.
Where do parasympathetic preganglionic fibres arise from? What about sympathetic?
Parasympathetic > cranio-sacral
Sympathetic > thoraco-lumbar
What is a nerve, ganglion, tract and nuclei?
Nerve > A bundle of axons in the PNS
Ganglion > A cluster of cell bodies in the PNS
Tract > A bundle of axons in the CNS
Nuclei > A cluster of cell bodies in the CNS
What type of information does the dorsal root of the spinal cord carry versus the ventral root?
The dorsal root carries information in (the afferent sensory information) while the ventral root carries information out ( the efferent motor information) to the effector.
What is the dorsal root ganglion?
The bundle of cell bodies of the afferent sensory nerves coming in. It is a ganglion because it is within the PNS?
What differentiates the CNS vs. the PNS?
Anything that is outside of the brain or the spinal cord is considered the PNS.
What is the difference between white and grey matter?
Whit matter is the outer portion of the spinal cord and is made of the myelinated axons carrying information - it is the "through lanes". The grey matter is where integration occurs and where the synapses occur - it contains cell bodies and dendrites.
What region of the dorsal horn grey matter integrate somatic sensory information? Visceral sensory? Autonomic sensory?
Somatic is in the most dorsal portion of the dorsal horn. Visceral is just slightly further in. And the autonomic is the most central/ventral.
Why is there no such thing as a central root ganglion?
This is because the cell bodies of the somatic motor neurons are within the ventral horn grey matter.
What are the ascending and descending tracts of the brain?
Ascending tracts - dorsal columns and the spinal thalamic
Descending tracts - lateral and ventral corticospinal tracts
What is a "spinal reflex"?
A reflex tat does not involve sending information to the brain
What structures make up the brain stem?
The pons, medulla and midbrain
What is the function of the midbrain? The pons? The medulla? What "section" of the brain are the medulla and pons a part of?
The midbrain is coordination of eye movement, and visual and auditory reflexes. The pons is a relay station between the cerebrum and cerebellum. And the medulla is the site of decussation for most neurons. They are a part of the hind brain.
What is the reticular formation?
A network of diffuse neurons involved in processes such as arousal/sleep, muscle tone, coordination of breathing and blood pressure. It is responsible for basal functions
What is the function of the cerebellum?
To coordinate movements.
What structures make up the diencephalon? (x4) What are each of their functions?
The thalamus (relay and integration centre for sensory information), the hypothalamus (centre of homeostasis), the pineal gland (secretes melatonin and controls circadian rhythms) and the pituitary gland (secretes hormones under the control of the hypothalamus).
Why is the cerebrum folded?
it is to increase surface area and the amount of surface area os somehow related to intelligence
What is a sulcus vs a gyrus?
A sulcus os the grove between two ridges. A gyros is the top of the hill
What are the three regions of white matter within the cerebrum?
The basal "ganglia", the limbic system, and the cereal cortex
What type of functional area takes up the most space in the brain?
Where is the primary motor cortex? What is the other name for this centre? The cell bodies of what type of neurons originate here?
On the ridge just ANTERIOR to the central gyrus. A.k.a the precentral gyrus. The cell bodies of upper or first order motor neurons
Where is the primary somatosensory cortex? What is the other name for this centre? Where does information for this cortex come from?
On the ride just POSTERIOR to the central gyrus. A.k.a. the post-central gyrus. The terminals of the sensory pathways from the skin, musculoskeletal system and viscera