Term
| What two substances does the brain rely on? |
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Definition
|
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Term
| How do vessels supplying the brain regulate bloodflow? |
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Definition
| Response to local CO2, pH, BP |
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Term
| (T/F) Vessels supplying the brain are innervated from outside sources |
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Definition
| False, they rely solely on local stimuli |
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Term
| What is functional significance of the circle of willis? |
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Definition
| Allows blood supply to all parts of the brain, even in an instance of circulation issue in a certain |
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Term
| What are anastomoses? How do they contribute to the COW? |
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Definition
| Connections between two blood vessels you normally wouldn't see connected; allows alternate pathways for bloodflow |
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Term
| (T/F) The brain is very sensitive to re-perfusion issues |
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Definition
|
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Term
| What two arteries supply the frontal lobe? |
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Definition
| Anterior cerebral artery and anterior communicating artery |
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Term
| What arteries supply the temporal/parietal lobe? |
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Definition
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Term
| What arteries supply the occipital lobe? |
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Definition
| Posterior cerebral and communicating arteries |
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Term
| What arteries supply the brainstem? |
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Definition
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Term
| List 4 characteristics of the BBB |
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Definition
|
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Term
| What are astrocytes, and what is their function? |
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Definition
| Glial cells in the brain, that surround the capillaries in the brain and support/contribute to the BBB |
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Term
| Name 5 reasons that the BBB could be breached |
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Definition
- hypertension
- development issues: BBB not fully formed at birth
- kernicterus
- infection
- trauma, ischemia |
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Term
|
Definition
| Bilirubin crossing the BBB |
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Term
| (T/F) A developmental issue usually manifests as the BBB not being fully formed at birth |
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Definition
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Term
| What can breach of the BBB allow? |
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Definition
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Term
| Where is the CSF sythesized? |
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Definition
|
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Term
| Why is the choroid plexus the location of CSF formation? |
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Definition
| Because it allows nutrients from blood vessels to enter the CSF |
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Term
| (T/F) CSF contains a lot of protein |
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Definition
| False, there is almost no protein |
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Term
| Describe the circulation and absorption of CSF |
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Definition
| Circulates through ventricles and the subarachnoid space before being absorbed and removed by the venous sinus |
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Term
| What is the function of the arachnoid villi? |
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Definition
| To absorb CSF from subarachnoid space to the venous sinus |
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|
Term
| Name the 3 roles of the CSF |
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Definition
- Protection
- Bouyancy
- Removal of waste products |
|
|
Term
| How does CSF provide protection? |
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Definition
| Cushions against blows to the head |
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Term
| What is the significance of the CSF providing bouyancy to the brain? |
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Definition
| Reduces pressure on the base of the brain (ie brainstem) ensuring proper function |
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|
Term
| How does the circulation of the CSF provide an ideal environment to remove wastes? |
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Definition
| CSF flows one way so nutrients can be removed |
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|
Term
| What can cause increased cranial pressure (ICP)? |
|
Definition
- brain hemorrhage
- tumours
- trauma
- cerebral edema
- infection (increased pressure because of the associated inflammation) |
|
|
Term
| What is the consequence of the brain not being able to expand? |
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Definition
| Less arterial blood flow to brain |
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|
Term
| (T/F) Decreased arterial blood flow to brain means that less CSF is made |
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Definition
|
|
Term
|
Definition
- Lethargy
- Headache
- Vomiting
- Papillidema |
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|
Term
|
Definition
| When the optical nerves bulge out into the eye |
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|
Term
| (T/F) Brain tissue can be herniated |
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Definition
|
|
Term
| List 3 types of brain herniation, and which is most common |
|
Definition
1. Cingulate (most common)
2. Uncal
3. Tonsillar |
|
|
Term
| Describe cingulate herniation |
|
Definition
| Frontal lobe is herniated |
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|
Term
| Describe uncal herniation |
|
Definition
| Temporal lobe is pushed into the brainstem |
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|
Term
| Describe tonsillar herniation |
|
Definition
| Portions of the cerebellum are pushed into the lower part of the brainstem |
|
|
Term
| Why can issues arise from brain herniation? |
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Definition
| Increased pressure on both the brain and the brainstem can negatively affect both the control centres in the brainstem, and functions of the cerebral lobes |
|
|
Term
| List the visual signs of increased ICP |
|
Definition
- Ptosis
- Ipsilateral pupil is unresponsive
- Dilated pupils |
|
|
Term
| What is the cause of the visual signs of ICP? |
|
Definition
| Intracranial pressure on CNIII, which impairs transmission |
|
|
Term
| Describe the Cushing's reflex |
|
Definition
| Cerebral ischemia signals vasomotor centres, which cause systemic vasoconstriction, increasing BP. Baroreceptors detect this, and slow heart rate accordingly. Furthermore, the increase in BP means that low CO2 reaches the lungs, which also triggers a slow in the respiratory rate. Ischemia improves so the BP drops. Drop in BP causes ischemia to return, and the cycle repeats. |
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|
Term
| (T/F) A gradual rise in pulse pressure is seen in patients with ICP |
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Definition
|
|
Term
| What is the main brain transmitter? |
|
Definition
|
|
Term
| Which receptor does it bind? |
|
Definition
|
|
Term
| (T/F) The NMDA receptor is g-protein coupled |
|
Definition
| False, it is a ionotropic receptor. |
|
|
Term
| What does glutamate binding to NMDA cause? |
|
Definition
| Opening of a Ca2+ channel |
|
|
Term
| (T/F) NMDA binding glutamate alone is enough to trigger channel opening |
|
Definition
| False, other neuronal depolarization is needed as well |
|
|
Term
| Describe the process of excitation injury to the brain |
|
Definition
| Ischemia in the brain slows reuptake of glucose, due to a lack of ATP. This means that there is more glutamate at the synapse. More glutamate = more channel opening and more Ca influx. Ca overload triggers the apoptotic cascade. |
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|
Term
| Where are supratentorial lesions located, and what do these lesions cause? |
|
Definition
- Above tentorium cerebelli
- Specific dysfunction, usually in a discrete area of the body |
|
|
Term
| Where are infratentorial lesions located, and what do these lesions cause? |
|
Definition
- In the brainstem/cerebellum
- Widespread impairment of multiple systems |
|
|
Term
| (T/F) Cardiac and respiratory systems are not affected by these lesions |
|
Definition
| False, infra-tent regions can occur in the brainstem, where the cardio and resp control centres are lcoated |
|
|
Term
| What is the left hemisphere responsible for? |
|
Definition
| Logical thinking, language, analytical thinking |
|
|
Term
| What occurs if there is a lesion between the reticular activating system (RAS) the cortex of the brain? |
|
Definition
|
|
Term
| List the progression of consciousness issues |
|
Definition
| lethargy -> confusion -> disorientation -> memory loss -> unresponsiveness -> arousal difficulty -> coma |
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|
Term
| What are the upper motor neurons of the pyramidal tract responsible for? Extrapyramidal upper motor neurons? |
|
Definition
| Innervation of voluntary actions; innervation of postural muscles |
|
|
Term
| (T/F) motor neurons behave in a contralateral manner |
|
Definition
| True, left side of brain controls the right side of the body |
|
|
Term
| What are the two tracts they can travel in? |
|
Definition
1. Pyramidal
2. Extrapyramidal |
|
|
Term
| Where do pyramidal upper motor neurons (most neurons) cross sides of body? Where do extrapyramidal neurons cross the body? |
|
Definition
| At the medulla; at level of exit |
|
|
Term
| What does lesion to the upper motor neurons cause? Is this seen ipsilaterally or contralaterally? |
|
Definition
- Spastic hyperreflexia
- Lack of fine movements
- Seen ipsilaterally |
|
|
Term
| (T/F) Reflexes are inhibited by pyramidal lesions to the upper motor nerves |
|
Definition
| False, they still occur because motor neurons innervating the postural muscles are not damaged |
|
|
Term
| What is seen with spastic hyperreflexia? |
|
Definition
- Increased vigour of reflexes (b/c of no motor control)
- Decreased reflex threshold |
|
|
Term
| What do lesions of the extrapyramidal upper motor neurons cause? |
|
Definition
- Flaccid paralysis
- Contralaterally |
|
|
Term
| What occurs when there is a lesion to lower motor neurons? Is this seen ipsilaterally or contralaterally? |
|
Definition
- Flaccid paralysis
- Ipsilaterally |
|
|
Term
| Why do LMN lesions cause flaccid paralysis? |
|
Definition
| Because the motor output is damaged |
|
|
Term
| (T/F) The sensory deficit experienced with a lesion depends on the crossover point of the afferent nerve |
|
Definition
|
|
Term
| Where does the dorsal column cross over? What are these neurons responsible for sensing? |
|
Definition
| Medulla; touch and pressure |
|
|
Term
| Where do the spinothalamic tracts (ventral and lateral) cross over? What are these neurons responsible for sensing? |
|
Definition
| At their level of entry into the spinal cord; crude touch/pain/temp |
|
|
Term
| What sensory phenomena would be seen in someone with a lesion to only the right side of the spinal cord? |
|
Definition
| - Lack of crude touch/pain/sensation on the contralateral side of the body (because it crosses over right away) - Lack of fine touch/pressure sensation on the same side of the body |
|
|
Term
| What is CNII responsible for? |
|
Definition
|
|
Term
| What is CNVIII responsible for? |
|
Definition
|
|
Term
| Where do nerves from the inner retina cross over? What field of vision do these neurons associate with? |
|
Definition
| Cross over at the optic chiasm; outer fields of view |
|
|
Term
| Where do nerves from the outer retina cross over? What field of vision do these neurons associate with? |
|
Definition
| Stay on same side; Inner field of vision |
|
|
Term
| What would a lesion at the optic chaism cause? |
|
Definition
| Loss of both outer fields of vision |
|
|
Term
|
Definition
| The inability to express or understand language |
|
|
Term
|
Definition
- Expressive
- Receptive
- Global |
|
|
Term
| What does damage to Broca's area cause? |
|
Definition
| Expressive aphasia - cannot express language but can understand it |
|
|
Term
| What does damage to Wernicke's area cause? |
|
Definition
|
|
Term
| What causes global aphasia? |
|
Definition
| Damage to both Broca's and Wernicke's area, plus te connecting fibres |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| A loss of half the field of vision |
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