blood supply to the brain

how much of the oxygen does the brain use?

20%

what causes the most neurological disorders?

lesions of the vascular organ

what 2 blood supply systems supply blood to the CNS

carotid and vertebral basilar

internal carotid artery split and supply what

middle and arterial cerebral arteries that supply the frontal, temporal, and parietal lobes

occlusion of internal carotid artery

blindness of ipsilateral eye, blindness of contralateral half of visual field of other eye, contralateral hemiplegia, aphasia

middle cerebral artery

key supplier of the blood to the areas that mediate language that runs along lateral or sylvian fissure

occlusion of the middle cerebral artery

contralateral paralysis in lower part of the face and arm, somatosensory deficits, hemianopsia contralateral fields, aphasia, constructional apraxia, cognitive impairments

anterior cerebral artery

supplies much of the medial surface and supports primary motor and sensory cortex and frontal lobe areas

What does the left and right anterior cerebral arteries form

circle of willis

circle of willis

a and p cerebral artery, a and p communicating artery, internal carotid artery, sometimes basal and middle cerebral arteries are included

occlusion of anterior cerebral artery

paralysis and sensory deficits of contralateral leg and perineum, urinary incontinence, contralateral upper motor neuron weakness of face tongue and upper limb, proximal occlusion leads to ipsilateral anosima, mental confusion or dysphasia

Vertebral artery

supplies cerebellar arteries that provide blood and oxygen to the cerebellum and brain stem areas- mid brain, pons, medulla

internal artery ‘labyrinthne’ artery

travels along the acoustic nerve and is distributed to the ear

branches of basilar and veritable artery

provide blood to spinal artery

Vascular lesions

paralysis of all extremities, heavy disturbances in sensation, and difficulty in swallowing and respiration

posterior cerebral artery

provide blood to temporal and occipital lobe

lesion of posterior cerebral artery

most commonly affect vision, may affect hippocampus, medial temporal lobe, spelenium and other mid brain thalamic structures

deficits with PCA

visual fields deficits, loss of pain and temp sensations, prosopagnosia (inability to recognize faces), memory loss, alexia without agraphia

what are the 3 sources of blood flow regulation?

autoregulation, response of cerebral vessels to metabolites, innervation of cerebral vessels by autonomic fibers

autoregulation

controls caliber (diameter of small arteries), muscular walls contract if pressure rises and relax if it falls

response of cerebral vessels to metabolites

increases CO2 tension in extracellular fluid in the brain and increase blood flow

innervation of cerebral vessels by autonomic fibers

sympathetic and parasympathetic NS innervate most blood vessels and control the resistance by opposing actions, help in adapting to stress

main causes of disruption of obstruction of blood flow

occlusive, hemerrohagic, ischemic strokes, AVM

occlusive events

arteriosclerosis, artherosclerosis, thrombosis, hypertension, embolism

arteriosclerosis

blood vessels that transport oxygen and nutrients form heart are thickened

artherosclerosis

accumulation of fats, cholesterol, and other substances on your wall

thrombosis

local build up of fatty substances

hypertension

increase of pressure on inner walls of blood vessels making the vessels less flexible and more vunerable for a wall build up

embolism

blockage of a distant artery that clots break free and travel

Hemorrhagic types

aneurysm and subdural hematoma

aneurysm

weak area of wall and can fill with blood and burst

subdural hematoma

from trauma

Ischemic stroke

insufficient blood supply, transient ischemic attach TIA

Arteriovenous malformation (AVM)

congenial condition which tangled and twisted arteries are interconnected in a localized area