Brain blood supply & blood brain barrier Flashcards
(15 cards)
2 SOURCES OF BLOOD SUPPLY TO THE BRAIN
PARTS OF BRAIN EACH SUPPLIES
BRANCHES (2) FOR EACH
WHAT ARE THE 2 SOURCES CONNECTED BY - (name the 2 connections) & WHAT IS FORMED BY THIS CONNECTION
- INTERNAL CAROTID ARTERY (ICA)
Anterior circulation
branches: anterior cerebral artery (ACA)
middle cerebral artery **_(MCA)_**
- VERTEBRAL ARTERIES (VA)
posterior circulation
branches: 2VAs join to form basilar (BA)
BA divides into 2 posterior cerebral art **_(PCA)_**
Anastomotic vessels-anterior communicating artery
-posterior communicating artery
Circle of Willis
REGIONS/STRUCTURES SUPPLIED BY THE
MCA/ACA
VA
- frontal - parietal - parts of temporal lobes
- temporal - occipital - brain stem - diencephalon - cerebellum
SUPERFICAL BRANCHES OF ARTERIES = ?
DEEP BRANCHES OF ARTERIES =
- CORTICAL
- CENTRAL
BRAIN CONTAINS ? MILES OF BLOOD VESSELS.
FUNCTIONAL LOSS AFTER AN INJURY DEPENDS ON ?
- 400
- Site of lesion
WHAT IS THE MOST COMMON ARTERY COMPROMISED IN A STROKE (loss of blood supply to internal structures)
WHAT ARE THE INTERNAL STRUCTURES (3)
WHAT IS THE DEEP BLOOD SUPPLY CALLED
WHAT PARTS OF BODY ARE AFFECTED
- MCA
- Internal capsule / putamen / claustrum
- lenticulostriate arteries branches of MCA
- UPPER LIMB - FACE - LANGUAGE CENTERS(Broca’s, Wernicke’s area)
CAPSULAR STROKE
- CAUSED BY
- EFFECTS WHAT
- intracerebral hemorrhages caused by rupture of the deep branches
- motor & sensory axons in the internal capsule
MOST COMMON SITE FOR CEREBRAL ‘BERRY ANEURYSMS.
WHAT CAN IT CAUSE
CIRCLE OF WILLIS
SUBARACHNOID HEMORRHAGE - spread out around brain
EPIDURAL HEMATOMA
- CAUSED BY
- ARTERY AFFECTED
- HOW IS BRAIN DAMAGED BY THIS
- HOW RECOGNIZED
- blows to side of head - rupture artery
- middle meningeal artery (branch of external carotid)
- compression of tissue by large accumulation of blood
- smooth medial edge formed by dura being pressed down on the brain
SPINAL CORD SUPPLIED BY 3 ARTERIES ARISING FROM THE VA & BY 3 OTHER TYPES OF ARTERIES ARISING FROM THE ?
WHAT PARTS OF THE SPINAL CORD DO THE 3 MAIN ARTERIES SUPPLY
WHAT DOES DAMAGE TO EACH LEAD TO
VA arteries
- 1 anterior spinal artery (ASA) - ANT 2/3rd
- loss of motor fnc, pain/temp sensation of body wall - 2 posterior spinal arteries - POS 1/3rd
- loss of fine touch and proprioception
Radicular Arteries - branches of aorta
- inntercostal
- lumbar
- sacral
FLOW OF BLOOD AS IT DRAINS FROM CEREBRAL VEINS TO VENOUS SINUSES
- superior sagital sinus
- transverse sinus
- sigmoid sinus
- internal jugular vein
SUBDURAL HEMATOMA
- TYPE OF BLEED
- WHAT CAUSES IT
- WHAT IS SHEERED
- HOW IS BRAIN TISSUE DAMAGED
- Venous
- blows to front or back of head will rock brain in the anterior-posterior direction
- bridging veins in the subarachnoid space which cross the subdural space and drain into superior sagittal sinus (sheered at point where cross dura)
- pressure caused by venous blood accumulating in the subdural space.
BLOOD BRAIN BARRIER
- HOW DISCOVERED
- WHY SUBSTANCES MAY ONLY PASS BY ACTIVE TRANSPORT
- WHEN IS BARRIER ESTABLISHED WHAT IMPLICATIONS DOES THE TIMING HAVE
- blue dye stained every organ except the brain
- cappillary endothelial cells are linked by tight junctions
- tight junctions established during 4th month of fetal development
so permeability to small water-soluble molecules is greater during developing brain
think about maternal alcohol consumption and drug abuse
WHAT CAN CROSS THE BBB and how (4)
AND WHAT CANNOT (3)
- Gases rapidly diffuse into the CNS
(N2O & other volatile anesthetics)
- Hydrophobic substances (O2, CO2, hormones)
rapidly cross
- Drugs like heroin rapidly cross
- Glucose - facilitated transport
- polar molecules
- blood cells
- bacteria
WHAT ARE THE AREAS CALLED THAT DON’T HAVE A BBB
WHY DON’T THEY HAVE BBB
WHAT ARE THE MOST KNOWN AREAS
Circumventricular Organs (CVOs)
to allow the brain to respond to changes in the chemical content of the blood
and to
secret modulatory neuropeptides into the bloodstream
- Median eminence & neurohypophysis - regulation & release of pituitary hormones
- area postrema - caudal part of 4th ventricle of medulla (aka chemotatic trigger zone) - detects circulating toxins & initiate vomit reflex. - negative side effects of drugs
WHAT ARE THE DIFFERENCES BETWEEN A EPIDURAL HEMATOMA AND A SUBDURAL HEMATOMA
Epidural - artery - above dural - hit on side of head - fast bleed
Subdural - vein - in subarachnoid space - hit front or back of head - slow bleed
