1 / 26

Blood supply

Blood supply. Vascular Supply. About 18% of the total blood volume in the body circulates in the brain, which accounts for about 2% of the body weight.

challock
Download Presentation

Blood supply

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Blood supply

  2. Vascular Supply • About 18% of the total blood volume in the body circulates in the brain, which accounts for about 2% of the body weight. • The blood transports oxygen, nutrients, and other substances necessary for proper functioning of the brain tissues and carries away metabolites. • Loss of consciousness occurs in less than 15 seconds after blood flow to the brain has stopped, and irreparable damage to the brain tissue occurs within 5 minutes. • Cerebrovascular disease, or stroke, occurs as a result of vascular compromise or hemorrhage and is one of the most frequent sources of neurologic disability. • Nearly half of the admissions to many busy neurologic services are because of strokes. • Cerebrovascular disease is the third most common cause of death in industrialized societies.

  3. BLOOD SUPPLY TO THEBRAIN • High demand for oxygen and nutrients • Arterial blood through: internal carotid andvertebral arteries • Venous blood from brain in the internal jugular veins • Cerebrovascular accidents (CVA): stroke,shutting off blood supply to brain

  4. Arterial supply • The circle of Willis (after the English neuroanatomist Sir Thomas Willis) is a confluence of vessels that gives rise to all of the major cerebral arteries. • Supplied by the paired internal carotid arteries and the basilar artery. • Contains a paired posterior communicating artery and an unpaired anterior communicating artery. • The circle of Willis shows many variations among individuals. • Occlusion of major cerebral arteries produces a characteristic clinical picture.

  5. Why do individual differences in vascular supply matter? • What might they achieve? • What problems might they give? • How might they assist after damage?

  6. VENOUS DRAINAGE • The venous drainage of the brain and coverings includes: • the veins of the brain itself, • the dural venous sinuses, • the dura's meningeal veins, • and the diploic veins between the tables of the skull.

  7. CRANIAL MENINGES • Dura mater: outer and inner layers • Arachnoid mater: epithelial layer and arachnoid trabeculae • Pia mater: sticks to brain surface • Pia and arachnoid = leptomeninges • Dural folds hold the brain in position - Falx cerebri Tentorium cerebelli • Dural sinuses (veins located within the folds)

  8. VENTRICLES OF THE BRAIN • Lined with ependymal cells • Lateral ventricle (each hemisphere) • Third ventricle (diencephalon) • Cerebral aqueduct (midbrain) • Fourth ventricle: (btw pons andcerebellum,continuous with central canal ofspinal cord) • CSF flows within ventricles, central canal and into subarachnoidspace

  9. Ventricles

  10. CEREBROSPINAL FLUID Surrounds and bathes the CNS Functions: 1. Supporting of brain and spinal cord 2. Transport of nutrients, chemical messengers, and waste products

  11. THE FORMATION OF CSF • Choroid plexus: contains specialised ependymalcells and capillaries (500ml/day), total volume:150ml • Choroid plexuses secrete CSF into ventricles • Circulation:from choroid plexus to ventricles and central canalof spinalcord to subarachnoid space to sinuses

  12. Circulation (cont.): • CSF reaches subarachnoid space through two lateral apertures and a single medial aperture in the 4th ventricle • Arachnoid granulations: penetrate dura mater meningeal layer of venous sinuses, CSF absorbed into the venous circulation • Hydrocephalus: “water in the brain”

More Related