The Brain and Cranial Nerves
Biology 315. Anatomy and Physiology I. Chapter 14. The Brain and Cranial Nerves. Tortora and Grabowski, 13th edition. 2012.
I. Brain Organization, Protection, and Nourishment. A. Major Parts of the Brain: brain stem, cerebellum, diencephalon, and cerebrum
B. Blood Flow Through the Brain.: substantial; 20% cardiac output at rest; Lack of blood flow > a couple of minutes = permanent damage. Glucose supply must be constant (Sx of hyper/hypoglycemia) 1. Arterial supply A. internal carotid arteries
B. Vertebral arteries. R. and L vertebral arteries join to become basilar artery inside the cranium 2. Venous drainage: venous sinuses into internal jugular veins 3. Blood Brain Barrier: protective A) Tight jctns. seal endothelial cells of brain capillaries B. Astrocytes processes press up against capillary walls
C. Lipid soluble substances pass easily; some other substances cross via AT, some slowly
C. Protective coverings of the brain 1. Cranial meninges like spinal meninges: dura, arachnoid, pia 2. Extensions of dura separate parts of the brain *falx cerebri = separates the 2 hemispheres of cerebrum *falx cerebelli = separates the 2 hemispheres of the CBLM *tentorium cerebelli = separates the cerebrum from CBLM
D. Cerebrospinal Fluid; 1. Mechanical protection: shock absorber
2. Chemical protection: optimal chemical environment for accurate neuronal signaling. 3. Circulation/ medium for exchange of O2, nutrients, wastes, etc.
4. Produced in choroid plexuses = capillary networks and ependymal cells in ventricular walls; A. 1. Continuous circulation of CSF thru ventricles, spinal canal, and subarachnoid space. Lateral ventricles (separated by septum pellucidum) ≡ through Interventricular foramina≡
3rd ventricle (in diencephalon) ≡ cerebral aqueduct of Sylvius in midbrain ≡ 4th ventricle in brain stem ≡Three openings in roof of 4th ventricle ≡Subarachnoid space, central
I. Brain Organization, Protection, and Nourishment. A. Major Parts of the Brain: brain stem, cerebellum, diencephalon, and cerebrum
B. Blood Flow Through the Brain.: substantial; 20% cardiac output at rest; Lack of blood flow > a couple of minutes = permanent damage. Glucose supply must be constant (Sx of hyper/hypoglycemia) 1. Arterial supply A. internal carotid arteries
B. Vertebral arteries. R. and L vertebral arteries join to become basilar artery inside the cranium 2. Venous drainage: venous sinuses into internal jugular veins 3. Blood Brain Barrier: protective A) Tight jctns. seal endothelial cells of brain capillaries B. Astrocytes processes press up against capillary walls
C. Lipid soluble substances pass easily; some other substances cross via AT, some slowly
C. Protective coverings of the brain 1. Cranial meninges like spinal meninges: dura, arachnoid, pia 2. Extensions of dura separate parts of the brain *falx cerebri = separates the 2 hemispheres of cerebrum *falx cerebelli = separates the 2 hemispheres of the CBLM *tentorium cerebelli = separates the cerebrum from CBLM
D. Cerebrospinal Fluid; 1. Mechanical protection: shock absorber
2. Chemical protection: optimal chemical environment for accurate neuronal signaling. 3. Circulation/ medium for exchange of O2, nutrients, wastes, etc.
4. Produced in choroid plexuses = capillary networks and ependymal cells in ventricular walls; A. 1. Continuous circulation of CSF thru ventricles, spinal canal, and subarachnoid space. Lateral ventricles (separated by septum pellucidum) ≡ through Interventricular foramina≡
3rd ventricle (in diencephalon) ≡ cerebral aqueduct of Sylvius in midbrain ≡ 4th ventricle in brain stem ≡Three openings in roof of 4th ventricle ≡Subarachnoid space, central