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Protection

Protection. What is the major protection for the brain? There are also 3 connective tissue membranes called the meninges : Cover and protect the CNS Protect blood vessels Contain cerebrospinal fluid The 3 meninges from superficial to deep: Dura mater Arachnoid mater Pia mater. Skin.

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Protection

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  1. Protection • What is the major protection for the brain? • There are also 3 connective tissue membranes called the meninges: • Cover and protect the CNS • Protect blood vessels • Contain cerebrospinal fluid • The 3 meninges from superficial to deep: • Dura mater • Arachnoid mater • Pia mater

  2. Skin Galea Aponeurotica Connective Tissue Bone Dura Mater Arachnoid mater

  3. Dura Mater • Tough and leathery. • Most superficial. • 2 layers: • Periosteal attached to the skull • Meningeal  true external covering, extends downward and surrounds spinal cord • In several locations, the inner dura mater extends in to the cranial cavity, forming a sheet that dips inward and then returns. These dural folds provide additional support for the brain.

  4. Arachnoid and Pia Mater • Arachnoid: • Loose spider-web of connective tissue. • Beneath it is the subarachnoid space – filled with blood vessels and CSF • Pia Mater • Deepest and most delicate • Covers the brain tissue • Follows its every ridge and groove • What do you call an inflammation of the meninges?

  5. The Adult Brain Figure 14.1b

  6. The Circulation of Cerebrospinal Fluid • Functions: • -CSF cushions delicate neural structures • Supports the brain (think of brain as floating in the CSF) • -Transports nutrients, chemical messengers, and waste products (proteins, urea, glucose, salt) • -Circulates through subarachnoid space, around the brain and spinal cord, and through the ventricles of the brain Figure 14.5a, b

  7. Hydrocephalus Hydrocephalus – “water on the brain” – in infants skull enlarges to accommodate the extra fluid volume -caused by infections, developmental abnormalities

  8. Blood supply to the brain • Brain requires 20 % of the body’s oxygen supply • Blood brain barrier isolates neural tissue from general circulation • Blood – brain barrier : endothelial cells + astrocytes • Blood –CSF barrier: (note: no astrocytes in the choroid plexus) but ependymal cells surround capillaries in the choroid plexus • Getting through blood-brain barrier : Parkinson’s (L-dopa instead of Dopamine) • Diagnosis of broken blood-brain barrier: labeled albumin

  9. BRAIN • Made up of about 100 billion neurons and • 1000 billion neuroglia • About 98% of total neural tissue • Weighs about 3 lb (1300 g)

  10. FOUR PRINCIPAL PARTS CREBRUM Thalamus Hypothalamus DIENCEPHALON CEREBELLUM Midbrain BRAIN STEM Pons Medulla oblongata Spinal Cord

  11. An Introduction to Brain Functions Figure 14.2

  12. Cerebrum • Largest part of brain (90% of brain’s weight) • Controls higher mental functions • Divided into left and right cerebral hemispheres • Surface layer of gray matter (neural cortex) • Also called cerebral cortex • Folded surface increases surface area • Elevated ridges (gyri) • Shallow depressions (sulci) • Deep grooves (fissures)

  13. Cerebrum Some functions: Behavior: Abstract thought processes Problem solving Attention Creative thought Some emotion Intellect Reflection Judgment Initiative Inhibition Coordination of movements

  14. Cerebellum • Second largest part of brain • Coordinates repetitive body movements • 2 hemispheres • Covered with cerebellar cortex

  15. Cerebellum • Functions: • The cerebellum coordinates many neuromuscular functions, such as balance and coordination. • Disorders related to damage of the cerebellum often result in ataxia (problems with coordination), dysarthria (unclear speech resulting from problems controlling the muscles used in speaking), and nystagmus (uncontrollable jerking of the eyeballs). • A brain tumor that is relatively common in children known as medulloblastoma grows in the cerebellum.

  16. Diencephalon • Located under cerebrum and cerebellum • Links cerebrum with brain stem • 3 divisions: • Thalamus - relays and processes sensory information • Hypothalamus - hormone production, emotion, & autonomic function • Epithalamus (Pineal gland)

  17. Diencephalon Diencephalon Functions: Hypothalamus: Moods and motivation Sexual maturation Temperature regulation Hormonal body processes Optic nerve Pituitary Gland: Hormonal body processes Physical maturation Growth (height and form) Sexual functioning

  18. The Brain Stem • Processes information between: • spinal cord and cerebrum or cerebellum • Includes: • Mesencephalon (midbrain) • Processes sight, sound, and associated reflexes, & maintains consciousness • Pons • Connects cerebellum to brain stem & is involved in somatic and visceral motor control • Medulla oblongata • Regulates autonomic functions: HR, BP, and digestion

  19. The Brain Stem The Brain Stem Function: Motor and sensory pathway to body and face Vital centers: cardiac, respiratory, vasomotor

  20. The Cerebral Hemispheres PLAY Figure 14.17

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