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Central Nervous System

Central Nervous System. The Brain. 2 hemispheres and 4 major portions one of the largest organs (3 lbs) contains approximately 100 billion neurons made up of gray matter (cell bodies) and white matter (axons with myelin). Brain Stem: medulla oblongata, pons, and midbrain. Medulla oblongata

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Central Nervous System

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  1. Central Nervous System

  2. The Brain • 2 hemispheres and 4 major portions • one of the largest organs (3 lbs) • contains approximately 100 billion neurons • made up of gray matter (cell bodies) and white matter (axons with myelin)

  3. Brain Stem: medulla oblongata, pons, and midbrain • Medulla oblongata • Cardiac center- regulates heartbeat • respiratory center – rate, rhythm, and depth of breathing • vasomotor center – regulates dilation of blood vessels • other: swallowing, coughing, sneezing, hiccupping, vomiting

  4. Brain Stem: medulla oblongata, pons, and midbrain • Pons : “bridge” • connects medulla oblongata to midbrain • transmits impulses from the cerebrum to the cerebellum • Midbrain • controls reflexive movements of head and eyes in response to visual stimuli • controls reflexive movements of head and trunk in response to auditory stimuli

  5. Diencephalon • Thalamus • central relay station for sensory impulses (except smell) • interpretation center for pain, temperature, light touch, pressure

  6. Diencephalon • Hypothalamus • body temperature • water balance • control of hunger and body weight • control of movements and glandular secretions of the stomach and intestines • production of hormones that stimulate the pituitary gland to secrete other hormones • sleep and wakefulness • limbic system (emotional (experiences & expression), memory)

  7. Cerebellum • coordinates but does not initiate voluntary motor action • coordination • maintains posture/balance • damage to the cerebellum will likely result in tremors, inaccurate movement of voluntary muscles, loss of muscle tone, loss of equilibrium • Pons important bc relays info between cerebrum (Mvnt) and cerebellum (coordination)

  8. Cerebrum • many raised folds called gyri • the deep grooves are called sulci • consists of 2 hemispheres connected by nerve fibers called the corpus callosum • has four lobes: frontal, parietal, temporal, occipital • provides higher order mental functions • interprets sensory impulses and initiates voluntary muscular movements • stores memory and uses it for reason • intelligence and personality stem from cerebral activity

  9. Lobes of the Cerebrum • Frontal • primary motor area for upper and lower limbs • Broca’s area – (SPEECH) coordinates tongue, mouth, and larynx for speech • movement of the eyes and eyelids • higher intellectual processes like problem solving. • Parietal • Receives and sends out sensory input (Senses); temperature, touch, pressure, pain in the skin • understanding speech and using words to express feelings and thought

  10. Lobes of the Cerebrum • Temporal • hearing • interpreting sensory experiences, visual scenes, music and patterns • Occipital • vision • combining visual experiences with other sensory experiences; recognition

  11. Meninges • found between bone and soft tissue of the nervous system; cover and protect brain and spinal cord • dura mater “tough mother”- outer most covering • arachnoid mater “spider” - middle layer • Well Vascularized – therefore main site of blood brain barrier. • pia mater “ delicate”- inner layer

  12. Blood Brain Barrier • BLOOD-BRAIN BARRIER • capillary walls in brain contain more densely packed cells (called astrocytes) and have a continuous basement membrane • This protects the brain by keeping toxins out and protecting brain from a direct rise in temperature (fever). • Some substances permeable through barrier: • Water - Carbon dioxide - Glucose • Insulin - Alcohol - Heroin - Nicotine • Some substances impermeable to the barrier: • Hydrogen ions - Proteins - Antibiotics • Other characteristics of blood brain barrier: • Trauma can destroy it and lead to brain injury • Keeps out many useful drugs; researchers are developing ways to attach drugs to molecules that can cross the barrier

  13. Spinal Cord • column of nerve tissue that starts in the medulla oblongata and runs down the vertebral column • consists of 31 segments; each associated with a pair of spinal nerves • contains a core of gray matter that roughly resembles a butterfly with its wings spread or a flattened H; surrounded by white matter • conveys sensory impulses from PNS to the brain and conducts motor impulses from brain to PNS

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