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Nervous System. Identify Principle Parts of the Brain. Objectives. Identify the principle parts of the nervous system Describe the cells that make up the nervous system Describe what starts and stops a nerve impulse (action potential) The role of neurotransmitters
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Nervous System Identify Principle Parts of the Brain
Objectives • Identify the principle parts of the nervous system • Describe the cells that make up the nervous system • Describe what starts and stops a nerve impulse (action potential) • The role of neurotransmitters • Compare the functions of the CNS & PNS • Identify the principle parts of the brain
The Brain – command central • Brain receives incoming info from spinal cord and nerves integrates/processes info and generates responses • 3 anatomical & functional divisions • Hindbrain – basic autonomic and vital tasks • Midbrain – muscle groups, responses to sights & sounds • Forebrain – receives & integrates sensory input & determines our more complex behavior
Hindbrain – vital tasks • Connected to spinal column • Oldest, most primitive brain division • Most similar among animals • Structures: • Medulla oblongata • Cerebellum • Pons
1) Medulla oblongata • Controls autonomic functions • Heart rate • Blood pressure • Respiratory information – O2 & CO2 levels • Cough reflex • Swallowing • Sneezing • Vomiting • This is where the neurons cross over to the other side and the left brain controls the right side of the body and vice versa
2) Cerebellum • Located just behind the medulla oblongata and coordinates basic (unconscious) movements • Ensures that antagonistic muscles don’t contract at the same time • Stores sequenced information – tying shoes • Receives sensory input from joint & muscle receptors, balance & position receptors in ear and visual receptors • Excess alcohol disrupts these functions
3) Pons • Located just above and partly surrounding the medulla oblongata • Contains groups of axons that extend from the cerebellum to the rest of the CNS & • Coordinates the flow of information between the cerebellum and the higher brain centers • Aids the medulla oblongata in regulating respiration
Midbrain – vision & hearing • Visual & auditory sensory input passes through the midbrain before being relayed to the higher brain centers • Coordinates movements of the head related to vision and hearing (e.g. turning towards sound or flashing lights) • Controls eye movement and pupil size • Monitors unconscious movement of skeletal muscles (smooth moves) • Reticular formation located here-neuron bundle aids in posture, balance & muscle tone, level of wakefulness
Forebrain – complex behavior • Emotions • Conscious thought • Parts: • Hypothalmus • Thalmus • Limbic system • Cerebrum • Glands – 2 – pineal, pituitary
1) Hypothalmus • Located @ base of forebrain just above midbrain • Coordinates some autonomic fxns, pituitary gland, water & solute balance, T control, carbohydrate metabolism, breast milk production • Monitors sensory signals: sight, smell, taste, noise, body T • Hunger center • Thirst center
2) Thalmus – receiving, processing, transferring info • Together w/hypothalmus maintains homeostasis & processes information • Accepts sensory signals & channels them to cerebrum for interpretation (e.g. thalmus may have a consciousness of pain but does not know the location of the pain – the cerebrum interprets the signal and we know where it hurts)
3) Limbic System – emotions & memory • A group of neural pathways that connects parts of the thalmus & hypolthalmus & inner portions of the cerebrum • “border” – to describe structures that bordered the basal regions of the cerebrum – but has come to describe all neuronal structures that control emotional behavior and motivational drives • Limbic activities are monitored by hypothalmus and modified by cerebrum (social norms)
Cerebrum – human functioning • Most developed brain region • Language • Decision making • Conscious thought • Left and right cerebral hemispheres are connected in the middle by the corpus callosum = enables 2 hemispheres to share sensory-motor info
Cerebral Cortex • Consists of an outer layer of mostly gray matter (unmylenated CNS neurons, neuroglial cells) • Inner portion consists of white matter containing mylenated nerve axons connecting the lower brain area to the cerebral cortex
Cerebral cortex structure • This structure - inner section of ascending and descending axons and an outer layer of cells – makes it ideally suited to • direct incoming info to the proper brain region for processing • Integrate and process info • Route outgoing motor activity to appropriate areas of the body