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The Nervous System
Functions: Control and Communication Center 1. Sensory Stimuli Changes 2. Integrative Processing Decision-making 3. Motor Reaction Effector organs 3
Nervous System: Main Goal What is the main goal?
Organization Central nervous system (CNS) Brain and spinal cord Integration & command center 2. Peripheral nervous system (PNS) Nerves Information delivery system
Neurons AKA nerve cells Structural units of nervous system Conduct electrical impulses
Cell body Dendrites Main receptive surface Axon Conducts impulses away from cell body
3 functional types Sensory PNS to CNS Interneurons In CNS only Motor CNS to PNS
Signal Transmission: The Synapse Junction between 2 neurons Neurotransmitters Excitatory transmitter Inhibitory transmitter One way conduction Transmitter can be exhausted.
Nerves Bundle of axons Structure similar to muscles 3 types Sensory Motor Mixed Nerve Pathways Route an impulse follows Reflex Arc
Reflex Arc
The Brain 100 billion neurons 3-3.5 lbs. 4 major regions Cerebral hemispheres Cerebellum Diencephalon Brain stem
Motor Sensory Association Cerebrum Cerebral Cortex Paired left & right hemispheres Corpus callosum Gyri, sulci, fissures Functions: Word formation Personality Sensory association Estimation Auditory processing Language memory Judgment Speech Vision Reasoning Verbalizing Memory storage Intelligence Voluntary responses Motor Sensory Association Corpus callosum video in picture
Cerebellum Coordination center Damage Smooth movements Maintain muscle tone Maintain equilibrium Damage
Diencephalon Thalamus Hypothalamus Limbic System Pineal Gland Sensory relay station Hypothalamus Homeostasis powerhouse Limbic System Emotional experience and expression Pineal Gland Sleep-Activity cycles Pituitary Gland “Master gland”
Brain Stem Regulates involuntary activities 3 regions Medulla oblongata Cardiac, respiratory, vasomotor centers Pons Breathing Midbrain Reflex sight and hearing Reticular formation Comas
The Meninges Cerebrospinal Fluid Tough membranes Dura mater Allows brain to float Homeostatic environment Tough membranes Dura mater Arachnoid mater Pia mater
Cranial Nerves 12 pairs Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglosseal Cranial Nerves
Spinal Cord Starts where nervous tissue leaves the cranial cavity 31 segments with paired nerves 2 major functions Conducting nerve impulses Center for spinal reflexes Cauda equina
Peripheral Nervous System Nerves and cells outside the CNS Information transmission 2 Functional Divisions 1. Sensory (afferent) division 2. Motor (efferent) division 2 Divisions 1. Somatic nervous system 2. Autonomic nervous system 1. Sympathetic 2. Parasympathetic