Unit 2-Part 4- Organization of Nervous System PDF

Unit 2-Part 4- Organization of the nervous system p. 218-222, 229-238, 304-308  The nervous system  Collects information about the environment (internal and external), analyzes it, and initiates the appropriate responseof the nervous system 3 Functions 1) Monitor sensory input...

Unit 2-Part 4- Organization of the nervous system p. 218-222, 229-238, 304-308  The nervous system  Collects information about the environment (internal and external), analyzes it, and initiates the appropriate responseof the nervous system 3 Functions 1) Monitor sensory input respond to stimuli (changes) occurring inside and outside the body Job performed by sensory neurons 2) Integration process sensory information and initiate responses Job performed by interneurons 3) Motor output send messages to muscles/glands to respond to original stimuli Job performed by motor neurons  Nervous System Integrati receptor effector ng centre Respons Stimulus e  Divisions of the Nervous System (Fig.7.1) Joints, Muscles etc. Vision, Hearing, etc. Internal environment Volunt ary involunt Somatic = voluntary, ary skeletal muscle Autonomic = involuntary, smooth muscle, cardiac muscle, glands Sensory = afferent The Central Nervous System  CNS facts 15% of resting CO 2% of BW 20% of oxygen consumed at rest 50% of glucose consumed at rest Glucose is main energy supply (Can not burn protein or fat for energy) Can use ketone bodies for energy 3 sources Protection for CNS 1. Bone Cranium Vertebral column 2. Connective tissue (also called ‘the meninges’) 3 layers of meninges (Duramater, Arachnoid mater, pia mater) Cover both the brain and spinal cord 3. Fluid Cerebrospinal fluid (CSF) Bathes the brain and spinal cord Can be found in subarachnoid space Provides nutrients for brain function CSF-homeostasis and the blood brain barrier  Blood Brain Barrier** Is a protective mechanism that helps maintain a stable environment for the brain. Formed by tight junctions between the endothelial cells of the capillaries in the brain. Many drugs can not pass the blood brain barrier, thus they may not have an effect on the CNS. Practical application** What is a concussion?  Cerebral Hemispheres** Form the superior part of the brain and make up 83% of its mass Contain ridges (gyri (ji-ri)) and shallow grooves (sulci (sul-ki)) Contain deep grooves called fissures Are separated by the longitudinal fissure Each cerebral hemisphere has 3 basic regions: -Cerebral cortex -Cerebral white matter -Basal nuclei  Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere Deep sulci divide the hemispheres into 5 lobes: – Frontal – Parietal – Temporal – Occipital – Insula  Cerebral Cortex The cortex – superficial gray matter; accounts for 40% of the mass of the brain It enables sensation, communication, memory, understanding, and voluntary movements Each hemisphere acts contralaterally (controls the opposite side of the body) Hemispheres are not equal in function  Functional Areas of the Cerebral Cortex The 3 types of functional areas are: 1) Motor areas – control voluntary movement 2) Sensory areas – conscious awareness of sensation 3) Association areas – integrate information Areas of note Homunculi Cortex: Sensory Areas of Note 1. Primary somatosensory cortex – Receives information from skin and skeletal muscles 2. Somatosensory association cortex – Receives sensory inputs (temperature, pressure, etc) 3. Visual and auditory areas – Visual: Receives visual info from the eye – Auditory: Sound stimulus 4. Olfactory, gustatory, and vestibular cortices – Olfactory: Sense different odours – Gustatory: taste – Vestibular: conscious awareness of balance (located in insula)  Cerebral white and gray matter Cerebral white matter is made up primarily of myelinated neurons – Fast comunication Gray matter is made up primarily of internereurons (nonmyelinated), and axon cell bodies. Gray vs. white matter Whit Gray e Matte Matte r 40% of 60% of CNS r CNS Inteneuro Myelinate ns d axons Synapses