CNS & PNS PDF

1 Cristian Dezdrobitu, DVM, MSc, PhD Assistant Professor “The right half of the brain controls the left half of the body. This means that only left handed people are in their right mind.” https://www.pinterest.com/pin/565483296946963803/ !!! ‘’Pathways of nerve impulses are crossed pathways — mea...

1 Cristian Dezdrobitu, DVM, MSc, PhD Assistant Professor “The right half of the brain controls the left half of the body. This means that only left handed people are in their right mind.” https://www.pinterest.com/pin/565483296946963803/ !!! ‘’Pathways of nerve impulses are crossed pathways — meaning that the Left side of the brain controls the RIGHT side of the body, and the Right side of the brain controls the LEFT side of the body’’ !!! 2 3 https://www.slideshare.net/wyllhy/the-nervous-system-slide-show 4 Role: • controls and coordinates all essential functions of the body • in the smooth functioning of the different parts of our body • without the nervous system we wouldn't be able to think, feel, move or survive • the most important function of the nervous system is to 5 integrate and respond to the environment ‘’The detection of environmental changes, their subsequent integration and interpretation, and finally, the production of a behavioral response are the function of the nervous system, incomparably the most complicated of the body systems.’’ DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 6 Function: SENSORY • sensory receptors used to monitor changes both inside and outside of the body • gathered informations : Sensory input 7 Function: INTEGRATIVE • process and interprets the sensory input and takes decisions about what should be done - INTEGRATION MOTOR • NS sends informations to the effectors (muscle, glands, internal organs) 8 DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 A simplified receptor: effector neural circuit. 1. Skin receptor; 2, afferent or sensory neuron; 3, synapses on interneuron; 4, interneuron; 5, efferent or motor neuron; 6, striated muscle (effector). 9 10 DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 11 Brain and spinal cord act like the integrating and command center of the nervous system. Role:  to interpret incoming sensory information and issue instructions based on past experience and current conditions 12 Outside the CNS Carries impulses from the sensory receptors to the CNS and from the CNS to effectors Cranial nerves: to and from the brain Spinal nerves: to and from the spinal cord 13 Divided functionally in:  afferent division (also termed the sensory component, conducts impulses toward the spinal cord and brain)  efferent division (or motor component of the peripheral nervous system conveys impulses away 14 from the brain and spinal cord)  Afferent and Efferent  subdivided into the SOMATIC and VISCERAL systems 15  Somatic system  is concerned with both sensory and motor functions that determine the relationship of the organism to the outside world  they include detection of stimuli  in the skin  in the tissues of the limbs and trunk 16  behavioral actions such as locomotion Somatic system  is sometimes referred to as the voluntary system, because there is a greater conscious awareness and greater voluntary control of somatic functions than of the visceral functions 17 Visceral system  concerned with sensory and motor functions that relate to the internal viscera. E.g: the regulation of the blood pressure and heart rate, the control of glandular activity and digestive processes  the motor component of the visceral peripheral nervous system is also referred to as18the autonomic nervous system Autonomic nervous system: Sympathetic Parasympathetic Most organs receive innervation from both components. The sympathetic and parasympathetic components are often described as having antagonistic actions on each organ, although “balancing” might better describe their cooperative role. Visceral efferent fibers of the sympathetic division leave the central nervous system via the spinal nerves in the thoracolumbar regions of the spinal cord; those of the parasympathetic division are found in a small group of cranial nerves (III, VII, IX, X) and in spinal nerves in the sacral region of the spinal cord. 19other Many visceral efferent fibers travel to their target organ by joining with nerves so that they obtain a very widespread peripheral distribution. Somatic Nervous System Regulates the voluntary movement of the body Regulates movements of the body via the skeletal muscles, along with sensory stimuli related to vision, smell, taste, pain, noise, touch, and temperature Made up of the afferent nerves (sensory nerves) and efferent nerves (motor nerves) that stimulate skeletal muscle movement Divisions include the spinal nerves and the cranial nerves Autonomic Nervous System Regulates the involuntary movement of the body Regulates bodily functions such as respiratory rate, heart rate, urination, digestion, sexual arousal, pupillary response Made up of a complex network of motor neurons, which control glands, cardiac muscles, and smooth muscles Divisions include the sympathetic and the parasympathetic nervous 20 system 21 https://www.slideshare.net/wyllhy/the-nervous-system-slide-show DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 Neurons (nerve cells) are the basic elements of the nervous system. 22 Thin branching extensions of the cell body that conduct nerve impulses toward the cell body Courtesy of Drs Ray Wilhite, Dan Hillmann and Joe Rowe https://www.slideshare.net/itutor/nervous-system-22589837 A single branch (in most neurons) which conducts nerve impulses away from the cell body. 23 CROSS SECTION OF SPINAL CORD 24 DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 Dorsal view of the spinal cord and the vertebral pedicles of the horse. The spinal cord is shorter than the vertebral canal (ascensus medullae spinalis). (B) Enlargement of the caudal part. 1, Atlas; 2, ilium; 3, sacrum; 4, cervical intumescence; 5, lumbar intumescence; 6, cauda equina. 25 NERVES Based on the direction of the nerve impulse, there are: Sensory (afferent) nerves Motor (efferent) Mixed nerves nerves = sensory + motor (somatic and/or autonomic) 26 Based on the site of emergence, there are:  Spinal nerves (emerge from the spinal cord)  Cranial nerves (emerge from the brain) NOTE! All spinal nerves are mixed nerves. Not all cranial nerves are mixed nerves. 27 CONSCIOUS PERCEPTION OF SENSORY INPUT AND INITIATION OF CONSCIOUS MOVEMENT DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 COORDINATION AND FINE TUNING OF MOVEMENT CEREBRUM CEREBELLUM BRAINSTEM (midbrain, pons and the medulla oblongata) RELAY CENTER/ FILTERS SENSORY28 INPUT, WHICH ALLOWS US TO CONCENTRATE 29 DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 CEREBRUM CEREBELLUM Enabling communication between hemispheres BRAINSTEM MEDIAN SECTION 30 CEREBRUM CEREBELLUM BRAINSTEM White matter Gray matter 31 CP T CRANIAL PG RC RC CC CORD CC T CN IV CAUDAL CP BRAINSTEM –dorsal view 32 CN III OT CRANIAL CN II OC CN II CAUDAL H OT P CN III BRAINSTEM –ventral view MO CORD CN VI 33 • Olfactory (I) • Optic (II) • Oculomotor (III) • Trochlear (IV) • Trigeminal (V) • Abducens (VI) • Facial (VII) • Vestibulocochlear (VIII) • Glossopharyngeal (IX) • Vagus (X) • Accessory (XI) • Hypoglossal (XII) 34 35 http://baronerocks.com/images/Anatomy/cranialnerves.jpg 36 https://mindblogger.files.wordpress.com/2010/12/cranialnervescopy.gif?resize=600%2C400 http://www.scientificanimations.com/wp-content/uploads/2018/05/Cranialnerves.jpg 37 CRANIAL NERVES MUSIC VIDEO  https://www.youtube.com/watch?v=sAFaTaavmO8 38 Palbebral reflex Menace response http://infovets.com/books/Canine/B/B548.htm Reflex Does not require cerebral input Does not imply consciousness This all happens BEFORE you are conscious of it! Response requires cortical awareness! 39 Basic neural pathway (reflex arc) 5 Basic Elements of Reflex Arc: PNS  Receptor  Sensory neuron  Integration center  Motor neuron  Effector CNS Afferent Efferent 40 Types of Reflexes based on the NS divisions:  Somatic Reflexes – include all reflexes that stimulate the skeletal muscle (e.g. When you quickly pulled your hand away from a hot object, a somatic reflex is working).  Autonomic Reflexes – regulate the activity of smooth muscles, the heart, and glands (i.e. Secretion of saliva and changes in the size of the eye pupils); autonomic reflexes - regulate such body functions as digestion, elimination, blood pressure and sweating. 41 42 Nerves Based on the direction of the nerve impulse, there are: • Sensory ? (afferent) nerves • Motor ? (efferent) nerves • Mixed ? nerves = sensory ? + motor (somatic and/or ? autonomic) ? Spinal Nerves are mixed ? nerves All ? nerves Not? all Cranial Nerves are mixed 43 Nerves Based on the direction of the nerve impulse, there are: • Sensory (afferent) nerves • Motor (efferent) nerves • Mixed nerves = sensory + motor (somatic and/or autonomic) All Spinal Nerves are mixed nerves Not all Cranial Nerves are mixed nerves 44 Basic neural pathway (reflex arc) PNS ? ? ? CNS Input Output ? 45 Basic neural pathway (reflex arc) PNS CNS Input Output 46 The part of the brain indicated by the arrow is the: A. Right hemisphere and Left hemisphere B. Cerebellum C. Right hemisphere D. Corpus callosum E. Left hemisphere 47 The part of the brain indicated by the arrow is the: A. Right hemisphere and Left hemisphere B. Cerebellum C. Right hemisphere D. Corpus callosum E. Left hemisphere 48 OBJECTIVES  Describe the role of the NS  Describe how the CNS and PNS work  Describe the functions of the NS (3 functions described/slides 6 and 7)  Describe the subdivisions of both CNS and PNS  Describe the role of both CNS and PNS  Understand how the PNS is divided functionally  Understand the difference between SOMATIC and AUTONOMIC  Define the SYMPATHETIC and PARASYMPATHETIC  Define the types of nerves based on the direction of the nerve impulse and based on the site of emergence  Describe the main roles of the Cerebrum, Cerebellum, Brainstem and Corpus Calossum  Have knowledge of the Cranial Nerves and their type (sensory/motor/mixed) – Not responsible for their distribution and role 49  The difference between a reflex and a response  Comprehend the basic elements of the Reflex Arc https://www.bing.com/images/search 50