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Nervous system

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Nervous system

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Nervous system

  1. 1. Nervous system Case 1: Biology. G5 PBL.
  2. 2. Objectives ● How many Types of communications are there ? ● Define the nervous system ● Describe briefly about brain and spinal cord ● Explain the somatic and autonomic nervous system ● Explain how the nerve impulses are initiated and transmitted ● What is a synapse ? ● How does the nervous system connects with the body ? ● What are the Malfunction of nervous system ● What is Multiple sclerosis
  3. 3. Types of communications Humans have two types of communication systems.These are : 1.Endocrine system. 2. Nervous system.
  4. 4. Endocrine system. ● collection of glands that produce hormones. ● regulate metabolism, growth, tissue function, reproduction, sleep etc. ● made up of the pituitary gland, thyroid gland, parathyroid glands etc. ● each type of hormone is targeted toward certain organs and tissues, ● A gland selects and removes materials from the blood, processes them and secretes the finished chemical product for use somewhere in the body
  5. 5. What is the nervous system? The nervous system : It’s a highway along which your brain sends and receives information about what is happening in the body and around it. EX: Breathing, producing digestive enzymes, memory and intelligence. -This highway is made up of nerve cells, or neurons which join together to make nerves. ❖ A nerve is a fiber that sends impulses through the body. ❖ Theses fibers are covered by fatty substance called (Myelin). ❖ Myelin helps the messages go fast through the neurons..
  6. 6. ➢ The nervous system is the master controlling and communicating system of the body. ○ Every thought, action, and emotion reflects its activity. Its signaling device, or means of communicating with body cells, is electrical impulses, which are rapid and specific and cause almost immediate responses.
  7. 7. ➢ To carry out its normal role, the nervous system has three overlapping functions: 1. It uses its millions of sensory receptors to monitor changes occurring both inside and outside the body. These changes are called stimuli, and the gathered information is called sensory input. 2. It processes and interprets the sensory input and decides what should be done at each moment—a process called integration. 3. It then effects, or causes, a response by activating muscles or glands (effectors) via motor output.
  8. 8. ➢ The human nervous system consists of: A. The central nervous System (CNS) B. The Peripheral Nervous System (PNS).
  9. 9. A. Central Nervous System Made up: 1 - Brain 2 - Spinal cord CNS: It is the main information processing center -which serves as the main control center for all body activities.
  10. 10. The Brain The brain is an amazing three-pound organ that controls all functions of the body, interprets information from the outside world, and embodies the essence of the mind and soul. Intelligence, creativity, emotion, and memory are a few of the many things governed by the brain. Protected within the skull, the brain is composed of the cerebrum, cerebellum, and brainstem. The brainstem acts as a relay center connecting the cerebrum and cerebellum to the spinal cord.
  11. 11. Anatomy of the Brain The brain is composed of the cerebrum, cerebellum, and brainstem. ● The cerebrum is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement. ● The cerebellum is located under the cerebrum. Its function is to coordinate muscle movements, maintain posture, and balance. ● The brainstem includes the midbrain, pons, and medulla. It acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Ten of the twelve cranial nerves originate in the brainstem.
  12. 12. Anatomy of the Brain The surface of the cerebrum has a folded appearance called the cortex. The cortex contains about 70% of the 100 billion nerve cells. The nerve cell bodies color the cortex grey-brown giving it its name – gray matter (Fig). Beneath the cortex are long connecting fibers between neurons, called axons, which make up the white matter. The folding of the cortex increases the brain’s surface area allowing more neurons to fit inside the skull and enabling higher functions. Each fold is called a gyrus, and each groove between folds is called a sulcus. There are names for the folds and grooves that help define specific brain regions. Figure: The surface of the cerebrum is called the cortex. The cortex contains neurons (grey matter), which are interconnected to other brain areas by axons (white matter). The cortex has a folded appearance. A fold is called a gyrus and the groove between is a sulcus.
  13. 13. PARTS OF THE BRAIN 1. Cerebrum(the largest) it is divided into two sides called hemispheres,it controls the voluntary activities in the body. 2. Cortex:the outer layer which contain cell with fibers that send messages to other brain area.The folds or wiggly visible lines makes us more intelligent than other animals the have smooth cortex.
  14. 14. The cortex is divided into four regions: 1.Frontal lobe –for personality and emotions like higher thinking skills. 2.Temporal lobe-process hearing and other senses,it also helps reading. 3.Parietal lobe-senses,attention and language 4.Occipital lobe-helps the eye see including recognition of shapes and colors.
  15. 15. ● Thalamus-relays sensory and motor information to the cortex,consciousness and alertness. ● Cerebellum-motion control,coordination and special navigation. ● Brain stem-connects the brain to the spinal cord and nerve part way. The brain stem include the: 1. The ponds_controls breathing. 2. Medulla oblongata_regulates heart beat and some other body reflexes like vomiting,coughing,sneezing and swallowing.
  16. 16. ● The limbic system which is found under the cortex,processes emotion and drives(to satisfy your need).it contains the brain reward circuit which releases dopamine. Parts of the limbic system: 1.Amygdala_processes emotions 2.Hippocampus_memory indexer,it send memory for storage and retrieval ● Hypothalamus_secrets hormones that controls different cell and organs ● Pituitary gland_controls body growth,temperature,pregnancy and childbirth ● Pineal gland_controls sleep and circadian rhythms
  17. 17. Brain cells ● The brain is made up of two types of cells: nerve cells (The brain is made up of two types of cells: nerve cells (neurons) and glia cells. Nerve cells ● There are many sizes and shapes of neurons, but all consist of a cell body, dendrites and an axon. ● Neurons transmit their energy, or “talk”, to each other across a tiny gap called a synapse. A neuron has many arms called dendrites, which act like antennae picking up messages from other nerve cells. These messages are passed to the cell body, which determines if the message should be passed along.
  18. 18. Glia cells Glia (Greek word meaning glue) are the cells of the brain that provide neurons with nourishment, protection, and structural support. There are about 10 to 50 times more glia than nerve cells and are the most common type of cells involved in brain tumors. ● Astroglia or astrocytes transport nutrients to neurons, hold neurons in place, digest parts of dead neurons, and regulate the blood brain barrier. ● Oligodendroglia cells provide insulation (myelin) to neurons. ● Ependymal cells line the ventricles and secrete cerebrospinal fluid (CSF). ● Microglia digest dead neurons and pathogens.
  19. 19. THE SPINAL CORD Spinal cord, major nerve tract of vertebrates, extending from the base of the brain through the canal of the spinal column. It is composed of nerve fibres that mediate reflex actions and that transmit impulses to and from the brain.
  20. 20. THE SPINAL CORD ● The spinal cord is approximately 17 inches (42 cm) long. ● The spinal cord extends from the foramen magnum of the skull to the first or second lumbar vertebra. ● In humans, 31 pairs of spinal nerves arise from the cord and exit from the vertebral column . ● the spinal cord is cushioned and protected by meninges.
  21. 21. Anatomy of the spinal cord In humans, 31 pairs of spinal nerves arise from the cord and exit from the vertebral column . ◄ The cervical region ◄ The thoracic region ◄ The lumbar region ◄ The sacral region:
  22. 22. The grey matter in the spinal cord:
  23. 23. White Matter of the Spinal Cord ● It is composed of myelinated fiber tracts . ● There are two types of tracts:
  24. 24. The white matter regions: •The white matter on each side of the cord is divided into three regions which Each of them contains a number of fiber tracts made up of axons with the same destination and function:
  25. 25. The spinal cord functions : The spinal cord works a bit like a telephone switchboard operator, helping the brain communicate with different parts of the body, and vice versa. Its three major roles are: ● To relay messages from the brain to different parts of the body (usually a muscle) in order to perform an action. ● To pass along messages from sensory receptors (found all over the body) to the brain. ● To coordinate reflexes (quick responses to outside stimuli) that don't go through the brain and are managed by the spinal cord alone
  26. 26. A. B. Peripheral nervous system (PNS) PNS is composed of nerves derived from the brain and spinal cord: - 12 pairs of cranial nerves. - 31 pairs of spinal nerves. These nerves serve as linkage between the CNS and the body.
  27. 27. Peripheral nervous system ● consists mainly of the nerves that extend from the brain and spinal cord. ● Spinal nerves carry impulses to and from the spinal cord. ● Cranial (kra′ne-al) nerves carry impulses to and from the brain. ● These nerves serve as communication lines .They link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles. ★ PNS = Cranial nerves* and spinal nerves, nerve plexuses and ganglia. ~10% (10 Bil) of all neurons in body are in PNS. *Cranial nerves are the nerves that emerge directly from the brain.
  28. 28. ➢ Maintenance of a conscious state and an ability to respond to changes in our environment involves the coordinated activity of the central and peripheral nervous systems.
  29. 29. ➢ PNS can be subdivided into sensory (afferent) nerves and motor (efferent) nerves. ● Sensory nerves send nerve impulse from the body to CNS to effector organs. ● The motor, or efferent (ef′er-rent), division carries impulses from the CNS to effector organs, the muscles and glands. These impulses activate efferent motor nerves that carry information to the target cells in the peripheral tissues.
  30. 30. Motor nerves are divided into: A. The somatic nervous system (SNS) which regulates the voluntary contraction of the skeletal muscles. B. The autonomic nervous system (ANS) which regulates the involuntary control of smooth, cardiac muscles and glands. It is also responsible for our reflexes, that do not require brain input.
  31. 31. SOMATIC NERVOUS SYSTEM ● The somatic motor nerves that control movement and posture. ● In the somatic nervous system a single axon leaves the CNS and innervates the effector skeletal muscle cell which becomes active in response to stimulation and is termed the effector cell. ● The somatic (so-mat′ik) nervous system allows us to consciously, or voluntarily, control our skeletal muscles. Hence, we often refer to this subdivision as the voluntary nervous system.
  32. 32. AUTONOMIC NERVOUS SYSTEM ● Autonomic N.S is the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes. ● Autonomic functions include control of respiration, cardiac regulation (the cardiac control center), vasomotor activity (the vasomotor center), and certain reflex actions such as coughing, sneezing, swallowing and vomiting.
  33. 33. ➢ The autonomic nervous system (ANS) is finally divided into two branches : A. The sympathetic nervous system. B. The parasympathetic nervous system.
  34. 34. 1) Sympathetic ● It is constantly active at a basic level to maintain homeostasis. ● Its primary process is to stimulate the body's fight-or-flight response. ● Sympathetic nerves arise from near the middle of the spinal cord in the intermediolateral nucleus of the lateral grey column, beginning at the first thoracic vertebra and are thought to extend to the second or third lumbar vertebra. ● Control the body's response during perceived threat. ● It makes the body more alert. ● Very short neurons, but very fast system.
  35. 35. Structure: ➢ There are two kinds of neurons involved in the transmission of any signal through the sympathetic system: ● pre-ganglionic and post-ganglionic. ● The shorter preganglionic neurons originate from the thoracolumbar region of the spinal cord specifically at T1 to L2~L3.
  36. 36. SYMPATHETIC N.S FUNCTION ● Fibers from the SNS innervate tissues in almost every organ system, providing at least some regulatory function to things as diverse as pupil diameter, and urinary system output and function. ● It is perhaps best known for mediating the neuronal and hormonal stress response commonly known as the fight-or-flight response. ● SNS is responsible for priming the body for action, particularly in situations threatening survival.
  37. 37. 2) Parasympathetic ● Generally inhibits the effector organ (except in digestive tract). ● All pre and postganglionic fibers product Ach and are cholinergic. ● Location of ganglia (terminal ganglia) is in or near effector organ. ● Preganglionic fibers arise from the CNS (brainstem) and sacral region of spinal cord (S2 – S4). ● Long preganglionic fibers. ● Short postganglionic fibers. ● Postganglionic fibers are limited to the head, viscera of chest, abdomen and pelvis.
  38. 38. STRUCTURE Formed by neurons in cranial nerves: ● III (oculomotor) ● VII (facial) ● IX (glossopharyngeal) ● X (vagus) ● And fibers in some sacral (S2-S4) spinal nerves ● No chain ganglia, fibers not interconnected ● Ganglia are usually near organs they innervate
  39. 39. cranial nerve: each of twelve pairs of nerves which arise directly from the brain, not from the spinal cord, and pass through separate apertures in the skull.
  40. 40. PARASYMPATHETIC N.S FUNCTION ● Most active in non-stressful, non-emergency situations. ● This division, sometimes called the “resting-and-digesting” system, is chiefly concerned with promoting normal digestion, with elimination of feces and urine, and with conserving body energy, particularly by decreasing. ● Tends to have a calming effect on body: reduced energy expenditure and normal body maintenance. ● Organs are individually activated (no mass activation) - a short lived, localized effects.
  41. 41. PARASYMPATHETIC FUNCTION ● decrease heart rate and breathing. ● increase digestion, increase mucous flow. ● Signals originate in: * Oculomotor nerve (Cranial Nerve 3) ->constricts the pupil. * Pelvic nerve (Sacral region of spinal cord) ->empty bladder/rectum, erection. ● We might also consider the parasympathetic division as the “housekeeping” system of the body.
  42. 42. Anatomy of ANS
  43. 43. Sympathetic Vs Parasympathetic Nervous System
  44. 44. SUMMARY Parasympathetic nervous system Sympathetic nervous system Introduction The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system (ANS). Its general function is to control homeostasis and the body's rest-and-digest response. The sympathetic nervous system (SNS) is one of two main divisions of the autonomic nervous system (ANS). Its general action is to mobilize the body's fight-or-flight response. Function Control the body's response while at rest. Control the body's response during perceived threat. Originates in Sacral region of spinal cord, medulla, cranial nerves 3, 7, 9, and 10 Thoracic and lumbar regions of spinal cord Activates response of Rest and digest Fight-or-flight Neuron Pathways Longer pathways, slower system Very short neurons, faster system General Body Response Counterbalance; restores body to state of calm. Body speeds up, tenses up, becomes more alert. Functions not critical to survival shut down.
  45. 45. Resting Potential •Outside of the cell is positive because positively charged sodium ions Na+ gather around the outside of cell membrane. •At rest, the neuron’s plasma membrane is permeable to K, but not to Na.
  46. 46. •Thus positively charged of K+ contribute to the positive charge by diffusing out of the cell to join Na+ •The inside of the cell become negative in relation to the exterior of the cell because of the presence of large, negatively charged protein and other molecule that remain inside the cell because of their size. •Potential energy of neuron cell can be measured by voltage -70mV.
  47. 47. Action Potential •The process of Conduction is termed an action potential
  48. 48. Depolarization •Adding positively charged ion causes the inside of the axon to become positive compared to the outside.
  49. 49. Repolarization •As K + exit the cell, the inside of the cell becomes negative again because of the presence of large, negatively charged ion trapped inside the cell.
  50. 50. How can the nervous system be damaged? Most neurons in the central nervous system cannot repair or renew themselves, unlike other cells in the body. So, if some die through illness or damage, the nervous system can permanently lose some of its abilities.
  51. 51. How can the nervous system be damaged? The symptoms of disorders of the nervous system depend on which part is attacked - Alzheimer's disease destroys cells in the memory area of the brain. For example, There are currently no cures for these disorders, but promising research includes new drug treatments, vaccines and nerve cell transplants
  52. 52. How does the nervous system connects with the body ? ● The nervous system controls the functions of every part of body. ● It also tells the body how to respond when it comes in contact with some stimulus.
  53. 53. ● The peripheral nervous system is controlled by the central nervous system and connected to every muscle in our bodies.
  54. 54. ● The entire nervous system is made up of billions of pyramidical cells called neurons. ● Short thread-like branches called dendrites connect the neurons to each other.
  55. 55. ● Neurons send message throughout the body in the form of short bursts of electricity. ● The brain and spinal cord receive impulses from different organs and senses and tell them how to react.
  56. 56. ● Impulses travel at the speed of several hundred miles per hour. ● So, an impulse can go from your head to foot in just a very small fraction of a second.
  57. 57. Synapse. ● The junction between the axon of one neuron and the dendrite of another neuron is called synapse.
  58. 58. Kinds of Neurotransmitters and its classes.
  59. 59. Nervous system diseases ● Multiple Sclerosis. ● Cerebrovascular accident (CVA). ● Transient Ischemic Attack (TIA). ● Epilepsy. ● Aphasia.
  60. 60. Multiple Sclerosis (MS) •Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord (central nervous system). •In MS, the immune system attacks the protective sheath (myelin) that covers nerve fibers and causes communication problems between your brain and the rest of your body. Eventually, the disease can cause the nerves themselves to deteriorate or become permanently damaged.
  61. 61. •Signs and symptoms of MS vary widely and depend on the amount of nerve damage and which nerves are affected. Some people with severe MS may lose the ability to walk independently or at all, while others may experience long periods of remission without any new symptoms. •There's no cure for multiple sclerosis. However, treatments can help speed recovery from attacks, modify the course of the disease and manage symptoms.
  62. 62. In multiple sclerosis, the protective coating on nerve fibers (myelin) is damaged and may eventually be destroyed. Depending on where the nerve damage occurs, MS can affect vision, sensation, coordination, movement, and bladder and bowel control.
  63. 63. References ★ http://www.cyh.com/HealthTopics/HealthTopicDetailsKids.aspx?p=335&np= 152&id=2612 ★ https://www.youtube.com/watch?v=-s8yEhRZgvw ★ https://www.mayfieldclinic.com/PE-AnatBrain.htm ★ https://global.britannica.com/science/spinal-cord ★ faculty.washington.edu ★ Livescience.com ★ http://study.com/academy/lesson/anatomy-of-the-spinal-cord-function-lesso n-quiz.html ★ ★
  64. 64. References ★ Essentials of human anatomy & physiology , Elaine N. Marieb , Eleventh Edition , chapter 6 & 7. ★ Human Biology 14th edition.
  65. 65. THANK YOU

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