The Nervous System

1. Ch 10 The Nervous System

2. Major Structures Combining Form • Brain cerebr/o, encephal/o • Spinal Cord myel/o • Nerves neur/i, neur/o • Sensory Organs and will talk about eachReceptors individually • Eyes, Ears, Nose Ch 11 eyes and ears, 7 • Skin, Tongue Nose, 12 skin, 8 tongue Overview

3. Word Parts • Caus/o • Concuss/o • Contus/o • Encephal/o • -esthesia • Esthet/o • -graphy • Klept/o • -mania • Mening/o • Myel/o • Neur/i, neur/o • -phobia • Psych/o • -tropic

4. Describe the functions and structures of the nervous system • Identify the major divisions of the nervous system and describe the structures of each by location and function • Identify the medical specialist who treat disorders of the nervous system • Recognize, define, spell and pronounce terms related to the pathology and the diagnostic and treatment procedures of the nervous system • Recognize, define, spell and pronounce terms related to the pathology and the diagnostic and treatment procedures of mental health disorders Objectives

5. The nervous system, with the brain as its center, coordinates and controls all bodily activities When the brain ceases to function, the body dies Functions of the Nervous System

6. The major structures of the nervous system are the nerves, brain, spinal cord, and sensory organs (which are discussed in other chapters) Structures of the Nervous System

7. 2 major divisions: • The Central Nervous System (CNS) – the brain and spinal cord • It’s function is to receive and process information, and to regulate all body activity • The Peripheral Nervous System (PNS) – includes the 12 pairs of cranial nerves extending from the brain and the 31 pairs of peripheral spinal nerves extending outward from the spinal cord • It’s function is to transmit nerve signals to and from the CNS Divisions of the Nervous System

9. Nerve – one or more bundle of neurons that connect the brain and the spinal cord with other parts of the body Ascending Nerve Tract – carry nerve impulses toward the brain Descending Nerve Tract – carry nerve impulses away from the brain Ganglion – a nerve center made up of a cluster of nerve cell bodies outside the CNS The Nerves

10. Innervation – the supply of nerves to a specific body part • Plexus – a network of intersecting spinal nerves • Receptors – sites in the sensory organs that receive external stimulation • The stimulus is sent through sensory neurons to the brain for interpretation • Stimulus – anything that excites (activates) a nerve and causes an impulse • Impulse – a wave of excitation transmitted through nerve fibers and neurons

13. Reflex – an automatic, involuntary response to some change, either inside or outside the body • Ex: heart rate, breathing rate, and blood pressure • Coughing and sneezing • Response to a painful stimuli • Deep tendon reflexes (Ch 4) The Reflexes

14. Neurons – the basic cells of the nervous system that allows different parts of the body to communicate with each other • The body has billions of neurons carrying signals through the body via an electrochemical process • This process creates patterns known as brain waves • Known as A-C-E and S-A-M The Neurons

15. A – afferent neurons (afferent means toward) • C – connecting neurons • E – efferent neurons (efferent means away) • S – sensory neurons • A – associative neurons (link sensory to motor) • M – motor neurons

16. Neuron Parts • Dendrites – root-like processes that receive impulses and conduct them to the cell body • Axon – a process that extends away from the cell body and conducts impulses away from the nerve cell • Can be more than 3 ft long • Most are covered with a myelin sheath (a fatty white tissue covering) • Terminal End Fibers – the branching fibers at the end of the axon; lead nerve impulse from the axon to the synapse • Synapse – the space between two neurons, or neuron and receptor organ.

17. Sensory Motor

20. Neurotransmitters – chemical substances that make it possible for messages to cross from the synapse to the target receptor Between 200 and 300 known and each has a specialized fxn Examples (next slide) Neurotransmitters

21. Examples • Acetylcholine – released in the spinal cord and at neuromuscular junction; influences m axn • Dopamine – released within the brain; believed to be involved in mood and thought disorders and in abnormal movement disorders such as Parkinson’s disease • Endorphins – naturally occurring substances that are produced by the brain to help relieve p! • Norepinepherine – released at synaptic nerve endings, responds to hypotension and physical stress • Serotonin – released in the brain, has roles in sleep, hunger and pleasure recognition; sometimes linked in mood disorders

25. Glial Cells - provide support and protection for neurons • 4 main functions: • Surround neurons and hold them in place • Supply nutrients and oxygen to neurons • Insulate one neuron from another • Destroy and remove dead neurons Glial Cells

27. Myelin Sheath – a protective covering made up of glial cells • A white sheath that forms the white matter of the brain and covers some parts of the spinal cord and the axon of most peripheral nerves • Myelinated areas are white and create white matter • Portions of the nerves, brain and spinal cord that are unmyelinated are grey, giving us grey matter The Myelin Sheath

28. Made up of the brain and spinal cord Protected by the cranium and vertebrae, meninges and cerebrospinal fluid The Central Nervous System (CNS)

29. Meninges – the system of membranes that enclose the brain and spinal cord • Consists of 3 layers of connective tissue (will get each individually on the next slides) • Dura mater • The arachnoid membrane • Pia mater The Meninges

31. The Dura Mater – is the thick, tough, outermost membrane • The inner surface of the skull is lined with dura mater • The inner surface of the spinal column is known as the epidural space • Dura means hard and mater means mother

33. The Arachnoid Membrane – resembles a spider web; the 2nd layer of the meninges located between the dura mater and pia mater • Loosely attached to the other meninges to allow space for fluid flow

35. The Pia Mater – the 3rd layer of the meninges, located nearest the brain and spinal cord • Contains delicate connective tissue that contains a rich blood supply

37. Cerebrospinal Fluid – (CSF) spinal fluid; produced by special capillaries within the four ventricles located in the middle region of the cerebrum • Clear, colorless, and watery • Flows throughout the brain and spinal cord • Cools and cushions from shock or injury • Nourishes the brain and spinal cord by transporting nutrients and chemical messengers Cerebrospinal Fluid

39. The Parts of the Brain

40. The largest and upper-most portion of the brain • Responsible for thought, judgment, memory and emotion, as well as for controlling and integrating motor and sensory functions • The cerebral cortexis made up of grey matter and is the outer layer of the cerebrum and is arranged in deep folds known as fissures The Cerebrum

43. The Cerebral Hemispheres • Connected together via the corpus callosum • The left cerebral hemispherecontrols the majority of functions on the right side of the body • The right cerebral hemispherecontrols most functions on the left side of the body

45. The Cerebral Lobes • Named for the bones that cover them • Frontal Lobe– skilled motor functions, memory, and behavior • Parietal Lobe– receives and interprets nerve impulses from sensory receptors in the tongue, skin and muscles • Occipital Lobe– controls eyesight • Temporal Lobe– controls the senses of hearing and smell, the ability to create, store and access new information

47. Located below the cerebrum, produces sensations by relaying impulses to and from the cerebrum and the sensory organs of the body • Suppresses some stimuli and magnifies others The Thalamus

49. Located below the thalamus (hypo- = below) • 7 major regulatory functions… Regulates… • …and integrates the autonomic nervous system (ANS), including controlling heart rate, BP, respiratory rate, and digestive tract activity • …emotional response, including fear and pleasure • …body temp • …food intake by controlling hunger sensation • …H2O balance by controlling thirst sensations • …sleep-wakefulness cycles • …the pituitary gland and endocrine system activity The Hypothalamus