Nervous system central nervous system peripheral nervous system
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The document discusses the nervous system, including its main divisions and components. It begins by explaining that the nervous system controls all body activities and is divided into the central nervous system (CNS) and peripheral nervous system (PNS). The CNS includes the brain and spinal cord, while the PNS includes cranial and spinal nerves. The brain is made up of several parts, including the cerebral hemispheres, cerebellum, and brain stem. The brain stem contains the midbrain, pons, and medulla oblongata. The document also describes the meninges, ventricles, and lobes of the brain. It then discusses the spinal cord, peripheral nervous system, and autonomic nervous system.
Nervous system central nervous system peripheral nervous system
- 2. GROUP MEMBERS HABIB UR REHMAN SHEIKH WAQAS NAWAZ NOUMAN RIAZ KHURRAM SHAHZAD KHALEEQ UR REHMAN HASSAN ALI ALI HASSAN UL ISLAM
- 4. Nervous system DIVISIONS OF NERVOUS SYSTEM Nervous system controls all the activities of the body. It is quicker than other control system in the body, namely endocrine system. Primarily, nervous system is divided into two parts: 1. Central nervous system 2. Peripheral nervous system.
- 6. CENTRAL NERVOUS SYSTEM Central nervous system (CNS) includes brain and spinal cord. It is formed by neurons and supporting cells called neuroglia. Structures of brain and spinal cord are arranged in two layers, namely gray matter and white matter. Gray matter is formed by nerve cell bodies and the proximal parts of nerve fibers, arising from nerve cell body. White matter is formed by remaining parts of nerve fibers.
- 7. In brain, white matter is placed in the inner part and gray matter is placed in the outer part. In spinal cord, white matter is in the outer part and gray matter is in the inner part.
- 9. Brain is situated in the skull. It is continued as spinal cord in the vertebral canal through the foramen magnum of the skull bone. Brain and spinal cord are surrounded by three layers of meninges called the outer dura mater, middle arachnoid mater and inner pia mater.
- 10. The space between arachnoid mater and pia mater is known as subarachnoid space. This space is filled with a fluid called cerebrospinal fluid. Brain and spinal cord are actually suspended in the cerebrospinal fluid. Important parts of brain and segments of spinal cord are shown in fig above.
- 11. Parts of Brain
- 12. BRAIN The human brain is the center of the human nervous system and is a highly complex organ. • Enclosed in the cranium. • It weighs about 3 pounds (1.5 kg) Major Parts: 1. Cerebral hemisphere 2. Cerebellum 3. Diencephalon 4. Brain Stem
- 13. CEREBRAL HEMISPHERE The paired cerebral hemisphere collectively called Cerebrum, are the most superior part of the brain and are larger than other parts of brain. The entire surface of cerebral hemispheres exhibits elevated ridges of tissue called gyri separaed by shallow grooves called sulci. There are few deeper grooves called fissures, which separates large regions of brain. The cerebral hemisphere are separated by a single deep fissure, the longitudinal fissure, Other fissures or sulci divide each cerebral hemisphere into a number of Lobes, named after cranial bones that lie over them.
- 15. Each cerebral hemisphere has 3 basic regions: a superficial cortex of gray matter An internal white matter The Basal nuclei (islands of grey matter which present deep within the white matter)
- 16. Each cerebral hemisphere has 3 basic regions. a superficial cortex of gray matter An internal white matter and the Basal nuclei (islands of grey matter) which present deep within the white matter) Involve in Speech, memory, logical and emotional response Consists of fibers carrying impulses to and from or within cortex Help to regulate voluntary motor activites
- 17. CEREBRAL LOBES The cerebral hemisphere are separated by a single deep fissure, the longitudinal fissure, Other fissures or sulci divides ; each cerebral hemisphere into a number of Lobes, named after cranial bones that lie over them.
- 18. CEREBRAL LOBES The cerebral hemisphere are separated by a single deep fissure, the longitudinal fissure, Other fissures or sulci divide. each cerebral hemisphere into a number of Lobes, named after cranial bones that lie over them.
- 19. LOCATION CHARACTERISTIC FRONTAL LOBE The frontal lobe is found in the area around your forehead. It is concerned with emotions, reasoning, planning, movement, and parts of speech. It is also involved in purposeful acts such as creativity, judgment, problem solving, and planning. PARIETAL LOBE The parietal lobes are found behind the frontal lobes, above the temporal lobes, and at the top back of the brain. They are connected with the processing of nerve impulses related to the senses, such as touch, pain, taste, pressure, and temperature. They also have language functions
- 20. LOCATION CHARATERISTIC TEMPORAL LOBE The temporal lobes are found on either side of the brain and just above the ears. The temporal lobes are responsible for hearing, memory, meaning, and language. They also play a role in emotion and learning. The temporal lobes are concerned with interpreting and processing auditory stimuli. OCCIPITAL LOBE The occipital lobe is found in the back of the brain. The occipital lobe is involved with the brain's ability to recognize objects. It is responsible for our vision.
- 22. VENTRICLE There are four cavities in the brain, called ventricles. The ventricles are filled with cerebrospinal fluid (CSF). There are four ventricles: Each of two lateral ventricles (ventricles 1 and 2) occupies a cerebral hemisphere. The third ventricle is connected by a passage to each of the two lateral ventricles. The fourth ventricle connects to the third ventricle (via the cerebral aqueduct) and to the central canal of the spinal cord (a narrow, central tube extending the length of the spinal cord).
- 25. CEREBELLUM It is projects dorsally from under occipital lobe of the cerebrum. • Like cerebrum it also has two hemisphere. The cerebellum also has an outer cortex made up of gray matter and inner region of white matter.
- 26. FUNCTION OF CEREBELLUM Cerebellum provides the precise timing of skeletal muscle activity and controls our balance and equilibrium. • It plays its role less well when sedative with alcohol. • if cerebellum is damaged movement become clumsy and disorganized, a condition called ataxia.
- 28. Diencephalon Diencephalon sits at top of brain stem and is enclosed by cerebral hemisphere. Major structure of Diencephalon: Thalamus Hypothalamus epithalamus
- 29. THALAMU S HYPOTHALAMU S EPITHALAMUS • Responsible for sensory responses • Decides what is pleasant or unpleasant • Integrate sensory (taste, hearing, emotions, sight and touch) Imp for regulation of body temperature, water balance and metabolism • Limbic system in it, responsible for emotions ( thirst, appetite, pain ) •Pineal Gland present in this region behind the thalamus • Pineal gland is sensitive to variation in light
- 30. BRAIN STEM Brain Stem is about size of thumb in diameter and approximately 3 inches long. Structures are: Mid brain Pons Medulla Oblongata
- 31. FUNCTIONS Midbrain Also called mesencephalon, The midbrain is a small region in the brain located at the front part of the brain stem. The midbrain acts as a relay information system for the auditory, visual, and motor systems of the body. Pons The pons is a portion of the brain located above the medulla oblongata and below the midbrain. Although it is small, at roughly 2.5 centimeters long, it serves several important functions as it serves as a bridge between various parts of the nervous system, including the cerebellum and cerebrum. There are many important nerves that originate in the pons.
- 32. FUNCTIONS Medulla oblongata, also called medulla, is a portion of the hindbrain that controls autonomic functions such as breathing, digestion, heart and blood vessel function, swallowing and sneezing. Motor and sensory neurons from the midbrain and forebrain travel through the medulla. As a part of the brainstem, the medulla oblongata helps in the transferring of messages between various parts of the brain and the spinal cord.
- 34. SPINAL CORD Cylinderical spinal cord which is approximately 17inches (42cm) long is a glistening white continuation of the brain stem. From the brain the spinal cord descends down the middle of the back and is surrounded and protected by the bony vertebral column. The spinal cord is surrounded by a clear fluid called Cerebral Spinal Fluid (CSF), that acts as a cushion to protect the delicate nerve tissues against damage from banging against the inside of the vertebrae. The spinal cord provides a two way conduction pathway to and from the brain, and is a major reflex center. Vertebral column grows faster than the spinal cord, so spinal cord does not reach the end of the vertebral column.
- 36. Regions – Cervical – Thoracic – Lumbar – Sacral – Coccygeal Not uniform in diameter Cervical enlargement: supplies upper limbs Lumbar enlargement: supplies lower limbs In humans, 31 pair of spinal nerves arise from the cord and exit from the vertebral column to serve the area close by.
- 37. Spinal cord also consist of gray matter and white matter. Gray matter: neuron cell bodies, dendrites, axons White matter: Myelinated axons
- 38. PERIPHERAL NERVOUS SYSTEM Peripheral nervous system (PNS) is formed by neurons and their processes present in all regions of the body. It consists of cranial nerves, arising from brain and spinal nerves, arising from the spinal cord. It is again divided into two subdivisions: 1. Somatic nervous system 2. Autonomic nervous system.
- 39. 1. Somatic Nervous System Somatic nervous system is concerned with somatic functions. It includes the nerves supplying the skeletal muscles. Somatic nervous system is responsible for muscular activities and movements of the body
- 40. 2. Autonomic Nervous System Motor neurons form autonomic nervous system which controls involuntry responces by influencing organs, glands, and smooth muscles. Autonomic nervous system is concerned with regulation of visceral or vegetative functions. So, it is otherwise called vegetative or involuntary nervous system. This system helps to control arterial pressure, gastrointestinal secretion, sweating, body temperature, and many other activities. Autonomic nervous system consists of two divisions, sympathetic division and parasympathetic division.
- 41. DIVISION OF ANS From anatomical and physiological point of view, ANS is divided into two divisions: 1. Sympathetic division 2. Parasympathetic division. Both of these system function automatically, innervate all internal organs, utilize two neuron and one ganglion for each impulse.
- 42. SYMPATHETIC DIVISION This system is important during emergency situations and is associated with “fight or flight.” This system accelarates the heart beat, dilates the pupil, and inhibit the digestion of food etc Sympathetic division supplies smooth muscle fibers of all the visceral organs such as blood vessels, heart, lungs, glands, gastrointestinal organs, etc. Sympathetic division is otherwise called thoracolumbar outflow
- 43. Most ganglion fibers of the symphathatic system arise from middle portion of the spinal cord and almost terminate in ganglia that lie near the cord. Preganglionic fibers leave the spinal cord through anterior nerve root and white rami communicantes and terminate in the postganglionic neurons, which are situated in the sympathetic ganglia. The axon of Preganglionic fiber is myelinated and the axon of postganglionic fiber is non- myelinated.
- 45. PARASYMPATHETIC SYSTEM A few cranial nerves including the vagus nerve together with the nerves from the bottom portion of spinal cord, form the parasympathetic nervous system. It promotes all internal responces which are associated with the relax state i.e. contraction of pupils, promotes digestion of food, retard heart beat etc. Parasympathetic division of ANS is otherwise called the craniosacral outflow Because, the fibers of this division arise from brain and sacral segments of spinal cord.
- 46. CRANIAL OUTFLOW OR CRANIAL PORTION OF PARASYMPATHETIC DIVISION Cranial outflow or cranial portion of parasympathetic division arises from brainstem. It innervates the blood vessels of head and neck and many thoraco abdominal visceral organs. Cranial outflow includes the following cranial nerves: 1. Oculomotor (III) nerve 2. Facial (VII) nerve 3. Glossopharyngeal (IX) nerve 4. Vagus (X) nerve. Preganglionic fibers of these cranial nerves arise from neurons situated at two different levels: 1. Tectal or midbrain outflow (III cranial nerve) 2. Bulbar level or bulbar outflow (VII, IX and X cranial nerves).
- 47. BULBAR LEVEL OR BULBAR OUTFLOW VII cranial nerve send information to Lacrimal gland Submaxillary gland Sublingual gland IX cranial nerve send information to Parotid gland X cranial nerve send information to Visceral organs
- 49. SACRAL OUTFLOW OR SACRAL PORTION OF PARASYMPATHETIC DIVISION Sacral outflow or sacral portion of parasympathetic division arises from the sacral segments of spinal cord. It innervates smooth muscles forming the walls of viscera and the glands such as large intestine, liver, spleen, kidneys, bladder, genitalia, etc. Preganglionic fibers arise from sacral segments of spinal cord and form the pelvic nerve. Fibers end on postganglionic neurons, which are situated on or near the visceral organs. Sacral parasympathetic fibers supply those visceral organs which are not supplied by vagus nerve
- 50. FUNCTIONS Autonomic nervous system control involuntary actions like heart beat, breathing,digestion etc. By controlling the various vegetative functions, ANS plays an important role in maintaining constant internal environment (homeostasis). Almost all the visceral organs are supplied by both sympathetic and parasympathetic divisions of ANS and the two divisions produce antagonistic effects on each organ.
- 52. SYMPATHETIC FIBERS . Preganglionic fibers: Acetylcholine (Ach) 2. Postganglionic noradrenergic fibers: Noradrenaline 3. Postganglionic cholinergic fibers: Ach Postganglionic sympathetic cholinergic nerve fibers supply sweat glands and blood vessels in heart and in skeletal muscle.
- 53. PARASYMPATHETIC FIBERS 1. Preganglionic fibers: Ach 2. Postganglionic fibers: Ach