nervous system part 1 Dr Ahmed H Ahmed.pdf
- 1. CENTRAL NERVOUS SYSTEM Ahmed H. Ahmed Cell Physiologist Biology department-College of Science- Salahaddin University 2023-2024 for 2nd year dental students Nervous system
- 3. CNS vs. PNS
- 6. V
- 7. NEURON TYPES
- 8. NEUROGLIA & NEURONAL CELLS
- 12. PNS
- 13. GANGLIA
- 16. MAJOR LEVELS OF CENTRAL NERVOUS SYSTEM FUNCTION • Higher brain or cortical level • Lower brain or subcortical level • Spinal cord level
- 21. CONDITIONAL RESPONSE: PAVLOVIAN CONDITIONING Pavlovian conditioning refers to the behavioral and physiological changes brought about by experiencing a predictive relationship between a neutral stimulus and a consequent biologically significant event (Pavlov, 1927).
- 23. SPINAL CORD LEVEL • Walking movements. • Reflexes that withdraw portions of the body from painful objects. • Reflexes that stiffen the legs to support the legs against gravity. • Reflexes that control local blood vessels, gastrointestinal movements, or urinary excretion.
- 24. LOWER BRAIN OR SUBCORTICAL LEVEL • subconscious control of arterial pressure and respiration is achieved mainly by Medulla and pons . • Control of Equilibrium is a combined function of the older portions of the cerebellum and the reticular substances of the medulla, pons.
- 25. Feeding reflexes, such as salivation and licking of the lips in response to the taste of food, are controlled by areas in the medulla, pons, amygdala, and hypothalamus. many emotional patterns, such as anger, excitement, sexual response, reaction to pain, and reaction to pleasure, can still occur after destruction of much of the cerebral cortex.
- 26. CENTRAL NERVOUS SYSTEM OVERVIEW It is estimated that the CNS contains about a hundred billion (1011) neurons and a hundred trillion (1014) synapses, all within the brain and the spinal cord.
- 27. CENTRAL NERVOUS SYSTEM OVERVIEW 90% of the CNS is composed of Glial cells (neuroglia): 1. Oligodendrocytes 2. Microglia 3. Ependymal cells 4. Astrocytes They are not merely supportive cells.
- 28. NEUROGLIA Astrocytes: ▪ Are most diverse of the glial cells. ▪ Function in development of neuronal connections. ▪ Guide developing neurons to their correct destinations and regulate development and maintenance of synapses. ▪ Some astrocytes are wrapped around synapses, seemingly, they modulate synaptic activities. ▪ astrocytes remove neurotransmitters, such as glutamate and biogenic amines from the synaptic cleft. Because high levels of glutamate are toxic. ▪ Astrocytes release neurotransmitters that communicate to neurons and affecting the synaptic communications between two neurons. ▪ Astrocytes maintain normal electrolyte compositions of the extracellular fluids, the necessary to maintain normal neuronal excitability. ▪ Astrocytes also protect neurons from oxidative stress and help remove cellular debris. ▪ Astrocytes contribute to blood-brain barrier (BBB)
- 29. GLIAL CELLS IN NEURODEGENERATIVE DISEASE Glial cells contribute to neurodegenerative diseases such as; multiple scleroses, Alzheimer’s disease, and Parkinson’s disease.
- 30. GLIAL CELLS IN NEURODEGENERATIVE DISEASE Multiple sclerosis: is an autoimmune disease (in which the immune system attacks a part of the body ), that attacks oligodendrocytes. The loss of myelin and some axons in the CNS slows down or stops communications along certain neural pathways. Symptoms include blurred vision, muscle weakness, and difficulty maintaining balance.
- 31. GLIAL CELLS IN NEURODEGENERATIVE DISEASE Alzheimer’s disease; is caused by the loss of cholinergic neurons in certain brain areas and replacement of the lost neurons with scar tissue called plaques. During the degeneration of cholinergic neurons, astrocytes and microglia become overly active that release inflammatory chemicals that enhance further degeneration of cholinergic neurons.
- 32. GLIAL CELLS IN NEURODEGENERATIVE DISEASE Early signs of Alzheimer’s disease include loss of memory and confusion. Later signs include motor dysfunction, loss of communication skills, and decrease in cognitive functions.
- 36. BRAIN PLACES WITHOUT BBB
- 37. PHYSICAL SUPPORT OF THE CNS Bony skull (cranium), Vertebral column; protects CNS against outside hazard Meninges protect CNS against inside hazard; such as crashing into hard inner surface of the skull or vertebral parts during, for example, a sudden stop in a car moving at freeway speeds. Cerebrospinal fluid (CSF); bathes the CNS and provides a cushion background.
- 38. HOW BRAIN CELLS STORE INFORMATION
- 41. Floating brain
- 42. HIGHER BRAIN Extremely large memory storehouse. The cortex never functions alone but always in association lower centers of the nervous system. Lower brain functions, without cerebral cortex, are often imprecise. Essential for most of our thought processes. Lower brain centers initiate wakefulness in the cerebral cortex, thus opening its bank of memories to the thinking machinery of the brain.
- 45. CEREBRAL CORTEX 1. Sensory perception 2.Voluntary control of movement 3. Language 4. Personality traits 5. Sophisticated mental events, such as thinking, memory, decision making, creativity, and self-consciousness
- 46. BASAL NUCLEI 1. Inhibition of muscle tone 2. Coordination of slow, sustained movements 3. Suppression of useless patterns of movement
- 47. THE BASAL NUCLEI PLAY AN IMPORTANT INHIBITORY ROLE IN MOTOR CONTROL The basal nuclei play a complex role in controlling movement. In particular, they are important in (1) inhibiting muscle tone throughout the body (proper muscle tone is normally maintained by a balance of excitatory and inhibitory inputs to the neurons that innervate skeletal muscles), (2) selecting and maintaining purposeful motor activity while suppressing useless or unwanted patterns of movement, and (3) helping monitor and coordinate slow, sustained contractions, especially those related to posture and support
- 48. The importance of the basal nuclei in motor control is evident in Parkinson’s disease (PD). This condition is associated with a gradual destruction of neurons that release the neurotransmitter dopamine in the basal nuclei. Because the basal nuclei lack enough dopamine to exert their normal roles, three types of motor disturbances characterize PD: (1) increased muscle tone, or rigidity; (2) involuntary, useless, or unwanted movements, such as resting tremors (for example, hands rhythmically shaking, making it difficult or impossible to hold a cup of coffee); and (3) slowness in initiating and carrying out different motor behaviors
- 49. THALAMUS 1. Relay station for all synaptic input 2. Crude awareness of sensation 3. Some degree of consciousness 4. Role in motor control
- 50. HYPOTHALAMUS 1. Regulation of many homeostatic functions, such as temperature control, thirst, urine output, and food intake 2. Important link between nervous and endocrine systems 3. Extensive involvement with emotion and basic behavioral patterns 4. Role in sleep–wake cycle
- 51. CEREBELLUM 1. Maintenance of balance 2. Enhancement of muscle tone 3. Coordination and planning of skilled voluntary muscle activity
- 52. BRAIN STEM 1. Origin of majority of peripheral cranial nerves 2. Cardiovascular, respiratory, and digestive control centers 3. Regulation of muscle reflexes involved with equilibrium and posture 4. Reception and integration of all synaptic input from spinal cord; arousal and activation of cerebral cortex 5. Role in sleep–wake cycle
- 55. ASYMMETRIC VS. SYMMETRIC BRAIN
- 57. AMYGDALAE The amygdalae ,Latin, from Greek ἀμυγδαλή, amygdalē, 'almond', 'tonsil', are almond-shaped groups of nuclei located deep and medially within the temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a primary role in the processing of memory and emotional reactions, the amygdalae are considered part of the limbic system.
- 58. HIPPOCAMPUS The hippocampus (named after its resemblance to the seahorse, from the Greek hippos meaning "horse" and kampos meaning "sea monster") is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long- term memory and spatial navigation. Humans and other mammals have two hippocampi, one in each side of the brain.
- 59. EMOTION, BEHAVIOR, AND MOTIVATION The limbic system is not a separate structure but a ring of forebrain structures that surround the brain stem and are interconnected by intricate neuron pathways. It includes portions of each of the following: the lobes of the cerebral cortex (especially the limbic association cortex), the basal nuclei, the thalamus, and the hypothalamus. This complex interacting network is associated with emotions, basic survival and sociosexual behavioral patterns, motivation, and learning.
- 60. WERNICKE’S AREA Wernicke’s area is highly developed in the dominant side of the brain – the left side in almost all right-handed people. Wernicke’s area plays the greater role for higher comprehension levels of the brain that we call “intelligence”. This area was first described in 1874 by German neurologist Carl Wernicke
- 61. Severe damage in Wernicke’s area causes inability to arrange words into coherent thoughts, that means reading words without knowing the thought they conveyed. Activation of Wernicke’s area can call forth complicated memory patterns else where.
- 62. BROCA’S AREA Broca’s area initiates and executes plans and motor patterns for expressing individual words or even short phrases. Broca’s area works in close association with the Wernicke’s language comprehension center. Paul Broca was born on 28 June 1824 in Sainte-Foy-la- Grande, Bordeaux, France
- 63. SPEECH PATHWAYS
- 64. CORPUS CALLOSUM Manly, makes information stored in the cortex of one hemisphere available to corresponding cortical areas of the opposite hemisphere . Corpus callosum, a thick band consisting of an estimated 300 million neuronal axons that connect the two hemispheres .The corpus callosum is the body’s “information superhighway.”The two hemispheres communicate and cooperate with each other by means of constant information exchange through this neural connection
- 65. FACIAL RECOGNITION AREA • Prosopagnosia is inability to recognize faces. • This occurs in people who have extensive damage on the medial undersides of both occipital lobes and along the medioventral surfaces of the temporal lobes. • But why so much of the cerebral cortex should be reserved for the simple task as face recognition?
- 66. ANGULAR GYRUS INTERPRETATION OF WRITTEN INFORMATION Located between Wernicke’s area and visual area of the occipital lobe Damage to this area causes difficulty in interpreting words meanings a state called dyslexia or “ word blindness”
- 67. THE DOMINANT HEMISPHERE • The cerebral hemisphere that is more involved than the other in governing certain body functions, such as controlling the arm and leg used preferentially in skilled movements.
- 70. COMA Coma Is defined as unconsciousness from which the person cannot be aroused.
- 71. DEPRESSION Depression is among the psychiatric disorders associated with defects in limbic system neurotransmitters. (As a distinction, psychiatric disorders involve abnormal activity in specific neurotransmitter pathways in the absence of detectable brain lesions, whereas neurological disorders are associated with specific lesions of the brain and may or may not involve abnormalities in neurotransmission
- 72. THE LAZY BRAIN
- 73. THE LAZY BRAIN • A lazy brain is a shrinking brain • Those who don't engage in complex mental activity over their lifetime have twice the shrinkage in a key part of the brain in old age.