Physiology Lecture l4 PDF

Physiology Nervous System LECTURE (4) DR. El-Sawy 0  Physiology Nervous System Importance : Cont...

Physiology Nervous System LECTURE (4) DR. El-Sawy 0  Physiology Nervous System Importance : Control body functions : 1. Receives information from the body. 2. Integrates all of information. 3. Determine the response. Definition : Structural ( anatomical ) unit of nervous system. Formed of: 1. Cell body (soma): Control the activity of whole neuron. 2. Cell processes: Dendrites Axon  Multiple short processes  Single long process.  Receptive part.  Conducting part.  Conduct impulse towards cell  Conduct impulses away from cell body body. DR. El-Sawy 1  Physiology Nervous System Near the termination of axon, it either joins : Muscle  Neuro-muscular junction. Gland  Neuro-epithelial junction. Another neuron  Neuro-neural junction. Types Of Neurons : Neuron Function Afferent neuron =  Carries impulses from receptors to CNS. sensory neuron Efferent neuron =  Carries impulses from CNS to effector organs motor neuron  Located inside CNS. Interneuron = associative  Act as a link between neurons. neuron  99% of nerve cells. DR. El-Sawy 2  Physiology Nervous System  Involuntary (programmed )response to a stimulus.  Carried out through reflex arc which is considered Definition functional or physiological unit of the nervous system. 1. Receptors. 2. Afferent (sensory). Components of 3. Center (in CNS). reflex pathway 4. Efferent (motor). 5. Effectors (muscles or glands). DR. El-Sawy 3  Physiology Nervous System Definition :  Part of nervous system which is protected by bones (skull & vertebral column). Structure: A. Brain : Cerebral cortex. Cerebrum (two cerebral Subcortical centers (thalamus, hypothalamus & basal hemispheres) ganglia). Mid brain. Brian stem Pons. Medulla. Cerebellum B. Spinal Cord : 31 segment Each spinal segment gives a pair of spinal nerves on both sides. Cervical 8 Thoracic 12 Lumbar 5 Sacral 5 Coccygeal 1 DR. El-Sawy 4  Physiology Nervous System Importance:  Provides a communication between CNS & other tissues via nerves. Division : A. Anatomical classification : cranial nerves spinal nerves 12 pairs 31 pairs B. Physiological classification : Somatic Nervous System Autonomic Nervous System Control  Voluntary.  Involuntary.  Skin.  Smooth muscles. Connections  Skeletal muscles.  Cardiac muscles.  Tendons, bones & joints.  Glands. DR. El-Sawy 5  Physiology Nervous System Definition :  Nerves that connected to the brain (12 pairs). Include : From cerebrum : CI Olfactory nerve  Smell. C II Optic nerve  Vision. from midbrain : C III Oculomotor nerve  Moving eye ball. C iV Trochlear nerve  Moving eye ball. from pons :  Sensory to face. Cv trigeminal nerve  Motor for mastication muscles. C Vi Abducent nerve  Motor to eye muscles. C VII Facial nerve  Motor to muscles of face. C VIII Auditory nerve  Hearing & equilibrium. from medulla :  Taste sensation. C IX Glossopharyngeal nerve  Secretory to salivary glands.  Sensory & motor to ms of CX Vagus nerve thoracic & abdominal viscera. C XI Accessory nerve  Motor to ms of back of neck. C XII Hypoglossal nerve  Motor to ms of tongue. DR. El-Sawy 6  Physiology Nervous System DR. El-Sawy 7  Physiology Nervous System Note Cranial nerves may be : Purely sensory: C 1 , 2 & 8. Purely motor: C 3 , 4 & 6. Mixed: the remaining. Number  31 pairs Site  Attached to spinal cord.  Dorsal root. Roots  Ventral root. All spinal nerves are mixed nerves (sensory and motor). DR. El-Sawy 8  Physiology Nervous System Origin : Sympathetic Parasympathetic  Cranial part:  3, 7 ,9 ,10 cranial nerves.  LHCs of all thoracic & upper 3  Sacral part: lumbar segments of spinal cord.  S2, S3, S4 (called pelvic nerve). DR. El-Sawy 9