General Physiology Lecture - University of the Visayas - PDF

UNIVERSITY OF THE VISAYAS - GULLAS “GENERAL PHYSIOLOGY LECTURE” Prepared by: Mr. Rommeljun Solijon Datiles  Signaling -Test “GENERAL PHYSIOLOGY MYSTERY” Guess me? You are CORRECT! Amygdala Guess me? You are CORRECT! Hypothalamus Guess me? You are CORRECT! Schizoph...

UNIVERSITY OF THE VISAYAS - GULLAS “GENERAL PHYSIOLOGY LECTURE” Prepared by: Mr. Rommeljun Solijon Datiles  Signaling -Test “GENERAL PHYSIOLOGY MYSTERY” Guess me? You are CORRECT! Amygdala Guess me? You are CORRECT! Hypothalamus Guess me? You are CORRECT! Schizophrenia Guess me? You are CORRECT! Cerebrum Guess me?  You are CORRECT! Epilepsy (Epileptic Seizure Disorder) Guess me? You are CORRECT! Synapses Guess me? You are CORRECT! Stroke Guess me? You are CORRECT! Cell body Guess me? You are CORRECT! Medulla Oblongata Guess me? ??? You are CORRECT! ??? Myelin Sheath LEARNING OBJECTIVES At the end of the lesson, the student should be able to: 1. explain the fuctional division of nervous system; 2. r e l a t e t h e f u n c t i o n a l a n d s t r u c t u ra l differences between gray matter and white matter structures of the nervous system to the structure of neurons; and 3. list the basic functions of the nervous system NERVOUS SYSTEM  The picture you have in your mind of the nervous system probably includes the brain, the nervous tissue contained within the cranium, and the spinal cord, the extension of nervous tissue within the vertebral column. That suggests it is made of two organs— and you may not even think of the spinal cord as an organ—but the nervous system is a very complex structure.  Within the brain, many different and separate regions are responsible for many different and separate functions. It is as if the nervous system is composed of many organs that all look similar and can only be differentiated using tools such as the microscope or electrophysiology. In comparison, it is easy to see that the stomach is different than the esophagus or the liver, so you can imagine the digestive system as a collection of specific organs. What is Nervous System? The nervous system is a network of neurons whose main feature is to generate, modulate and transmit information between all the different parts of the human body. Function of the Nervous System § To carry out its normal role, the nervous system has three overlapping functions. ORGANIZATION OF NERVOUS SYSTEM § The nervous system does not work alone to regulate and maintain body homeostasis; the endocrine system is a second important regulating system. Structural Classification § The structural classification, which includes all of the nervous system organs, has two subdivisions- the central nervous system and the peripheral nervous system. o The CNS consists of the brain and spinal cord, o which occupy the dorsal body cavity and act as the integrating and command centers of the nervous system Structural Classification o The PNS, the part of the nervous system outside the CNS, o consists mainly of the nerves that extend from the brain and spinal cord. Functional Classification § The functional classification scheme is concerned only with PNS structures. o Sensory Division. § The sensory, or afferent division, consists of nerves (composed of nerve fibers) that convey impulses to the central nervous system from sensory receptors located in various parts of the body. Functional Classification o Sensory Division. § Sight § Hearing § Smell § Taste § Touch Functional Classification o Sensory Division is Divided into two components: § (1) Somatic sensory fibers. Sensory fibers delivering impulses from the skin, skeletal muscles, and joints are called somatic sensory fibers. § (2) Visceral sensory fibers. Those that transmit impulses from the visceral organs are called visceral sensory fibers. Functional Classification § Motor division. The motor, or efferent division carries impulses from the CNS to effector organs, the muscles, and glands; the motor division has two subdivisions: § Somatic nervous system and § Autonomic nervous system. Functional Classification § Somatic nervous system. The somatic nervous system allows us to consciously, or voluntarily, control our skeletal muscles. § Autonomic nervous system. The autonomic nervous system regulates events that are automatic, or involuntary; this subdivision, commonly called the involuntary nervous system, has two parts: the sympathetic and parasympathetic, which typically bring about opposite effects. Review of Functional Classification Nervous Tissue: Structure and Function o Supporting Cells § Supporting cells in the CNS are “lumped together” as neuroglia, which literally means “nerve glue”. Nervous Tissue: Structure and Function v Neuroglia. § Neuroglia includes many types of cells that generally support, insulate, and protect the delicate neurons; in addition, each of the different types of neuroglia, also simply called either glia or glial cells, has special functions. Nervous Tissue: Structure and Function o Neurons § Neurons, also called nerve cells, are highly specialized to transmit messages (nerve impulses) from one part of the body to another. o Parts of a Neurons with Functions Types of Neurons § Neurons may be classified either according to how they function or according to their structure. Different Kinds of Neurons Functional Classification of Neurons § Functional classification groups neurons according to the direction the nerve impulse is traveling relative to the CNS; on this basis, there are sensory, motor, and association neurons. Functional Classification of Neurons Central Nervous System § During embryonic development, the CNS first appears as a simple tube, the neural tube, which extends down the dorsal median plan of the developing embryo’s body. Brain § Because the brain is the largest and most complex mass of nervous tissue in the body, it is commonly discussed in terms of its four major regions – Ø cerebral hemispheres, Ø diencephalon, Ø brain stem, and Ø cerebellum. Cerebral Hemispheres § The paired cerebral hemispheres, collectively called the cerebrum, are the most superior part of the brain, and together are a good deal larger than the other three brain regions combined. Cerebral Hemispheres § These two regions within nervous system structures are often referred to as gray matter (the regions with many cell bodies and dendrites) or white matter (the regions with many axons). Cerebral Cortex § Speech, memory, logical and emotional response, as well as consciousness, interpretation of sensation, and voluntary movement, are all functions of neurons of the cerebral cortex. § insular cortex is responsible for sensory processing, decision- making, and motor control. Diencephalon § The diencephalon is a central part of the brain that includes the thalamus, hypothalamus, epithalamus, and subthalamus. Diencephalon Brain Stem § The brain stem is about the size of a thumb in diameter and approximately 3 inches long. Brain Stem Protection of the Central Nervous System Meninges § The three connective tissue membranes covering and protecting the CNS structures are the meninges. Meninges Cerebrospinal Fluid § Cerebrospinal fluid (CSF) is a watery “broth” similar in its makeup to blood plasma, from which it forms. The Blood-Brain Barrier § No other body organ is so absolutely dependent on a constant internal environment as is the brain, and so the blood-brain barrier is there to protect it. Spinal Cord § The cylindrical spinal cord is a glistening white continuation of the brain stem. Spinal Cord § The cylindrical spinal cord is a glistening white continuation of the brain stem. Gray Matter of the Spinal Cord and Spinal Roots § The gray matter of the spinal cord looks like a butterfly or a letter H in cross- section. White Matter of the Spinal Cord § The white matter of the spinal cord is composed of myelinated fiber tracts- some running to higher centers, some traveling from the brain to the cord, and some conducting impulses from one side of the spinal cord to the other. Peripheral Nervous System § The peripheral nervous system consists of nerves and scattered groups of neuronal cell bodies (ganglia) found outside the CNS. Functional Classification Structure of a Nerve § A nerve is a bundle of neuron fibers found outside the CNS. Nerve Impulse § Neurons have two major functional properties: irritability, the ability to respond to a stimulus and convert it into a nerve impulse, and conductivity, the ability to transmit the impulse to other neurons, muscles, or glands. Nerve Impulse Nerve Impulse The Nerve Impulse Pathway § How the nerve impulse actually works is detailed below. The Nerve Impulse Pathway Communication of Neurons at Synapses § The events occurring at the synapse are arranged below. Communication of Neurons at Synapses