Autonomic Pharmacology Lecture Notes PDF

AUTONOMIC PHARMACOLOGY Lecture no 1: Introduction Presented by: Dr Iman Elmahdi Albousafi Head of Pharmacology and Toxicology Department  Intended Learning Outcomes By the end of this lecture, you will be able to: Ø Discuss the organization of the autonomic nervou...

AUTONOMIC PHARMACOLOGY Lecture no 1: Introduction Presented by: Dr Iman Elmahdi Albousafi Head of Pharmacology and Toxicology Department  Intended Learning Outcomes By the end of this lecture, you will be able to: Ø Discuss the organization of the autonomic nervous system. Ø Identify the functions of the autonomic nervous system. Ø Classify types of neurons within peripheral nervous system. Ø Distinguish somatic versus autonomic pathways. Ø Compare dual innervation control of body organs by sympathetic and parasympathetic nervous systems. 22/12/2021 By: Iman Elmahdi 2  Introduction The nervous system is divided into two anatomical divisions: central nervous system (CNS) & peripheral nervous system. The central nervous system (CNS), which is composed of the brain and spinal cord. The peripheral nervous system any nerves that enter or leave the CNS. The peripheral nervous system is subdivided into the efferent and afferent divisions. The efferent neurons carry signals away from the brain and spinal cord to the peripheral tissues. The afferent neurons bring information from the periphery to the CNS. 22/12/2021 By: Iman Elmahdi 3  Introduction 22/12/2021 By: Iman Elmahdi 4  Introduction Afferent neurons provide sensory input to modulate the function of the efferent division through reflex arcs or neural pathways that mediate a reflex action. Functional divisions within the nervous system: The efferent portion of the peripheral nervous system is further divided into two major functional subdivisions: the somatic and the ANS. The somatic efferent neurons are involved in the voluntary control of functions such as contraction of the skeletal muscles essential for locomotion. The ANS involved involuntary nature and regulates the vital bodily functions without the conscious participation of the mind. 22/12/2021 By: Iman Elmahdi 5  Peripheral Nervous System Autonomic nervous system Somatic nervous system Innervation of various tissues Innervation of skeletal muscle Involuntary processes Voluntary processes 22/12/2021 By: Iman Elmahdi 6  Anatomy of the ANS 1. Efferent neurons: The ANS carries nerve impulses from the CNS to the effector organs by way of two types of efferent neurons: the preganglionic neurons and the postganglionic neurons. 2. Afferent neurons: The afferent neurons (fibers) of the ANS are important in the reflex regulation of this system. 3. Sympathetic neurons: The pre- ganglionic neurons of the sympathetic system come from the thoracic and lumbar regions (T1 to L2) of the spinal cord, and they synapse in two cord-like chains of ganglia that run close to and in parallel on each side of the spinal cord. 22/12/2021 By: Iman Elmahdi 7 22/12/2021 By: Iman Elmahdi 8  Continuing…. 4. Parasympathetic neurons: The parasympathetic preganglionic fibers arise from cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus). Also. from the sacral region (S2 to S4) of the spinal cord and synapse in ganglia near or on the effector organs. 5. Enteric neurons: The enteric nervous system is the third division of the ANS. It is a collection of nerve fibers that innervate the gastrointestinal (GI) tract, pancreas, and gallbladder. It constitutes the “brain of the gut.” 22/12/2021 By: Iman Elmahdi 9  Continuing…. This system functions independently of the CNS and controls the motility, exocrine and endocrine secretions, and microcirculation of the GI tract. It is modulated by both the sympathetic and parasympathetic nervous systems. 22/12/2021 By: Iman Elmahdi 10 22/12/2021 By: Iman Elmahdi 11  Somatic nervous system The efferent somatic nervous system differs from the ANS in that a single myelinated motor neuron, originating in the CNS, travels directly to skeletal muscle without the mediation of ganglia. the somatic nervous system is under voluntary control, whereas the ANS is involuntary. Responses in the somatic division are generally faster than those in the ANS. 22/12/2021 By: Iman Elmahdi 12  Functions of the sympathetic nervous system Fight-or-flight response. Increase heart rate and contractility. Increase blood pressure. Dilation of the pupils and the bronchioles. Increase GIT motility and the function of the bladder and sexual organs. Stimulation of the adrenal medulla to release epinephrine and lesser amounts of nor- epinephrine. 22/12/2021 By: Iman Elmahdi 13  Functions of the parasympathetic nervous system The parasympathetic division is involved with maintaining homeostasis within the body. “Rest-and-digest” situations. Decrease heart rate and contractility. Decrease GIT motility. Constriction, increased secretions of trachea and bronchioles. Contraction of iris sphincter muscle (pupil contracts). Blood vessel contraction. Stimulation of tears. 22/12/2021 By: Iman Elmahdi 14  Neurotransmitters 22/12/2021 By: Iman Elmahdi 15  Differences between sympathetic, parasympathetic 22/12/2021 By: Iman Elmahdi 16  Innervation by the ANS Dual innervation: Most organs in the body are innervated by both divisions of the ANS. Vagal parasympathetic innervation slows the heart rate, and sympathetic innervation increases the heart rate. One system usually pre- dominates in controlling the activity of a given organ. For example, in the heart, the vagus nerve is the predominant factor for controlling rate. 22/12/2021 By: Iman Elmahdi 17 Continuing… 2. Organs receiving only sympathetic innervation: Adrenal medulla, kidney, pilomotor muscles, and sweat glands, receive innervation only from the sympathetic system. 22/12/2021 By: Iman Elmahdi 18 22/12/2021 By: Iman Elmahdi 19  Summary 22/12/2021 By: Iman Elmahdi 20  Summary The video link https://www.youtube.com/watch?v=D96mSg2_h0c 22/12/2021 By: Iman Elmahdi 21 22/12/2021 By: Iman Elmahdi 22