Presentation on theme: "1 Saquiba Yesmine, PhD Fall 2014. 2 Brain function is the single most important aspect of physiology that defines the difference between humans and."— Presentation transcript:
1 Saquiba Yesmine, PhD Fall 2014
2 Brain function is the single most important aspect of physiology that defines the difference between humans and other species. Disorders of brain function, whether primary or secondary to malfunction of other systems, are a major concern of human society, It is a field in which pharmacological intervention plays a key role. Brain function is the single most important aspect of physiology that defines the difference between humans and other species. Disorders of brain function, whether primary or secondary to malfunction of other systems, are a major concern of human society, It is a field in which pharmacological intervention plays a key role.
3 Brain function is the single most important aspect of physiology that defines the difference between humans and other species. Disorders of brain function, whether primary or secondary to malfunction of other systems, are a major concern of human society, It is a field in which pharmacological intervention plays a key role. Brain function is the single most important aspect of physiology that defines the difference between humans and other species. Disorders of brain function, whether primary or secondary to malfunction of other systems, are a major concern of human society, It is a field in which pharmacological intervention plays a key role.
4 "Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows and griefs,”- Hippocrates Through much of history, the mind was thought to be separate from the brain. "Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows and griefs,”- Hippocrates Through much of history, the mind was thought to be separate from the brain.
Neuropharmacology can be defined simply as the study of drugs that affect nervous tissue. Neuropharmacology is the study of drugs that interact with neurons in the brain to affect mood, sensation, behavior, and thinking. What is Neuropharmacology?
But…. this is not an accomplished definition since a great many drugs whose therapeutic value is extraneural can affect the nervous system. For example, the cardiotonic drug digitalis commonly produce central nervous system (CNS) effects ranging from blurred vision to disorientation. What is Neuropharmacology?
Using drugs non-medicinally to alter states of consciousness is not a new concept. Alcohol, caffeine, nicotine, heroin, cocaine, cannabis all transitioned from medicinal use to the recreational improvement of mood and performance What is Neuropharmacology?
The scope of neuropharmacology generally limits to those drugs which specifically employed to affect the nervous system. Scope of Neuropharmacology Psychotropic drugs that affect mood and behavior, Anesthetics drugs, Sedatives drugs, Hypnotics drugs, Narcotics drugs, Anticonvulsants drugs, Analgesics drugs, and Drugs that affect the Autonomic Nervous System. The domain of neuropharmacology include -
9 Why understanding the action of drugs on the CNS presents a particularly challenging problem? Centrally acting drugs are of special significance to humankind CNS is functionally far more complex than any other system in the body Therapeutic Non-therapeutic (e.g. alcohol, tea and coffee, cannabis, nicotine, opioids, amphetamines etc.).
enormously difficult to comprehend
at the molecular level, an explanation of the action of a drug is often possible; at the cellular level, an explanation is sometimes possible; but – at the behavioral level, our ignorance is abysmal.
Neurons Neurons are highly polarized cells (it has distinct subcellular domains that subserve different functions). Morphologically, in a typical neuron, three major regions can be defined: 1)the cell body, or perikaryon, which contains the nucleus and the major cytoplasmic organelles; 2)a variable number of dendrites, which emanate from the perikaryon and which differ in size and shape and 3)a single axon, which extends in most cases much farther from the cell body than does the dendritic arbor. many axons are surrounded by an insulating myelin sheath, which facilitates rapid impulse conduction.
Sensory (afferent) neurons - - carry signals to the central nervous system (CNS) Interneurons - contained entirely within the CNS and carry signals from one neuron to another Motor (efferent) neurons - carry signals from the CNS to muscles and glands. Functional Classes of Neurons
The term neuroglia, or “nerve glue,” was coined in 1859 by Rudolph Virchow, who conceived of the neuroglia as an inactive “connective tissue” holding neurons together in the central nervous system. Supporting cells in the central nervous system (CNS)
Supportive Cells (Neuroglia)
Mediators of Immune Responses
Supportive Cells (Neuroglia) Form myelin in brain and spinal cord Oligodendrocytes branched and starlike shape
Supportive Cells (Neuroglia) Arrangement of astrocytes in human cerebellar cortex astrocytes are star-shaped process-bearing cells distributed throughout the central nervous system. They constitute from 20 to 50% of the volume of most brain areas Astrocytes have a wide range of functions
bulbous body with as many as 15 arm like processes Astrocytes Supportive Cells (Neuroglia) 1.Cover brain surface and nonsynaptic regions of neurons; 2.form supportive framework in CNS; induce formation of blood-brain barrier; 3.nourish neurons; 4.produce growth factors that stimulate neurons; 5.communicate electrically with neurons and influence synaptic signalling; 6.remove neurotransmitters and K from ECF of brain and spinal cord; 7.help to regulate composition of ECF; 8.form scar tissue to replace damaged nervous tissue
Myelin in the PNS is generated by Schwann cells, each of which wraps only a single axonal segment. It also aid in regeneration of Damaged nerve fibers Glutamate–Glutamine cycle
Overviews of Nervous system
Neuropharmacology The nervous system can be separated into parts based on structure and on function. structurally, it can be divided into the central nervous system (CNS) and the peripheral nervous system (PNS) functionally, it can be divided into – somatic and visceral parts. The CNS - composed of the brain and spinal cord The PNS - composed of all nervous structures outside the CNS that connect the CNS to the body. PNS consists of the spinal nerves cranial nerves, visceral nerves and plexuses enteric system.
Neuropharmacology Brain 1.cerebral hemispheres, 2.cerebellum, and 3.brainstem. 1. The cerebral hemispheres consist of - an outer portion or the gray matter containing cell bodies, an inner portion or the white matter made up of axons forming tracts or pathways, and the ventricles, which are spaces filled with cerebrospinal fluid (CSF). 2. The cerebellum has two lateral lobes and a midline portion. 3. The components of the brainstem are diencephalon, midbrain, pons, and medulla. Central nervous system – Brain and Spinal cord
The spinal cord is the part of the CNS in the superior two-thirds of the vertebral canal. It is roughly cylindrical in shape, and is circular to oval in cross-section with a central canal. Spinal cord has a small central canal surrounded by gray and white matter. the gray matter is rich in nerve cell bodies, which form longitudinal columns along the cord and in cross section, these columns form a characteristic H-shaped appearance in the central regions of the cord. the white matter surrounds the gray matter and is rich in nerve cell processes, which form large bundles or tracts that ascend and descend in the cord to other spinal cord levels or carry information to and from the brain. Spinal Cord
Meninges The meninges are three connective tissue coverings that surround, protect, and suspend the brain and spinal cord within the cranial cavity and vertebral canal. 1.Dura mater is the thickest and most external of the coverings; 2.Arachnoid mater is against the internal surface of the dura mater; 3.Pia mater is adherent to the brain and spinal cord.
Spinal nerves Each spinal nerve is connected to the spinal cord by posterior and anterior roots. contains the processes of sensory neurons carrying information to the CNS - the cell bodies of the sensory neurons are clustered in a spinal ganglion at the distal end of the posterior root. Peripheral Nervous System anterior root contains motor nerve fibers, which carry signals away from the CNS – the cell bodies of the primary motor neurons are in anterior regions of the spinal cord. Remember: all sensory information passes into the posterior aspect of the spinal cord, and all motor fibers leave anteriorly
Functionally, the nervous system can be divided into somatic parts visceral parts FUNCTIONAL SUBDIVISIONS OF THE CNS Somatic part ( 'soma' from the Greek for body ) innervates structures (skin and most skeletal muscle) derived from somites and is mainly involved with receiving and responding to information from the external environment Visceral part ( 'viscera' from the Greek for guts ) innervates organ systems in the body and other visceral elements, such as smooth muscle and glands, in peripheral regions of the body – it is concerned mainly with detecting and responding to information from the internal environment sensory nerves monitor changes in the viscera; motor nerves mainly innervate smooth muscle, cardiac muscle, and glands. carry conscious sensations from peripheral regions back to the CNS; innervate voluntary muscles.
Visceral Motor Neurons Visceral motor neurons arise from cells in lateral regions of spinal cord and send processes out anteriorly. These processes synapse with other cells, usually other visceral motor neurons The visceral motor neurons located in the spinal cord are referred to as preganglionic motor neurons and their axons are called preganglionic fibers; the visceral motor neurons located outside the CNS are referred to as postganglionic motor neurons and their axons are called postganglionic fibers.
Somatic ◦ Muscle movement ◦ No ganglia ◦ Transmitter: Acetylcholine ◦ Receptor: Nicotinic-M (“M” for muscle) Peripheral Pathways
Overview of Autonomic Functions Regulation of Heart Regulation of glands ◦ Salivary ◦ Gastric ◦ Sweat ◦ Bronchial Regulation of smooth muscle ◦ Bronchi, blood vessels, urogenital ◦ GI tract
Parasympathetic Functions Slow heart Increase gastric secretion and motility Emptying Bowel Focusing eye for near vision Constriction of pupil Contraction of bronchial smooth muscle Most cholinergic drugs affect: GI, bladder, eye
Sympathetic Functions Cardiovascular system Body temperature Stress: Fight or Flight ◦ Increase HR and BP ◦ Shunt blood from skin & viscera to muscles ◦ Dilation of bronchi ◦ Dilation of pupils ◦ Mobilization of stored energy: glucose, fatty acids
Control Mechanisms Innervation by both where effects are opposed ◦ Heart rate Innervation by both where effects are complementary ◦ Male reproductive processes Innervation by only one ◦ Blood vessels
Autonomic Tone Steady day-to-day influence exerted by the autonomic system ◦ Usually only one division provide tone ◦ Parasympathetic system usually provides the basal tone