DRUGS and Physiological Dependence

DRUGS

• A DRUG can be defined as a natural or synthetic substance that is used to produce physiological or psychological effects in humans or other higher-order animals.

• The word “drugs” means something different to each person.– Drugs can be necessary for sustaining or prolonging

life– Drugs can provide an escape from the pressures of

life– Drugs can be used as a means to end ones life

DRUGS

• During the 1960’s, successive waves of hallucinogens, amphetamines and barbiturates found their way out of laboratories, pharmacies and medicine chests and into the streets. During this decade, marijuana became the most widely used illicit drug in the United States, and alcohol consumption continued to rise – today 90 million Americans drink alcohol regularly, and 10 million of these are hopelessly addicted or have severe problems in coping with their drinking habits.

DRUGS

• Approximately 23 million people in the United States use illicit drugs, including about a half million heroin addicts and nearly six million users of cocaine.

• In the United States, more than 75% of the evidence evaluated in crime laboratories is drug related.– Guns– Drugs– Documents– Evidence from Drug related Homicides or Agg. Assaults

Drug Dependence

• Before we talk about Drug Dependence, lets review the neurophysiological effect of drugs. In order to do that, we must first study the anatomy and physiology of the human nervous system.

Anatomy and PhysiologyThe Nervous System

• The nervous system operates very much like a computer system. Information is entered into the computer by various “senses”: the keyboard, mouse, microphone, Internet connection, and so on. The main components of the computer’s “brain” are the hard drive (long term memory), and the central processing unit (thinking and decision making). The computer’s output – its interaction with the world – exits via ports and cables to printers, displays, speakers, and other devices.

Anatomy and PhysiologyThe Nervous System

• The Nervous System is divided into two main parts: The Central Nervous System (CNS) which is composed of the brain and spinal column, and the Peripheral Nervous System (PNS) which is composed of the input and output pathways of the nervous system; essentially the nerves outside of the brain and spinal cord.

The Nervous SystemNervous System

Central Nervous System(CNS)

Brain and Spinal Cord

Peripheral Nervous System(PNS)

Nerves outside of Brain and Spinal Cord

Somatic or Voluntary (skeletal muscles)

Autonomic (smooth and cardiac muscles and glands)

Parasympathetic Branch (homeostasis and daily

maintenance)

Sympathetic Branch(alert system)

Parts and Basic Operation of the Nervous System

• Central Nervous System: Brain and Spinal Cord: Controls all basic bodily functions and responds to external changes.

• Peripheral Nervous System: All nerves outside of the Central Nervous System: Provides a complete network of motor and sensory fibers connecting the central nervous system to the rest of the body.

• Autonomic Nervous System: Parasympathetic and sympathetic nervous system: Parallels the spinal cord but is separately involved in control of exocrine glands, blood vessels, viscera, and external genitalia.

Parts and Basic Operation of the Nervous System

• The nervous system’s “input devices” comprise the sensory system. Your senses sample the environment and bring the information to the nervous system. Your sensory system absorbs and measures information about everything and anything, both within your body and the outside environment. This sensory information then goes into the nervous system, where it is handled by the brain and spinal cord. The brain and spinal cord combine the input with other kids of information, compare it to information from past experiences, and make decisions about how to respond to the information.

Parts and Basic Operation of the Nervous System• Once the brain and spinal cord

determine an appropriate response to manage the new information, the output side is activated. The output side carries out the orders from the brain and spinal cord. The output side, often called the motor system, carries orders to all three types of muscles and to the body’s glands, telling them how to respond to the new information.

The Motor System• The motor system is divided into

two branches: the somatic nervous system, which controls skeletal muscle and voluntary movements, and the autonomic nervous system, which controls smooth and cardiac muscle in your organs and also several glands. Autonomic output is involuntary and not under conscious control.

• The autonomic nervous system is further divided into two branches: The parasympathetic and sympathetic.

The Autonomic Nervous System

• The Parasympathetic branch, often called “resting and digesting”, deals with normal body functioning.

• The Sympathetic branch, is the body’s alert system, commonly known as the “fight-or-flight” response system.

Nervous Tissue

• Like all organs, the components of the nervous system are made up of tissue.

• (This section is for the nursing students) But unlike other systems, the nervous system contains no epithelium, connective tissue, or muscle tissue. Nervous tissue is made up of two different types of cells:– Neuroglia– Neurons

Neuroglia

• The neuroglia or glial cells are specialized cells in nervous tissue that allow it to perform nervous system functions. In the CNS, there are four types of glial cells:

• ASTROCYTES• MICROGLIA• EPENDYMAL CELLS• OLIGODENDROCYTES

Neuroglia (CNS)

• Astrocytes: are metabolic and structural support cells that hold the neurons and blood vessels close together.

• Microglia: can attack microbes and remove debris.

• Ependymal cells: do the job of epithelial cells, covering surfaces and lining cavities.

• Oligodendrocytes: hold nerve fibers together and make a lipid insulation called myelin.

Neuroglia (PNS)• In the peripheral nervous system, there are only

two types of glial cells: Schwann Cells, which make myelin for the PNS, and satellite cells, which are support cells.

Neurons

• The glial cells do all the support activities for the nervous system, such as lining and covering cavities and supporting and protecting structures. None of the glial cells, however, are capable of measuring the environment, making decisions, or sending orders. All of the control functions of the nervous system must be carried out by a second group of cells called neurons.

Neurons• Neurons are rather bizarre-looking cells, often with many

branches and what appears to be a tail. The main function of a neuron is to transmit messages from one cell to another, throughout the body. Each part of a neuron has a specific function.

• The neuron cell body’s main function is that of cell metabolism.

• It’s dendrites receive information from the environment or from other cells that carry that information to the cell body.

• The axon generates and sends signals to other cells. Those signals travel down the axon until they reach the axon terminal, which then connects to a receiving cell. This space between the axon terminal and receiving cell is called a synapse. If the receiving cell is a skeletal muscle, the this particular synapse is called the neuromuscular synapse or junction.

Brain Anatomy and Physiology

• The Brain is divided into three main sections:The Cerebrum

The CerebellumBrain Stem

• The Cerebrum is the largest part of the brain, and is divided into two hemispheres, the right and left, and is divided by the longitudinal fissure. It is divided from the cerebellum (little brain) by the transverse fissure.

Brain Anatomy and Physiology• The brain is further divided into

four lobes, much like the major departments in a grocery store are separated by aisles.

• The lobes are named for the skull bones that cover them, and they occur in pairs, one in each hemisphere. The most anterior lobes, are the frontal lobes.

• Posterior to the frontal lobes are the parietal lobes.

• Posterior to the parietal lobes are the occipital lobes.

• The most inferior lobes are the temporal lobes.

Cerebral Hemispheres• There is a section of the brain,

the insula, deep inside the temporal lobes, which is often listed as the fifth lobe, but it is not visible on the surface of the cerebrum.

• Much of the information coming from your brain is contralateral, meaning that the left side of the body is controlled by the right side of your cerebrum, and the right side of the body is controlled by your left brain.

Cerebellum

• The cerebellum is posterior to the brain stem and plays an important role in sensory and motor coordination and balance. Its surface is also convoluted like that of the cerebrum. From its external appearance, it is easy to see why anatomists consider the cerebellum the “little brain”.

More Brain Anatomy

Forebrain(Proencephalon)

• In assessing the potential danger of drugs, society has become particularly conscious of their effects on human behavior. In fact, the first drugs to be regulated by law in the early years of the twentieth century were those deemed to have “habit-forming” properties. The early laws were aimed primarily at controlling opium and its derivatives, cocaine, and later, marijuana. The ability of a drug to induce dependence after repeated use is submerged in a complex array of physiological and social factors.

Drug Dependence

Drug Dependence• Dependence on drugs exists in numerous patterns and

in all degrees of intensity, depending on the nature of the drug, the route of administration, the dose, the frequency of administration, and the individual’s rate of metabolism. Furthermore, nondrug factors play an equally crucial role in determining the behavioral patterns associated with drug use. The personal characteristics of the user, his or her expectations about the drug experience, society’s attitudes and possible responses, and the setting in which the drug is used are all major determinants of drug dependence.

Drug Dependence

• The question of how to define and measure a drug’s influence on the individual and its danger to society is difficult to assess. The nature and significance of drug dependence must be considered from two overlapping points of view: – The interaction of the drug with the individual– The drugs impact on society

Psychological and Physical Dependence

• The common denominator that characterizes all types of repeated drug use is the creation of a psychological dependence for continued use of the drug.

• Not all drug users are hopeless “addicts”• Most users present quite a normal

appearance and remain both socially and economically integrated in the life of the community

Psychological and Physical Dependence

• The reasons why some people abstain from drugs while others become moderately of heavily involved are difficult if not impossible to delineate. Whatever the reasons, the underlying psychological needs and the desire to fulfill them create a conditioned pattern of drug abuse.– Desire to create a sense of Well Being– Escape from Reality

• Personal Problems• Stressful situations

– Sustaining a physical and emotional state of increased or enhanced performance

PSYCHOLOGICAL AND PHYSICAL DEPENDENCE

• The intensity of the psychological dependence associated with a drug’s use is difficult to define and largely depends on the nature of the drug used. For drugs such as alcohol, heroin, amphetamines, barbiturates, and cocaine, continued use will likely result in a high degree of involvement. Other drugs, such as marijuana and codeine, appear to have a considerably lower potential for the development of psychological dependence.

PSYCHOLOGICAL AND PHYSICAL DEPENDENCE

• Our general knowledge of alcohol consumption should warn us of the fallacy of generalizing when attempting to describe the danger of drug abuse. Obviously, not all alcohol drinkers are psychologically addicted to the drug; most are “social” drinkers who drink in reasonable amounts and on an irregular basis. Many people have progressed beyond this stage and consider alcohol a necessary crutch for dealing with life’s stresses and anxieties.

PSYCHOLOGICAL AND PHYSICAL DEPENDENCE

• Alcohol abusers exhibit a wide range of behavioral patterns, and to a large extent the determination of the degree of psychological dependence must be made individually. Likewise, it would be wrong to generalize that all users of marijuana can at worst develop a low degree of dependence on the drug. A wide range of factors also influence marijuana's effect, and heavy users of the drug expose themselves to the danger of developing a high degree of psychological dependence.

• Although emotional well-being is the primary motive leading to repeated and intensive drug use, certain drugs, taken in sufficient does and frequency, can produce physiological changes that encourage their continued use. Once the user abstains from such a drug, sever physical illness follows. The desire to avoid this withdrawal sickness, or abstinence syndrome, ultimately causes physical dependence , or addiction.

Physical Dependence

Physical Dependence

• Examples of Symptoms related to Abstinence Syndrome associated with Heroin:– Body Chills– Vomiting– Stomach Cramps– Convulsions– Insomnia– Pain– Hallucinations

Physical Dependence

• Some other of the more widely abused drugs have little or no potential for creating physical dependence. Drugs such as marijuana, LSD, and cocaine create strong anxieties when their repeated use is discontinued; however, no medical evidence attributes these discomforts to physiological reactions that accompany withdrawal sickness. On the other hand, use of alcohol, heroin, and barbiturates can result in development of physical dependence.

Delirium Tremens• Delirium Tremens is a severe form of alcohol withdrawal that

involves sudden and severe mental or nervous system changes.– Body Tremors– Changes in mental function

• Agitation• Confusion• Deep sleep that lasts for a day or longer• Delirium• Hallucinations• Sensitivity to light , sound, touch• Stupor, sleepiness, fatigue• Quick mood changes• Decreased attention span

– Seizures (generalized tonic-clonic seizures)– Symptoms of Alcohol Withdrawal