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Section 36.1 Summary – pages 943 - 950 Neurons conduct impulses throughout the nervous system. Neurons: Basic Units of the Nervous System Dendrite Axon.

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Presentation on theme: "Section 36.1 Summary – pages 943 - 950 Neurons conduct impulses throughout the nervous system. Neurons: Basic Units of the Nervous System Dendrite Axon."— Presentation transcript:

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2 Section 36.1 Summary – pages Neurons conduct impulses throughout the nervous system. Neurons: Basic Units of the Nervous System Dendrite Axon Myelin sheath Axon endings Cell body Nucleus

3 Section 36.1 Summary – pages A neuron is a long cell that consists of three regions: a cell body, dendrites, and an axon. Neurons: Basic Units of the Nervous System Dendrite Axon Myelin sheath Axon endings Cell body Nucleus

4 Section 36.1 Summary – pages Dendrites are branchlike extensions of the neuron that receive impulses and carry them toward the cell body. Neurons: Basic Units of the Nervous System Dendrite Axon Myelin sheath Axon endings Cell body Nucleus

5 The axon is an extension of the neuron that carries impulses away from the cell body and toward other neurons, muscles, or glands. Section 36.1 Summary – pages Neurons: Basic Units of the Nervous System Dendrite Axon Myelin sheath Axon endings Cell body Nucleus

6 Section 36.1 Summary – pages Neurons fall into three categories: sensory neurons, motor neurons, and interneurons. Neurons: Basic Units of the Nervous System Sensory neurons carry impulses from the body to the spinal cord and brain.

7 Section 36.1 Summary – pages Interneurons are found within the brain and spinal cord. Neurons: Basic Units of the Nervous System Interneuron Spinal cord Receptor in skin Motor neuron Sensory neuron Direction of impulse Muscle contracts

8 Section 36.1 Summary – pages Neurons: Basic Units of the Nervous System Motor neurons carry the response impulses away from the brain and spinal cord to a muscle or gland. Interneuron Spinal cord Receptor in skin Motor neuron Sensory neuron Direction of impulse Muscle contracts

9 Section 36.1 Summary – pages The nervous system sorts and interprets incoming information before directing a response. Relaying an impulse

10 Section 36.1 Summary – pages A neuron at rest Plasma membrane Outside cell Open ion channel Gated Na+ channel Open ion channel Gated Na+ channel Na+/K+ pump

11 Section 36.1 Summary – pages Motor Neuron NA K Pump Click image to view movie.

12 Section 36.1 Summary – pages Under these conditions, which exist when the cell is at rest, the plasma membrane is said to be polarized. A neuron at rest A polarized membrane has the potential to transmit an impulse.

13 Section 36.1 Summary – pages When a stimulus excites a neuron, gated sodium channels in the membrane open up and sodium ions rush into the cell. How an impulse is transmitted As the positive sodium ions build up inside the membrane, the inside of the cell becomes more positively charged than the outside. This change in charge, called depolarization, moves like a wave down the length of the axon.

14 Section 36.1 Summary – pages How an impulse is transmitted K Gated K+ channelOutside cell Na+ Gated Na+ channel Inside cell + +

15 Section 36.1 Summary – pages How an impulse is transmitted K Na+ Gated Na+ channel Gated K+ channel K+ Impulse Gated Na+ channel Na+Na+/K+ pump

16 Section 36.1 Summary – pages How an impulse is transmitted Gated K+ channel Impulse Gated Na+ channel Na+/K+ pump 3Na+

17 Section 36.1 Summary – pages How an impulse is transmitted Click image to view movie.

18 Section 36.1 Summary – pages Most axons are surrounded by a white covering of cells called the myelin sheath. White matter and gray matter Myelin sheath

19 Section 36.1 Summary – pages The myelin sheath insulates the axon, hindering the movement of ions across its plasma membrane. White matter and gray matter The ions move quickly down the axon until they reach a gap in the sheath.

20 Section 36.1 Summary – pages Here, the ions pass through the plasma membrane of the nerve cell and depolarization occurs. White matter and gray matter As a result, the impulse jumps from gap to gap, greatly increasing the speed at which it travels.

21 Section 36.1 Summary – pages The myelin sheath gives axons a white appearance. White matter and gray matter In the brain and spinal cord, masses of myelinated axons make up what is called white matter. The absence of myelin in masses of neurons accounts for the grayish color of gray matter in the brain.

22 Section 36.1 Summary – pages Connections between neurons Dendrite Axon Impulse Synapse Impulse Dendrite Axon

23 Section 36.1 Summary – pages Connections between neurons Dendrite Axon Impulse Synapse Impulse Dendrite Axon Dendrite Vesicle with neurotransmitters inside Vesicle fuses with membrane (exocytosis) Calcium channel Neurotransmitter diffuses across synapse and binds with receptor on dendrite Synaptic space Neurotrans- mitters released into synapse

24 Section 36.1 Summary – pages The Central Nervous System Cerebrum Skull Medulla oblongata Cerebellum Spinal cord Vertebra

25 Section 36.1 Summary – pages Two systems work together Another division of your nervous system, called the peripheral nervous system, is made up of all the nerves that carry messages to and from the central nervous system.

26 Section 36.1 Summary – pages Two systems work together Together, the central nervous system (CNS) and the peripheral nervous system (PNS) respond to stimuli from the external environment. Brain Spinal cord

27 Section 36.1 Summary – pages Motor area Sensory area Language area Vision area General interpretation area Cerebrum Speech area Taste area Intellect, learning, and personality Hearing area Brain stem Cerebellum Balance area Anatomy of the brain

28 Section 36.1 Summary – pages The brain stem is made up of the medulla oblongata, the pons, and the midbrain. Midbrain Cerebellum Medulla oblongata Pons Anatomy of the brain

29 Section 36.1 Summary – pages Anatomy of the brain The medulla oblongata is the part of the brain that controls involuntary activities such as breathing and heart rate. Midbrain Cerebellum Medulla oblongata Pons

30 Section 36.1 Summary – pages The pons and midbrain act as pathways connecting various parts of the brain with each other. Midbrain Cerebellum Medulla oblongata Pons Anatomy of the brain

31 Section 36.1 Summary – pages The Peripheral Nervous System The peripheral nervous system can be separated into two divisionsthe somatic nervous system and the autonomic nervous system.

32 Section 36.1 Summary – pages The somatic nervous system The somatic nervous system is made up of 12 pairs of cranial nerves from the brain, 31 pairs of spinal nerves from the spinal cord, and all of their branches. Brain (CNS) Spinal cord (CNS) Spinal nerves (PNS)

33 Section 36.1 Summary – pages The somatic nervous system The nerves of the somatic system relay information mainly between your skin, the CNS, and skeletal muscles. Brain (CNS) Spinal cord (CNS) Spinal nerves (PNS)

34 Section 36.1 Summary – pages The somatic nervous system This pathway is voluntary, meaning that you can decide whether or not to move body parts under the control of this system. Brain (CNS) Spinal cord (CNS) Spinal nerves (PNS)

35 Sensory neuron Direction of impulse Motor neuron Flexor muscle contracts and withdraws part being stimulated Pain receptors in skin Section 36.1 Summary – pages Reflexes in the somatic system

36 Section 36.1 Summary – pages The autonomic nervous system The autonomic nervous system carries impulses from the CNS to internal organs. These impulses produce responses that are involuntary, or not under conscious control.

37 Section 36.1 Summary – pages The autonomic nervous system There are two divisions of the autonomic nervous systemthe sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system controls many internal functions during times of stress.

38 Section 36.1 Summary – pages The sympathetic nervous system causes the release of hormones, such as epinephrine and norepinephrine, that results in the fight-or-flight response. A fight-or-flight response can occur when you see a rattlesnake. The autonomic nervous system

39 Section 36.1 Summary – pages The autonomic nervous system The parasympathetic nervous system on the other hand, controls many of the bodys internal functions when it is at rest. Both the sympathetic and parasympathetic systems send signals to the same internal organs.

40 Section 36.1 Summary – pages Central Nervous System (CNS) Peripheral Nervous System (PNS) Somatic Nervous System (voluntary) Relays information to and from skin and skeletal muscles. Nervous System Autonomic Nervous System (involuntary) Relays information to internal organs. Sympathetic Nervous System Controls organs in times of stress. Parasympathetic Nervous System Controls organs when body is at rest The autonomic nervous system

41 Section 36.2 Summary – pages Sensing Chemicals Olfactory nerve Olfactory bulb Olfactory nerve receptors Taste bud Sensory neuron Smell Molecules Taste Molecules

42 Section 36.2 Summary – pages Sensing Chemicals Tastes that you experience can be divided into four basic categories: sour, salty, bitter, and sweet. As seen with the sequence of electrochemical changes a neuron undergoes as it is depolarized, each of the different tastes produces a similar change in the cells of taste buds.

43 Section 36.2 Summary – pages Sensing Chemicals As these cells are depolarized, signals from your taste buds are sent to the cerebrum. There, the signal is interpreted and you notice a particular taste.

44 Section 36.2 Summary – pages Sensing Light Sclera Choroid Retina Optic nerve Iris Lens Light Pupil Cornea

45 Section 36.2 Summary – pages Sensing Light The retina contains two types of light receptor cellsrods and cones. Rods are receptor cells adapted for vision in dim light. They help you detect shape and movement.

46 Section 36.2 Summary – pages Sensing Light At the back of the eye, retinal tissue comes together to form the optic nerve, which leads to the brain, where images are interpreted. Cones are receptor cells adapted for sharp vision in bright light. They also help you detect color.

47 Section 36.2 Summary – pages The Eye Visual cortex in cerebrum Top view of brain Optic nerve Lens Retina Rod and cone cells Visual field Depth perception Brain image projections

48 Section 36.2 Summary – pages Eye Structure and Function Click image to view movie.

49 Section 36.2 Summary – pages Sensing Mechanical Stimulation Hearing and touch, depend on receptors that respond to mechanical stimulation.

50 Middle ear Section 36.2 Summary – pages Ear canal Eardrum MalleusIncusStapes Semicircular canals Auditory nerve Oval window Cochlea Your sense of hearing Outer ear Inner ear

51 Section 36.2 Summary – pages Ear Structure and Function Click image to view movie.

52 Section 36.2 Summary – pages Your sense of balance The inner ear converts information about the position of your head into nerve impulses which travel to your brain, informing it about your bodys equilibrium.

53 Section 36.2 Summary – pages Your sense of balance Body upright Head upright Body rotatingHead tilted Semicircular canals Gel-like fluid Hair cells Crista ampullaris Maculae Gel-like fluid Fluid Hair cells

54 Section 36.2 Summary – pages Your sense of touch Free nerve ending Heat Light Touch Cold Hair Shaft Opening of sweat gland Heavy pressure

55 Section 36.3 Summary – pages A drug is a chemical that affects the bodys functions. Drugs Act on the Body Most drugs interact with receptor sites on cells.

56 Section 36.3 Summary – pages Drugs Act on the Body Axon Dendrite Increased synthesis Increased release Synaptic space Decreased enzymatic breakdown

57 Section 36.3 Summary – pages A medicine is a drug that, when taken into the body, helps prevent, cure, or relieve a medical problem. Medicinal Uses of Drugs

58 Section 36.3 Summary – pages Medicines that relieve pain manipulate either the receptors that initiate the impulses or the central nervous system that receives them. Relieving pain

59 Section 36.3 Summary – pages Pain relievers that do not cause a loss of consciousness are called analgesics. Relieving pain Some analgesics, like aspirin, work by inhibiting receptors at the site of pain from producing nerve impulses.

60 Section 36.3 Summary – pages Analgesics that work on the central nervous system are called narcotics. Many narcotics are made from the opium poppy flower. Relieving pain

61 Section 36.3 Summary – pages Opiates, as they are called, can be useful in controlled medical therapy because these drugs are able to relieve severe pain from illness or injury. Relieving pain

62 Section 36.3 Summary – pages Many drugs have been developed to treat heart and circulatory problems such as high blood pressure. Treating circulatory problems These medicines are called cardiovascular drugs.

63 Section 36.3 Summary – pages Treating circulatory problems In addition to treating high blood pressure, cardiovascular drugs may be used to normalize an irregular heartbeat, increase the hearts pumping capacity, or enlarge small blood vessels.

64 Section 36.3 Summary – pages Treating nervous disorders Drugs that increase the activity of the central and sympathetic nervous systems are called stimulants. Amphetamines (am FE tuh meenz) are synthetic stimulants that increase the output of CNS neurotransmitters. Because they increase wakefulness and alertness, amphetamines are sometimes used to treat patients with sleep disorders.

65 Section 36.3 Summary – pages Treating nervous disorders Drugs that lower, or depress, the activity of the nervous system are called depressants, or sedatives. The primary medicinal uses of depressants are to encourage calmness and produce sleep.

66 Section 36.3 Summary – pages The Misuse and Abuse of Drugs Drug misuse occurs when a medicine is taken for an unintended use. Giving your prescription medicine to someone else, not following the prescribed dosage by taking too much or too little, and mixing medicines, are all instances of drug misuse.

67 Section 36.3 Summary – pages The Misuse and Abuse of Drugs Drug abuse is the inappropriate self- administration of a drug for non medical purposes. Drug abuse may involve use of an illegal drug, such as cocaine; use of an illegally obtained medicine, such as someone elses prescribed drugs; or excessive use of a legal drug, such as alcohol or nicotine.

68 Section 36.3 Summary – pages Addiction to drugs When a person believes he or she needs a drug in order to feel good or function normally, that person is psychologically dependent on the drug. When a persons body develops a chemical need for the drug in order to function normally, the person is physiologically dependent. Psychological and physiological dependence are both forms of addiction.

69 Section 36.3 Summary – pages Tolerance and withdrawal Tolerance occurs when a person needs larger or more frequent doses of a drug to achieve the same effect. The dosage increases are necessary because the body becomes less responsive to the drug. Withdrawal occurs when the person stops taking the drug and actually becomes ill.

70 Section 36.3 Summary – pages Classes of Commonly Abused Drugs Each class of drug produces its own special effect on the body, and its own particular symptoms of withdrawal.

71 Section 36.3 Summary – pages Table 36.1 Commonly Abused Drugs Category Substance Commercial or Street NamePotential Health Hazard Cannabinoid Stimulants Depressants Hallucinogens Opioids Other Marijuana Cocaine Methylphenidate Nicotine Methamphetamine MDMA Benzodiazepines Barbiturates LSD Heroin Inhalants Anabolic steroids Ketamine Grass, joints, pot, reefer, weed Blow, coke, crack, rock Ritalin, Skippy, vitamin R Chew, cigarettes, cigars Ice, speed, glass Ecstasy, Eve Librium, Valium, Xanax, downers, sleeping pills Barbs, red birds, yellows Cubes, microdot H, junk, skag, smack Paint thinners, gasoline, butane, nitrates, laughing gas Juice Special K, vitamin K Respiratory problems, impaired learning Increased heart rate and blood pressure, irregular heart beat, heart failure, and weight loss Respiratory depression and arrest, lowered blood pressure, poor concentration Chronic mental disorders, nausea, flashbacks Respiratory depression and arrest, collapsed veins Headache, nausea, vomiting, unconsciousness, sudden death Liver and kidney cancer, acne, high blood pressure Respiratory depression and arrest, nausea, vomiting

72 Section 36.3 Summary – pages Cocaine stimulates the CNS by working on the part of the inner brain that governs emotions and basic drives, such as hunger and thirst. Cocaine artificially increases levels of neurotransmitters in the brain. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

73 Section 36.3 Summary – pages The user quickly feels a euphoric high called a rush. This sense of intense pleasure and satisfaction cannot be maintained, however, and soon the effects of the drug change. As a result, false messages are sent to reward centers indicating that a basic drive has been satisfied. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

74 Section 36.3 Summary – pages Cocaine also disrupts the bodys circulatory system by interfering with the sympathetic nervous system. Physical hyperactivity follows. Often, anxiety and depression set in. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

75 Section 36.3 Summary – pages The result is high blood pressure. Although initially causing a slowing of the heart rate, it soon produces a great increase in heart rate and a narrowing of blood vessels, known as vasoconstriction. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

76 Section 36.3 Summary – pages Other adverse side effects of amphetamine abuse include irregular heartbeat, chest pain, paranoia, hallucinations, and convulsions. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

77 Section 36.3 Summary – pages Caffeinea substance found in coffee, some carbonated soft drinks, cocoa, and teais a CNS stimulant. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

78 Section 36.3 Summary – pages Caffeine also causes an increase in heart rate and urine production, which can lead to dehydration. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

79 Section 36.3 Summary – pages Nicotine, a substance found in tobacco, is also a stimulant. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

80 Section 36.3 Summary – pages By increasing the release of the hormone epinephrine, nicotine increases heart rate, blood pressure, breathing rate, and stomach acid secretion. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

81 Section 36.3 Summary – pages Although nicotine is the addictive substance in tobacco, there are many other harmful chemicals found in tobacco products. Smoking cigarettes leads to an increased risk of lung cancer and cardiovascular disease. Stimulants: Cocaine, amphetamines, caffeine, and nicotine

82 Section 36.3 Summary – pages Depressants: Alcohol and barbiturates One of the most widely abused drugs in the world today is alcohol. This depressant is distributed throughout a persons body via the bloodstream.

83 Alcohol also appears to block the movement of sodium and calcium ions across the cell membrane, a process that is important in the transmission of impulses and the release of neurotransmitters. Section 36.3 Summary – pages Depressants: Alcohol and barbiturates

84 Addiction to alcoholalcoholismcan cause the destruction of nerve cells and brain damage. Section 36.3 Summary – pages Cirrhosis, a hardening of the tissues of the liver, is a common affliction of alcoholics. Depressants: Alcohol and barbiturates

85 Barbiturates (bar BIH chuh ruts) are sedatives and anti-anxiety drugs. Section 36.3 Summary – pages When barbiturates are used in excess, the users respiratory and circulatory systems become depressed. Chronic use results in addiction. Depressants: Alcohol and barbiturates

86 Most narcotics are opiates. Section 36.3 Summary – pages Narcotics: Opiates They act directly on the brain. The most abused narcotic in the United States is heroin. It depresses the CNS, slows breathing, and lowers heart rate. Tolerance develops quickly, and withdrawal from heroin is painful.

87 Hallucinogens stimulate the CNSaltering moods, thoughts, and sensory perceptions. Section 36.3 Summary – pages Hallucinogens: Natural and synthetic Some hallucinogens are found in nature.

88 This disorientation can impair the users judgment and place him or her in a potentially dangerous situation. Section 36.3 Summary – pages The user sees, hears, feels, tastes, or smells things that are not actually there. Hallucinogens: Natural and synthetic

89 Section 36.3 Summary – pages Hallucinogens also increase heart rate, blood pressure, respiratory rate, and body temperature, and sometimes cause sweating, salivation, nausea, and vomiting. After large enough doses, convulsions of the body may even occur. Hallucinogens: Natural and synthetic

90 Section 36.3 Summary – pages LSDor acidis a synthetic drug. The mechanism by which LSD produces hallucinations is still debated, but it may involve the blocking of a CNS neurotransmitter. Hallucinogens: Natural and synthetic

91 Section 36.3 Summary – pages Anabolic steroids are synthetic drugs that are similar to the hormone testosterone. Anabolic steroids

92 Section 36.3 Summary – pages Anabolic steroids Anabolic steroids stimulate muscles to increase in size. Physicians use anabolic steroids in the treatment of hormone imbalances or diseases that result in a loss of muscle mass. Abuse of anabolic steroids is associated with infertility in men, high cholesterol, and extreme mood swings.

93 Section 36.3 Summary – pages Breaking the Habit Once a person has become addicted to a drug, breaking the habit can be very difficult. Besides the desire to break the addiction, studies have shown that people usually need both medical and psychological therapysuch as counselingto be successful in their treatment.

94 Section 36.3 Summary – pages Nicotine replacement therapy Nicotine replacement therapy is one example of a relatively successful drug treatment approach.

95 Section 36.3 Summary – pages Nicotine replacement therapy To ease the intensity of the withdrawal symptoms, patients wear adhesive patches that slowly release small amounts of nicotine into their bloodstream. Alternatively, pieces of nicotine-containing gum are chewed periodically to temporarily relieve cravings.


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