What is the nervous system?

Transcription

1 Nervous System

2 What is the nervous system? Made up of the brain, the spinal cord, and a large network of nerves that covers all parts of the body. Detects and responds to changes outside and inside our bodies (stimulus) Controls and coordinates all essential functions of the human body including all other body systems allowing us to maintain homeostasis.

3 Neurons Single nerve cells Carry information as tiny electrical signals (impulses/action potential)

4 Nerves Message pathway of the nervous system Made of many neurons connected together

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6 Flowchart of the Nervous System

7 Two Main Divisions Central nervous system. Peripheral nervous system.

8 Central Nervous System Brain Spinal Cord

9 Brain and Spinal Cord Receive and interpret sensory information. Sends impulses to and from the brain. High mental processing done by brain. Stores memories Generates thoughts and emotions Controls some reflexes

10 Brain and Spinal Cord Well protected Skull Vertebrae Meninges (protective membranes) Cerebrospinal fluid (fills space between layers to create a cushion)

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12 Peripheral Nervous System Neurons associated with the brain and spinal cord. Allows communication with the rest of the body.

13 Divided into two sections: Somatic Nervous System (SNS) Controls voluntary functions (skeletal muscles) When we think of doing something and then do it Autonomic Nervous System (ANS) Controls involuntary functions (smooth muscles, glands, organs) Breathing Heart beat Blinking Digestion

14 Autonomic NS divided further Sympathetic NS Fight-or-flight Prepares body for immediate threat (increase heart rate, breathing) Parasympathetic NS Rest-and-digest Conserves energy (slow heart rate, breathing)

15 Neurons (nerve cells) A signal can pass through a nerve cell with a speed of over 400 km/hr

16 Cell Body Nucleus Other basic cell parts. Controls cell s functions

17 Dendrites Carry impulse to the cell body from other neurons or the environment.

18 Axon Carries the impulse away from the cell body. To muscle cell, gland, or other nerve cell. Myelin sheath fatty layer that acts as insulation Prevents nerve impulses from leaking out Nodes of Ranvier Help speed up impulses

19 What is Multiple Sclerosis (MS)?

20 Axon Terminal Transmits impulse to next neuron No two neurons touch each other Synaptic gap (space separating the axon terminal of one neuron and the dendrites of another neuron)

21 3 Types of Neurons: Sensory Neurons Interneurons Motor Neurons

22 Sensory Neurons Sense a stimulus and send impulses to brain/spinal cord Found in sensory organs: Skin Tongue Ears Eyes Nose Muscles Lining of organs

23 Sensory Neurons Ex: chemoreceptors (chemicals) photoreceptors (light) mechanoreceptors (touch) thermoreceptors (temperature) auditory receptors (sound)

24 Interneurons Connect sensory neurons with motor neurons Found within spinal cord and brain Interpret information

25 Motor Neurons Carry impulses from brain/spinal cord to muscles and glands (effectors) of the body where they can carry out the command

26 Reflex Action The brain interprets most stimuli However, sometimes spinal cord interprets the signal and sends a response without consulting the brain. Such a reaction is called a reflex action. Ex: when you place your hand on a hot object you automatically or unconsciously respond by removing your hand immediately. Reflex action allows your body to react to drastic situations to prevent injury to the body.

27 Nerve Cell Facts Nerve cells cannot be replaced A baby is born with over one trillion neurons that grow as the baby grows Nerve cells begin to die as you age Nerve cells can be killed due to injury (brain damage/paralysis)

28 Questions 1. What is the difference between a nerve and a neuron? 2. What makes up the Central Nervous System? 3. What makes up the Peripheral Nervous System? 4. How is the nervous system protected? 5. What does the somatic nervous system do? 6. What does the autonomic nervous system do? 7. A bright light flashes in your eyes and you close them. Trace the path that the impulse takes through the nervous system. 8. Draw and label a neuron with these parts: cell body, dendrites, nucleus, axon, myelin sheath, nodes of Ranvier, axon terminal.

29 The Brain Controls all functions of the body Interprets information from the outside world Centre of intelligence, creativity, emotion, and memory

30 Brain Facts 2% of the body s weight (~3 lbs) Contains 15% of the body s blood supply Consumes 20% of the body s oxygen and glucose 100 billion neurons (roughly equal to the number of stars in our galaxy)

31 Structure Cerebrum, cerebellum, brainstem

32 The Cerebrum Largest part of the brain Right and left hemispheres Performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement.

33 The Cerebrum Cerebral cortex Outer layer where most information is processed (often called grey matter)

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35 Left Hemisphere more adept at language, math, and logic Right Hemisphere is stronger at pattern recognition, nonverbal thinking, and emotional processing

36 Cerebrum Left and right hemispheres joined by corpus collosum Transmits messages from one side to the other Each hemisphere controls the opposite side of the body If a stroke occurs on the right side of the brain, your left arm or leg may be weak or paralyzed.

37 Each side has 4 lobes

38 Frontal Lobe Personality, behavior, emotions Judgment, planning, problem solving Speech: speaking and writing Body movement Intelligence, concentration, self awareness

39 Parietal Lobe Receives and processes sensory information from the body including calculating location and speed of objects.

40 Occipital Lobe Processes visual data and routes it to other parts of the brain for identification and storage.

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42 Temporal Lobe Controls memory storage area, emotion, hearing, and, on the left side, language.

43 Cerebellum Coordinate muscle movements, maintains posture, and balance.

44 Brainstem Where the brain connects to the spinal cord. Controls many automatic functions (keeping the heart beating, breathing, and digesting food). Made up of the midbrain, pons, and medulla oblongata

45 Brainstem Midbrain Interprets auditory and visual information and regulates movement Pons Carries signals between various parts of the brain. Medulla Oblongata Controls several functions including breathing, cardiovascular activity, swallowing, vomiting, and digestion

46 Hypothalamus It also regulates body temperature, blood pressure, emotions, and secretion of hormones. Pituitary Gland Helps control growth, puberty, and other important functions. It does this by releasing hormones to different parts of the body.

47 How do neurons talk to one another? Synapse The point of communication between two neurons or between a neuron and a target cell

48 Synapse Nerve impulses cannot jump to the next neuron The impulse triggers the neuron to release chemical messengers called neurotransmitters. Drifts across the gap between the two neurons. On reaching the other side, it fits into a tailor-made receptor on the surface of the target neuron, like a key in a lock. This docking process converts the chemical signal back into an electrical nerve impulse.

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50 PA 1I

51 Optical Illusions

52 Optical Illusions Rabbit or duck?

53 Brain Training Reflex tests fi yuo cna raed tihs, yuo hvae a sgtrane mnid too. Cna yuo raed tihs? Olny 55 plepoe out of 100 can. i cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno t mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht the frsit and lsat ltteer be in the rghi t pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Azanmig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt! if you can raed tihs forwrad it.

54 Brain Training Say the colour, not the name.

55 Messages in our body Nervous system Responds quickly to stimulation through the use of electrical impulses and neurotransmitters Responses are quick but short-lived Endocrine System Responds to stimulation by secreting hormones into the circulatory system that travel to the target tissue Responses are slow but long lasting

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57 Endocrine System Collection of glands and the hormones they produce Regulates overall metabolism, homeostasis, growth, and reproduction Bloodstream carries hormones (chemical messengers) to the tissues of our body to cause a reaction

58 Teamwork The two systems work together Ex: When you run from danger, the NS controls your muscles and stimulates parts of the ES. The ES stimulates your heartbeat and respiration rate Together, the two systems provide the oxygen and energy you need

59 Glands Organs specialized in the secretion of substances needed by the organism Two types: Exocrine and endocrine

60 Glands Exocrine glands Secretions flow into ducts or tubes to where they are used

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62 Glands Endocrine glands Release secretions directly into bloodstream (ex: hormones).

63 Hormone Chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of the target organs.

64 Ex: Adrenaline Released by the adrenal gland Fight-or-flight response

65 How do hormones work? Endocrine glands produce hormones (chemical messengers) and secrete them into the bloodstream where they are distributed throughout the body.

66 How do hormones work? Although hormones are broadcast throughout the body, they affect only specific target cells. These target cells have receptors on the plasma membrane which recognize and bind to the hormone.

67 How do hormones work? The binding of hormone and receptor triggers the response in the target cell. Cells are unresponsive to a hormone if they do not have the appropriate receptors.

68 What are the different glands and what do they do?

69 Pituitary Gland Master gland -Secretes many important hormones and regulates the other glands Its actions are controlled by hypothalamus Growth hormone (GH) Promotes growth ADH Water balance

70 Hypothalamus Connects nervous system to the endocrine system Controls the release of hormones from the pituitary by telling it when to do so Controls body temperature, blood pressure, hunger, thirst, fatigue, sleep, and circadian cycles.

71 Hypothalamus

72 Pineal Gland Melatonin Controls your circadian rhythm (24-hour internal clock that cycles between sleepiness and alertness at regular intervals.

73 Thyroid Gland Absorbs iodine from bloodstream and produces T3/T4 hormones Regulates the rate of metabolism. Controls how fast the body uses up proteins, carbohydrates and fat for energy

74 Thyroid Gland

75 Thyroid Gland Hyperthyroidism hormone production is high Fast heartbeat, increased appetite, anxiety, sudden weight loss Hypothyroidism hormone production is low Slows metabolism, lead to weight gain and tiredness

76 Goiter Different thyroid disorders as well as a lack of iodine can lead to goiter (enlarged thyroid)

77 Parathyroid Works with thyroid to control calcium in the blood Calcitonin in thyroid, PTH in parathyroid

78 Thymus Gland Thymosin produces and matures T-cells. Shrinks after puberty and is replaced by fat

79 Pancreas Produce hormones insulin and glucagon Insulin lowers blood sugar Glucagon raises blood sugar

80 Remember Type 1 Diabetes The immune system attacks and destroys insulin producing cells in the pancreas, therefore you produce little or no insulin Type 2 Diabetes There is a problem on the insulin receptors on the cells, therefore the cells cannot take in glucose

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82 Symptoms frequent urination feeling very thirsty and drinking a lot feeling very hungry feeling very fatigued blurry vision

83 Why do people with diabetes tend to have poor circulation? Over time, high levels of blood glucose can damage blood vessels and cause plaque to build up.

84 Adrenal Glands Adrenaline(Epinephrine) secretes hormones for sudden stress. Fight-or-flight response Aldosterone Reabsorption of sodium in kidney

85 Adrenal Glands

86 Testes Testosterone Sperm production Development of male reproductive system Responsible fore secondary male characteristics.

87 Ovaries Estrogen Egg production Development of female reproductive system responsible for secondary female sex characteristics.

88 Female Reproductive Hormones

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90 How can we stop our brain from getting an infection? Blood-brain barrier (BBB) Layer of cells keeps your brain safe from pathogens and other toxins. highly selective permeable barrier

91 How can we stop our brain from getting an infection? Blood-brain barrier (BBB) Substances that the brain needs to survive (water, glucose, and amino acids) can get through the barrier. However, the barrier stops many harmful things, like bacteria and viruses, from getting into the brain.

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93 How can we stop our brain from getting an infection? w

94 Concussions A violent blow to your head that can cause your brain to slide back and forth forcefully against the inner walls of your skull.

95 Concussions Different degrees of severity, from symptoms lasting less than 15 minutes to loss of consciousness Symptoms can last days, weeks, or longer

96 What are the symptoms of a concussion? confusion or feeling dazed clumsiness slurred speech nausea or vomiting headache balance problems or dizziness blurred vision sensitivity to light sensitivity to noise sluggishness ringing in ears behavior or personality changes concentration difficulties memory loss

97 Delayed Symptoms Concentration and memory complaints Irritability and other personality changes Sensitivity to light and noise Sleep disturbances Psychological adjustment problems and depression Disorders of taste and smell

98 Concussions Second impact syndrome Condition in which the brain swells rapidly and catastrophically after a person suffers a second concussion before symptoms from an earlier one have subsided Cuts off flow of fresh blood to brain 50% of the individuals with SIS die Second blow can be mild

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100 After suffering a concussion, should an athlete be sidelines for the rest of the season?

101 Drugs and the Brain z6m SYI

102 Lack of Sleep and the Brain vy

103 Steroids and the Brain Fo4

104 Diet and the Brain Vk ors8 I