Transcript Chapter 18
Chapter 20 Human Nervous System Regulation Is achieved by both the nervous system and the endocrine system in humans *Both systems secrete chemicals and play a major role in homeostasis Neurons The nervous system is made up of nerve cells called neurons Neurons are used for the transmission of impulses (message) Three types of neurons: Sensory neurons Interneuron Motor neuron http://psych.hanover.edu/Krantz/neurotut.html Sensory neuron Transmit impulses from the sense organs (receptors) to the spinal cord Sense organs include eyes, ears, tongue, nose, and skin Interneuron Found in the spinal cord and brain Transmit impulses from the sensory neuron to the motor neurons Motor neuron Transmit impulses from the brain and spinal cord to effectors (muscle or gland) Reflex Arc The difference between both: Nervous System Endocrine System Nerve responses Endocrine are more rapid responses are of a (neurons) than the longer duration endocrine system than that of nerve (blood) responses (II) Central Nervous System Consist of a brain and spinal cord A) Brain The most active organ in the body Receives 20% of the blood pumped by the heart Is a large mass of neurons located in the cranium (skull) Three major division: Cerebrum Cerebellum Medulla Oblongata The Human Brain A) Brain Note that the brain is convoluted or folded. The convolutions of the brain allow for a greater surface area for gray matter. Cerebrum Largest part of the brain Center of control for: a) voluntary body movements b) 5 senses c) memory (learning + thought) Cerebrum Divided into left and right hemispheres. Outer layer of the cerebrum is the cortex (cerebral cortex). Different areas are responsible for different functions. Brain Scans PET scan on the left shows two areas of the brain (red and yellow) that become particularly active when volunteers read words on a video screen: the primary visual cortex and an additional part of the visual system, both in the back of the left hemisphere. Other brain regions become especially active when subjects hear words through ear-phones, as seen in the PET scan on the right. Cerebellum Coordinates motor activities (voluntary movement) Aids in maintaining balance Medulla Involuntary activities like breathing and heartbeat B) Spinal Cord Extends from the brain and is protected by the vertebrae of the spinal column. Is not the backbone or spine. The spinal cord coordinates activities between the brain and other body structures B) Spinal Cord It is the center for reflex action a) a reflex is an involuntary, automatic response to a given stimulus b) reflex behavior involves a pathway known as the reflex arc over which impulses travel C) Peripheral Nervous System Consist of nerves extending throughout the body Is separated into 2 parts: Autonomic Nervous System Somatic Nervous System Autonomic Nervous System Consists of nerves that regulate involuntary actions like heartbeat and gland secretions Somatic Nervous System Consist of nerves that regulate voluntary muscles of the skeleton http://www.illusionworks.com/html/breathing_square.html http://www.illusionworks.com/html/color_aftereffect.html http://www.illusionworks.com/html/motion_aftereffect.html http://www.illusionworks.com/html/shadow.html Olfactory senses "The VNO appears to be a much more primitive structure that uses a different set of molecular machinery than the main olfactory system ," Disorders of the Nervous System Cerebral Palsy A group of diseases caused by damage to the parts of the brain that control voluntary movement This damage occurs during embryonic development Meningitis Inflammation of the membrane that surrounds the brain and spinal cord Stroke A disorder in which the brain is damaged as a result of cerebral hemorrhage (a broken vessel in the brain) or a blood clot in a blood vessel located in the brain Polio A viral disease of the central nervous system which may result in paralysis It is now prevented through immunization What is Alzheimer's? Is a progressive and fatal brain disease. More than 5 million Americans now have Alzheimer’s disease. Alzheimer's destroys brain cells, causing problems with memory, thinking and behavior severe enough to affect work, lifelong hobbies or social life. Alzheimer’s gets worse over time, and it is fatal. Today it is the seventh-leading cause of death in the United States. http://alz.org/alzheimers_disease_what_is_alzheimers.asp What is Alzheimer's? Alzheimer’s disease leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all its functions. http://alz.org/alzheimers_disease_what_is_alzheimers.asp What is Alzheimer's? Alzheimer tissue has many fewer nerve cells and synapses than a healthy brain. Plaques, abnormal clusters of protein fragments, build up between nerve cells. Dead and dying nerve cells contain tangles, which are made up of twisted strands of another protein. Scientists are not absolutely sure what causes cell death and tissue loss in the Alzheimer brain, but plaques and tangles are prime suspects. http://alz.org/alzheimers_disease_what_is_alzheimers.asp What is Alzheimer's? Some change in memory is normal as we grow older, but the symptoms of Alzheimer’s disease are more than simple lapses in memory. People with Alzheimer’s experience difficulties communicating, learning, thinking and reasoning — problems severe enough to have an impact on an individual's work, social activities and family life. What is Alzheimer's? Age Family history (genetics) Scientists have so far identified one Alzheimer risk gene called apoliprotein Ee4 (APOE-e4). Major head trauma Continuous head trauma What is Parkinson disease? Parkinson disease is a brain disorder. It occurs when certain nerve cells (neurons) in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce a vital chemical known as dopamine. Dopamine allows smooth, coordinated function of the body's muscles and movement. When approximately 80% of the dopamine-producing cells are damaged, the symptoms of Parkinson disease appear. What is Parkinson disease? What are the signs and symptoms of Parkinson disease? The loss of dopamine production in the brain causes the primary symptoms of Parkinson disease. The key signs of Parkinson disease are: Tremor (shaking) Slowness of movement Rigidity (stiffness) Difficulty with balance Other signs of Parkinson disease may include: Small, cramped handwriting Stiff facial expression Shuffling walk Muffled speech Depression