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Unit 1 Lesson 5 The Nervous and Endocrine Systems Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems Brainiac! What is the function of the nervous system? • The nervous system is made up of the structures that control actions and reactions of the body in response to stimuli in the environment. • The nervous system has two parts: the central nervous system (CNS) and the peripheral nervous system (PNS). Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What is the function of the nervous system? • The CNS is made up of the brain and spinal cord. • The brain is the body’s central command organ. • The spinal cord allows the brain to communicate with the rest of the body. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What is the function of the nervous system? • The PNS connects the CNS to the rest of the body. • Involuntary processes are those you have no control over, such as your heart beating. • Voluntary processes are actions your brain can control, such as moving an arm or a leg. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of the CNS? • The CNS is made up of the brain and the spinal cord. • The cerebrum is the largest part of the brain. It is where you think, solve problems, and store memories. • The cerebrum controls voluntary movements and processes information from your senses. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of the CNS? • The cerebellum processes information from your body, keeps track of body position, and coordinates movements. • The brain stem connects your brain to the spinal cord. • A part of the brain stem called the medulla controls involuntary processes in the body. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of the CNS? • Describe the part of the brain that made one activity that you did today possible. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of the CNS? • The spinal cord is a bundle of nerves protected by bones called vertebrae. • Nerves are a collection of nerve-cell extensions bundled together with blood vessels and connective tissue. • The spinal cord carries messages to and from the brain. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems You’ve Got Nerves! How do signals move through the nervous system? • The nervous system translates environmental information into electrical signals. • A neuron is a special cell that moves messages in the form of fast-moving electrical energy. • These messages are called impulses. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems How do signals move through the nervous system? • Signals move through the CNS and PNS with the help of glial cells that protect and support neurons. • Sensory neurons gather information from in and around your body and move it to the brain. • Motor neurons move impulses from the brain and spinal cord to other parts of the body. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of a neuron? • The cell body of a neuron has a nucleus and organelles. • A dendrite is a typically short, branched extension of the cell body. • The cell body gathers information from dendrites and creates an impulse. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of a neuron? • An axon is an extension of the neuron that carries impulses away from the cell body. • A neuron has only one axon. • At the end of the axon is the axon terminal that changes the electrical signal to a chemical signal, or neurotransmitter. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the parts of a neuron? • How is a message transformed from an electrical message to a chemical message in a neuron? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems That Makes Sense! What are the main senses? • The sensory organs sense the environment around you. • Sight allows you to see objects, motion, and light. • The front of the eye is protected by a membrane called the cornea. • Light passes through an opening called the pupil. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the main senses? • Light-sensitive receptor cells, called rods and cones, in the retina change light into electrical impulses that are sent to the brain. • Impulses travel to your brain, creating an awareness of touch called a sensation. • The skin has different kinds of receptors that detect pressure, temperature, pain, and vibration. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the main senses? • Hearing happens when sound-wave vibrations are turned into electrical impulses in the ear. • Sound is funneled through the outer ear, making the eardrum vibrate. • Tiny bones in the ear vibrate, causing the fluid in the cochlea to move in waves. • Hair cells in the fluid cause neurons to send electrical impulses to the brain via the auditory nerve. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are the main senses? • The tongue is covered with taste buds that contain taste cells. They respond to signals in dissolved molecules in food. • Olfactory cells react to chemicals in the air that dissolve in the lining of the nasel cavity, triggering signals. • The nose sends signals to the brain for processing taste and smell. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems Keep Your Cool! What is the function of the endocrine system? • The endocrine system controls body functions and helps maintain homeostasis by using hormones. • A hormone is a chemical messenger made in one cell or tissue that causes a change in another cell or tissue elsewhere in the body. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems How do hormones work? • Hormones are produced by endocrine glands or tissues and travel through the bloodstream. • A gland is a group of cells that make special chemicals in your body. • Hormones only affect specific target cells that have a specific receptor to that hormone. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What glands make up the endocrine system? • The pituitary gland secretes hormones that control other glands. • The hypothalamus controls the release of hormones from the pituitary gland. • The pineal gland makes hormones that control sleep, aging, reproduction, and body temperature. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What glands make up the endocrine system? • The thyroid gland controls metabolism. • The parathyroid gland controls calcium in the blood. • Reproductive hormones control reproduction. • The pancreas regulates blood-sugar levels. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems Feedback How are hormone levels controlled? • The endocrine system helps maintain homeostasis by increasing or decreasing hormone levels. • The endocrine system uses feedback to maintain homeostasis. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems How are hormone levels controlled? • A feedback mechanism is a cycle of events in which information from one step controls or affects a previous step. • In negative feedback, the effects of a hormone cause the release of that hormone to be turned down. • In positive feedback, the effects of a hormone stimulate the release of more of that hormone. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 1 Lesson 5 The Nervous and Endocrine Systems What are disorders of the endocrine and nervous systems? • Hormone imbalances can happen when the endocrine system makes too much or too little of a hormone. • Type 1 diabetes is caused by a hormone imbalance. • Parkinson’s disease, multiple sclerosis, and spinalcord injuries are disorders of the nervous system. Copyright © Houghton Mifflin Harcourt Publishing Company