Nervous System Intro 2023 PDF

The Human Nervous System Your nervous system is constantly at work as your senses detect and respond to changes in the environment. Nervous system works with other systems, especially in times of stress… or competition!  What’s Happening? You hear your friend...

The Human Nervous System Your nervous system is constantly at work as your senses detect and respond to changes in the environment. Nervous system works with other systems, especially in times of stress… or competition!  What’s Happening? You hear your friend’s voice(used your senses) electrical signal sent through nerves in ears to the brain🡪 brain interprets the information 🡪 sent electrical signal to muscles 🡪 you respond by turning your head, or walking toward them This all happens in the blink of an eye, thanks to your nervous system. How Does this Happen? Electrical impulses (or messages) are sent through NEURONS, (specialized cells of your nervous system) that help you detect and respond to changes in your environment  How Does this Happen? NEURONS connect end to end, forming long fibrous chains called NERVES which transmit messages throughout your body Messages are transmitted from nerves to your brain and back through your body using two systems (CNS and PNS)  2 DIVISIONS: CNS and PNS 1. CNS – Central Nervous System Made up of your brain and spinal cord The ultimate processor, divided Thickness of a into 2 pencil, relays hemispheres, messages from receives and nerves to brain interprets and back information, controls many bodily functions A Closer look at the Brain 2 hemispheres, divided into four lobes (cerebrum) Contains 9 billion neurons Receives 25% of blood pumped from the heart Left side controls right half of body, and vice versa https://www.yout Weighs about 1.2 kg ube.com/watch? v=pUOG2g4hj8s A Closer look at the Brain: The Cerebral Cortex  PNS 2. Peripheral Nervous System Sends messages to and from the CNS Sensory neurons detect changes in the environment and motor neurons respond to them (muscles and glands react in response) Ex: You smell a delicious Big Mac combo that the person next to you is eating, so you turn to look at it and smile!  PNS The motor neurons of the peripheral nervous system have two divisions: Autonomic and Somatic Autonomic – influences the function of internal organs and glands (involuntary and happens unconsciously) 🡪 within the brain is controlled by the hypothalamus Sympathetic (“fight or flight”) Parasympathetic (“rest and digest”)  PNS Somatic – voluntary control of skeletal muscles and movement Motor neurons influence movement of skeletal muscles via nerve impulses - The Neural Pathway  If Someone Shouts Your Name… Sensory neurons (afferent neurons) (PNS) detect a stimulus in the environment using your senses (taste, touch, smell, etc) and send a message via an electrical impulse through nerves to your CNS (brain and spinal cord). Interneurons (relay neurons) (CNS) Here, the message is transmitted by the spinal cord, and they are processed by specialized regions of the brain. The message is interpreted, and then responded to. Motor neurons (efferent neurons) (PNS) will receive signals from the interneurons, and in response, an impulse will travel through motor neurons to glands or muscles (effectors) to produce a response. Neural Pathway  Homework H.W: Complete glossary of terms, and answer Q’s # 1 – 6 on page 417.  Activity: Testing Your Reaction Time Work in groups of 3 Need a stopwatch and meter stick Discussion and analysis in 15 – 20 minutes