1、The Nervous System Neurons Central Nervous System Brain Spinal Cord(脊椎） Peripheral Nervous System The Senses,Control each system has one major role,A distinct body part that carries out one or more main functions,A group of similar cells that carry out a specialized job,The basic building block of a

2、ll living things, plant or animal,Specialized structures inside a cell that have specific functions,A collection of systems,The Nervous System,Helps the body adjust to changes in your environment,The Nervous System,Stimulus Any change inside or outside your body that brings about a response Homeosta

3、sis Regulation of steady conditions inside the body,The Nervous System,Central Nervous System =Brain + Spinal Cord Peripheral Nervous System =Nerves to rest of body,Neurons,Building blocks of the nervous system 100 billion neurons in your brain alone 30,000 on a pinhead They communicate with each ot

4、her thousands of times a second. Bundles of neurons make up NERVES,3 Types of Nerve Cells,Sensory Neurons Receive information form a sensory receptor and send impulses to the CNS Interneurons Relay impulses from sensory neurons to motor neurons Motor Neurons Carry impulse from the CNS to muscles and

5、 glands through out the body,Parts of a Neuron,3 MAIN PARTS Dendrites - receive messages from other neurons Cell Body nucleus is found here Axon - sends messages to other neurons,Parts of a Neuron,Dendrites,Cell Body,Axon,Synapse,Space between each neuron Neurotransmitters are the messengers that tr

6、avel across each synapse They are chemical signals that neurons use to talk to each other, which is what makes your brain work. They help determine how you feel, think and act.,Neurotransmitters,Serotonin - involved in mood (such as helping you to feel happy), sleep, mental health, blood pressure an

7、d heartbeat. Dopamine - important in helping to regulate physical movement, pleasure, and thought. Missing in patients with Parkinsons Disease.,Neurotransmitters,Acetylcholine - involved in regulating muscles, memory, mood, sleep, and organs (like the heart). Lowered amounts associated with Alzheime

8、rs Disease,Central Nervous System(C.N.S.),BRAIN,SPINAL CORD,Cerebrum,Largest part of the brain Interprets impulses from the senses Responsible for: thinking and learning creativity five senses memory and emotion problem-solving decisions,Cerebellum,Coordinates voluntary muscle movement Helps maintai

9、n balance When a ball is thrown to you, the cerebellum coordinates the proper response to prevent injury,Brainstem,Controls involuntary actions Connects the brain to the spinal cord Regulates heart rate, breathing, swallowing, blinking, and more Made up of: the midbrain pons medulla,Spinal Cord,Made

10、 up of bundles of neurons Carries impulses to and from the brain Together, the brain and spinal cord make up the Central Nervous System (C.N.S.) Fun fact: The spinal cord is about 45 cm long in men and 43 cm long in women.,Peripheral Nervous System(P.N.S.),Connects the C.N.S. with the rest of the bo

11、dy sensory nerves take impulse from stimulus (sensory receptors) to the the CNS motor nerves take impulse from the CNS to the muscles and glands that take action.,Reflex,REFLEX An involuntary, automatic response to a stimulus controlled by the spinal cord Like when the doctor uses the rubber mallet

12、on your tendon below your knee Movement when someone unexpectedly throws something at you,Reflex Arc,When the body receives a painful stimulus (stepping on a nail, touching a hot surface, etc), the body responds super-fast. Reflex Arc A short-cut an impulse takes for a quicker response Path of refle

13、x arc: STIMULUS sensory receptor sensory nerve spinal cord (interneuron) motor nerve muscle RESPONSE An impulse continues up to the brain to be interpreted by the cerebrum, BUT, meanwhile the affected area has already produced a response!,Autonomic Nervous System(part of the P.N.S.),Fight or flight

14、Often referred to as your fight-or-flight system, your sympathetic nervous system prepares your body for emergencies. It shunts your blood to your muscles and increases your blood pressure, heart rate and breathing rate, enabling you to cope with stressful situations. Rest and digest Your parasympat

15、hetic nervous system maintains and restores your energy. It directs blood to your digestive tract and makes sure you actively digest food. It also maintains your blood pressure, heart rate and breathing rate at a low level. Thats why it is sometimes called your rest and digest system.,EXTRA,Fight or

16、 flight,Return to normal,Senses,Vision Sensory Receptors Rods sense brightness Cones sense color,The retina, in the back of your eye, has cells that are sensitive to light. They connect directly to your brain.,Senses,Hearing Sound waves make your eardrum vibrate. Small bones in your ear vibrate (ham

17、mer, anvil, stirrup) Vibrations go through the snail-like cochlea, which turns them into nerve impulses to your brain.,Senses,Taste 10,000 taste buds in your mouth Your tongue picks up four types of taste: sweet sour bitter salty Sweet and salty are least sensitive Bitter ones are most sensitive,Sen

18、ses,Smell Odor particles drift into your nose Stimulate sensory receptors olfactory cells in nasal passages Sensory receptors send impulses to your brain to be interpreted.,Senses,There are at least six types of touch receptors in your skin: Hot Cold Pain Pressure Touch Fine touch,Touch,Questions,What are the main parts of the brain? What is the function of each? Describe a neuron What is it? What typ