Pages 546 – 564 Date Chapter 20: The Nervous and Endocrine Systems

Nervous System at Work (pg. 546 – 547) 1. Neurons = nerve cell – working unit of nervous system 1. Made up of a cell body & branches called dendrites & axons 2. Dendrites = receive messages & send them 2 cell body 3. Axon = carries messages away from cell body 1. Branches help carry messages 4. Impulse = messages carried by neurons 1. Sent across a small space (from axon 2 den) 2 another neuron = synapse 5. Three types of neurons: 1. Sensory = receive info & send impulses 2 brain or spine 2. Motor = conduct impulses from brain/spine 2 muscles or glands 3. Interneurons = relay impulses from sensory 2 motor

Central Nervous (pg. 548 – 549) 1. Central nervous system (CNS) = brain & spinal cord 2. Peripheral nervous system = all nerves outside of CNS 1. These systems work together 2 coordinate body activities 2. Brain has three major parts: 3. Cerebrum = largest part, divided into hemispheres, memory is stored, voluntary muscles R controlled, senses are interpreted 4. Cerebellum = behind cerebrum, maintains balance & voluntary muscle movements 5. Brain stem = connects the cerebrum to spinal cord, controls heartbeat, breathing, blood pressure, involuntary movements 3. Brain is made up of 100 billion neurons

Reflexes (pg. 551) 1. Reflex = involuntary and automatic response to a stimulus 1. Involves a simple nerve pathway called a reflex arc 2. U touch something hot, sensory receptors in finger send an impulse 2 spine, impulse passes 2 an interneuron in spine that immediately relays that info 2 a motor neuron, motor neurons transmit impulse 2 muscles  U move hand

Drugs and the Nervous System (pg. 552) 1. Alcohol is a depressant drug, which slows down the nervous system (N.S.) 1. It is absorbed into bloodstream through walls of stomach & small intestine 2. Heavy alcohol use can destroy brain & liver cells 2. Depressant = slows down activities of N.S.: judgment, reasoning, memory, concentration, muscle functions 1. Other depressants: marijuana, benzodiazepines 3. Caffeine is a stimulant drug, which speeds up the N.S. 1. There is also a physical dependence noticeable once people stop 4. Stimulant = speeds up activities: heartbeat rate, restlessness, tremors, insomnia, kidneys produce more urine 1. Other stimulants: nicotine, cocaine, amphetamines

The Senses (pg. 554 – 556) 1. Hearing: objects vibrate making air around vibrate, producing sound waves, which stimulate nerve cells in your ear  impulses travel 2 brain 2 recognize the sound 1. Outer ear: traps sound waves & funnels them 2 middle ear 2. Middle ear: vibrations move three bones: hammer, anvil, & stirrup 3. Inner ear: cochlea  fluid filled structure shaped like a snail shell 1. When sound waves vibrate this fluid, it stimulates nerve endings 2. Vision: light enters eye, which the lens & cornea bend toward the retina = a the back of eye that is sensitive 2 light energy 1. Cones = respond 2 bright light & color 2. Rods = respond 2 dim light 3. Light energy creates impulses 2 the optic nerve, which carries them 2 the brain where they are interpreted

Smell & Taste (pg. 558 – 559) 1. Smell: Things that smell give off molecules into the air, which go through nasal passageways which contain sensitive nerve cells called olfactory cells that are stimulated by gas molecules 1. Then an impulse is sent to brain for interpretation 2. Taste: taste buds on your tongue are the major sensory receptors for taste 1. Four basic taste sensations = sweet, salty, sour, & bitter 2. Saliva helps with taste as it washes over the taste buds and an impulse is sent 2 your brain for interpretation 3. Taste & smell R related  with a stuffy nose, nasal passages R blocked 3. Your senses help send impulses 2 your brain regarding your environment, this allows your brain 2 respond & maintain homeostasis

Endocrine System (pg. 562 – 564) 1. The endocrine system uses chemicals 2 control your body 1. Hormones = endocrine chemicals produced in glands throughout body 2. Hormones affect target tissues which R usually located in another part of the body, which makes the endo system slower than nervous 1. Ex: pancreas, which produces insulin enables cells 2 take in glucose

Diabetes is one of the most common diseases worldwide, and it is estimated that about 346 million people suffer from this disease. (WHO, 2011).

All Done!