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

Chapter 20: The Nervous and Endocrine Systems

Pages 546 564DateChapter 20: The Nervous and Endocrine Systems

Nervous System at Work (pg. 546 547) Neurons = nerve cell working unit of nervous systemMade up of a cell body & branches called dendrites & axonsDendrites = receive messages & send them 2 cell bodyAxon = carries messages away from cell bodyBranches help carry messages Impulse = messages carried by neuronsSent across a small space (from axon 2 den) 2 another neuron = synapse Three types of neurons:Sensory = receive info & send impulses 2 brain or spineMotor = conduct impulses from brain/spine 2 muscles or glandsInterneurons = relay impulses from sensory 2 motor

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

Reflexes (pg. 551)Reflex = involuntary and automatic response to a stimulusInvolves a simple nerve pathway called a reflex arcU 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)Alcohol is a depressant drug, which slows down the nervous system (N.S.)It is absorbed into bloodstream through walls of stomach & small intestineHeavy alcohol use can destroy brain & liver cellsDepressant = slows down activities of N.S.: judgment, reasoning, memory, concentration, muscle functionsOther depressants: marijuana, benzodiazepinesCaffeine is a stimulant drug, which speeds up the N.S.There is also a physical dependence noticeable once people stopStimulant = speeds up activities: heartbeat rate, restlessness, tremors, insomnia, kidneys produce more urine Other stimulants: nicotine, cocaine, amphetamines

The Senses (pg. 554 556)Hearing: objects vibrate making air around vibrate, producing sound waves, which stimulate nerve cells in your ear impulses travel 2 brain 2 recognize the soundOuter ear: traps sound waves & funnels them 2 middle earMiddle ear: vibrations move three bones: hammer, anvil, & stirrupInner ear: cochlea fluid filled structure shaped like a snail shellWhen sound waves vibrate this fluid, it stimulates nerve endingsVision: light enters eye, which the lens & cornea bend toward the retina = a tissue @ the back of eye that is sensitive 2 light energyCones = respond 2 bright light & colorRods = respond 2 dim lightLight energy creates impulses 2 the optic nerve, which carries them 2 the brain where they are interpreted

Smell & Taste (pg. 558 559)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 moleculesThen an impulse is sent to brain for interpretation Taste: taste buds on your tongue are the major sensory receptors for tasteFour basic taste sensations = sweet, salty, sour, & bitterSaliva helps with taste as it washes over the taste buds and an impulse is sent 2 your brain for interpretationTaste & smell R related with a stuffy nose, nasal passages R blockedYour senses help send impulses 2 your brain regarding your environment, this allows your brain 2 respond & maintain homeostasis

Endocrine System (pg. 562 564)The endocrine system uses chemicals 2 control your bodyHormones = endocrine chemicals produced in glands throughout bodyHormones affect target tissues which R usually located in another part of the body, which makes the endo system slower than nervousEx: 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!