biology. the nervous system two main parts: –central nervous system consists of the brain and...
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BiologyBiology
The Nervous SystemThe Nervous System
Two main parts:Two main parts:– Central Nervous SystemCentral Nervous System
Consists of the brain and spinal cordConsists of the brain and spinal cord
– Peripheral Nervous SystemPeripheral Nervous SystemConsists of nerve cells that send messages Consists of nerve cells that send messages between the central nervous system and all the between the central nervous system and all the parts of the bodyparts of the body
NeuronsNeurons
Neurons- nerve cellsNeurons- nerve cells– Send and receive messages from other Send and receive messages from other
structures in the body such as muscles and structures in the body such as muscles and glandsglands
NeuronsNeurons
Components of a neuronComponents of a neuron– Cell Body- produces energy that fuels the activity of Cell Body- produces energy that fuels the activity of
the cellthe cell– Dendrites- thin fibers which branch out of the cell, Dendrites- thin fibers which branch out of the cell,
receive information from other neurons and pass the receive information from other neurons and pass the message through the cell bodymessage through the cell body
– Axon- carries messages away from the neuron, single Axon- carries messages away from the neuron, single fiberfiber
– Myelin- covering of the axon, insulates and protects Myelin- covering of the axon, insulates and protects the axon, helps to speed up the transmission of the the axon, helps to speed up the transmission of the messagemessage
– Axon terminal- small fibers branching out from an Axon terminal- small fibers branching out from an axonaxon
Types of NeuronsTypes of Neurons
Sensory- carry messages from sense Sensory- carry messages from sense organs to spinal cord or brainorgans to spinal cord or brain
Motor- carry messages from spinal cord or Motor- carry messages from spinal cord or brain to muscles or glandsbrain to muscles or glands
Interneurons- carry messages from one Interneurons- carry messages from one neuron to another and do most of the work neuron to another and do most of the work of the nervous systemof the nervous system
How do Neurons communicate?How do Neurons communicate?
Neurons send messages across synapses Neurons send messages across synapses through the release of neurotransmittersthrough the release of neurotransmitters– Chemicals that are stored in sacs in the axon Chemicals that are stored in sacs in the axon
terminalterminal
Nerve ImpulsesNerve Impulses
Absolute refractory period-Absolute refractory period- after one cell after one cell firing, it will not fire again regardless of firing, it will not fire again regardless of how strong the incoming message ishow strong the incoming message isRelative refractory period-Relative refractory period- time when time when neuron is returning to normal and may neuron is returning to normal and may refire if message is stronger then usual refire if message is stronger then usual All or none law-All or none law- a neuron fires at full a neuron fires at full capacity or does not fire at allcapacity or does not fire at all
Firing of a nerve cellFiring of a nerve cell
Dendrite or cell body picks up messageDendrite or cell body picks up message
If message is strong enough, neuron fires If message is strong enough, neuron fires and impulse starts down the axonand impulse starts down the axon
Out the end of the axon terminal to the Out the end of the axon terminal to the synaptic knobsynaptic knob
On to the next nerve cellOn to the next nerve cell
Central Nervous SystemCentral Nervous System
2 major parts2 major parts– Central Nervous System- brain and spinal Central Nervous System- brain and spinal
cordcord– Peripheral Nervous System- connects brain, Peripheral Nervous System- connects brain,
spinal cord to every other part of the bodyspinal cord to every other part of the body
BrainBrain
Areas of the BrainAreas of the Brain– Hindbrain- co-ordinate motor activity, posture, Hindbrain- co-ordinate motor activity, posture,
equilibrium, sleep patterns, and regulate unconscious equilibrium, sleep patterns, and regulate unconscious functions (ex. blood circulation and breathing)functions (ex. blood circulation and breathing)
– Midbrain- vision, hearing, motor control, sleep/awake Midbrain- vision, hearing, motor control, sleep/awake cycle, arousal (alertness), and temperature regulationcycle, arousal (alertness), and temperature regulation
– Forebrain- controls cognitive, sensory, and motor Forebrain- controls cognitive, sensory, and motor functions, regulate body temperature, reproductive functions, regulate body temperature, reproductive functions, eating, sleeping, and display of emotionsfunctions, eating, sleeping, and display of emotions
BrainBrain
Parts of the BrainParts of the Brain– Amygdala- storing & classifying emotional memories, Amygdala- storing & classifying emotional memories,
produces emotionsproduces emotions– Hippocampus- memory formation, classifying Hippocampus- memory formation, classifying
information, long-term memoryinformation, long-term memory– Thalamus- sensory signals, visual information, Thalamus- sensory signals, visual information,
information from skin and internal organs, motor information from skin and internal organs, motor controlcontrol
– Hypothalamus- metabolic processes, body Hypothalamus- metabolic processes, body temperature, hunger, thirst, fatigue, anger, and temperature, hunger, thirst, fatigue, anger, and circadian cyclescircadian cycles
BrainBrain
– Cerebellum- regulates & coordinates Cerebellum- regulates & coordinates movement, posture, and balancemovement, posture, and balance
– Pons- relays messages to other parts of the Pons- relays messages to other parts of the brain, controls arousal, and respirationbrain, controls arousal, and respiration
– Medulla Oblongata- heart rate, respiration, Medulla Oblongata- heart rate, respiration, blood pressure, swallowing, vomiting, and blood pressure, swallowing, vomiting, and defecation, relay station for nerve signals defecation, relay station for nerve signals going to/from the braingoing to/from the brain
BrainBrain
Lobes of the BrainLobes of the Brain– Occipital- receives and interprets visual informationOccipital- receives and interprets visual information– Temporal- controls hearing and some processing of Temporal- controls hearing and some processing of
visual and olfactory informationvisual and olfactory information– Parietal- responds to sensations of touch bodily Parietal- responds to sensations of touch bodily
positionposition– Frontal- responsible for voluntary movement- Frontal- responsible for voluntary movement-
attention, goal-directed behavior, and appropriate attention, goal-directed behavior, and appropriate emotional experiencesemotional experiences
BrainBrain
HemispheresHemispheres– Left- right-hand touch and movement, speech, Left- right-hand touch and movement, speech,
language, and writinglanguage, and writing– Right- left-hand touch and movement, spatial Right- left-hand touch and movement, spatial
construction, non-verbal imagery, and face construction, non-verbal imagery, and face recognitionrecognition
Peripheral Nervous SystemPeripheral Nervous System
Carries messages to and from the Central Carries messages to and from the Central Nervous SystemNervous System
Made of two major partsMade of two major parts– Somatic Nervous SystemSomatic Nervous System– Autonomic Nervous SystemAutonomic Nervous System
Somatic Nervous SystemSomatic Nervous System
Composed of all sensory (afferent) Composed of all sensory (afferent) neurons that carry information to the CNS neurons that carry information to the CNS and all the motor (efferent) neurons that and all the motor (efferent) neurons that carry messages from the CNS to the carry messages from the CNS to the skeletal muscles of the bodyskeletal muscles of the body
The senses have their origin in the The senses have their origin in the somatic part of the Peripheral Nervous somatic part of the Peripheral Nervous SystemSystem
Autonomic Nervous SystemAutonomic Nervous System
Composed of all the neurons that carry Composed of all the neurons that carry messages between the CNS and all the internal messages between the CNS and all the internal organs of the body (glands and smooth muscles organs of the body (glands and smooth muscles such as the heart and digestive system)such as the heart and digestive system)Important in breathing, blood flow, and emotionsImportant in breathing, blood flow, and emotionsHas two branches- sympathetic and Has two branches- sympathetic and parasympatheticparasympathetic– Both are involved in controlling and integrating actions Both are involved in controlling and integrating actions
of the glands and smooth musclesof the glands and smooth muscles
Sympathetic and Parasympathetic Sympathetic and Parasympathetic Nervous SystemsNervous Systems
SympatheticSympathetic– Tell the body to prepare for Tell the body to prepare for
an emergencyan emergencyHeart pounds, breathe Heart pounds, breathe faster, pupils enlarge, & faster, pupils enlarge, & digestion stopsdigestion stops
Tells the endocrine system Tells the endocrine system to release chemicals into to release chemicals into bloodstreambloodstream
Connect to every internal Connect to every internal organ of bodyorgan of body
ParasympatheticParasympathetic– Calms the body down Calms the body down
after stressafter stress
The Endocrine SystemThe Endocrine System
Consists of glands which secrete Consists of glands which secrete hormoneshormones into the bloodstream into the bloodstream– Hormones-Hormones- stimulate growth and affect stimulate growth and affect
behavior and emotional reactionsbehavior and emotional reactionsproduced by different glands- pituitary, thyroid, produced by different glands- pituitary, thyroid, adrenal, testes, and ovariesadrenal, testes, and ovaries
Pituitary GlandPituitary Gland
Lies below the hypothalamusLies below the hypothalamusConsidered the “Master Gland”Considered the “Master Gland”Secretes different hormonesSecretes different hormones– Growth- regulates growth of muscles, bones, Growth- regulates growth of muscles, bones,
and glandsand glands– Prolactin- stimulates production of milk in Prolactin- stimulates production of milk in
nursing womennursing women– Oxytocin- stimulates labor in pregnant womenOxytocin- stimulates labor in pregnant women
Thyroid GlandThyroid Gland
Produces thyroxinProduces thyroxin– Affects the body’s metabolism- the rate of Affects the body’s metabolism- the rate of
converting food to energyconverting food to energy– Low production can lead to hypothyroidism- Low production can lead to hypothyroidism-
can cause people to be overweightcan cause people to be overweight– High production can lead to hyperthyroidism- High production can lead to hyperthyroidism-
can cause excitability, inability to sleep, and can cause excitability, inability to sleep, and weight lossweight loss
Adrenal GlandAdrenal Gland
Located above the kidneysLocated above the kidneysSecretes cortical steroids- increase the Secretes cortical steroids- increase the resistance to stress and promote muscle resistance to stress and promote muscle development, can cause the liver to release development, can cause the liver to release stored sugar in emergenciesstored sugar in emergenciesProduce adrenaline and noradrenalineProduce adrenaline and noradrenaline– Arouse the body for an emergencyArouse the body for an emergency– Adrenaline- can intensify emotions (fear & anxiety)Adrenaline- can intensify emotions (fear & anxiety)– Noradrenaline- raises blood pressureNoradrenaline- raises blood pressure
Testes and OvariesTestes and Ovaries
Testes- malesTestes- males
Ovaries- femalesOvaries- females
Each produces hormones- testosterone, Each produces hormones- testosterone, estrogen, and progesteroneestrogen, and progesterone
TestosteroneTestosterone
Testosterone- male sex hormone, small Testosterone- male sex hormone, small amount found in femalesamount found in females
Influences the development of sex organs (if Influences the development of sex organs (if secreted child will be male, if not- female)secreted child will be male, if not- female)
Aids in growth of muscle and bone, primary and Aids in growth of muscle and bone, primary and secondary sex characteristicssecondary sex characteristics
– Primary sex characteristics- directly involved in Primary sex characteristics- directly involved in reproductionreproduction
– Secondary sex characteristics- distinguish males from Secondary sex characteristics- distinguish males from femalesfemales
Estrogen & ProgesteroneEstrogen & Progesterone
Female sex hormones but small amounts Female sex hormones but small amounts are found in malesare found in males
Females- ovaries produce estrogen and Females- ovaries produce estrogen and progesteroneprogesterone
Males- testes produce estrogen and Males- testes produce estrogen and progesteroneprogesterone
Estrogen & ProgesteroneEstrogen & Progesterone
Estrogen-Development of primary and Estrogen-Development of primary and secondary sex characteristicssecondary sex characteristicsProgesterone- stimulates growth of female Progesterone- stimulates growth of female reproductive organs and prepares the body for reproductive organs and prepares the body for pregnancypregnancyBoth regulate menstrual cycle and vary during Both regulate menstrual cycle and vary during the cyclethe cycle– Changing levels of estrogen are linked to PMSChanging levels of estrogen are linked to PMS– Estrogen is connected to cognitive functioning and Estrogen is connected to cognitive functioning and
feelings of well-being among womenfeelings of well-being among women
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