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