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 System

Consists of nerve cells that send messages Consists of nerve cells that send messages between the central nervous system and all between the central nervous system and all the parts of the bodythe parts 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 structures in the body such as muscles and glandsand glands

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 Motor- carry messages from spinal cord or brain to muscles or glandscord or brain to muscles or glands

Interneurons- carry messages from Interneurons- carry messages from one neuron to another and do most one neuron to another and do most of the work of the nervous systemof the work of the nervous system

How do Neurons How do Neurons communicate?communicate?

Neurons send messages across Neurons send messages across synapses through the release of synapses through the release of neurotransmittersneurotransmitters Chemicals that are stored in sacs in the Chemicals that are stored in sacs in the

axon terminalaxon terminal

Nerve ImpulsesNerve Impulses

Absolute refractory period-Absolute refractory period- after one after one cell firing, it will not fire again cell firing, it will not fire again regardless of how strong the regardless of how strong the incoming message isincoming message is

Relative refractory period-Relative refractory period- time time when neuron is returning to normal when neuron is returning to normal and may refire if message is and may refire if message is stronger then usual 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 Dendrite or cell body picks up messagemessage

If message is strong enough, neuron If message is strong enough, neuron fires and impulse starts down the fires and impulse starts down the axonaxon

Out the end of the axon terminal to Out the end of the axon terminal to the synaptic knobthe synaptic 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 Central Nervous System- brain and

spinal cordspinal cord Peripheral Nervous System- connects Peripheral Nervous System- connects

brain, spinal cord to every other part of brain, spinal cord to every other part of the bodythe 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 equilibrium, sleep patterns, and regulate unconscious functions (ex. blood circulation and unconscious functions (ex. blood circulation and breathing)breathing)

Midbrain- vision, hearing, motor control, Midbrain- vision, hearing, motor control, sleep/awake cycle, arousal (alertness), and sleep/awake cycle, arousal (alertness), and temperature regulationtemperature regulation

Forebrain- controls cognitive, sensory, and Forebrain- controls cognitive, sensory, and motor functions, regulate body temperature, motor functions, regulate body temperature, reproductive functions, eating, sleeping, and reproductive functions, eating, sleeping, and display of emotionsdisplay of emotions

BrainBrain Parts of the BrainParts of the Brain

Amygdala- storing & classifying emotional Amygdala- storing & classifying emotional memories, produces emotionsmemories, produces 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, information from skin and internal organs, motor controlmotor control

Hypothalamus- metabolic processes, body Hypothalamus- metabolic processes, body temperature, hunger, thirst, fatigue, anger, temperature, hunger, thirst, fatigue, anger, and circadian cyclesand circadian cycles

BrainBrain

Cerebellum- regulates & coordinates Cerebellum- regulates & coordinates movement, posture, and balancemovement, posture, and balance

Pons- relays messages to other parts of Pons- relays messages to other parts of the brain, controls arousal, and the brain, controls arousal, and respirationrespiration

Medulla Oblongata- heart rate, Medulla Oblongata- heart rate, respiration, blood pressure, swallowing, respiration, blood pressure, swallowing, vomiting, and defecation, relay station vomiting, and defecation, relay station for nerve signals going to/from the for nerve signals going to/from the brainbrain

BrainBrain

Lobes of the BrainLobes of the Brain Occipital- receives and interprets visual Occipital- receives and interprets visual

informationinformation Temporal- controls hearing and some Temporal- controls hearing and some

processing of visual and olfactory informationprocessing of visual and olfactory information Parietal- responds to sensations of touch Parietal- responds to sensations of touch

bodily positionbodily position Frontal- responsible for voluntary movement- Frontal- responsible for voluntary movement-

attention, goal-directed behavior, and attention, goal-directed behavior, and appropriate emotional experiencesappropriate emotional experiences

BrainBrain

HemispheresHemispheres Left- right-hand touch and movement, Left- right-hand touch and movement,

speech, language, and writingspeech, language, and writing Right- left-hand touch and movement, Right- left-hand touch and movement,

spatial construction, non-verbal spatial construction, non-verbal imagery, and face recognitionimagery, and face recognition

Peripheral Nervous Peripheral Nervous SystemSystem

Carries messages to and from the Carries messages to and from the Central Nervous SystemCentral Nervous 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 neurons that carry information to the CNS and all the motor (efferent) the CNS and all the motor (efferent) neurons that carry messages from neurons that carry messages from the CNS to the skeletal muscles of the CNS to the skeletal muscles of the bodythe body

The senses have their origin in the The senses have their origin in the somatic part of the Peripheral somatic part of the Peripheral Nervous SystemNervous System

Autonomic Nervous Autonomic Nervous SystemSystem

Composed of all the neurons that carry Composed of all the neurons that carry messages between the CNS and all the messages between the CNS and all the internal organs of the body (glands and internal organs of the body (glands and smooth muscles such as the heart and smooth muscles such as the heart and digestive system)digestive system)

Important in breathing, blood flow, and Important in breathing, blood flow, and emotionsemotions

Has two branches- sympathetic and Has two branches- sympathetic and parasympatheticparasympathetic Both are involved in controlling and integrating Both are involved in controlling and integrating

actions of the glands and smooth musclesactions of the glands and smooth muscles

Sympathetic and Sympathetic and Parasympathetic Nervous Parasympathetic Nervous

SystemsSystems SympatheticSympathetic

Tell the body to Tell the body to prepare for an prepare for an emergencyemergency

Heart pounds, breathe Heart pounds, breathe faster, pupils enlarge, faster, pupils enlarge, & digestion stops& digestion stops

Tells the endocrine Tells the endocrine system to release system to release chemicals into chemicals into bloodstreambloodstream

Connect to every Connect to every internal organ of bodyinternal organ 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 reactions produced by different glands- pituitary, produced by different glands- pituitary,

thyroid, adrenal, testes, and ovariesthyroid, adrenal, testes, and ovaries

Pituitary GlandPituitary Gland

Lies below the hypothalamusLies below the hypothalamus Considered the “Master Gland”Considered the “Master Gland” Secretes different hormonesSecretes different hormones

Growth- regulates growth of muscles, Growth- regulates growth of muscles, bones, and glandsbones, and glands

Prolactin- stimulates production of milk Prolactin- stimulates production of milk in nursing womenin nursing women

Oxytocin- stimulates labor in pregnant Oxytocin- stimulates labor in pregnant womenwomen

Thyroid GlandThyroid Gland

Produces thyroxinProduces thyroxin Affects the body’s metabolism- the rate Affects the body’s metabolism- the rate

of converting food to energyof converting food to energy Low production can lead to Low production can lead to

hypothyroidism- can cause people to be hypothyroidism- can cause people to be overweightoverweight

High production can lead to High production can lead to hyperthyroidism- can cause excitability, hyperthyroidism- can cause excitability, inability to sleep, and weight lossinability to sleep, and weight loss

Adrenal GlandAdrenal Gland Located above the kidneysLocated above the kidneys Secretes 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 development, can cause the liver to release stored sugar in emergenciesrelease stored sugar in emergencies

Produce adrenaline and noradrenalineProduce adrenaline and noradrenaline Arouse the body for an emergencyArouse the body for an emergency Adrenaline- can intensify emotions (fear & Adrenaline- can intensify emotions (fear &

anxiety)anxiety) Noradrenaline- raises blood pressureNoradrenaline- raises blood pressure

Testes and OvariesTestes and Ovaries

Testes- malesTestes- males Ovaries- femalesOvaries- females Each produces hormones- Each produces hormones-

testosterone, estrogen, and testosterone, estrogen, and progesteroneprogesterone

TestosteroneTestosterone

Testosterone- male sex hormone, Testosterone- male sex hormone, small amount found in femalessmall amount 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 Aids in growth of muscle and bone, primary and secondary sex characteristicsand secondary sex characteristics

Primary sex characteristics- directly involved in Primary sex characteristics- directly involved in reproductionreproduction

Secondary sex characteristics- distinguish males Secondary sex characteristics- distinguish males from femalesfrom females

Estrogen & ProgesteroneEstrogen & Progesterone

Female sex hormones but small Female sex hormones but small amounts are found in malesamounts are found in males

Females- ovaries produce estrogen Females- ovaries produce estrogen and progesteroneand progesterone

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 characteristics Progesterone- stimulates growth of female Progesterone- stimulates growth of female

reproductive organs and prepares the reproductive organs and prepares the body for pregnancybody for pregnancy

Both regulate menstrual cycle and vary Both regulate menstrual cycle and vary during the cycleduring the cycle Changing levels of estrogen are linked to PMSChanging levels of estrogen are linked to PMS Estrogen is connected to cognitive functioning Estrogen is connected to cognitive functioning

and feelings of well-being among womenand feelings of well-being among women