What’s the function???
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Transcript of What’s the function???
What’s the function???
Nervous systems contain neural cells and glial cells
Types of neurons
Fig. 28-1b
Sensoryreceptor
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Sensory neuron
Brain
Spinalcord
Motorneuron
Quadricepsmuscles
Flexormuscles
Nerve
Interneuron
CNS
PNS
Reflex Arc•Simplest example•Does not send message to brain
Fig. 28-2
Signal direction Dendrites
Cellbody
Nucleus Axon
Schwanncell
Myelin sheath
Signalpathway
Synaptic terminals
NucleusSchwanncell
Layers ofmyelin sheaths
Cell Body
Neurons work by sending an electrical impulse (action potential) from one end of the neuron (cell body) to the other (synaptic terminal)
-works in ONE DIRECTION only
There is a difference in the distribution of charges inside the cell compared to outside
-inside is negative; outside is positive
There is a difference in the concentration of certain ions inside compared to outside
outside high concentration of Na+inside high K+
Resting Potential
Animation link
Action PotentialA stimulus to a neuron causes Na+ gates to open (Na+ rushes into the cell) reversing the charge
cell is DEPOLARIZED
Charge distribution is reestablished when K+ is allowed to leave the cell
Cell is Repolarized
Na+/K+ pump reestablishes the ion concentrations (expends the most energy in your body)
Sending the message onSignal reaches synaptic terminal causing vesicles containing neurotransmitters to be released into synapse
Neurotransmitters diffuse across the synapse and bind to receptors on receiving cell
These receptors are also gated channels-may be Na+ effect?-may be K+ effect?
Sending neuron
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Axon ofsendingneuron
Vesicles
Synapticterminal
Vesicle fuseswith plasmamembrane
Synapticcleft
Receivingneuron
Receivingneuron
Ion channelsNeurotransmittermolecules
Neurotransmitteris released into synaptic cleft
Neurotransmitterbinds to receptor
Synapse
Actionpotentialarrives
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Fig. 28-7a
Dendrites
Myelinsheath
Axon
Receivingcell body
Inhibitory Excitatory
Synaptic terminals
Fig. 28-7b
Synapticterminals
Botulinum toxin -inhibits release of acetylcholine
Serotonin & dopamine in brain affect sleep/moodAcetylcholine
motor neurons / muscles
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Neurotransmitter
Ion channel closesIon channel opens
Receptor
Ions
Neurotransmitter brokendown and released
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Fig. 28-12
Peripheralnervous system
Somaticnervoussystem
Autonomicnervoussystem
Sympatheticdivision
Parasympatheticdivision
Entericdivision
Fig. 28-13
Brain
Parasympathetic division
Constrictspupil
Eye
Stimulatessalivaproduction
LungConstrictsbronchi
Slowsheart
Spinalcord
Stimulatesstomach,pancreas,and intestines
Liver
Stimulatesurination
Promoteserection ofgenitals
Intestines
Genitalia
Bladder
Pancreas
Stomach
Adrenalgland
Heart
Salivaryglands
Sympathetic division
Dilatespupil
Inhibitssalivaproduction
Dilatesbronchi
Acceleratesheart
Stimulatesepinephrineand norepi-nephrine release
Stimulatesglucose release
Inhibitsstomach,pancreas,and intestines
Inhibitsurination
Promotes ejacu-lation and vaginalcontractions
• Sensory receptors– Specialized cells or neurons that detect stimuli
Copyright © 2009 Pearson Education, Inc.
• All senses trigger the same type of action potential
• The brain distinguishes the type of stimulus
• Perception is the brain’s integration of sensations
MidbrainHindbrain
Forebrain
Embryo (one month old)
Cerebralhemisphere Diencephalon
Midbrain
Pons
Cerebellum
Medullaoblongata
Spinal cord
Fetus (three months old)
EmbryonicBrain Regions
Brain StructuresPresent in Adult
Cerebrum (cerebral hemispheres; includescerebral cortex, white matter, basal ganglia)
Diencephalon (thalamus, hypothalamus,posterior pituitary, pineal gland)
Midbrain (part of brainstem)
Pons (part of brainstem), cerebellum
Medulla oblongata (part of brainstem)
Forebrain
Midbrain
Hindbrain
Midbrain
Hindbrain
Forebrain
Cerebrum
Thalamus
Hypothalamus
Pituitary gland
Pons
Medullaoblongata
Cerebellum
Cerebralcortex
Spinalcord
Left cerebralhemisphere
Right cerebralhemisphere
Corpuscallosum
Basalganglia
Frontal lobe Parietal lobe
Temporal lobe Occipital lobe
Frontal associationarea
Somatosensoryassociationarea
VisualassociationareaAuditory
associationarea
Speech
Smell
Hearing
Taste
Speech
Reading
Vision
Mot
or c
orte
xS
omat
osen
sory
cor
tex
Copyright © 2009 Pearson Education, Inc.
The hypothalamus “master controller” influences many hormones
• The hypothalamus – Links the endocrine and nervous systems
– Receives input from nerves about body conditions
– Responds by sending out appropriate nervous or endocrine signals
– Uses the pituitary gland to exert master control over the endocrine system
Brain
Hypothalamus
Posterior pituitary
Anterior pituitary
(Bone)
Hypothalamus
Posteriorpituitary
Anteriorpituitary
Hormone Neuroncell
Bloodvessel
Oxytocin ADH
Kidney tubulesUterine musclesMammary glands
Endocrine cells ofthe anterior pituitary
Pituitary hormones
Releasing hormonesfrom hypothalamus
Neuroncell
Bloodvessel
FSHandLH
TSH ACTH Prolactin(PRL)
Growthhormone
(GH)
Endorphins
Thyroid Adrenalcortex
Testes orovaries
Mammaryglands
(in mammals)
Entirebody
Painreceptors
in the brain
Copyright © 2009 Pearson Education, Inc.
HORMONES AND HOMEOSTASIS
TSH
TRH
Hypothalamus
Anteriorpituitary
Thyroid
Thyroid hormones
Inhibition
Inhibition
Thyroid hormones-regulate metabolism
Copyright © 2009 Pearson Education, Inc.
• The pancreas secretes two hormones that control blood glucose
– Insulin—signals cells to use and liver to store glucose
– Glucagon—causes liver to release stored glucose into the blood
Insulin
4Beta cellsof pancreas stimulatedto release insulin intothe blood
Glucoselevel
Homeostasis: Normal blood glucose level(about 90 mg/100 mL)
Glucoselevel
Glucagon
Low bloodglucose level
High bloodglucose level
Bodycellstake up moreglucose
Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes
Liver takesup glucoseand stores it asglycogen
Alphacells ofpancreas stimulatedto release glucagoninto the blood
Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)
Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)
Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes
Liverbreaks downglycogen andreleases glucoseto the blood
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Insulin
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Beta cellsof pancreas stimulatedto release insulin intothe blood
Glucoselevel
Homeostasis: Normal blood glucose level(about 90 mg/100 mL)
Glucoselevel
High bloodglucose level
Bodycellstake up moreglucose
Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes
Liver takesup glucoseand stores it asglycogen
Stimulus:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal)
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Glucoselevel
Homeostasis: Normal blood glucose level(about 90 mg/100 mL)
Glucoselevel
Glucagon
Low bloodglucoselevel
Alphacells ofpancreas stimulatedto release glucagoninto the blood
Stimulus:Declining bloodglucose level(e.g., afterskipping a meal)
Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes
Liverbreaks downglycogen andreleases glucoseto the blood
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Reproductive hormones• Testosterone
– Supports sperm formation– Promotes development of secondary sex
characteristics
• Estrogen – Promotes female secondary sex characteristics
• FHS (folicle stimulating hormone)– Stimulates production of eggs and sperm
• Progesterone – Promotes growth of the uterine lining