Post on 18-Jan-2020
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Three main control systems
NERVOUS SYSTEM • Fine, rapid movements – Muscle control
• Neurons • Synapses
ENDOCRINE SYSTEM • Slow movements, wide temporal range – Metabolic processes
• Hormones
SENSORY SYSTEM • How body receives/sends sensory signals
• Most Bssues under control of both nervous and endocrine systems
Chapter 14: Nervous system • General organizaBonal scheme – Central Nervous System – Peripheral Nervous System
• Vertebrate Nervous System – FuncBon and Structure – Body Control
Nervous System • Groups of cells specialized for repeated producBon of electrical signals between cells – Conducts impulses – Integrates signals from mulBple neurons
– Generates new impulses based on sensory sBmuli
Signal Movement
1. Signal arrives at neuron 2. Transduced to adjacent neurons OR to
sensory receptor cells 3. Signal sent to organs to carry out funcBon
Signal (sBmulus)
Sensory receptor cells
Other neurons
Organs (carry out funcBons)
Structural division of nervous system 1. Central Nervous System: large
structures – Brain, spinal cord
2. Peripheral Nervous System: all other neurons outside of CNS
Central Nervous System • Lots of neurons and support cells interact to perform funcBons 1. Sensory neurons: Relay messages FROM
receptor cells TO the CNS (brain or spinal cord)
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Central Nervous System • Lots of neurons and support cells interact to perform funcBons 2. Motor neurons: Relay messages from the CNS to
effectors (muscles and organs)
Central Nervous System • Lots of neurons and support cells interact to perform funcBons 3. Interneurons: Relay informaBon WITHIN the
CNS
InformaBon travels in neural circuits 1. SBmulus excites
sensory neurons – Sends info TO CNS
2. Info moves within CNS (processed)
3. Info leaves via motor neurons – Axons innervate
effectors 4. Effector cells receive
info – Carry out funcBon
Peripheral Nervous System • All sensory or motor neurons outside of CNS
• Composed of nerves • Axons of neurons bundled together
Peripheral Nervous System
a. SomaBc Nervous System (voluntary)
b. Autonomic Nervous System (involuntary)
• Different neurons make up different pathways 1. Sensory pathway à sensory neurons 2. Motor pathway à motor neurons
Peripheral Nervous System 1. SomaBc Nervous System • Observable behaviors
and movements • Skeletal muscles
2. Autonomic Nervous System • Controls involuntary
behaviors • Cardiac muscles,
glands
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Chapter 14: Nervous system • General organizaBonal scheme – Central Nervous System – Peripheral Nervous System
• Vertebrate Nervous System – FuncBon and Structure – Body Control
Vertebrate Central Nervous System: FuncBon and Structure
• CNS: Brain and spinal cord – Centralized and cephalized
CentralizaBon and cephalizaBon • CentralizaBon: neurons collected into a central region of the body
• CephalizaBon: concentraBon of neurons at one end of the body (BRAIN)
More interneurons (BeZer control)
More complex spaBal arrangement (CephalizaBon) Larger brains
(control over more funcBons)
Vertebrate Central Nervous System: FuncBon and Structure
• 2 types of Bssues: 1. Grey maZer: neuronal cell bodies, processes, and
synapses 2. White maZer: myelinated axons
The Brain
• Three regions, 5 subdivisions – FuncBon varies by region – Many funcBons use several regions
The Brain • Brain is the “processing center” for sensory input – Input arrives at different regions
– Processing occurs in different regions
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Inside the brain
1. Brain funcBon is localized 2. Brains have maps 3. Size maZers 4. EvoluBon favors expansion of forebrains 5. Neural circuits are plasBc
1. Brain funcBon is localized • Neurons in different regions perform different
funcBons • Phrenology: study of “brain bumps” • Traits and behaviors
• FuncBonal magneBc resonance imaging (fMRI) and Positron emission tomography (PET) scans • Confirm localizaBon of
funcBons
1. Brain funcBon is localized • Neurons in different regions perform different
funcBons
2. Brains have maps
• Somatotopic map: parts of body are mapped onto the corresponding parts of the brain à sBmulus in specific secBon of brain elicits response in that part of the body
• Roughly correspond to locaBon on body
3. Size maZers • Bigger is beZer!
More complex
spaBal arrangement (CephalizaBon)
Larger brains (control over
more funcBons)
More interneurons (BeZer control)
4. EvoluBon favors expansion of forebrains
• Bigger forebrain is EVEN beZer!
More complex
spaBal arrangement (CephalizaBon)
Larger brains (control over
more funcBons)
More interneurons (BeZer control)
Larger forebrain (cerebral cortex)
• Many vertebrate lineages evolved larger forebrains
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5. Neural circuits are plasBc • Change in strength and effecBveness over Bme – Storage of long-‐term memory: long-‐term memories generally aren’t lost in concussed paBents
• New neurons may develop within lifeBme – Recent findings have sBmulated research in the stem cell field!
Peripheral Nervous System • PNS: collecBon of nerves that relay informaBon to/from CNS • Axons of neurons bundled together
Vertebrate Peripheral Nervous System: FuncBon and Structure
• Afferent neurons (sensory neurons) carry nerve impulses to CNS
• Efferent neurons (motor neurons): carry impulses away from CNS to effectors
Vertebrate Peripheral Nervous System: FuncBon and Structure
• Nerves are not integrated within the PNS – All informaBon funneled through CNS for processing
• Cranial nerves connect PNS to brain
• Spinal nerves connect PNS to spinal cord
Vertebrate Peripheral Nervous System: FuncBon and Structure
• Peripheral Nervous System: 1. SomaBc Nervous
System
2. Autonomic Nervous System
Vertebrate Peripheral Nervous System: FuncBon and Structure
1. SomaBc Nervous System – Observable behaviors: LocomoBon, muscles, speech, breathing
– Motor signals DO NOT synapse (communicate) with other neurons • Motor neurons extend from CNS directly to effector (organ, muscle)
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Vertebrate Peripheral Nervous System: FuncBon and Structure
2. Autonomic Nervous System – Smooth muscles, glands, acid-‐secreBng cells in stomach
– Motor neurons synapse with other neurons at peripheral ganglia
CNS Ganglia Effector Preganglionic neurons
-‐ Neurons from CNS
Postganglionic neurons
-‐ Neurons to effectors -‐ Neurons release Ach (sBmulates AP)
Vertebrate Peripheral Nervous System: FuncBon and Structure
2. Autonomic Nervous System 1. ParasympatheBc 2. SympatheBc
SympatheIc :“fight or flight” • Movements, stressful acBviBes
• Ganglia connect spinal cord to effectors – Ganglia located near spinal cord – Short preganglionic neurons (from
CNS), long postganglionic neurons (to effectors)
• Most neurons release epinephrine (stress hormone)
Vertebrate Peripheral Nervous System: FuncBon and Structure
ParasympatheIc :“business as usual”
• Internal metabolic processes
• Ganglia connect brain stem to effectors – Ganglia located near effector – Long preganglionic neurons (from
CNS), short postganglionic neurons (to effectors)
• All release acetylcholine(neurotransmiZer)
Vertebrate Peripheral Nervous System: FuncBon and Structure
• May funcBon together – Regulate different specific funcBons within system – Oppose the effects of the other (keeping system balanced)
Vertebrate Peripheral Nervous System: FuncBon and Structure