L.E. Bio Topic 10 Regulation Part I. The Nervous System

Regulation Control and Coordination of life activities. Two Ways. 1.Nerve 1.Nerve- electro-chemical Fast ActingShort Duration - Fast Acting, but Short Duration. 2.Chemical 2.Chemical- hormones-proteins “chemical messengers” -Slow ActionLong Lasting -Slow to Action, but Long Lasting. homeostasis * Through 1 & 2 – homeostasis is maintained. Like a car on cruise control the body is constantly making adjustments. It is never at rest!

Part I. Nerve Control Nerve Cells NeuronsNerve Cells – Neurons - specialized for the transition of impulses from one part of the body to another. cannot divideNeurons cannot divide. –Cannot be replaced. If outside the brain and spinal cord may slowly grow back.

Structure of a Neuron

Recognize the major parts of the neuron, and what each does; dendrite, cell body or cyton, axon, myelin sheath, terminal branch, synapse, neurotransmitter. DendritesDendrites take in information from surrounding neurons. Cell Body or CytonCell Body or Cyton Processes incoming information and decides whether to “fire’ or not myelin sheathThe myelin sheath is an insulating cover around the axon. Terminal BranchesTerminal Branches release neurotransmitters into the synapse. Axon Axon sends messages out to the terminal branches

Impulses: a region of electrical & chemical change that travels over the membrane of a neuronImpulse: a region of electrical & chemical change that travels over the membrane of a neuron axonReceived by dendrites and pass to cell body and then to axon neurotransmitterWhen it reaches the terminal branches it stimulates the release of a neurotransmitter. LD:HBSD 2, neuron and impulse

Synapse gap muscles glandsA gap (junction) between adjacent neurons, or between neurons and target cells, (muscles or glands) They don’t actually touch. Gap is temporarily bridged by a neurotransmitter ex. Acetylcholine.

Effectors What an impulse acts onWhat an impulse acts on The axons of some neurons have junctions with a muscle or gland –The impulse initiates a response muscleContraction – muscle glandSecretion - gland

Stimulus Any change in the environment detected by a receptor. (sense organ)Any change in the environment detected by a receptor. (sense organ) Types of sense receptors –Touch/pressure –Heat/cold –Smell –Taste –Pain –Ect.

Response A reaction to a stimulus carried out by effectors.A reaction to a stimulus carried out by effectors. –Types of effectors MusclesMuscles GlandsGlands/.

Sub-Human Nerve Control

Protists simple responses –Have some simple responses. CNSNo CNS (Central Nervous System)

Hydra CNSNo CNS, NetHas a crude “Nerve Net” –When a neuron is stimulated the impulse travels in all directions.

Earthworm CNSHas CNS. ventral nerve cord.primitive brain (fused ganglia) and ventral nerve cord. peripheral extend brainHas peripheral nerves that extend from brain and nerve cord. –Impulses travel in one direction over definite pathways,

Grasshopper Similar to earthworm CNSperipheralHas CNS & peripheral nerves sense receptorsHas highly developed sense receptors –Eyes, tympana (sound), antennae (touch)

Human Nervous dorsalCNS – Highly developed brain & dorsal nerve cord PeripheralPeripheral nerves sense receptorsHas highly developed sense receptors

Neurons Nerve Cells 3 Types 1.Sensory Neurons 2.Motor Neurons 3.Inter Neurons or Associative Neurons

Sensory Neuron from receptors to CNS –Transmit impulses from receptors to CNS Eyes, ears, tongue, nose, and skin –Receptors – Eyes, ears, tongue, nose, and skin

Motor Neuron from CNS to effectorsTransmit impulses from CNS to effectors

Interneuron / Associative Neuron brain spinal cordFound in brain and spinal cord from sensory to motor neuronsTransmit impulses from sensory to motor neurons. May split impulse and sends it to CNS Sensory Neuron Motor Neuron

Central Nervous System (CNS) Brain and spinal cordBrain and spinal cord

The Human Brain Three Parts 1.Cerebrum 2.Cerebellum 3.Medulla

1. Cerebrum Largest part messagesReceives and interoperates messages from sense organs thought, memory, learning emotionsCenter for thought, memory, learning and emotions voluntaryinitiates all voluntary movements

2. Cerebellum balancecoordinationCenter for balance and coordination of muscle movements BelowBelow and behind cerebrum

3. Medulla base of brainAt the base of brain and Top of spinal columnTop of spinal column Connects the brain to spinal column vital involuntary functionsControls vital involuntary functions –Heart beat, breathing, blood pressure, peristalsis

Pathway of an Impulse

Peripheral Nervous System (PNS) outsideAll sensory and motor neurons that are outside of the CNS CNS rest of bodyCarry impulses between the CNS and the rest of body. Has two divisions 1.Somatic 1.Somatic nervous system 2.Autonomic 2.Autonomic nervous system

1. Somatic Nervous System Made up of voluntary 1.Nerves that control the voluntary muscles of the body CNS 2.Nerves that transmit impulses from receptors to the CNS

Autonomic Nervous System involuntaryControl involuntary actions (automatic) –Smooth muscle – ex. Peristalsis –Cardiac Muscle – ex. Heart beat –Other involuntary actions – circulation, respiration, ect.

Overview of the Nervous System

Habits Learned automatic repetitionLearned behavior that becomes automatic through repetition. rapid responseEstablishes nerve pathways for rapid response Examples of habits. ( List )

Simple Reflex Arc

Reflexes Automatic, inborn responses to a particular stimulusAutomatic, inborn responses to a particular stimulus. Example Reflex Arc –Set of pathways followed by an impulse in a reflex –No involvement of the brain –Reflexes are usually protective in nature receptor sensory neuron interneuron –1. receptor  2. sensory neuron  3. interneuron (in spinal cord)  motor neuron effector –4. motor neuron  5. effector (muscle or gland.)

Nervous System Disorders Cerebral Palsy Meningitis Stroke Polio