1. Chapter 15:Coordination
Part 1

2. The Nervous System
Function to pass information between different parts of the body to coordinate activities of the body
Take in large amount of information from environment and allow organisms body to respond to it
Purpose of information transfer:
Coordinate regulation of substances within in an organism
Ex. Maintain blood glucose concentration
Change the activity of apart of organism ins response to external stimulus
Ex. Pulling hand away from hot stove
Two types of information transfer to coordinate activity in organism:
Nerves
Transmit info in form of electrical impulses
Chemical messengers
“Hormones” that travel in blood to different parts of organism to cause a change

3. Organization of the Nervous System
Components:
Brain
Nerves
Spinal cord
White matter  mostly axons
Grey matter  mostly cell bodies; contain all synapses
Divisions by location:
Central Nervous System (CNS)
Brain and spinal
Function: processing of information received from PNS and coordinating a response
Peripheral Nervous System (PNS)
Nerves and receptors
Function: transmits information going in and going out of the body

6. Peripheral Nervous System Divisions
Afferent/sensory component
Brings info INTO brain
Incoming signal
Efferent/motor component
Sends info/signal OUT of the brain
Outgoing signal
2 types of efferent signals:
Somatic Nervous system (SNS): voluntary control
Skeletal muscle
Things under our control
Autonomic Nervous System (ANS): involuntary control
Heart rate, blood pressure, pupil dilation, rate of digestion, etc
Things not under our conscious control
Operate in TWO directions/Two Categories:
Sympathetic Nervous System  Speed Up
Parasympathetic nervous system  Slow Down

8. Autonomic Nervous System Divisions
Sympathetic
Speed everything up
“Gas pedal”
Speeds up body during stress
“Fight or Flight” response
Sympathetic-Speed-Stress (all S’s)
Parasympathetic
Slows everything down
“Brake pedal”
Slows body down during non- stress
‘Rest and digest” side of NS….no need to be ramped up b/c no stress in environment
Two systems work together…called ANTAGONISTIC CONTROL

10. Nerve Cell Structure
Some nerves bring info INTO brain (afferent signal)
Some nerves bring info OUT of brain (efferent signal)
Nerve cells can transmit signals very quickly from brain to receiving structure
Nerve cells called NEURONS
Function: highly specialized cells adapted for rapid transmission of electrical impulses called ACTION POTENTIALS, from one part of the body to another part
Three Different Types of Neurons:
Sensory Neurons
Transmits impulses from receptors TO CNS
Intermediate Neurons
Aka relay or connector neurons
Transmit impulses from sensory neurons to motor neurons
Motor Neurons
Transmits impulses from the CNS to effectors (effectors carry out needed response…muscles and glands)

12. 3 main Parts of Neuron: Dendrite Soma (cell body) Axon
Antennae takes in lots of signals coming in
Thin, cytoplasmic extensions from the cell body
Some short, many branches
Increases surface area for attachment to endings of other neurons
Soma (cell body)
Contains all organelles: mitochondria, ER, lots of ribosomes
Processes information received from the Dendrites
Axon
Very long structure that sends the signal processed by the soma down to another cell down LONG distances
Can be 3-4 ft long!
Cytoplasm contains organelles (mitochondria)
Thick areas surround axons SCHWANN CELLS
Secrete MYELIN biological insulator that protects signal that travels along axon; prevents signal degradation; allows signal to travel faster
Spaces between Schwann cells on axon NODES OF RANVIER
Important in propagation of signal down an axon
AXON TERMINAL: end of axon
Lots of mitochondria
Many vesicles containing TRANSMITTER SUBSTANCES (chemicals called NEUROTRANSMITTERS)
Important in passing impulses to effector cell
SYNAPSE: composed of the parts of the two adjacent neurons and the SYNAPTIC CLEFT (gap between two neurons that is about 20 nm wide)

14. Motor vs. Sensory vs. Intermediate Neuron
All work together to bring about a response to a stimulus

15. Motor vs. Sensory vs. Intermediate Neuron Structure
Motor Neuron
Sensory Neuron
Intermediate Neuron
Cell body lies in spinal cord or brain
Many dendrites coming off of cell body
Dendrites HIGHLY branched
LONG axons
Ends of axons contain lots of mitochondria and transmitter chemicals in vesicles
Some are myelinated
Cell body lies in the CNS
May form synapse with relay neuron
Cell body lies within the spinal nerve
One long axon with cell body that may be near source of stimuli or in swelling of a spinal nerve (GANGLION)
Dendron is usually longer than the axon
Contains many dendrites
Relay neurons
Found entirely in CNS

17. Schwann Cells Specialized support cell
Wrap them selves around axons of MOTOR and SENSORY neurons
Encloses axons with many layers of its cell membrane
Inner most layer of Schwann cell that actually encloses axon is called the MYELIN SHEATH it secretes MYELINE
Secretes Myelin
composed of lipids and protein
Helps insulate axons
Prevents signal degradation
Helps neve impulses travel faster
Myelinated cat fiber = carry impulses up to 100 m/s
Unmyelinated cat fiber = carry impulses only 5 m/s
1/3 of motor and sensory neurons are MYELINATED
2/3 of motor and sensory neurons are UNMYELINATED
Nodes of Ranvier
Areas of the axon NOT covered by the Schwann cells
2-3 um in diameter
Found every 1-3 mm in human neurons (between Schwann cells)

18. Reflex Arc
Pathway along which impulses are transmitted from a receptor to an effector without involving conscious regions of the brain
Sensory neuron connects to motor neurons through interneurons in the central nervous system (either brain or spinal cord)
Sometimes interneurons NOT involved
Impulse passes directly from sensory neuron to motor neuron
Different types of reflex arcs
Brain reflex arc
Pupil dilation/constriction
Spinal reflex arc
Impulse is passed from neuron to neuron inside spinal cord

20. Reflex Action
When an effector responds to the stimulus BEFORE there is any voluntary response involving conscious regions of the brain
Example
Receptor detects signal, impulse passed from one neuron to the next in spinal cord, heading to brain while attach same time impulses are traveling along the motor neuron to the effector and the effector responds first
Fast automatic response to a stimulus
Useful in response to danger signals
Touching hot object
Something flying at your head

21. Practice Paper 4 Question 2

22. Optional portion of question 2