The Scientific Method

What parts of the reflex experiment make up the scientific method?

Scientific Method

Ask a Question Make a Hypothesis Test the Hypothesis--Experiment Analyze Results Make a Conclusion

Variables

Dependent Variable What is effected by the independent

variable. Independent Variable

What you control in the experiment

Variables

What were our independent and dependant variables in the Reflex Lab?

Variables

ControlThe experimental condition that receives no

treatment. Ex. Drug testingWas there a control in the Reflex Lab?

Variables

ConstantsAn experimental condition that does not

change.

Were there any constants in our reflex experiment?

Variables

Repeated TrialsWhy do we do this?

Experimental ErrorWere there any errors in the Reflex Lab?

THE NERVOUS SYSTEM--REFLEXES

The Central Nervous System The Parts

Brain○ Collection of over 100 billion neurons

collectively known as “grey matter”Spinal Cord

○ Contains 31 pairs of spinal nerves that connect the brain to the different parts of the body.Head, neck, shoulders, arms, hands, chest,

abdomen etc.

Peripheral Nervous System All the nerve cells outside the brain and

spinal cord. Two parts of Peripheral Nervous System

Somatic NS = Voluntary Movement (Biking)Autonomic NS= Automatic Responses (blink

etc.)

Question

Which part of the Peripheral Nervous System did we experiment on? How do you know?

What are Neurons?

Neurons are special cells that help the different parts of the body communicate with the Central Nervous System, and Peripheral Nervous System.

Types of Neurons

Sensory Neuron (Input)A neuron that transmits towards the spinal

cord and brain (messenger).

Motor Neuron (Output)A neuron that transmits away from the spinal

cord and brain to the body (e.g. muscle control).

The Neuron

Neuron Function

Nerves from the Peripheral NS work together to let different parts of the body communicate messages to the brain and spinal cord.

The brain or spinal cord then sends a message back which results in a response known as…

REFLEXES!

A quick automatic response to a stimulus Voluntary and Involuntary!

Voluntary Reflex = the reflex game and labThese are more commonly known as

RESPONSES Involuntary Reflex

BlinkingSneezing/CoughingFrightened jump (fight/flight response)

The Reflex Arc

The nerve pathway (loop) that activates a reflex.Part I: A stimulus activates a nerve that

sends a signal to the spinal cordPart II: The spinal cord replies with a new

message that results in a physical reaction (reflex!).

A Short Video

http://www.sumanasinc.com/webcontent/animations/content/reflexarcs.html

The Response Arc (Voluntary)

The Reflex Arc (Involuntary)

What now?

Using your notes on experimental design, create an experiment that tests your INVOLUNTARY reflexes.