B6 Flashcards
What two systems in the human body are used for communication?
The nervous system and the hormonal system
What does the nervous system do?
To send electrical signals using nerves known as neurons
What does the hormonal system do?
It sends chemical messages in the form of hormones
Compare the signals sent by each system
Nervous system : quick, short lasting responses
Hormonal system : slow, long lasting responses
How is the nervous system in mammals composed?
It is made of the central nervous system (CNS), the brain and the spinal chord, and the peripheral nervous system (PNS) which connects the central nervous system to the rest of the body
A receptors job is to…
detect changes in the environment
Our eyes and ears are examples of receptors
Effectors are…
the organ or gland that responds to external stimuli after the signal has been passed along the nervous system
Name the 3 type of neurons and what they do
Sensory - connect to receptors to the CNS
Relay - found in the CNS, takes message from the sensory neuron to the motor neurone
Motor neuron - connects the CNS to the effector
How are hormones transported?
Through the blood but they only affect the ‘target cells’
What does a neuron consist of?
Cell body Dendrites Nucelus Axon Myelin sheath
What do dendrites do?
They receive the signals from other neuron or receptors
What is the function of the axon?
It carries the electrical impulses away from the cell body. It is an extension of the cytoplasm
What is the function of the myelin sheath?
To insulate the neuron from other cells
Name the 3 factors that affect the sped at which a nerve signal is sent
The temperature - signals are always faster in warm blooded animals
The diameter of the axon
The condition of the myelin sheath - the signal can ‘jump’ between the gaps in the myelin sheath speeding up the signal
What is the name of the gap between neurons?
Synapse
Why don’t neurons touch?
So they can communicate with several different neurons at once
How does a signal pass from one neuron to the next?
As the electrical signal reaches the end of the pre-synapse neuron, the appropriate neurotransmitter is triggered and released from the vesicle where it is stored. Theses diffuse across the synapse and bind with the appropriate receptor which triggers and electrical signal to start in the post-synpase neuron
What happens to neurotransmitters after they have bound with receptors?
They are released to be reabsorbed by the neuron or broken down by an enzyme
How do drugs like ecstasy and anti depressants affect neurotransmission?
They prevent the reabsorption of neurotransmitters for a period of time allowing them to remain in the synapse and able to trigger the post-synapse neutron more frequently. These drugs often stop serotonin or dopamine reabsorption allowing the person taking them to feel happier for longer
What is a reflex?
An instantaneous response to a stimulus