Responding to Stimuli 7.2B Flashcards
What are Receptors?
Receptorsare special organs or cells that transmit a signal to a sensory neuron
*Chemoreceptor
sensitive to chemicals, such as odour molecules in the air.
*Mechanoreceptor
sensitive to touch, pressure, sound and motion.
*Pain receptor
sensitive to chemical changes in damaged cells
*Thermoreceptor
sensitive to temperature changes
*Photoreceptor
sensitive to light
Stimulus-response model
Stimulus -> Receptor -> Sensory Neuron -> Relay Neuron -> Control Center -> Motor Neuron -> Effector -> Response
What is reflex arc
in dangerous situations e.g. touching something hot or sharp, we often have a rapid and involuntary response
Reflex arc takes a ‘short-cut’ through the spinal cord allow instant action
The brain is informed later and may trigger tears or cry of pain
Divisions of the nervous system
PNS can be broken into:
Somatic nervous system – effect the skeletal muscles and voluntary movement.
Autonomic nervous system – effect smooth muscles, involuntary movement including digestion and breathing.
The autonomic nervous system can be further grouped into:
Sympathetic nervous system – fight or flight
Parasympathetic nervous system – rest and digestion
Sympathetic nervous system
prepares the body to flee or fight when faced with a dangerous situation. This may include:
Dilation of pupils to clear vision
Dilation of bronchioles increasing oxygen intake
Digestion is slowed to conserve energy
Parasympathetic nervous system
rest and digest
Constrict pupils
Constrict bronchioles
Stimulates digestion