Responding to Stimuli 7.2B

Question 1

What are Receptors?

Answer 1

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

Question 2

Stimulus-response model

Answer 2

Stimulus -> Receptor -> Sensory Neuron -> Relay Neuron -> Control Center -> Motor Neuron -> Effector -> Response

Question 3

What is reflex arc

Answer 3

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

Question 4

Divisions of the nervous system

Answer 4

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

Question 5

Sympathetic nervous system

Answer 5

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

Question 6

Parasympathetic nervous system

Answer 6

rest and digest
Constrict pupils
Constrict bronchioles
Stimulates digestion