| What are receptors? | able to detect a change in the body's internal or external environments
can be grouped together in a sense organ or as a specialised nerve ending |
| Thermoreceptors
function and location | thermoreceptors detect temperature changes
located within the skin and in the hypothalamus (temperature of blood flowing through the brain)
hypothalamus regulates body temp using this info |
| Osmoreceptors
function and location | located in the hypothalamus
detect changes in osmotic pressure even if minimal
osmotic pressure refers to the amount of solute in the blood plasma (High osmotic pressure = more solute/low osmotic pressure = less solute)
body water content is strictly controlled |
| Chemoreceptors
function and location | stimulated by certain chemicals
found in the nose and mouth giving the sense of taste and smell
internal receptors in carotid/aortic bodies and medulla
internal receptors sensitive to pH level, O2 and CO2 |
| Mechanoreceptors
function and location | found mainly in skin, detect touch
types include
1=close to surface, sensitive to light touch (more common in sensitive areas)
2=located deeper, sensitive to pressure and vibrations |
| Nociceptors (Pain Receptors)
function and location | stimulated through damage to tissue
concentrated in skin and lining of internal structures
does not adapt quickly so pain is consistent (protective mechanism) |
| Photoreceptors
function and location | located as cones and rods in the eye (specifically the retina)
respond to light
convert light in to signals sent to the brain for processing |
| What are reflexes | rapid automatic response to a change in environment
mostly coordinated by spinal cord (spinal reflex)
some involve unconscious parts of the brain
pathway of impulse called reflex arc |
| The four properties of a reflex | -stimulus
-involuntary
-rapid
-stereotyped |
| 5 stages of the spinal reflex | 1=receptor, reacts to a change in the environment and initiates a nerve impulse
2=sensory neuron, carries the impulse to the CNS
3=synapse, at least one and one or more interneurons
4=motor neuron, nerve impulse to the effector
5=effector, receives nerve impulse and acts |
| other impulses include... | -protective reflexes (present from birth)
-learned reflexes (acquired due to repetition) |
