REFLEX ACTION MECHANISM, for instance, patellar reflex = knee-jerk
Striking
the patellar
tendon with
a reflex
hammer [4]
just
below
the patella
[11] stretches [1] the quadriceps muscle. This produces a signal (an afferent [9]
impulse) which travels back, through a sensory neuron, to the spinal cord [3] and
synapses [5] in the spinal cord, completely independent of any higher centre [10]. From
there, a motor neuron [6] conducts an efferent [8] impulse back to the quadriceps
muscle, triggering [7] contraction. This contraction, coordinated with the relaxation of
the flexor hamstring [2] muscle causes the leg to kick. This reflex is a reflex of
proprioception [12] which helps maintain posture and balance, allowing to keep one's
balance with little effort or conscious thought.
The patellar reflex is a clinical and classic example of the monosynaptic reflex arc. The
bipolar sensory neuron synapses directly on a motor neuron in the spinal cord.
1.- To pull something so that it becomes longer
7.- To make something function
2.- A muscle at the back of the upper part of your leg
8.- An impulse that comes
3.- A set of nerves that connect the brain to other nerves
in the body (it's made of gray and white matter)
4.- A tool with a rubber part at the top that a doctor uses
to hit a tendon and test a reflex
5.- To establish a connection between nerve cells
6.- A nerve cell that conducts an impulse
9.- An impulse that goes
10.- The brain, for instance
11.- The kneecap or knee bone
12.- Perception of your own position or
movement
THE FIVE SENSES
STIMULUS
Receptor
Type
Organ
Sense
Light
Cones and rodes
in the retina.
Photoreceptors
Eye
Sight or vision
Sound
vibrations
Receptor cells in
cochlea.
Inner ear
Hearing or audition
Contact,
pressure or
puncture
Receptors and
nerve endings of
the dermis.
Skin
Touch
Changes of
temperature
Specific
receptors in the
dermis.
Skin
Touch
Substances
dispersed in
the air
Receptor cells in
the olfactory
epithelium
Olfactory
epithelium
Smell
Tongue
Taste
Mechanoreceptors
Thermoreceptors
Chemoreceptors
Molecules
dissolved in
water or saliva
Receptor cells in
taste buds