... • In many receptors, the threshold level for a
particular stimulus may rise after continuous
stimulation; this is called sensory adaptation
• Impulses are generated at decreasing rates
until they stop completely and the sensation
• This prevents the brain from being overloaded
by information t ...
... information from sensory receptors (e.g.,
in skin, eyes, nose, tongue, ears)
TOWARD the central nervous system.
• Motor (or efferent) neurons: send
information AWAY from the central
nervous system to muscles or glands
... Directed study: to complement your understanding of the sensory pathways, now study the
body’s receptors and the ‘special’ senses.
Choose from the following texts to support your learning: Chapter 15 in Tortora, Chapter 11 in Seikel
et al (2005), Chapter 5 in Love & Webb (2001), and/or Chapter 9 in ...
... Involuntary control of smooth muscle, cardiac muscle, internal organs and glands
Brings info about body’s internal environment to CNS and carries signals back to
regulate internal environment
The ANS uses 2 groups of motor neurons to stimulate target effectors
a. Preganglionic neurons (CNS gan ...
... divided into two major parts: the
brain and the spinal cord. In the
average adult human, the brain
weighs 1.3 to 1.4 kg (about 3
pounds). The brain contains about
100 billion nerve cells (neurons)
and trillons of "support cells"
called glia. The spinal cord is
about 43 cm long in adult women
and 45 ...
... long. The cytons for the nerves of the legs are located in the spinal cord and the axons
travel the entire length of the legs.
Propagation of impulses
The nerve cell has a positive charge on the outside and a negative charge on the
inside. The nerve impulse causes a temporary change in the charge of ...
... The Neuropathy Trust states that: ‘Peripheral neuropathy is not a complete diagnosis, but simply a
statement that the peripheral nerves are not working properly.’
The afferent peripheral nerves conduct sensory information from receptors on the surface and organs to
the central nervous system (CNS) a ...
... • THE EYE
• CORNEA AND LENS: BEND LIGHT RAYS
AND FOCUS THEM ON THE RETINA
• CILLIARY MUSCLES LOSSEN OR TIGHTEN
TO ADJUST LENS THICKNESS
• RETINA: SITE OF PHOTORECEPTORS
• FOVEA: MOST SENSITVE PART OF RETINA
... b) Bones of the skull and shoulder blades are flat.
c) The spine is composed of regular-shaped bones.
d) The rounded end of a long bone is called epiphysis.
e) Flat bones are made up of two layers of spongy bone.
f) The tibia is an example of a long bone.
g) Short bones are found in the fingers and ...
... o Second order neurons decussate to the contralateral side and group together
At the thalamus they converge at the ventral posterior lateral nucleus (VPL)
The sensory information finally reaches the primary somatosensory cortex (PSSC)
... • Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
• Spinal nerves arising from the spinal cord
• Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
... Monosynaptic reflex arc.
This reflex helps avert injury by preventing
overstretching of a muscle.
Reciprocal inhibition – when the stretched muscle
contracts, the antagonistic muscle(s) relax.
... Any pain which lasts for six months or
more (in athletes we may consider chronic
pain to be pain which is continue from
months but is not in proportion to tissue
injury or activity... i.e... chronic tendinitis
may be long lasting but have organic root)
No real purpose (?)
numerous by-passes. Also ...
... • Carry impulses from pain, thermal, tactile, muscle and joint receptors to the
• Some of this information eventually reaches a conscious level (at the
• while some is destined for subconscious centers (e.g at the cerebellum).
... • Carry impulses concerned with
proprioception (movement and joint
position) and discriminative touch
from ipsilateral side of the body
• Contain the axons of primary afferent
neurons that have entered cord
through dorsal roots of spinal nerves
• Fasciculus Gracilis contains fibers that
are received ...
Hereditary sensory and autonomic neuropathy (HSAN) or hereditary sensory neuropathy (HSN) is a condition used to describe any of the types of this disease which inhibit sensation. They are less common than Charcot-Marie-Tooth disease.