It's about physiology of kedny

1. OBJECTIVES
At the end of the lecture, students should be able to:
1- Define pain and its types
2- Describe the physiological importance.
3- list sites and type of pain receptors.
4- Mechanism of stimulation of pain receptors.
5- Compare between fast and slow pain
6- List in details: reactions of pain.
7- Definition of hyperalgesia

3. Pain Sensation
Pain is an unpleasant sensory and emotional
experience associated with actual or potential tissue
damage.
Pain sensation is a protective mechanism for the body; it
motivates the individual to withdraw from damaging
situations, to protect a damaged body part while it
heals, and to avoid similar experiences in the future.

4. Pain receptors
Free never ending: slowly adapting they are
excited by the following agents:
• Chemicals: Chemo-sensitive pain receptors.
• Excessive heat : Thermo-sensitive pain
receptors.
• Mechanical stress : Mechano-sensitive pain
receptors.

5. Mechanism of stimulation of pain receptors:
They are stimulated chemically by certain
substances released from damaged tissues
e.g. Bradykinin, substance P, histamine,
Serotonin, K+ ions, Proteolytic enzymes and
prostaglandins.

6. Types of pain
According to location of pain :
• cutaneous (skin),
• somatic (joints and bones),
• visceral (body organs).
According to the quality of pain:
• Sharp pricking
• Dull aching

8. Afferent: Aδ fibers( fast pain)& C fibers (slow pain)
1st order neuron: dorsal root ganglia
2ndorder neuron: posterior horn cells on the same side. Pain fibers
then cross to the opposite side & ascend in the lateral spinothalamic
tract:
Fast pain: neo spinothalamic tract
Slow pain: paleo spinothalamic tract
PAIN PATHWAY
3rd order neuron:thalamus
Fast pain---thalamus---------sensory cortex(SSI,II)
Slow pain:
-1/10 of fibers----thalamus-------sensory cortex(SSI,II)
9/10 of fibers-----reticular formation—non specific nuclei of
thalamus– whole cortex

12. Cutaneous pain
This type of pain is perceived as a result of
stimulation of pain receptors in the skin.
Pain receptors are slowly-adapting receptors,
which continuously inform the CNS about
tissue damage.

13. Cutaneous Pain
•This may be fast well-localizd pricking pain or
slow diffuse burning pain.
•It is not referred to other areas
•Resulted in a serious of reactions

15. Reactions of
Pain
Somatic
Relexe
withdrawal
reflex
- protective,
& prepotent
Autonomic
effects:
- Symp
effects
- If severe,
Parasymp
effects
Emotional
effects
(e.g. crying,
restlessness
and anxiety)
due to
stimulation
of the limbic
system
Cutaneous
hyperalgesia
(tenderness)

16. HEADACHE
Intra cranial
Meningitis/Meningeal trauma
Brain tumors
Alcohol
Hypertension
Migraine headache
Change in intra cranial pressure
Constipation
Extra cranial
EYE: glaucoma /Error of refraction
Sinusitis
Toothache
Otitis media
Tension headache: spasm of neck & scalp muscles

17. References
• Human physiology, 2001, 1st edition, Andrew Davis,
Asa G.H. Blackelery and Cecil Kidd. CHURCIL
LIVINGSTONE.
• Review of Medical Physiology, 2003, 21th edition,
William Ganong, McGraw-Hillcompanies. Inc
• Medical physiology, 1995, Rodney A Roades and
George A. Tanner, Little brownb and company,
Boston USA.
• Guyton and Hall Textbook of Medical Physiology,
John E.Hall Elsevier Health Seciences, 13th edition
2012.