1. ﴿و ما أوتيتم من العلم إلا قليلا﴾
بسم الله الرحمن الرحيم
﴿و ما أوتيتم من العلم إلا قليلا﴾
صدق الله العظيم الاسراء اية 58

2. Physiology of Special Senses Lecturer of Medical PhysiologyBy
Dr. Abdel Aziz M. Hussein
Lecturer of Medical Physiology
Member of American Society of Physiology
Physiology of Special senses, Abdelaziz Hussein

3. Physiology of Special senses, Abdelaziz Hussein

4. Physiology of Special senses, Abdelaziz Hussein

5. Physiology of Special senses, Abdelaziz Hussein

6. Intraocular Fluids

7. Intraocular Fluids
Aqueous humour
Vitreous humour

8. A) Aqueous Humour

9. The Aqueous Humour
Transparent colourless alkaline fluid that fills the anterior and posterior chambers of the eye

10. The Aqueous Humour Mechanism of formation Rate At a rate 1-2 µL/min
Formed continuously by the Ciliary epithelium by facilitated diffusion and active transport mechanisms
Na by active transport
Cl and HCO3 and H2O follow Na passively
Rate
At a rate 1-2 µL/min

11. The Aqueous Humour Composition
Nearly protein free (contains about mg/L).
Na+ concentration is higher plasma
Vitamin C concentration is times higher than plasma
Bicarboante concentration is higher than plasma.

12. The Aqueous Humour
Circulation and drainage of aqueous humour

13. The Aqueous Humour Functions
1. It is one of the important refractive media of the eye
2.It nourishes the avascular cornea and lens.
3.It also buffers the acid produced by the anaerobic metabolism of the cornea and lens.
4.It has a mechanical function to keep the eyes rigid and to maintain its refractory power.
5.It maintains the intraocular pressure constant by means of its steady formation and drainage

14. Intraocular Pressure (I.O.P.)
It is the pressure inside the eyeball
It is due to the resistance of flow in the narrow channels of drainage
is kept constant by balance between the rate of drainage of aqueous and the rate of its secretion
Value
The I.O.P. of a normal eye is mmHg
Intraocular Pressure

15. Intraocular Pressure (I.O.P.)
A normal I.O.P. is essential for the focusing mechanism of the eye and proper accommodation of the lens
↑ lens convexity and power
↓ lens convexity and power
↑ IOP
↑ suspensory ligament tension
↓ IOP
↓ suspensory ligament tension

16. Intraocular Pressure (I.O.P.)
It is measured by special apparatus called Tonometer

17. Glaucoma
It is a pathological condition due to excessive rise of IOP e.g. 80 mmHg

18. B) Vitreous Humour

19. Vitreous Body
Hyaloid canal
Retrolental space
Capsule

20. Vitreous Body Functions It is one of the refractive media of the eye.
It supports the retina
It supports the crystalline lens and prevents it from falling back
It maintains the spherical shape of the eye

21. The Middle Layer or
Uveal Tract

22. Uveal Tract
Choroid
Iris
Ciliary ms

23. The Iris
Iris

24. Radial or Dilator Pupillae ms Circular or Constrictor Pupillae ms
The iris
Muscles of the iris
Radial or Dilator Pupillae ms
Circular or Constrictor Pupillae ms

25. Functions of the Iris
The pigments of iris absorb all light rays which enter into the eye except though which pass through the pupil.

26. Functions of the Iris
2. It prevents light from falling on the peripheral parts of the lens. Thus it prevents spherical and chromatic aberration

27. Spherical Aberrations

28. Chromatic Aberrations

29. Functions of the Iris
3. It regulates the amount of light which enters into the eye by regulating the size of the pupil.
4. Pupillary constriction increases the depth of focus i.e. the distance of the object can be changed but its image is still focused on the retina without change in accommodation.

30. Functions of the Ciliary Body
1. The ciliary muscle is essential for accommodation
2. The ciliary processes secrete the aqueous humour into the posterior chamber & give attachment to the suspensory ligament of the lens.

31. Functions of the Choroid
1. It is a vascular layer which provides blood supply to the eye
2. The pressure inside its vessels maintains the intraocular pressure
3. It contains melanin pigments which absorb light & prevent its reflection inside the eye which cause blurring of vision

32. THANKS