Content: - Introduction - Physiology of thirst

1. Prepared by:
Shorouq Alhoutary

14. • Under normal conditions, most
water intake is due NOT to thirst but
to
• social factors
• cultural factors
• (e.g. drinking with meals or at
work breaks, water in food)

15. Fluid Physiology
‘’Thirst’’
‘’Thirst’’

16. How do we feel
thirsty?

17. There are 4
stimuli for thirst

18. Hypertonicity

19. Hypertonicity
Hypovolaemia

20. Hypertonicity
Hypovolaemia
Hypotension

21. Hypertonicity
Hypovolaemia
Hypotension
Angiotensin II

22. I. Hypertonicity
• Higher concentration of
solutes outside the cell
than inside the cell —>
cellular dehydration
• Causes:
• High sodium diet

23. II. Hypovolaemia
• Decreased blood volume;
more specifically, decrease
in volume of blood plasma
(ICF volume is decreased)
• Causes:
• Haemorrhage

24. III. Hypotension
• = low blood pressure
• Causes:
• Pregnancy
• Heart problems
• Endocrine problems
• Haemorrhage
• Dehydration .. etc

25. VI. Angiotensin II

26. Hypertonicity
Osmorec
eptors
in the
hypothala
mus

27. Hypertonicity
Hypovolaemia
Osmorec
eptors
in the
hypothala
mus
Low
pressure
baroreceptor
s in the great
veins and
right atrium

28. Hypertonicity
Hypovolaemia
Hypotension
Osmorec
eptors
in the
hypothala
mus
Low
pressure
baroreceptor
s in the great
veins and
right atrium
High
pressure
baroreceptor
s in carotid
sinus & aorta

29. Hypertonicity
Hypovolaemia
Hypotension
Angiotensin II
Osmorec
eptors
in the
hypothala
mus
Low
pressure
baroreceptor
s in the great
veins and
right atrium
High
pressure
baroreceptor
s in carotid
sinus & aorta
consequent to
the release of
renin by the
kidney (in
response to
renal
hypotension)

30. In
Summary ..

33. Thank You…
Any Question?
Thank You..