thirst-physiological response to deficency of fluid,need of water

1. THIRST
 A physiological manifestation of need of
water
 Thirst motivates an organism to drink

3. Loss of water
 Water is gradually eliminated through
 Defecation - faeces (4%)
 Perspiration - skin (8%)
 Respiration - lungs (28%)
 Excretion - urine (60%)

4. Dehydration
 Definition ;
 Dehydration is a condition that occurs when there is a
loss of body fluid in excess amount.
 Symptoms of dehydration
 Increased thirst
 Decreased urine output

5. RAAS (renin angiotensin-aldosterone system)

6. Decreased blood volume
Animal
drinks
G
Decreased
blood volume
CORTEX
KIDNEY
HYPOTHALAMUS
Kidney
reabsorbs
water
Message sent to
cortex to drink
Message sent to
hypothalamus
BLOOD VESSELS
Message sent to
blood vessels

7. Cellular dehydration
Animal
drinks
G
Cellular
dehydration
CORTEX
KIDNEY
HYPOTHALAMUS
Kidney
reabsorbs
water
Message sent to
cortex to drink
Message sent to
kidney to reabsorb
water