CHAPTER 14 : HOMEOSTASIS
HOMEOSTATIC CONTROL
-Homeostasis maintain a constant internal environment in the body
-this involves a receptor, effector and central control
Outline how a negative feedback mechanism works.[4]
When there is a change in factor away from the set-point, it is detected by a receptor
to release hormones. The hormones reach the target organs and carry out corrective
actions to return the factor back to the set-point.
Negative feedback - the body’s mechanism for reversing a change so that it returns back to
the optimum
Positive feedback - any change from the set point is increased (opposite of negative
feedback)
CONTROL OF BODY TEMPERATURE
-Thermoregulation is the control of body temperature which involves nervous and endocrine
systems
HYPOTHALAMUS
-central control for body temperature
-has thermoreceptor cells that monitor the temperature of the blood flowing through it which
is called the core temperature
-receives information about temperature from the receptors on the skin
Decrease in temperature of the surroundings
1)Skin receptors detect a decrease in the temperature of the surroundings
2)Hypothalamus sends impulses that activate physiological responses such as
vasoconstriction, shivering, raising body hairs, decreasing the production of sweat
Increase in temperature of the surroundings
1)Detected by skin receptors or the central thermoreceptors
2)Hypothalamus increases the loss of heat from the body and reduces heat production
(vasodilation, lowering body hairs, increasing sweat production)
, EXCRETION
-the removal of unwanted products of metabolism such as carbon dioxide and urea
UREA -produced in the liver, from excess amino acids
-main nitrogenous excretory product of humans
-it is transported from the liver to the kidneys, in solution in blood plasma
DEAMINATION
-the breakdown of excess amino acids in the liver, by the removal of the amine group which
forms ammonia and urea
AMMONIA
-very soluble and highly toxic compound
-ammonia would rapidly build up in the blood and cause immense damage. This is prevented
by converting ammonia into urea, which is less soluble and toxic
KIDNEY STRUCTURE
1)The whole kidney is covered by a capsule, beneath which lies the cortex
2)The central area is made up of the medulla
3)The area pelvis is where the ureter joins
4)Each kidney receives blood from a renal artery and returns blood via a renal vein
5)Ureter carries urine from the kidney to the bladder
NEPHRON FUNCTION
HOMEOSTATIC CONTROL
-Homeostasis maintain a constant internal environment in the body
-this involves a receptor, effector and central control
Outline how a negative feedback mechanism works.[4]
When there is a change in factor away from the set-point, it is detected by a receptor
to release hormones. The hormones reach the target organs and carry out corrective
actions to return the factor back to the set-point.
Negative feedback - the body’s mechanism for reversing a change so that it returns back to
the optimum
Positive feedback - any change from the set point is increased (opposite of negative
feedback)
CONTROL OF BODY TEMPERATURE
-Thermoregulation is the control of body temperature which involves nervous and endocrine
systems
HYPOTHALAMUS
-central control for body temperature
-has thermoreceptor cells that monitor the temperature of the blood flowing through it which
is called the core temperature
-receives information about temperature from the receptors on the skin
Decrease in temperature of the surroundings
1)Skin receptors detect a decrease in the temperature of the surroundings
2)Hypothalamus sends impulses that activate physiological responses such as
vasoconstriction, shivering, raising body hairs, decreasing the production of sweat
Increase in temperature of the surroundings
1)Detected by skin receptors or the central thermoreceptors
2)Hypothalamus increases the loss of heat from the body and reduces heat production
(vasodilation, lowering body hairs, increasing sweat production)
, EXCRETION
-the removal of unwanted products of metabolism such as carbon dioxide and urea
UREA -produced in the liver, from excess amino acids
-main nitrogenous excretory product of humans
-it is transported from the liver to the kidneys, in solution in blood plasma
DEAMINATION
-the breakdown of excess amino acids in the liver, by the removal of the amine group which
forms ammonia and urea
AMMONIA
-very soluble and highly toxic compound
-ammonia would rapidly build up in the blood and cause immense damage. This is prevented
by converting ammonia into urea, which is less soluble and toxic
KIDNEY STRUCTURE
1)The whole kidney is covered by a capsule, beneath which lies the cortex
2)The central area is made up of the medulla
3)The area pelvis is where the ureter joins
4)Each kidney receives blood from a renal artery and returns blood via a renal vein
5)Ureter carries urine from the kidney to the bladder
NEPHRON FUNCTION
