TEMERATURE REGULATION & HOMEOSTASIS
o Process of maintaining a constant, internal environment within narrow limits,
despite changes that take place internally and externally.
o Tissue uid composition will always affect the cells around it
o Organs involved in homeostasis!skin, kidney, lungs and liver
TISSUE FLUID:
− Forms the immediate environment of every cells!it must be carefully
regulated
− Must be regulated with regard to the following:
1. Water:
• Makes up bulk of tissue uid and cells
• Affects osmotic and water potentials of the uids
• Determines whether water moves into or out of cells
2. Oxygen + Glucose concentration:
• In uences rate of cellular respiration
3. Carbon dioxide concentration:
• In uences the breathing rate
4. pH:
• in uences enzyme action.
• Extreme changes in pH causes enzymes to denature
5. Temperature:
• In uences enzyme actions
• High temperatures!enzymes denature
• Low temperatures!enzymes inactive
6. Proteins
• Needed for growth and repair of cells
7. Salts and fats
• Correct concentrations for the proper functioning of cells
8. CO2 + Nitrogenous waste:
• Waste products must be removed continuously
• If they accumulate!toxic effect
, NEGATIVE FEEDBACK
o Regulatory/control mechanisms in the body
o Important in HOMEOSTASIS
o Any deviation by a component from the normal is recti ed by a change in
the opposite direction
o Consists of 3 parts:
− Sensory/afferent mechanism: detects deviations from the normal
and activates the control center
− Control center: Receives information and processes it. Programs an
instruction which is sent out to the motor/efferent mechanism.
(includes endocrine/nervous system)
− Motor/efferent mechanism: Involves muscle/glands!they respond
to instruction and correct the deviation
o Amounts to:
Change/deviation creates a STIMULUS ! Stimulus detected by RECEPTOR
! CONTROL CENTRE (brain/ endocrine system) ! EFFECTOR causes a
reaction ! REACTION corrects change/deviation ! NEGATIVE FEEDBACK
MECHANISM
o Means: increase in end product causes a decrease in production OR
decrease in end product causes an increase in production
REGULATION OF BLOOD GLUCOSE (ROLE OF INSULIN &
GLUCAGON):
o GLUCOSE:
− Blood glucose level increases, a series of processes (insulin secretion)
cause a decrease in glucose
− Blood glucose level decreases, a series of processes cause an increase in
glucose in blood (glucagon secretion)
−
o IF BLOOD IS SUGAR IS HIGH:
(After a meal with carbohydrates)
− Digestion results in high level of glucose in blood (stimulis)
− Beta Cells (in Islets of Langerhans in pancreas) secrete insulin (receptor) +
less glucagon secreted
− Raised insulin tells liver: glucose converted —> glycogen (effector)
glucose taken out of blood
− Blood glucose level drops back to normal
o IF BLOOD IS SUGAR IS LOW:
− Glucose level drops below normal (stimulus)
− Alpha Cells (in Islets of Langerhans in pancreas) secrete glucagon
(receptor) + less insulin secreted
o Process of maintaining a constant, internal environment within narrow limits,
despite changes that take place internally and externally.
o Tissue uid composition will always affect the cells around it
o Organs involved in homeostasis!skin, kidney, lungs and liver
TISSUE FLUID:
− Forms the immediate environment of every cells!it must be carefully
regulated
− Must be regulated with regard to the following:
1. Water:
• Makes up bulk of tissue uid and cells
• Affects osmotic and water potentials of the uids
• Determines whether water moves into or out of cells
2. Oxygen + Glucose concentration:
• In uences rate of cellular respiration
3. Carbon dioxide concentration:
• In uences the breathing rate
4. pH:
• in uences enzyme action.
• Extreme changes in pH causes enzymes to denature
5. Temperature:
• In uences enzyme actions
• High temperatures!enzymes denature
• Low temperatures!enzymes inactive
6. Proteins
• Needed for growth and repair of cells
7. Salts and fats
• Correct concentrations for the proper functioning of cells
8. CO2 + Nitrogenous waste:
• Waste products must be removed continuously
• If they accumulate!toxic effect
, NEGATIVE FEEDBACK
o Regulatory/control mechanisms in the body
o Important in HOMEOSTASIS
o Any deviation by a component from the normal is recti ed by a change in
the opposite direction
o Consists of 3 parts:
− Sensory/afferent mechanism: detects deviations from the normal
and activates the control center
− Control center: Receives information and processes it. Programs an
instruction which is sent out to the motor/efferent mechanism.
(includes endocrine/nervous system)
− Motor/efferent mechanism: Involves muscle/glands!they respond
to instruction and correct the deviation
o Amounts to:
Change/deviation creates a STIMULUS ! Stimulus detected by RECEPTOR
! CONTROL CENTRE (brain/ endocrine system) ! EFFECTOR causes a
reaction ! REACTION corrects change/deviation ! NEGATIVE FEEDBACK
MECHANISM
o Means: increase in end product causes a decrease in production OR
decrease in end product causes an increase in production
REGULATION OF BLOOD GLUCOSE (ROLE OF INSULIN &
GLUCAGON):
o GLUCOSE:
− Blood glucose level increases, a series of processes (insulin secretion)
cause a decrease in glucose
− Blood glucose level decreases, a series of processes cause an increase in
glucose in blood (glucagon secretion)
−
o IF BLOOD IS SUGAR IS HIGH:
(After a meal with carbohydrates)
− Digestion results in high level of glucose in blood (stimulis)
− Beta Cells (in Islets of Langerhans in pancreas) secrete insulin (receptor) +
less glucagon secreted
− Raised insulin tells liver: glucose converted —> glycogen (effector)
glucose taken out of blood
− Blood glucose level drops back to normal
o IF BLOOD IS SUGAR IS LOW:
− Glucose level drops below normal (stimulus)
− Alpha Cells (in Islets of Langerhans in pancreas) secrete glucagon
(receptor) + less insulin secreted
