MODULE 5
5.1.1 COMMUNICATION AND HOMEOSTASIS
(a) The need for communication - Respond to abiotic and biotic factors
systems in multicellular - Coordinate activities of different organs
organisms - Optimum temp for enzyme reaction involved in metabolic reaction
(b)The communication between - Communication between cells
cells by cell signalling - Cells recognition
- To trigger a response
(c) The principles of homoestasis - Maintaining a stable internal environment around the set point despite
internal and external changes
- Receptors (detects the change) vs effectors (muscle or gland that brings
about change)
- Negative feedback -> mechanism that reverses the change bringing the
system back to optimum/ set point
- Positive feedback -> mechanism that increases a change, taking the
system further away from optimum
(d)The physiological and Endotherms Ectotherms
behavioural responses involved Organisms that uses heat from Organisms that replies on external
in temp control in ectotherms metabolic reactions to maintain temp to maintain body temp, cannot
and endotherms body temperature increase metabolic rate to maintain
temp
Peripheral temperature receptors
peripheral temperature Thermoregulatory centre in the Behavioural responses
hypothalamus contains
receptors, the role of the hypothalamus and thermoreceptors
effectors in skin and muscles; behavioural Vasodilation/ vasoconstriction
responses Hair erector muscle
Sweating/ shivering
More vulnerable to fluctuation in
environment temperature
,5.1.2 EXCRETION
(a) Excretion and its importance in - The removal of metabolic waste from the body
maintaining metabolism and - CO2 can cause respiratory acidosis and urea are toxic and would cause
homeostasis damage if not removed
(b)Liver Structure:
- Located below the diaphragm
- Hepatic artery (oxygenated blood from aorta to liver)
- Hepatic portal vein (deoxygenated blood from small intestines to liver)
- Hepatic vein (deoxygenated blood from liver to right side of heart)
- Sinusoid (increase oxygen content for cells to work)
, Functions (hepatocytes):
- Storage of glycogen
- Makes bile
- Urea formation:
Deamination (amino acid + oxygen -> ammonia + keto acid) removal
of amine group
Ornithine cycle (ammonia converted to urea)
- Detoxification of alcohol
Ethanol -> ethanal -> ethanoate -> acetyl CoA
(c) Kidney Structure (nephron):
5.1.1 COMMUNICATION AND HOMEOSTASIS
(a) The need for communication - Respond to abiotic and biotic factors
systems in multicellular - Coordinate activities of different organs
organisms - Optimum temp for enzyme reaction involved in metabolic reaction
(b)The communication between - Communication between cells
cells by cell signalling - Cells recognition
- To trigger a response
(c) The principles of homoestasis - Maintaining a stable internal environment around the set point despite
internal and external changes
- Receptors (detects the change) vs effectors (muscle or gland that brings
about change)
- Negative feedback -> mechanism that reverses the change bringing the
system back to optimum/ set point
- Positive feedback -> mechanism that increases a change, taking the
system further away from optimum
(d)The physiological and Endotherms Ectotherms
behavioural responses involved Organisms that uses heat from Organisms that replies on external
in temp control in ectotherms metabolic reactions to maintain temp to maintain body temp, cannot
and endotherms body temperature increase metabolic rate to maintain
temp
Peripheral temperature receptors
peripheral temperature Thermoregulatory centre in the Behavioural responses
hypothalamus contains
receptors, the role of the hypothalamus and thermoreceptors
effectors in skin and muscles; behavioural Vasodilation/ vasoconstriction
responses Hair erector muscle
Sweating/ shivering
More vulnerable to fluctuation in
environment temperature
,5.1.2 EXCRETION
(a) Excretion and its importance in - The removal of metabolic waste from the body
maintaining metabolism and - CO2 can cause respiratory acidosis and urea are toxic and would cause
homeostasis damage if not removed
(b)Liver Structure:
- Located below the diaphragm
- Hepatic artery (oxygenated blood from aorta to liver)
- Hepatic portal vein (deoxygenated blood from small intestines to liver)
- Hepatic vein (deoxygenated blood from liver to right side of heart)
- Sinusoid (increase oxygen content for cells to work)
, Functions (hepatocytes):
- Storage of glycogen
- Makes bile
- Urea formation:
Deamination (amino acid + oxygen -> ammonia + keto acid) removal
of amine group
Ornithine cycle (ammonia converted to urea)
- Detoxification of alcohol
Ethanol -> ethanal -> ethanoate -> acetyl CoA
(c) Kidney Structure (nephron):
