COMMUNICATION, HOMEOSTASIS AND ENERGY

Transcription

1 MODULE 5 COMMUNICATION, HOMEOSTASIS AND ENERGY BIOLOGY NOTES snaprevise.co.uk

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3 INDEX TOPIC 1: COMMUNICATION AND HOMEOSTASIS The Need for Communication Systems Cell Signalling Homeostasis Ectotherms and Endotherms TOPIC 2: EXCRETION AS AN EXAMPLE OF HOMEOSTATIC CONTROL The Importance of Excretion The Mammalian Liver The Kidney The Control of Blood s Water Potential Kidney Failure The Use of Excretory Products in Medical Diagnosis TOPIC 3: NEURONAL COMMUNICATION Sensory Receptors Sensory, Relay and Motor Neurones Nerve Impulse Generation & Transmission Synapses TOPIC 4: HORMONAL COMMUNICATION Endocrine Communication by Hormones The Adrenal Glands The Pancreas Regulation of Blood Glucose Concentration Diabetes Mellitus TOPIC 5: PLANT AND ANIMAL RESPONSES Plant Responses Plant Hormones Experimental Evidence for The Role of Auxins The experimental evidence for the role of gibberellin The Commercial use of Plant Hormones The Mammalian Nervous System The Human Brain Reflexes Nervous and Endocrine Coordination

4 10. Regulation of Heart Rate The Neuromuscular Junction Mammalian Muscle and Muscular Contraction TOPIC 6: PHOTOSYNTHESIS Photosynthesis and Respiration Chloroplasts and Photosynthesis Factors Affecting the Rate of Photosynthesis TOPIC 7: RESPIRATION The Need for Cellular Respiration The Mitochondrion Glycolysis The Link Reaction The Krebs Cycle Anaerobic Respiration The Difference in Respiratory Substrates The Respiratory Quotient (RQ) Practical investigations into factors affecting the rate of respiration

5 TOPIC 1 Communication and Homeostasis

6 Communication and Homeostasis 1 The Need for Communication Systems Keeping Cells Active All organisms needs to maintain a limited set of conditions Need to respond to changes in external and internal environments This is because cellular activities rely on enzymes which require a specific set of conditions to work effectively Organs need to coordinate their activity to maintain optimal internal conditions that support survival 2 Cell Signalling When cells communicate by signalling, one cell releases a chemical This chemical is detected by another cell The second cell then responds to this signal There are 2 major systems of communication: Neuronal System Network of neurons Quick signals Rapid responses Hormonal System Uses blood to transport signals Endocrine organs secrete hormones directly into blood Carried all over the body Only recognized by specific target cells Enables long-term responses to be coordinated Specific target cells have receptors that have a shape that is complementary to the shape of the hormone snaprevise.co.uk 6

7 3 Homeostasis Homeostasis is the regulation of internal environments independently of external environments These include: Temperature Blood glucose concentration Blood salt concentration Water content Blood pressure Blood carbon dioxide partial pressure (blood ph) Negative Feedback Reversal of a change in the environment to return to the optimum position Receptor detects the change Communication systems inform the effectors The effector reacts to reverse the change Eg: maintaining blood pressure Pathway: Positive Feedback Response causes change to increase Destabilizes the system Usually more harmful Does not lead to homeostasis Can be useful in certain situation Eg: childbirth - uterine contractions Pathway: snaprevise.co.uk 7

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