Chapter Summary

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Chapter 3 Summary

• Homeostasis is the maintenance of a relatively constant internal environment and it is made possible by the coordination and integration of physiological systems.
• The nervous system receives sensory information from receptor organs such as the skin, the ears, the eyes, processes this information and generates responses, it regulates and coordinates so as to maintain homeostasis, it is responsible for higher functions such as emotion, memory, thinking, and it also controls muscular movement.
• The endocrine system acts through chemical messengers (hormones) and has a key role in homeostasis. It is involved in the regulation of growth, development and reproduction, and, control of the storage and utilisation of energy substrates.
• The heart and blood vessels comprise the cardiovascular system, and its function is to circulate blood around the body – a transport system that serves other systems to maintain homeostasis.
• The respiratory system provides an infrastructure to ventilate the lungs and exchange gas, linking with the cardiovascular system to transport blood gases and maintain acid-base balance.
• The lymphatic system returns excess interstitial fluid to the vascular system, is a pathway for the absorption of fats from the intestine, and has a role in defence/immune responses.
• A complex array of offensive organisms and environmental agents require a complex defence or immune system, and there exists varying degrees and types of immune system specificity and components to protect us.
• Ingested materials pass by orderly and controlled means from the mouth to the anus in the digestive system, aided by smooth muscle activity that is responsible for gastric and intestinal motility, and absorptive processes that utilise a leaky epithelium – the small intestine, to take up ions, water, minerals and vitamins, monosaccharides, peptides and lipids.
• The liver is the largest gland in the body and hepatic cells are responsible for functions such as bile production, the storage and interconversion of nutrients, and detoxification of harmful metabolites and substances.
• The kidneys regulate the volume and composition of the body fluids, and excess intake of water and ions is excreted in the urine.