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
- 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
- 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.