Intro

• Physiology is the study of normal body functions.
• The study of the normal functions of a living organism is known as physiology.
• The basic unit of both structure and function is the cell.
• A cell is the smallest structure of living matter, which is capable of functioning as an independent unit.
• In a unicellular organism like Amoeba, the cell performs all vital processes needed for life such as respiration, digestion, movement, and reproduction.
• In a multicellular organism like humans, group of cells collect together to form tissues or organs to perform specific functions, but each cell can sustain its own life.
• The body systems are: Circulatory, Digestive, Respiratory, Urinary, Skeletal, Muscular, Reproductive, Immune, Nervous, Endocrine.
• In an adult male, body weight is 70 kilograms, with 18% of his body weight being proteins, 15% being fats, 7% being minerals, 60% being water, and 1% being other substances.
• Water content in the body decreases with obesity, and females have lower water content than males.
• Total body water decreases with age.
• Intra-Cellular fluid (ICF) is the water inside cells, while Extra-Cellular fluid (ECF) is the water outside cells, which is subdivided into Interstitial fluid (ISF) and plasma.
• Sources of water loss include urine (1500 ml), insensible water loss via respiratory tract & skin (900 ml), stool (100 ml), drinking (1300 ml), water contained in solid food (800 ml), and water derived from oxidative metabolism in our body (400 ml).
• Under pathological conditions, patients have severe vomiting & diarrhea, and in patients receiving intra-venous infusions, water balance means water gain = water loss.
• If water loss > water gain, it is referred to as dehydration, while if water gain > water loss, it is referred to as overhydration or water loaded.
• The fluid inside the cells of the body, intracellular fluid (ICF), is very different from that outside the cells, the extracellular fluid (ECF).
• The digestive system involves different dissolved nutrients being absorbed into blood through the wall of the gastrointestinal tract.
• The nervous system involves sending impulses to muscles to control movement.
• Homeostasis is the maintenance of constant conditions in the internal environment of the body, essential to maintain constant conditions in this internal environment, since normal cell function depends upon this constancy.
• The composition of body fluids is extremely important to the life of the cell.
• ICF contains very large amounts of phosphates & proteins & small amount of Cl-, the main ICF anions are phosphates & proteins.
• The respiratory system involves blood passing through the lungs, picking up oxygen and releasing carbon dioxide into the alveoli.
• Factors in the internal environment that must be homeostatically maintained include pH, blood volume, blood pressure, and temperature.
• ECF contains large quantities of Na+ & small quantities of K+, the main ECF cation is Na+.
• The circulatory system involves continuous movement of blood in the circulatory system.
• The endocrine system involves regulating cellular functions by hormones.
• The external environment is the surrounding environment in which the organism lives, while the internal environment is the fluid that surrounds the cells, i.e., ECF.
• Homeostasis increases the chances of survival, allows freedom to live in a variety of conditions, and permits proper functioning of the brain.
• ICF contains large quantities of K+ & small quantities of Na+, the main ICF cation is K+.
• The kidneys and urinary system involve blood passing through the kidneys, with wastes and excesses of water being removed.
• The skin serves as an outer protective barrier.
• The nervous and the endocrine systems are the two major regulatory systems.
• The reproductive system involves continuity of species.
• The musculoskeletal system involves the body moving to obtain its requirements as food and to move away from adverse surrounding, serving as a protective function.
• Homeostatic mechanisms of the major functional systems include the circulatory system, respiratory system, digestive system, kidneys and urinary system, immune system, musculoskeletal system, nervous system, and endocrine system.
• ECF contains large amount of Cl- & small amount of phosphates & proteins, the main ECF anion is Cl-.
• The immune system involves defending against foreign invaders.