Chapter 1 Physiology

• Physiology is the study of the physical and chemical mechanisms that are responsible for the origin, development, and progression of life.
• Pathophysiology is the study of body function disorders and the basis for clinical medicine.
• Cells are the basic units of the body and every cell in the human body performs specific functions.
• Human body contains 35 to 40 trillion human cells.
• A vast amount of microbes live on the skin, gut, mouth and nose.
• Human body consists of 50 to 70% fluid, a water solution of ions and other substances.
• Intracellular Fluid (ICF) is 2/3rd of fluid within the cell, with major cations including K+ and Mg2+ and phosphate, and has special mechanisms for transporting ions through cell membranes.
• Extracellular Fluid (ECF) is 1/3rd of fluid outside the cells, also known as the internal environment due to ions and nutrients being placed here which are needed by cells in order to function and maintain homeostasis.
• Homeostasis is the maintenance of a constant internal environment despite changes in the external environment.
• Disease can disrupt homeostasis.
• The respiratory system originates nutrients in the extracellular fluid by allowing blood to be picked up by oxygen in the alveoli.
• The gastrointestinal system changes the chemical compositions of substances to more usable forms by absorbing nutrients from ingested food into the extracellular fluid of the blood.
• The liver and other organs primarily function by changing the chemical compositions of substances to more usable forms.
• The musculoskeletal system provides protection against surroundings and allows us to move to obtain foods required for nutrition.
• The nervous system controls muscular and secretory activity of the body through three parts: sensory input portion, central nervous system, and motor output portion.
• The initial decrease in arterial pressure is initiated by a negative feedback system that brings the arterial pressure back to normal.
• Sensory receptors detect the state of the body and its surroundings.
• The central nervous system is composed of brain and spinal cord.
• The brain stores information, creates thoughts/ambition, determines reactions that the body performs in response to stimuli, and then signals are transmitted to the motor output portion of the nervous system to carry out one’s desires.
• The autonomic nervous system is an important segment of the nervous system, operated at a subconscious level, controlling functions of internal organs such as pumping activity of heart, gastrointestinal tract movements, and body gland secretions.
• Feed-forward is used by the brain to cause required muscle contractions.
• Parathyroid hormone controls bone calcium and phosphate.
• Regulation of Oxygen and Carbon dioxide Concentrations in ECF depends on characteristics of hemoglobin and the regulation is known as the oxygen-buffering function of hemoglobin.
• The immune system differentiates between its own cells from harmful foreign substances and destroys invaders through phagocytosis.
• All body structures are efficient to maintain automaticity and continuity of life.
• Gain is an object of measure how well a certain control system can bring an abnormal change to your homeostasis back to normal.
• Adaptive Control, also known as delayed negative feedback; if correction is necessary then the process will be performed again.
• Endocrine glands are within the body that are organs and tissues that secrete hormones.
• Thyroid hormone increases the rate of chemical reactions in all cells, which helps set the tempo of bodily activity.
• Reproduction is not considered a homeostatic function but helps maintain homeostasis by creating/producing humans to replace those who are dying.
• Hormone Systems regulates many metabolic processes.
• Adrenocortical hormones control sodium and potassium ions and protein metabolism.
• Deep rapid breathing allows expiration of CO2 which allows the excess CO2 to be removed from the blood and tissues.
• Baroreceptors are many nerve receptors that are activated by the stretch of the arterial wall and senses our blood pressure.
• The integumentary system includes the skin, hair, nails, and glands.
• Positive feedback system can both be vicious cycle/cause death, and sometimes useful.
• The integumentary system is significant for temperature regulation and excretion of wastes.
• Insulin controls glucose metabolism.
• Hormones are transported to the ECF (extracellular fluid) to other parts of the body to assist regulation of cellular functions.
• The integumentary system is the largest organ on the human body composed of 12% to 15% of body weight, covers, cushions, and protects the deeper tissues and organs of the body and serves as a boundary between the body’s inside environment and the outside world.