physiology: introduction

• Physiology is the study of the functions of living things.
• Homeostasis is the process that regulates the body's internal environment.
• Homeostatic control systems are characterized by their response time, sensitivity, and specificity.
• Intercellular chemical messengers are responsible for carrying out various processes related to homeostasis.
• The body is organized from the molecular to an organismic level.
• The human body is composed of atoms which are the smallest building blocks of matter.
• The most common atoms in the human body are C, H, O and N, which make up approximately 96%.
• These atoms combine to form the biomolecules carbohydrates, proteins, fats, and nucleic acids.
• Cells are the fundamental unit of both structure and function in a living being.
• The plasma membrane encloses the contents of each cell and controls movement of materials in and out of the cell.
• The interior of a cell contains a combination of atoms and molecules that are different from the exterior of the cell.
• Cells of similar structure and specialized function combine to form tissues.
• There are four primary tissues: muscle, nervous, epithelial, and connective.
• Epithelia may form from any type of epithelial cell and are characterized and named according to their unique shapes: cuboidal, columnar, squamous, ciliated.
• Epithelia may be arranged as a single-cell thick tissue (simple epithelium) or numerous layers of cells (stratified epithelium).
• Many homeostatic systems regulate the balance between addition and removal of a chemical substance from the body.
• The negative-feedback homeostatic responses are corrective responses.
• When homeostasis is maintained, we refer to physiology; when it is not, we refer to pathophysiology.
• Biological rhythms enable homeostatic mechanisms to be utilized immediately and automatically by activating them at times when a challenge is likely to occur but before it actually does occur.
• Tissue Level – Nervous Tissues consists of cells specialized to initiate, integrate and conduct electrical signals to other cells.
• Biological Rhythms and Homeostasis add an anticipatory component to homeostatic control systems and in effect are a feed-forward system operating without detectors.
• Axons from many neurons are packaged together along with connective tissue to form a nerve.
• During any period of time, total-body balance depends upon the relative rates of net gain and net loss to the body.
• Types of connective tissues include: Loose Connective, Dense Connective, Blood, Cartilage, and Adipose.
• Stable balance in the homeostasis of chemical substances in the body means gains equal loss.
• Homeostasis is a dynamic, not a static, process.
• Sodium Balance is a state of total-body balance in the homeostasis of chemical substances in the body.
• Tissue Level – Muscle Tissues consists of cells specialized for contracting, which generates tension and produces movement.
• Negative balance in the homeostasis of chemical substances in the body means loss exceeds gain, so that the total amount of the substance in the body is decreasing.
• Electrical impulses act as signals that are important in communication, coordination, and control in the body.
• The pool concentration depends not only upon the total amount of the substance in the body, but also upon exchanges of the substance within the body.
• The stomach is lined with epithelial tissue, has a wall containing smooth muscle and nervous tissues, and is bound together by connective tissue.
• Homeostatic responses are initiated after the steady state of the individual has been perturbed.
• The digestive system is an example of a body system that includes many different organs.
• Circadian Rhythm is a biological rhythm that syncs your sleep-wake cycles.
• Physiological variables can change dramatically over a 24-hour period, but the system is still in overall balance.
• Positive balance in the homeostasis of chemical substances in the body means gain exceeds loss, so that the total amount of the substance in the body is increasing.
• Body systems are collections of organs that perform related functions and interact to accomplish a common activity.
• Homeostasis was originally defined as a state of reasonably stable balance between physiological variables.
• Organs are combinations of two or more types of tissues that function together.