Introduction to Physiology PDF

What is physiology?  Physiology vs. Anatomy Physiology (Function) Anatomy (Structure) Form dictates function. How a molecule is shaped determines the job that it does. Levels of Physiological Organization Molecules (ATP, water, neurotransmitter receptors) Cell...

What is physiology?  Physiology vs. Anatomy Physiology (Function) Anatomy (Structure) Form dictates function. How a molecule is shaped determines the job that it does. Levels of Physiological Organization Molecules (ATP, water, neurotransmitter receptors) Cells (neurons, epithelial cells) Tissue (nervous tissue, muscle tissue) Organs (heart, liver) Organ Systems (cardiovascular, gastrointestinal)  The four major cell/tissue types 1. Neurons/nervous tissue (motor neurons, cortical interneurons, etc.). Specialized for sending and receiving information.  The four major cell/tissue types 2. Muscle cells/muscle tissue (cardiac myocytes, skeletal muscle, etc.). Specialized for contraction.  The four major cell/tissue types 3. Epithelial cells/epithelial tissue (intestinal epithelial cells, etc.). Found on organs, glands, and lining body cavities.  Endocrine vs. Exocrine Endocrine glands: secrete molecules (usually hormones) directly into the blood stream. i.e. pancreatic and thymus glands. Exocrine glands: utilize a duct. secrete molecules into a body cavity, or to the exterior of the body. i.e. stomach, salivary, sweat glands. Exocrine vs. Endocrine Glands  The four major cell/tissue types 4. Connective tissue cells (bone cells, blood cells, fat cells, etc.) Characterized by very few cells and lots of extracellular materials.  Homeostasis The ability to maintain a relatively stable internal environment despite fluctuations in the external environment Essential for survival and function of all cells Deviation from homeostasis indicates disease Homeostasis is most often accomplished through negative feedback.  Negative Feedback Involves: Returning internal conditions to a ”set point” A negative feedback loop helps return internal conditions to a set point when they deviate too far outside of an acceptable range. The input and the output are opposites. Example: shivering when you get cold.  Negative Feedback Involves: – Sensors in the body to detect change and send information to the integrating center – Integrating center assesses change around a set point. The integrating center then sends instructions to an effector – Effector makes the appropriate adjustments.  Why do people often shiver when they have a fever? Fever is a physiological response Involves changing the body temperature set point (hypothalamus) Elevated set point causes heat retaining/producing physiological responses such as vasoconstriction and shivering Shivering helps make fever happen Individuals with fever feel cold because set point has changed  Antagonistic Effectors Homeostasis is often maintained by opposing effectors that move conditions in opposite directions. – This maintains conditions within a certain normal range, or dynamic constancy. – When you are hot, you sweat; when you are cold, you shiver. These are antagonistic reactions. Antagonistic Effectors  Positive Feedback Moves conditions further away from a set point. The input and the output in a positive feedback loop are the same. Example: uterine contractions during child birth. Release of oxytocin causes the uterus to contract. This pushes the baby’s head against the cervix, activating stretch receptors that signal to the hypothalamus. This results in more oxytocin release, which results in stronger contractions. etc. etc.