HP Chapter 1 The Study of Body Function – Flashcards
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What is Physiology ?
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The study of biological functions: how the body works - Concerns the normal functions of cells, tissues, organs, and systems - Emphasizes mechanisms - Is derived from scientific experiments
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The Scientific Method
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Steps: - Make observation - Form a hypothesis (must be testable) - Design and conduct experiments of make more observation - Analyze the data Results must be replicated many times before a conclusion is accepted
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Good physiological research requires
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- Quantifiable measurements - An experimental group and a control group - Statistical analysis - Review and publication by a peer-reviewed journal
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Developing Pharmaceuticals
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- Basic research is conducted for years before a drug is ever given to a person - Research begins by studying the effects of a chemical on cells in vitro (in a culture dish) - Next, studies are done in animals (usually rats and mice) to see if the same effects occur in vivo (in living culture) and if there are any toxic side effects (Animal trials may take several years)
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Phase I Clinical Trials
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Test the drug on healthy human volunteers to test for side effects
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Phase II Clinical Trials
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Test the drug's effectiveness on people with the particular disease
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Phase III Clinical Trials
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Tests are conducted on a large number of people. From here FDA can approve the drug for sale
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Phase IV Clinical Trials
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Test other applications for the drug
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Who coined the term "Homeostasis" ?
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Walter Cannon in 1932
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What is homeostasis ?
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Is the constancy of the internal environment
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Why our body want to maintain homeostasis ?
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- The main purpose of our physiological mechanism is to maintain homeostasis - Deviation from homeostasis indicates disease
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Negative Feedback Loops
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The mechanism in the body that works in the opposite direction of the deviation to help maintain homeostasis
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3 components of a Negative Feedback Loops
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- Sensors: to detect change and send information to the - Integrating center: assesses change around a set point and send instruction to - Effector: to make the appropriate adjustment
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Body Temperature and Negative Feedback Loops
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- Sensors in the brain detect deviation from 37 degree Celsius. Another part of the brain assesses this as actionable, and effectors (sweat glands) are stimulated to cool the body - Once the body is cool, sensors alert the integrating center, and sweat glands are inhibited
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Why the process is called "Negative feedback loop" ?
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Because the end result regulates the entire process. Production of the end product shuts off or down-regulates the process.
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Antagonistic Effectors
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- Homeostasis is often maintained by opposing effectors that move conditions in opposite directions. - This maintains conditions within a certain normal range, or dynamic constancy
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Example of Antagonistic Effector
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When you are hot, you sweat; when you are cold, you shiver
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Quantitative Measurements
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A knowledge of normal ranges aids in diagnosing diseases and in assessing the effects of drugs and other treatments in experiments E.g.: sodium level, calcium level, oxygen content
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Positive Feedback Loops
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Mechanism in the body that works in the same direction as the deviation. The end product in the process STIMULATES the process. - Does not work alone but contribute to many negative feedback loops
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Example of Positive Feedback Loops
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- Blood vessel damaged is fixed by forming the clot (positive feedback) and the clotting ends when the damage is fixed.(negative feedback) - The strength of uterine contractions during childbirth is also regulated by a positive feedback loop
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Intrinsic and Extrinsic Regulation
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Regulation processes within organs
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Intrinsic Regulation
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Cells within the organ sense a change and signal neighboring cells to respond appropriately
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Extrinsic Regulation
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The brain (or other organs) regulates an organ using the endocrine or nervous system
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Neural Regulation
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- Is an extrinsic regulation - The nervous system innervates organs with nerve fibers
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Endocrine Regulation
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- Is an extrinsic regulation - The endocrine system releases hormones into the blood, which transports them to multiple target organs
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Negative Feedback Inhibition of Hormone
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- Hormones are secreted in response to specific stimuli (increase in blood sugar results in the release of insulin, which removes sugar from the blood) - Secretion can be inhibited by its own effects (decrease in blood sugar inhibits the release of insulin)
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Feedback Control of Hormone Secretions
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Negative feedback inhibition usually involves an antagonist to make sure homeostasis is maintained within normal levels (low blood sugar results in the release of glucagon, which results in a rise in blood sugar)
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Insulin
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Hormone produced by the pancreas (islets of Langerhans) that is released when stimulated by elevated glucose levels. This hormone decreases blood sugar levels by accelerating the transport of glucose into the body cells where it is oxidized for energy or converted to glycogen or fat for storage.
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Glucagon
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The antagonist of insulin. Its release is stimulated by low blood glucose levels. It stimulates the liver, its primary target organ, to break down its glycogen stores to glucose and subsequently to release glucose to the blood.
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Four major categories of tissues
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- Muscle tissues - Nervous tissues - Epithelial tissues - Connective tissues
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Muscle Tissue
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- specialized for contraction - 3 types: skeletal muscle, cardiac muscle, and smooth muscle
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Skeletal muscle tissue
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- voluntary muscle (muscle you can consciously control) - associated with bones that are pulled to produce movements (tongue, esophagus, sphincters, and diaphragm) - has cells organized in striations (for contraction)
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Cardiac muscle tissue
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- involuntary muscle - only found in heart - has striation but very different in structure and action from skeletal muscle - has intercalated discs allow passage of sodium ions between cells
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Smooth muscle tissue
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- found in the walls of digestive, urinary, and reproductive organs, blood vessels, and bronchioles of the lungs - not striated
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Nervous Tissue
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- found in the brain, spinal cord, and nerves - composed of neurons and glial cells, which support the neurons
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Structure of Neuron that conduct impulses
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- Dendrites: receive signal - Axon: sends signal - Cell body: metabolic center
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Epithelial Tissue
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Forms the membranes that line/cover body surfaces as well as glands
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Simple Epithelium Tissue
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Has one layer and is specialized for TRANSPORT of substances
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Stratified Epithelium Tissue
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- Composed of multiple layers and provides PROTECTION - Are held together by structures called JUNCTIONAL COMPLEXES
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Squamous Epithelium Tissue
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Flattened cells
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Cuboidal Epithelium Tissue
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As tall as they are long
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Columnar Epithelium Tissue
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tall cells and have goblet cells that secret mucus. Also have cilia that move in a coordinated fashion
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Exocrine Glands
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- Derived from epithelial tissues - Secretions are transported by ducts - Example: lacrimal, sweat, and sebaceous glands; digestive enzyme glands; and the prostate
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Connective Tissues
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Characterized by a matrix made up of protein fibers and extracellular material
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4 major categories of Connective Tissues
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- Connective Tissue Proper - Cartilage - Bone - Blood
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Connective Tissue Proper
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Subtypes: Adipose tissue stores fat
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Cartilage ConnectiveTissue
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Composed of cells called CHONDROCYTES surrounded by a semisolid ground substance - Serves as a template skeleton during bone development - Found in joints to provide a gliding surface for bones
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Bones
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Cells called OSTEOBLASTS trap mineral salts, forming concentric layers of calcified material around a canal filled with blood vessels and nerves
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Organ
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Composed of two or more tissues that serve different functions in the organ
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Skin
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- The largest organ in the body - Has all four primary tissues
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Tissue Development
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- Tissues are composed of highly specialized cells that arise from three embryonic germ layers: Endoderm, Mesoderm, and Ectoderm
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Totipotent
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Cells can become any type of cell. Also call stem cell Ex: Zygotes
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Multipotent
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Cells are limited to a narrow range of possibilities but can become several related cells Ex: Adult stem cells
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Bone Marrow Cells
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- Can become any type of blood cell - Multipotent
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Systems
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Organs that perform related functions
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Intracellular
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Area inside the cell
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Extracellular
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Area outside the cells Ex: blood plasma and interstitial fluid
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Body Fluid Compartments
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Are filled primarily with water and are separated by membranes
