Homeostatsis Fall '07 Chap 22

Homeostatsis Fall '07 Chap 22 - Homeostasis & Body Org...

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Unformatted text preview: Homeostasis & Body Org Today we will Test results Obesity Paper due by 5pm Oct 1 Homeostasis Neg feedback Pos feedback Body sys act as one How are we organized Cells, tissues, organs, organ systems Homeostasis Claude Bernard @ 1850 "constancy of the internal milieu" William Cannon @ 1920 homeostasis Homeostasis the maintenance of an internal environment Allows existence in adverse external environments A coordinated body effort Seeks dynamic equilibrium Narrow band of physical and chemical properties Continual adjustment to changes needed Equilibrium maintained by feedback systems Neg Pos Homeostasis the maintenance of an internal environment Allows existence in adverse external environments A coordinated body effort Seeks dynamic equilibrium Narrow band of physical and chemical properties Continual adjustment to changes needed Equilibrium maintained by feedback systems Neg Pos Homeostasis the maintenance of an internal environment Allows existence in adverse external environments A coordinated body effort Seeks dynamic equilibrium Narrow band of physical and chemical properties Continual adjustment to changes needed Equilibrium maintained by feedback systems Neg Pos Homeostasis the maintenance of an internal environment Allows existence in adverse external environments A coordinated body effort Seeks dynamic equilibrium Narrow band of physical and chemical properties Continual adjustment to changes needed Equilibrium maintained by feedback systems Negative Positive Negative Feedback Systems Counteract the effect of change Or you could say production of (end) product triggers a response that stops the (end) product from forming We saw this in enzymes negative feed back Allosteric and competitive inhibition Neg feedback cont Switch off Sensor Product producer Off Heat On Out of range + Temp OK End product Out of range - Sensor Switch on Neg feedback cont. Neg feedback cont. 3 items required Control center w/set point 1 1 Effector Sensor 3 2 3 2 Neg feedback cont. example of how it works in body Body temp Nerve endings sense cold 2 Hypothalamus told body is below 1degree set point 98.6 Hypothalamus tells body to 1 start warming mechanisms Body heats by shivering, blood vessels contract, metabolic 3 rate increased Body temp rises Sensed by nerves 2 Set point reached Hypothalamus sends signal to 1 shut down warming mechanisms 3 1 2 3 Neg feedback cont. other things regulated by neg feedback Blood oxygen content Water balance Water Blood sugar lev el s positive feedback Drives events to a conclusion A change is sensed and the response to that change intensifies that change 2 Note: feedback mechanism still has 3 parts: Control center, effector, and sensor 1 3 Real world positive feedback Usually self limiting Usually infrequent Real world positive feedback Example: childbirth contractions 2 Head against cervix Stretch sensed; signal to Hypothalamus releases 1 hormone that prompts stronger contractions 3 Head forced against cervix, etc. 2 1 3 Etc. Cycle terminated by birth 2 1 3 Homeostatsis an integrated body effort Concept Any cell is connected to any other cells through the circulatory and nervous systems e.g. digestion works with circulatory system which works with urinary system, etc. Homeostatsis an integrated body effort Concept Any cell is connected to any other cells through the circulatory and nervous systems e.g. digestion works with circulatory system which works with urinary system, etc. Communication via chemical signals e.g. hormones How are we organized? Very well thank you Cells Smallest unit capable of supporting life; make Tissues Structurally similar cells doing a specific function; make Organs Built of 2 or more tissues to do complex functions; form Organ System 2 or more organs that function in a coordinated manner How are we organized? Very well thank you Cells Smallest unit capable of supporting life; make Tissues Structurally similar cells doing a specific function; make Organs Built of 2 or more tissues to do complex functions; form Organ System 2 or more organs that function in a coordinated manner How are we organized? Very well thank you Cells Smallest unit capable of supporting life; make Tissues Structurally similar cells doing a specific function; make Organs Built of 2 or more tissues to do complex functions; form Organ System 2 or more organs that function in a coordinated manner How are we organized? Very well thank you Cells Smallest unit capable of supporting life; make Tissues Structurally similar cells doing a specific function; make Organs Built of 2 or more tissues to do complex functions; form Organ System 2 or more organs that function in a coordinated manner How are we organized? Very well thank you Cells Smallest unit capable of supporting life; make Tissues Structurally similar cells doing a specific function; make Organs Built of 2 or more tissues to do complex functions; form Organ System 2 or more organs that function in a coordinated manner Tissues composed of similar cells that perform a specific function 4 major categories Epithelial Connective Muscle Nerve Epithelial tissue Made of epithelial cells Form, along with loose connective tissue, membranes Create barriers (skin) Permeable = allow specific substances to move across them (lung lining) or Structure of tissue adapted to function Lung lining: thin, flattened, 1 layer Trachea lining: thick, elongated, with cilia Glands Are specialized epithelial tissue (folded) Secrete a substance 2 categories Exocrine glands Endocrine glands Endocrine glands Secrete hormones Hormones are chemical messengers With specific targets Carried far and wide by circulatory system Can be stand alone structures Thyroid > thyroxine Can be a specialized cells within an organ Example Pancreas > islet cells > insulin Connective tissues Serve mainly to support and bind other tissues 3 categories Loose connective tissue e.g. dermis Collagen + Fibrous connective tissue Tendons and ligaments collagen Specialized connective tissue 5 Loose connective tissue Combines w/epithelial cells to form membranes E.g. the loose connective tissue "dermis" A network of collagen, a protein Has blood capillaries, nerves, glands woven through it All bathed in extracellular fluid Surrounds and cushions most organs of the body Connective tissues Serve mainly to support and bind other tissues 3 categories Loose connective tissue e.g. dermis Collagen + Fibrous connective tissue Tendons and ligaments collagen Specialized connective tissue 5 Connective tissues Serve mainly to support and bind other tissues 3 categories Loose connective tissue e.g. dermis Collagen + Fibrous connective tissue Tendons and ligaments collagen Specialized connective tissue 5 Specialized connective tissue Includes Cartilage Bone Adipose Blood And Lymph MUSCLE TISSUE Made of contractile cells aka: muscle cells or muscle fibers Contract when stimulated MUSCLE TISSUE Contract when stimulated Made of contractile cells aka: muscle cells or muscle fibers 3 types Smooth (embedded in walls of bladder, intestine, uterus, blood vessels Involuntary slow sustained contractions function Cardiac (heart muscle) Skeletal Voluntary control function Involuntary control, spontaneously active, gap junctions function Transmits electrical signals Makes up brain, spinal cord and nerves Composed of 2 types of cells Neurons Generate and conduct electrical signals (to others) Nervous tissue Glial cell Insulates, supports, protects neurons New research > memory, consciousness, the ID Organs Comprised of 2 or more tissues that function together The "skin" is a good example Has all four tissue types acting together Organ systems = 2 or more interacting organs doing a common function amen ...
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This note was uploaded on 04/07/2008 for the course BIO 110 taught by Professor Phil during the Spring '08 term at South Carolina.

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