Chapter 1 An introduction to the human body Six levels of structural organization 1 chemical level atoms to molecules 2 cellular level molecules that are organized into cells 3 tissue level groups of similar cells work together 4 organ level two or more tissues become an organ 5 system level related organs with common functions 6 organism level all of the cells tissues and organ systems become a human being I Homeostasis Chapter 1 balance equilibrium homeostasis is found in all living systems maintenance of relatively constant conditions inside the body Dynamic process are constantly adjusting internal activities to match changing needs this leads to stable conditions within the body o can have large external fluctuations or small internal fluctuations ex of stable conditions are blood glucose body temp and blood pressure A homeostatic control mechanisms 1 stimulus a change in the variable imbalance 2 change detected by receptor 3 input sends nerve impulse or chemical signal on a pathway to control center 4 output control center will take information and send nerve impulse or chemical signal to the effector 5 response the effort will feed back to influence the magnitude of the stimulus and return variable to homeostasis B Body fluids a key focus for homeostasis the volume and composition of the various fluids within our bodies are carefully regulated a body fluids include o intracellular fluid inside our cells o extracellular all body fluids other than ones inside our cells Can be subdivided according to locations interstitial fluid fluid between the cells plasma the fluid component of blood lymph fluid in our lymphatic vessels cerebrospinal fluid csf fluid within the CNS aka nervous system and brain synovial fluid fluid within most joints fat and water do not mix C restoring balance to the body feedback systems control our internal environment negative feedback systems MOST IMPORTANT acts to stabilize the body in the face of changing external and internal conditions These systems cause an opposite response to the intial change and are self eliminating three essential components 1 receptor detaches changes in controlled conditions 2 control center decides the type and amount of response required 3 effectors reacts to signals from the control center and produces the required response negative feedback is used because the response is opposite in direction to the original change ex Temp ex Blood pressure regulation three essential components increase in blood pressh 1 baroreceptor detect change in blood pressure and communicate with brain nerve impulses are sent to the brain 2 the brain control center interpretes information and sends signal to the heart and blood vessels nerve impulse 3 heart and blood vessels effector alter their activities based on signals form the brain if high blood pressure the heart will decrease which will lead to decrease in blood presh a high blood sugar after eating a carbohydrate rich meal insulin is released to blood which is given to body cells and liver liver takes up glucose and stores it as glycogen blood glucose level declines to set point stimulus for insulin release diminishes b low after skipping a meal release glucagon into blood liver breaks down glycogen and release glucose to blood blood glucose level rises to set point stimulus for glucagon relsease diminishes II Cell body and Genetics Chapter 3 Basic structure of the cell plasma membrane the flexible outer surface of the cell cytoplasm contains numerous organelles surrounded by cytosol nucleus large organelle that contains the cells chromosomes Functions of the cell Cell metabolism and energy use a maintains body temperature and fuels activities such as synthesis of molecules and muscle contractions Synthesis of molecules Communication a including proteins lipids nucleic acids a Cells produce and receive electrical and chemical signals Reproduction and inheritance a Each cell contains DNA Some cells are specialized to gametes for exchange during sexual intercourse Plasma Membrane Separation of intracellular vs extracellular materials production of charge difference membrane potential across the membrane by regulation of intracellular and extracellular ion concentrations o outside of membrane positively charged compared to inside because of gathering ions along outside and inside glycocalyx combinations of carbs and lipids glycolipids and proteins glycoproteins on outer surface fluid mosaic model A Membrane lipids phospholipids and cholesterol PREDOMINATE o phospholipid Forms the lipid bilayer Polar heads facing water in the interior and exterior of the cell hydrophilic non polar tails facing eachother on the interior of the membrane hydrophobic o cholesterol among phospholipids Amount determines fluid intersperced nature of the membrane Limits the movement of phospholipids providing stability for the plasma membrane Fluid nature provides allows distribution of molecules within the membrane phospholipids automatically reassembled if membrane is damaged membranes can fuse together a Lipid bilayers Key role of membrane lipids b membrane permeability small and or non polar molecules are able to pass easily through phospholipid bilayers the permeability of membranes to ions polar molecules depend on the number of specific transport proteins how quickly ions and molecules cross membranes depends on o the concentration gradient of the ion molecule o electrical gradients that can speed or slow the movement of ions B Membrane Proteins integral proteins intrinsic 1 large crossing the membrane to both sides important for movement a b c extends deeply into membrane often extending from one surface to the other d can form channels through membrane 2 peripheral proteins extrinsic a out and in b attach loosely to the integral proteins at either the inner ot outer surfaces of the lipid bilayer c or attached to the polar heads of phospholipds functions of membrane proteins o depends on 3D shape and chemical characterisitcis o transport from one side to the other o enzymatic activity substrate to produce proteins o receptors for signal transduction neurotransmitter hormonesfunctioning depends on a 3d shape and chemical characteristics integral proteins that allow ions or moleculs to move from one side of the Transport Proteins plasma membrane to to the other a channel protein forions ions or small molecules of the right size charge and shape can pass through the channel nongated always open responsible
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