Anatomy Notes Exam 1 Six levels of structural organization 1 Chemical level atoms to molecules 2 Cellular level molecules 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 Organismal level all of the cells tissues and organ systems become a human being Homeostasis is the maintenance of relatively constant conditions inside the body It is the balance we must maintain in our bodies There are a lot of variables inside the body such as blood pressure or glucose levels all of these things working together allows for the body to maintain stable conditions Our body doesn t handle large changes very well Our bodies can adapt to small changes very readily however large changes greatly affect our bodies Body Fluids A Key Focus for Homeostasis The volume and composition of the various fluids within our bodies are carefully regulated Our body fluids include Intracellular fluid the fluid inside our cells Extracellular fluid all body fluids other than the ones inside our cells Can be subdivided according to location Interstitial fluid the fluid between cells in tissues Plasma the fluid component of blood Lymph the fluid in our lymphatic vessels Cerebrospinal Fluid CSF the fluid within the CNS Synovial fluid the fluid within most joints Feedback systems control our internal environment Negative feedback systems act to stabilize the body in the face of changing external and internal conditions These systems cause an opposite response to the initial change and so are self limiting Positive feedback systems are important in specific situations when a very rapid or very strong effect is desired Unlike negative feedback here the response is the same as that caused by the initial change An outside event must break the positive feedback cycle Negative Feedback Systems Three essential components 1 receptor detects changes in controlled conditions 2 control center decides the type and amount of response required 3 effector reacts to signals from the control center and produces the required response The term negative feedback is used because the response is opposite in direction to the original change ONLY PUMP FOR EXAM 1 TO KNOW IS SODIUM POTASSIUM PUMP Blood Pressure Regulation Homeostatic Regulation by Negative Feedback Three essential components baroreceptors detect changes in blood pressure and communicate with the brain blood vessels the brain the brain interprets information and sends signals to the heart and heart and blood vessels alter their activities based on signals from Resulting in the blood pressure being restored to normal Positive Feedback A stimulus causes a response that reinforces the effect of the stimulus A positive feedback cycle must be stopped or limited by some event or condition outside of the cycle 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 Plasma Membrane Helps with the separation of intracellular vs extracellular materials Production of charge difference membrane potential across the membrane by regulation of intracellular and extracellular ion concentrations pretty much stating that without the membrane their would be no action potential across the cell membrane Outside of membrane extracellular is positively charged compared to inside intracellular because of gathering ions along outside and inside Glycocalyx combinations of carbohydrates and lipids glycolipids and proteins glycoproteins on outer surface Fluid mosaic model Membrane Lipids Cholesterol interspersed among phospholipids Amount determines fluid Phospholipids bilayer Polar heads facing water in the interior and Phospholipids and cholesterol predominate exterior of the cell hydrophilic nonpolar tails facing each other on the interior of the membrane hydrophobic nature of the membrane Fluid nature provides allows Distribution of molecules within the membrane Phospholipids automatically reassembled if membrane is damaged Membranes can fuse with each other Membrane Permeability bilayers of specific transport proteins Small and or non polar molecules are able to pass easily through phospholipid The permeability of membranes to ions polar molecules depends on the number How quickly ions and molecules cross membranes depends on The concentration gradient of the ion molecule Electrical gradients that can speed or slow the movement of ions Membrane Proteins There are 3 types of membrane proteins 1 Integral or intrinsic the other 2 Peripheral or extrinsic the lipid bilayer Extend deeply into membrane often extending from one surface to Can form channels through the membrane Attached to integral proteins at either the inner or outer surfaces of Functioning depends on 3 D shape and chemical characteristics Markers attachment sites channels receptors enzymes or carriers Channel Proteins Nongated ion channels always open the plasma membrane is at rest Responsible for the permeability of the plasma membrane to ions when Ligand gated ion channel open in response to small molecules that bind Gated ion channels can be opened or closed by certain stimuli to proteins or glycoproteins the plasma membrane Voltage gated ion channel open when there is a change in charge across Carrier Proteins Carrier proteins come in several forms Uniporters moves one particle Symporters move two particles in the same direction at the same time Antiporters move two particles in opposite directions at the same time ATP Powered Transport Requires ATP The use of energy allows the cell to accumulate substances Rate of transport depends on concentration of substrate and on concentration of ATP Receptor Proteins Proteins or glycoproteins in membranes with an exposed receptor site Can attach to specific chemical signal molecules neurotransmitter or hormone and act as an intercellular communication system Receptors Linked to Channel Proteins Receptor molecules linked to channel proteins Attachment of receptor specific chemical signals e g acetylcholine to receptors Channel opens or closes Changes permeability of cell to some substances e g sodium Receptors Linked to G Protein Complexes Alter activity on inner surface of plasma membrane Leads to intracellular chemical signals that affect cell function Some hormones function in this way Enzymes Enzymes some act to
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