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Chapter 40 Homeostasis—internal environment is maintained within normal limits, cells maintain a constant environment Controlled by the nervous system (faster) and endocrine system (slower)Conformers—needs less energy, maintain same composition as environment Regulators—requires more energy, works to maintain body different than environment (us)Set point—normal value for controlled variable Sensor—monitors particular variableIntegrator—compares signals from the senor to set point Effector—compensates for deviations between actual value and set point Tissue—group of cells, tissues bind together to form organs, organs come together to form organ systems 4 different tissues1.Muscle tissue (most abundant)a.Produces body movement, shortens and contractsb.Functional unit is sarcomere 2.Nervous tissuea.Network of neurons, initiates and conducts electrical signals b.Functional unit is neuron (stimulates muscle, glands, other neurons) 3.Epithelial tissuea.Sheets of packed cells, protects structures, asymmetrical, secretes, absorbsb.Classified by stratification or shape4.Connective tissue (most diverse) a.forms extracellular matrix i.Blood, bone, cartilage, ligaments, and tendons3 types of muscle tissue 1.Skeletal musclea.Linked to bones, striated, multinucleated, voluntary control 2.Smooth musclea.Surrounds tubes, involuntary control, not striated, single nuclei 3.Cardiac muscle a.Only in heart, involuntary control, striated, can have more than one nuclei Organs—need more than one type of tissue Intracellular fluid—cytoplasm inside the cellExtracellular fluid—interstitial fluid outside the cell and plasmaInterstitial fluid—in-between cells, cytoplasm
Prevents homeostatic responses from overcompensating Positive feedback loop—may accelerate a process, less commonNeurotransmitters—small signaling molecules that are synthesized and stored in neurons, alters the activity of that cellHormones—chemical messengers produced by the endocrine system of animals, long distance Osmotic homeostasis—regulating water within the body **know glucose homeostasis**Set point—how much glucose is circling in the bodyIntegrator—compares signals from sensor to set point (hypothalamus) Sensors in blood vessels to detect blood sugar levels Effector—pancreas in glucose regulationPancreas releases insulin when glucose levels are high Insulin acts on tissue cells glucose goes into the cells and allows blood sugar to decreaseInsulin turns glucose into glycogen in the liver to store it because you have too much glucose in the bloodGlucagon is released when blood sugar is lowGlucagon acts on the liver and produces glucose Pancreas releases glucagon and insulin (hormones)
Chapter 41 Nervous system—coordinated circuits of cells that sense internal and environmental changes and transmit signals that enable you to respond in an appropriate wayCentral nervous system—brain and spinal cord