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Published byOliver Blake Modified over 9 years ago
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Zygote: fertilized cell created by the union of the egg and sperm >200 types of human cells Embryonic stem cells –Created during earliest divisions –Potential to become any type of cell
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Determination –Stem cells commit to a specific type –Few weeks into development –Irreversible
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Differentiation –Cells acquire the structures & functions of a specialized cell –Specific genes activated
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Programmed cell death (apoptosis) between the fingers
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Cell: Basic unit Tissue: Group of cells –4 types Organ: Groups of tissue –Ex: lung contains each tissue Organ System: Group of organs working together –Digestive System Organism: all organ systems working together
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Click on picture to play video clip
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Muscle: contracting cells –Skeletal, cardiac cells
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Connective Tissue: Support the body –Bone, fat, tendons
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Epithelial: protection sheet of cells –skin, stomach lining
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Nerve Tissue: Transmit electric signals –Brain & Spinal Cord
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Homeostasis Reactions & enzymes work best in specific conditions Control systems adjust to internal/external changes –pH, temp, fluids Constant internal environment maintained
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Control Systems Sensors (aka: receptors) –Gather information about the body and environment –Ex: skin senses cold temps Control Center –Receives information from the sensors –Ex: Brain registers the cold Communication Center –Messages sent throughout the body to respond –Ex: Message from brain nervous system target Targets –Body part that changes its activity –Ex: Muscles start to shiver
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Negative Feedback Loops Regulates most of the body Counters changes in the body that move conditions away from a set point –Reverses the change Keeps internal environment stable
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Positive Feedback Loop Increases the changes away from set points Important when rapid changes needed Ex: Skin Cut –C–Clotting proteins increased to seal the wound
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