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Levels of Organization and Homeostasis

Levels of Organization and Homeostasis. Cell Specialization. Zygote: fertilized cell (egg + sperm) >200 types of human cells Embryonic stem cells Created during earliest divisions Potential to become any type of cell. Determination. Determination Stem cells commit to a specific type

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Levels of Organization and Homeostasis

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  1. Levels of Organization and Homeostasis

  2. Cell Specialization • Zygote: fertilized cell (egg + sperm) • >200 types of human cells • Embryonic stem cells • Created during earliest divisions • Potential to become any type of cell

  3. Determination • Determination • Stem cells commit to a specific type • Few weeks into development • Irreversible

  4. Stem cell programmed to become a muscle cell ON ON ON Genes (switches) exist in both cells, but are activated in one type and deactivated in the other. Stem cell programmed to become a nerve cell ON ON ON

  5. Differentiation • Differentiation • Cells acquire the structures & functions of a specialized cell • Specific genes activated

  6. Programmed cell death (apoptosis) between the fingers

  7. Webbed Toes

  8. Organization • 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

  9. Muscle: contracting cells Skeletal, cardiac cells Body Tissues

  10. Connective Tissue: Support the body Bone, fat, tendons Body Tissues

  11. Epithelial: protection sheet of cells skin, stomach lining Body Tissues

  12. Nerve Tissue: Transmit electric signals Brain & Spinal Cord Body Tissues

  13. Homeostasis • Process where the body maintains a constant internal environment • Reactions & enzymes work best in specific conditions • Control systems adjust to internal/external changes • pH, temp, fluids

  14. !*%!?%&# Control Systems • Sensors (aka: receptors) • Gather information about the body and environment • Ex: skin senses pressure • Communication Center • Messages sent throughout the body to respond • Ex: Impulse travel through your nerves • Control Center • Receives information from the sensors • Ex: Brain interprets the impulse • Targets • Body part that changes its activity • Ex: Muscles in foot stretch/contract abruptly

  15. 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 • Ex: Thermoregulation

  16. Negative Feedback Loop Holding breath, CO2 levels rise O2 /CO2 level returns to normal Control system forces exhale and inhale

  17. Positive Feedback Loop • Increases the changes away from set points • Important when rapid changes needed • Ex: Oxytocin released • When uterus contractions begin, oxytocin released to speed up the contractions (not stop them)

  18. platelets blood vessel fibrin clot white blood cell red blood cell Positive Feedback Loop • Ex: • Torn vessel stimulates release of clotting factors • growth hormones stimulate cell division

  19. Homeostasis disruption • Sensors fail • Wrong messages sent • Message doesn’t reach target • Serious injury • Microorganism infection • Short Term • Temporary discomfort (usually) • Ex: cold or flu

  20. Long Term: Diabetes • Normal • Insulin controls glucose level • High: cells intake more glucose • Low: pancreas creates more glucose • Type 1 • Immune system destroys cells to produce insulin • Pancreas fails • Blood pH decreases (more acidic) • Type 2 • Insulin production decreases • Glucose level in blood rises • Cells starve

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