human systems and homeostasis biology - chapter 28
TRANSCRIPT
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Human Systems and Homeostasis
Biology - Chapter 28
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KEY CONCEPT The human body has five levels of organization.
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Specialized cells develop from a single zygote.
• Organisms are made up of specialized cells.
red blood cell nerve cell
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Zygotes first divide into embryonic stem cells.
• Stem cells develop in two stages. – determination, or
committing to become one cell type
– differentiation, or acquiring specialized structures and functions
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cell
Specialized cells function together in tissues, organs, organ systems, & the whole organism. • Specialized cells perform specific tasks. • Tissues are groups of similar cells working together.
tissue
– epithelial tissue – connective tissue – muscle tissue – nervous tissue
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• Organs are different tissues working together. • Organ systems are two or more organs working together.• Organism is all organ systems working together.
ORGANS
ORGAN SYSTEM
ORGANISM
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There are 11 major organ systems in the human body.
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Organ Trail Assignment• Adrenal Glands Hypothalamus Rectum• Anus Kidneys Salivary Glands• Appendix Large Intestine Skeletal Muscles• Bladder Skin Larynx (voice box) • Bones Liver Small Intestine• Brain Lungs Spinal Cord• Bronchi Spleen Lymph Nodes • Ears Mouth Stomach• Esophagus Nose Thymus Gland• Eyes Trachea Pancreas • Gall Bladder Thyroid Parathyroid Glands • Genitals—Female/Male Ueters Pituitary Gland • Heart Urethra Prostate
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Conditions within the body must remain within a narrow range.
• Homeostasis involves keeping the internal environment within set ranges.
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• Control systems help maintain homeostasis. – sensors gather data– control center receives
data, sends messages – communication system
delivers messages to target organs, tissues
– targets respond to change
pore
sweat glands
hairfolliclemuscle
goosebump
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Negative feedback loops are necessary for homeostasis.
• Feedback compares current conditions to set ranges.• Negative feedback counteracts change.
Negative Feedback Loop
Holding breath, CO2 levels rise,
Control system forces exhale, inhale
O2 / CO2 level returns to normal
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Negative Feedback loop Modeling pg 861
Problem: how does a negative feedback loop work?Procedure: balance a hardcover book on your head; walk 3 meters forward and backward—once with eyes open, once with eyes closed.Questions: • 1)Describe the negative feedback loop that helped keep
the book balanced on your head. How did closing your eyes affect your ability to balance the book?
• 2)Think of another example of a negative feedback loop that you might observe in your everyday life. Explain how you think this loop works.
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• Positive feedback increases change. – Torn vessel stimulates release of clotting factors
– growth hormones stimulate cell division
platelets
fibrin
white blood cellred blood cell
blood vessel
clot
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Each organ system affects other organ systems.
• An organ system must do a specific job. • Organ systems must also work together to keep the
organism healthy.
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Organ systems must also work together to keep the organism healthy.
– Organ systems work together to produce Vitamin D.– Thermoregulation maintains a steady body temperature.
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Skin absorbs UV light
Liver produces inactive vitamin D
Kidneys produce active vitamin D Active vitamin D used in bones
UV light
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A disruption of homeostasis can be harmful.
• Homeostasis can be disrupted for several reasons. – sensors fail – targets do not receive messages– injury – illness
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• Short-term disruption usually causes little or no harm.• Long-term disruptions can cause more damage.• Diabetes is a serious long-term disruption of homeostasis.
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Pancreas cells attacked;insulin declines
Blood glucose levels rise,
Body burns fat; blood more acidic, Cells impaired; all organs damaged.
pancreas
fats
kidneys