28.1 Levels of Organization KEY CONCEPT The human body has five levels of organization.
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Transcript of 28.1 Levels of Organization KEY CONCEPT The human body has five levels of organization.
28.1 Levels of Organization
Specialized cells develop from a single zygote.
• Organisms are made up of specialized cells.
red blood cell nerve cell
28.1 Levels of Organization
• 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
28.1 Levels of Organization
cell
Specialized cells function together in tissues, organs, organ systems, and 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
28.1 Levels of Organization
• 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
28.1 Levels of Organization
KEY CONCEPT 28.2Homeostasis is the regulation and maintenance of the internal environment.
28.1 Levels of Organization
Conditions within the body must remain within a narrow range.
• Homeostasis involves keeping the internal environment within set ranges.
28.1 Levels of Organization
• 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
28.1 Levels of Organization
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
28.1 Levels of Organization
• 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
28.1 Levels of Organization
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.
28.1 Levels of Organization
• 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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3 4
Skin absorbs UV light
Liver produces inactive vitamin D
Kidneys produce active vitamin D Active vitamin D used in bones
UV light
28.1 Levels of Organization
A disruption of homeostasis can be harmful.
• Homeostasis can be disrupted for several reasons. – sensors fail – targets do not receive messages– injury – illness
28.1 Levels of Organization
• 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