Human Systems and Homeostasis

Biology - Chapter 28

KEY CONCEPT The human body has five levels of organization.

Specialized cells develop from a single zygote.

• Organisms are made up of specialized cells.

red blood cell nerve cell

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

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

• 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

There are 11 major organ systems in the human body.

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

Conditions within the body must remain within a narrow range.

• Homeostasis involves keeping the internal environment within set ranges.

• 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

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

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.

• 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

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.

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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2

3 4

Skin absorbs UV light

Liver produces inactive vitamin D

Kidneys produce active vitamin D Active vitamin D used in bones

UV light

A disruption of homeostasis can be harmful.

• Homeostasis can be disrupted for several reasons. – sensors fail – targets do not receive messages– injury – illness

• 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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2

3 4

Pancreas cells attacked;insulin declines

Blood glucose levels rise,

Body burns fat; blood more acidic, Cells impaired; all organs damaged.

pancreas

fats

kidneys