Download Maintaining Life and Homeostasis Vocabulary

Maintaining Life and Homeostasis Vocabulary
a. Movement: all activities promoted by muscular system
 Includes walking, swimming, manipulating external environment with fingers
 Muscular system is aided by skeletal system (provides bones that the muscles
pull on as they work)
 Also occurs when substances are propelled through internal organs (blood,
foodstuffs, and urine)
b. Responsiveness or irritability: ability to sense changes in the environment and
then react to them
 Something is hot, you pull away
 Also amount of carbon dioxide rises too high, breathing rate increases to blow
off excess carbon dioxide
 Nervous system bears major responsibility
 All cells exhibit to some extent
c. Digestion: process of breaking down ingested food into simple molecules that can
then be absorbed into the blood for deliver to all body cells by the cardiovascular
system
d. Metabolism: all chemical reactions that occur within body cells
 Includes breaking down complex substances into simpler building blocks,
making larger structures from smaller ones, using nutrients and oxygen to
produce ATP molecules
 Depends on digestive and respiratory systems to make oxygen and nutrients
available and cardiovascular to distribute systems throughout body
 Mainly regulated by hormones (endocrine system)
e. Excretion: process of removing wastes from the body produced during digesting
and metabolism
 Digestive system rids body of indigestible food in feces
 Urinary system disposes of nitrogen-containing wastes in urine
f. Reproduction: production of offspring
 Can occur on cellular or organismal levels
 Cellular is mitosis and meiosis
 Reproduction of human organism is task of reproductive organs that produce
eggs and sperm
 Sperm unites with egg, fertilizes it, fetus develops
 Regulated by hormones of endocrine system
g. Growth: increase in size, accompanied by increase in cells
 To happen: cell-constructing activities must occur at a faster rate than celldestroying ones
h. Survival needs: nutrients, oxygen, water, and appropriate temperature and
atmospheric pressure
 Nutrients: taken in via diet; contain chemicals used for energy and cell
building
i. Carbs are major provider
ii. Proteins are essential for building cell structures
iii. Fats cushion organs, provide reserve fuel
iv. Minerals and vitamins required for chemical reactions
 Oxygen: required for cells reactions that release energy from foods (cell
respiration)
i. Made available to blood and body cells by respiratory and cardiovascular
systems

Water: provides fluid base for body secretions and excretions
i. Obtained chiefly from ingested foods or liquids
ii. Lost from body by evaporation from lungs and skin in body excretions
(sweat)
 Body Temperature: must be maintained at 98 F; drops and metabolic
reactions become slower; too high and reactions proceed too rapidly and body
proteins begin to break down
i. Most body heat generated by the activity of skeletal muscles
 Atmospheric pressure: the force exerted on the surface of the body by the
weight of the air
i. Breathing and exchange of oxygen and carbon dioxide depend on
appropriate a.p.
ii. At high altitudes, air thin, a.p. is lower, gas exchange too low to support
cell metabolism
i. Homeostasis: body’s ability to maintain relatively stable internal conditions even
though the outside world is continuously changing
 Indicates dynamic state of equilibrium
 Not unchanging: internal conditions change and vary but always stay within
relatively narrow limits
 Every organ system plays a role: blood levels or nutrients; blood
pressure/heart activity constant; wastes cant accumulate; body temp
controlled
 All homeostatic control mechanisms have at least three components
i. Receptor: some type of sensor that monitors and responds to changes
in environment; responds to changes (stimuli) by sending info to control
center
ii. Control center: determines the level at which a variable is to be
maintained; analyzes info it receives, then determines appropriate
response or course of action
iii. Effector: provides the means for the control center’s response (output)
to the stimulus
1. Results of the response feed back to the influence the stimulus
a. Can either depress it (negative feedback)=shut off
b. Or can enhance it (positive feed back)=faster
2. Negative Feedback: net effect of the response to the stimulus is
to shut off the original stimulus or reduce its intensity
a. Example: home heating system…if thermostat is set to
68F, the heating system (effector) will turn on when house
temp drops below; furnace turns to raise the temp; when it
reaches that temp, the thermostat sends signal to turn off
furnace; your body has a “thermostat”
b. Negative feedback mechanisms regulate heart rate, blood
pressure, breathing rate, and blood levels of glucose,
oxygen, carbon dioxide, and minerals
3. Positive feedback: increase original stimulus (change) and push
variable farther from its original value
a. More rare in body
b. Examples: blood clotting, birth baby
 Most disease is regarded as a result of a homeostatic imbalance