the six basic life processes - leilehua high school...
TRANSCRIPT
1
Basic LifeProcesses &Homeostasis
August 2, 2012
AgendaGeneral
HousekeepingReview Chapter 1
1.3 1.4
AssignmentsStations
Video Activity
Review!• Which level of organization focuses on different
types of tissue working together to perform aspecific function?
• Name one system of the human body
1.4 Characteristics of Life• Objectives
– List and describe the major characteristics oflife
The Six Basic Life Processes
Metabolism
Responsiveness
Movement Growth
Differentiation
Reproduction
• 1. Metabolism– The sum of all chemical processes that occur in
the body.– Catabolism: the breakdown of complex chemical
substances into similar components.– Anabolism: the building up of complex chemical
substances from smaller, similar components
• 2. Responsiveness– The body’s ability to detect and respond to
changes
• 3. Movement– Motion of the whole body
•Individual organs, single cell, tiny structuresinside cells
• 4. Growth– An increase in body size that results from an
increase in the size of existing cells, in increasein the number of cells, or both.
– Tissue can increase in size when the materialbetween the cells increases.
• 5. Differentiation
– The development of a cell from an unspecified toa specified state
•Stem Cells: precursor cells which can divideand give rise to cells that can differentiate
• 6. Reproduction
– Formation of new cells for tissue growth, repair,or replacement
– Production of a new individual
• Other Processes– Respiration: obtaining oxygen, removing carbon
dioxide, and releasing energy from foods– Digestion: breakdown of food substances into
simpler forms that be absorbed and used– Absorption: passage of substances through
membranes and into bodily fluids– Circulation: movement of substances in body fluids– Assimilation: changing absorbed substances into
chemically different forms– Excretion: removal of wastes produced y metabolic
reactions
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• When any one of the life processes ceases tooccur properly, the result is death of cells andtissues, which may lead to the death of theorganism.
1.5 Maintenance of Life• Objectives
– List and describe the major requirements oforganisms
– Define homeostasis, and explain itsimportance to survival
– Describe a homeostatic mechanism
Requirements of Organisms• Water: provides the environment for metabolic reactions
and transports substances• Food: supplies energy, materials for building new living
matter, and chemicals vital for reactions• Oxygen: releases energy from food, which drives
metabolism• Heat: is a product of metabolism and helps to control
rates of reaction• Pressure: is an application of force; atmospheric and
hydrostatic pressures help breathing and bloodmovements
• Homeostasis is the condition of equilibrium inthe body’s internal environment due to theconstant interaction of the body’s regulatorysystems/processes– Equilibrium can shift within a narrow range
compatible with maintaining life•Each structure contributes to thisbalance
Homeostasis & Bodily Fluids Control of HomeostasisExternal
Environment
InternalEnvironment
PsychologicalStress
Disruption
Mild & Temporary:Body cells respondquickly to restore
balance
Intense & Prolonged:eg. Poisoning, severe
infection, major surgery
Regulation(together orindividually)
Nervous System:Sends nerve impulses to
organs that cancounteract changes from
the balanced state
Endocrine System:Glands secrete
hormones into the blood
Feedback Systems• Cycle of events in which the status of a body
condition is monitored, evaluated, changed,remonitored, reevaluated, etc.
– Controlled Condition: monitored variable
– Stimulus: disruption that causes change inthe controlled condition
Three Basic Components• 1. Receptor
– Body structure that monitors changes in a acontrolled condition and sends input to acontrol center
– Afferent Pathway: information travelstowards the control center
– Input is in the form of nerve impulses orchemical signals
• 2. Control Center
– Sets the range of values within which acontrolled condition should be maintained (setpoint), evaluates the input it receives from thereceptors, and generates output commandswhen they are needed
– Efferent Pathway: information travels away fromthe control center
– Output in the form of nerve impulses,hormones, and chemical signals
• 3. Effector
– Body structure that receives output from thecontrol center and produces a response ofeffect that changes the controlled condition
– Organs and tissues can act as effectors
• A feedback system involves a group ofreceptors and effectors communicating withtheir control center to regulate a controlledcondition
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Stimulus disruptshomeostasis by
controlled conditionthat is monitored by
RECEPTORSthat send input
to a
CONTROLCENTER that
receives the inputand provides output
to
EFFECTORS thatbring about change
or
Response thatalters thecontrolledcondition
Returns tohomeostasis whenthe response brings
the controlledcondition back to
normal
Operation of a Feedback System
Increasing ordecreasing a Negative Feedback Systems
• Reverses a change in a controlled condition
• Activity of the effector negates the originalstimulus
• Will slow and stop as the controlled conditionreturns to its normal state
• Regulates conditions that remain fairly stableover long periods of time
Stimulus disruptshomeostasis by
Blood Pressure(controlled condition)
Baroreceptors(RECEPTORS)
in certainblood vesselssend nerveimpulses(input) to
Brain (CONTROLCENTER) interpretsinput and send out
nerve impulses(output) to
Heart and bloodvessels
(EFFECTORS)
Decrease in heartrate decreasesblood pressure
Return tohomeostasis whenresponse brings
blood pressure backto normal
Negative Feedback System
Increasing
Positive Feedback System• Strengthens or reinforces a change in one of the body’s
controlled conditions• Activity of the effector produces a physiological
response that adds to or reinforces the initial change inthe controlled condition
• Will continue until it is interrupted by a mechanism (anevent outside the system must shut it off)
• If not stopped it can “run away” and even produce lifethreatening conditions
• Reinforces conditions that do not happen very often
Contractions of theuterus wall force baby’s
head/body into the cervix
Stretching of cervix
Stretch-sensitive nerve
cells(RECEPTORS)in cervix sendnerve impulses
(input) to
Brain (CONTROLCENTER) interpretsinput and releasesoxytocin (output)
Muscles in wall ofuterus (EFFECTOR)
contract moreforcefully
Baby’s bodystretches cervix
more
Positive Feedback:increased stretching
of cervix causesrelease of moreoxytocin, whichresults in morestretching of the
cervix
Positive Feedback System
Increasing
Interruption of Cycle: birthdecreases stretching of the cervix,
breaking the positive feedback cycle
Homeostatic Imbalances• The physiological processes responsible for maintaining
homeostasis are also responsible for good health. Factorsthat affect this balance include:– Environment/Behavior
– Genetics– The air you breathe, food you eat, even the thoughts you think
• The way you live your life can either support or interferewith your body’s ability to maintain homeostasis andrecover from stress
• Many diseases are the result of poor healthbehavior that interferes with the body’s naturaldrive to maintain homeostasis
• Need to develop a lifestyle that supports yourbody’s homeostatic processes– Maximize your potential for optimal health
and well-being
• If one or more components fail to contribute tohomeostasis, the normal balance is disturbed
Assignments• Review Feedback Systems & complete WS
• Read Sections 1.6 & 1.7
• Begin Anatomical & Directional Terms WS
• Go to http://www.hhmi.org and sign up toreceive the print copy of the HHMI Bulletin (it’sFREE!)
• Terminology Quiz next class (25 terms from1.1-1.5)