Includes atoms (the smallest units of matter that participate in chemical reactions) and molecules (two or more atoms joined together)
Molecules combine to form structures at the cellular level
Cellular level
The basic structural and functional units of an organism
Smallest living units in the human body
There are many different types of cells in your body including nerve cells and blood cells
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Differentiation
Tissue Level
Tissues are groups of cells and the materials surrounding them that work together to perform a particular function
There are four primary types of tissue in your body:
Muscle
Nervous
Epithelial
Connective
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Organ Level
Organs are structures that:
Are composed of 2 or more different types of tissues
Have specific functions
Usually have recognisable shapes
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System Level
A system consists of related organs that have a common function
There are 11 systems of the human body:
Integumentary
Skeletal
Muscular
Nervous
Endocrine
Cardiovascular
Lymphatic and immune
Respiratory
Digestive
Urinary
Reproductive
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Organism Level
An organism is any living individual
All parts of the human body functioning with one another constitute the total organism - one living person
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Homeostasis
Homeostasis: The ability of a system or living organism to adjust its internal environment to adjust its internal environment to maintain a stable equilibrium
Homeostasis in the human body is continually being disturbed
Environment
External (outside body), e.g. physical insult such as lack of oxygen or intense heat
Internal (within body), e.g. blood glucose is too low
Psychological stress in social environment, e.g. demands of school/work
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Regulating Systems
The body has many regulating systems that bring the internal environment back into balance
Most often, the nervous sytem and the endocrine system, working together or independently, provide the corrective measures needed when homeostasis is disrupted
Nervous system - detects deviations from balanced state, sends messages in form of nerve impulses back to organs that counteracts the deviations
Endocrine system - secretes hormones into the blood to regulate homeostasis, work more slowly than nervous responses
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Feedback Systems
The body can regulate its internal environment through a multitude of feedback systems
A feedback system is a cycle of events in which the status of a body condition is continually monitored, evaluated and changed
Each monitored variable, e.g. body temperature, blood pressure, blood glucose level, is termed a controlled condition
Any disruption that changes a controlled condition is called a stimulus
Three basic components make up a feedback system:
Sensor
Control centre
Responder
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Definitions
Sensor
a body structure that monitors changes in a controlled condition
Control centre
sets the range of values within which a controlled condition should be maintained
Responder
nearly every organ or tissue in the body can behave as a responder
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Feedback Systems
Feedback systems can produce either negative feedback or positive feedback
If the response reserves the original stimulus, the system is operating by negative feedback
If the response enhances or intensifies the original stimulus, the system is operating by positive feedback
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