Unit 2Organization of the Body
Hierarchy: a series of ordered groupings within a systemAlpha male &
female
Pups & adults
Outcasts / Dispersers
Levels of Organization
Stem Cells Undifferentiated cells
have the potential to develop into many different cell types during early life & growth
Can be induced to become specialized cells brain cells, red blood cells, skin cells, etc.
Embryonic stem cells: derived from fertilized eggs Induced pluripotent stem cells: adult specialized
cells that can be “reprogrammed” to become a different kind of cell
Blastocyst (early stage of development) stem cells differentiate into specialized cells
Adults: stem cells still exist (in organs & bone marrow) to replace old/damaged cells
Hierarchy of Human StructureGuided Reading:1. List the levels of organization, starting
with molecules.2. What are stem cells?
The Human Physiological Environment All the internal conditions that allow cells to
perform their functions effectively & efficiently. This positively impacts body organization
Involves internal & external cellular conditions.
Both rely on water. Needs specific conditions to maintain
homeostasis: pH, ions, chemical reactions, transport of molecules
between internal & external environments Allows us to maintain homeostasis…
The Human Physiological EnvironmentGuided Reading:1. If humans live on land, why does the
author say that the human physiological environment is “aqueous”?
2. What does it mean when people say that something acts as a “solvent”?
More on homeostasisHomeostasis ≠ balance. Allows us to adapt to changing
environments. Maintained by negative feedback loops
Maintain constant conditions inside the body when the external environment fluctuates. “Set point”
Often utilizes chemical messengers (e.g. hormones)
Negative Feedback Systems
Negative Feedback: Maintaining Homeostasis
“System” has a set point (ideal level) and “sensors” that detect changes…
If it drops below set point, something is produced…
If it exceeds that level, production stops… Examples:
Thermostat Toilet
Body Temperature Example
Negative Feedback Loop
Generic Example:Gland X releases hormone X…
This stimulates target cells to release hormone Y.
Eventually, an excess of hormone Y exists
Gland X "senses" this… and inhibits its release of hormone X.
XX Y
Positive Feedback
Defined… “Feedback in which the system
responds so as to increase the magnitude of any particular perturbation”
Results in amplification of the original signal instead of stabilization.
Any system where there is a net positive feedback will result in a runaway situation.
Requires a feedback loop to operate.Examples: Fruit ripening, childbirth,
breastfeeding
The Human Physiological Environment
The human physiological environment is aqueous.
Water is contained in the cells, the blood, body cavities, organ systems, and tissue. Not just sloshing around under the skin!!
Water’s atomic structure provides it with all the properties that make it useful for the body.
The universal solvent. . . .
Water is polar can dissolve most materials needed for human survival
Solvent = dissolves other chemicals & forms a solution
Solute = a particle that is dissolved in a solvent Water is a good bio solvent b/c it is polar
(charged) Most chemical reactions require an aqueous
environment
Water is a natural solvent for ions, needed for cellular functions
Adhesion & cohesion won’t evaporate quickly (so we won’t become easily dehydrated)
High specific heat water absorbs much heat energy when it evaporates
Living in a balance Dehydration: tissues deprived of water
Diarrhea Sweating Vomiting Indicators: extreme thirst, stop sweating, nausea
& exhaustion Water intoxication?
Body takes in more water than it loses at a given period of time.
Upsets natural balance of ions, mineralsA Fraternity Hazing Gone Wrong : NPR
Do you need a tissue? How cells work together to perform a function…
Stem cells again?!?! Remember… they retain ability to undergo cell
division Assist further body development and healing
later in life Stem cells from bone can produce a variety of
human tissues Brain stem cells can develop into many types
of cells
Embryological germ layers Ectoderm skin and brain Mesoderm Bone and muscle Endoderm Digestive organs
Lay down the 4 human tissue types into the hierarchy that eventually forms a human
Four Types of Tissues Connective: forms the
supportive framework of the organs & body
Epithelial: covers internal & external body surfaces; forms layers of cells that line body cavities
Muscle: provides body w/ movement & support
Nervous: conducts & coordinates body info; highly specialized cells
TissuesGuided Reading:1. What are the four types of tissue found
in humans?2. What are the major
characteristics/functions of the four types of tissue? (Recommend you make a chart)
Create a Concept Map (aka Mind Map) for One Type of Tissue…
How to create a concept map Constructing a concept map Example For each cell type…..
Names of cells & structures Characteristics Locations Functions Examples
Organs and Systems Cardiovascular regulates blood flow Digestive regulates nutrition Integumentary provides protection Lymphatic regulates body fluids, helps fight disease Muscular provides structure and movement Skeletal provides support and movement Endocrine regulates body function and development Reproductive regulates sexual function Respiratory regulates atmospheric gasses and
certain body wastes Urinary regulates production, storage, and removal
of urine
Organs, and SystemsGuided Reading1. What is the relationship between
tissues and organs/systems?2. What are the various organ systems
found in humans?
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