Unit 2

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?