Transport in Organisms
Don’t worry, urine good hands
What is transport?
• Transport – refers to all processes that
move materials into and out of cells
• Materials must enter and exit cells via the
plasma membrane
• Diffusion – material moving from high to low
concentration, no energy required
• Osmosis – diffusion of water, no energy
required
• Active transport – moves materials from low
to high concentration, takes energy
• Water is very important to transport
• makes up most of cytoplasm in a cell
• Dissolves most materials to be transported
• Cells must have enough water but not too
much
• Maintains homeostasis – internal balance of cells
How does transport in unicellular organisms
work?
• What is a unicellular organism?
• Most of these organisms use
diffusion
• Material moves through plasma
membrane based on
concentrations
How does transport work in multicellular
organisms?
• All animals are multicellular
• Hydras and flatworms only have a
few layers of cells (hydras only
have 2 layers)
• None of their cells are far from the
exterior environment
• These animals live in water where
materials are mostly exchanged by
diffusion
• Oxygen and carbon dioxide
What about larger multicellular organisms?
• Since most larger organisms cells
are not in direct contact with the
environment they have
circulatory systems
• network of tubes or spaces that
transport materials dissolved in a
fluid to or away from the cells of an
organism
• Purpose is to connect interior cells
with exterior environment
• 2 types
• Closed circulatory system
• Open circulatory system
What does the circulatory system need?
• This system needs 3 things:
• Fluid for transporting material
• System of tubes and spaces for
material to travel through
• Force that moves fluid through the
body
What are closed circulatory systems?
• Closed circulatory systems – the
fluids that transport materials never
leave their network of tubes
• Most animals have blood as the fluid
• Blood transports glucose and oxygen
while removing carbon dioxide
• Blood travels through hollow tubes
called blood vessels
• Heart provides force to move blood in
humans and most vertebrates
• 3 types of blood vessels
• Artery – carries blood away from heart
• Vein – carries blood to heart
• Capillaries – tiny vessels that allow gas
exchange between cells and blood
Can invertebrates have closed circulatory
systems?
• Earthworms, squid and octopi have closed circulatory systems
heart animation
Assignment!
• Virtual Earthworm dissection
• Read the earthworm guide and use it to label the organism
• Call me over once you have labeled it and I’ll check you off
• Answer the journal questions on your own paper and turn it in
• http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/labs/BL_17/i
ndex.html
What are open circulatory systems?
• Open circulatory systems are not made of closed vessels
• Body cavity contains fluid that surrounds cells, tissues, and organs with
nutrients and oxygen
• Fluid can’t be diverted to specific organs at specific times
• Common to mollusks (snails, oysters, clams) and arthropods (insects, spiders,
crustaceans)
How do plants transport materials?
• Plants do not have circulatory systems or
tubes but they do have tissues
• 2 types of plants
• Vascular plants (tracheophytes)
• Use vascular tissue to transport water and nutrients
• Includes some seedless plants like ferns, flowering
and nonflowering plants
• Nonvascular plants (bryophytes)
• Do not have specialized tissue for transport
• 3 types
• Mosses
• Liverworts
• Hornworts
• Live in shady places to prevent drying out
• Usually small
How do organisms get rid of waste?
• Waste is generated through life
processes and must be removed
from the organism
• Simple organisms rid themselves of
waste by diffusion
• Some cells store wastes in vacuoles
until they can be removed
• Circulatory systems transport
wastes to places they can be
removed
• Urinary system – filters cellular
wastes, toxins, and excess water
from the body
• aka. Excretory system
How does the urinary system work?
• Kidneys are main organ of urinary
system
• Blood enters kidney through
renal (think kidney when you see
renal) artery
• Blood is filtered to remove waste
and excess water
• Clean blood returns to circulatory
system through renal vein
• Waste leaves kidney as urine
Where does urine go once it leaves the
kidney?
• Urine travels down the ureter to a
saclike structure called urinary
bladder
• Urine is stored in the urinary
bladder until it leaves the body
through the urethra
excretory system
Does waste leave the body in other ways?
• Aside from the urinary and
digestive systems, waste also
leaves through skin and lungs
• Skin excretes water and salt as
sweat or perspiration
• Maintains homeostasis (what is this
again?) by cooling the body
• Lungs release carbon dioxide and
water from cellular respiration
Assignment!
• Complete the excretory system worksheet packet
• All you need is the worksheet and something to write with