How is diffusion time related to distance?
diffusion time is proportional to the square of the distance
Why is diffusion only efficient over small distances?
it requires more energy (?)….
it is a fairly slow process (?)
How do small/thin aminals exchange materials with the surrounding medium?
directly (open circulatory system)
How do most animals exchange materials with the environment?
cells exchange materials with the environment via a fluid-filled circulatory system
What are the 3 components of a general circulatory system?
- a circulatory fluid
- a set of interconnecting vessels
- a muscular pump (the heart)
What does a circulatory system allow organs to do?
exchange gases, absorb nutrients, dispose of wastes
What are the two types of circulatory systems?
open and closed
Why is gas exchange important?
need oxygen to produce energy to live
What is the importance of excreting wastes?
eliminate toxic substances that could interfere with biochemical processes or cause tissue/molecular damage
What types of organisms typically have an open circulatory system?
insects, other arthropods, and most molluscs
What does hemolymph mean?
blood (synonym)
In what type of circulatory system does hemolymph bathe the organs directly?
open
What types of organisms typically have a closed circulatory system?
annelids, cephalopods, vertebrates
How does a closed circulatory system work?
blood is confined to vessels - more efficient transport to tissues and cells
How does blood flow in blood vessels?
one way
What do arteries branch into?
arterioles
Where do arterioles carrry blood to?
capillaries
What are the sites of chemical exchange between the blood and interstitial fluid?
capillary beds (networks of capillaries)
What converges into veins?
venules
What is the function of veins?
return blood from capillaries to the heart
How are arteries and veins distinguished?
direction of blood flow
Are arteries and veins distinguished by oxygen content?
no
What direction does the blood flow in veins? in arteries?
- veins: to the heart
- arteries: away from the heart
How many chambers are in the hearts of humans?
4
What organisms have 2 chambers in the heart?
fish
How many chambers are in amphibian hearts?
3
Through what structure does blood enter the heart?
an atrium
Through what structure is blood pumped out of the heart?
ventricle
What occurs in single circulation?
blood leaving the heart passes through two capillary beds before returning
What organisms perform single circulation?
bony fishes, rays, sharks
How many chambers of the heart are invovled in single circulation?
2
What type of circulation occurs in the hearts of amphibians, reptiles, and mammals?
double circulation
How does double circulation work?
oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart
What are the chambers in an amphibian heart?
two atria and one ventricle
What type of circuit do amphibians use to breathe?
pulmocutaneous
Where does gas exchange occur in amphibians?
through the skin
What change occurs to blood flow in amphibians when underwater?
blood flow to the lungs is nearly shut off
What are the two circuits that make up the double circulation of reptiles, mammals, and birds?
pulmonary (lungs) and systemic
What is the difference betwen the hearts of alligators/caimans/crocodiles and most other reptiles?
- alligators, etc. have a septum dividing the ventricle (so have 4 chambers)
- most others have 3 chambers (2 atria, 1 ventricle)
Why do endotherms require more oxygen than ectotherms?
they rely on metabolism for heat
What kind of blood does the left side of a mammalian heart pump and receive?
oxygen-rich blood
What side of the mammalian heart pumps and receives only oxygen-poor blood?
right side
What two respiratory mediums can animals use as a source of oxygen?
air or water
How does the oxygen content compare between water and air?
less oxygen in water than in air (since oxygen must diffuse into water)
Why does obtaining oxygen from water require greater efficiency than air breathing?
water is a thicker, denser medium
What type of respiratory surfaces are required by most organisms?
large, moist surfaces for the exchange of gases between cells and the respiratory medium
What are evaginations of the body wall?
gills
How are gills ventilated?
by water movement
How are gills supported?
by buoyant effects of water
What are lungs?
invaginations of the body wall
How are lungs supported?
by connections to the body wall
How are lungs ventilated?
by breathing
What must oxygen diffuse through in the lungs?
motionless air in alveoli (much faster in air than water)
How are gills useful for gas exchange?
create a large surface area
How does countercurrent exchange happen in fish gills?
blood flows in the opposite direction to water passing over gills and is always less saturated with oxygen than the water it meets
What is the basic structure of the tracheal systems in insects?
tiny branching tubes that penetrate the body
How does the tracheal system in insects supply oxygen to body cells?
supplies oxygen directly
How are the respiratory and circulatory systems in insects related?
they’re separate
What must larger flying insects do to meet greater oxygen demands?
ventilate
What type of breathing does an amphibian use?
positive pressure breathing
How does positive pressure breathing work?
it forces air down the trachea
What is an important respiratory organ in amphibians?
skin
What do some species of amphibians not have?
lungs
How does a bird breathe?
(ANSWER)
How does a mammal ventilate its lungs?
negative pressure breathing
How does negative pressure breathing work?
pulls air into the lungs
What happens to the lung volume as the rib muscles and diaphragm contract?
it increases
What are respiratory pigments?
proteins that transport oxygen
What is the importance of respiratory pigments?
greatly increase the amount of oxygen that blood can carry
What respiratory pigment do arthropods and many molluscs have?
hemocyanin
What is the oxygen-binding component of hemocyanin?
copper
What is the repiratory pigment used by most vertebrates and some invertebrates?
hemoglobin
What is te oxygen-binding component of hemoglobin?
iron
In which type of blood cells is hemoglobin contained in vertebrates?
red blood cells (erythcrocytes)
How many molecules of oxygen can be carried by a single molecule of hemoglobin?
4 (one for each iron-containing heme group)
What is the blood to body volume ratio for diving mammals?
high blood to body volume ratio
What do deep-diving air breathers do to the oxygen they inhale?
stockpile it and deplete it slowly
What can diving mammals store oxygen in?
myoglobin proteins in their muscles
What are some ways in which diving mammals conserve oxygen?
- changing their buoyancy to glide passively
- decreasing blood supply to muscles
- deriving ATP in muscles from fermentation once oxygen is depleted
