Flashcards in Anatomy & Physiology - II Deck (79)
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?
In what type of circulatory system does hemolymph bathe the organs directly?
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?
What do arteries branch into?
Where do arterioles carrry blood to?
What are the sites of chemical exchange between the blood and interstitial fluid?
capillary beds (networks of capillaries)
What converges into veins?
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?
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?
What organisms have 2 chambers in the heart?
How many chambers are in amphibian hearts?
Through what structure does blood enter the heart?
Through what structure is blood pumped out of the heart?
What occurs in single circulation?
blood leaving the heart passes through two capillary beds before returning