Chapter 42.1 Flashcards
What must every organism do?
Exchange materials with its environment
How do exchanges usually occur?
at the cellular level by crossing the plasma membrane
How do exchanges occur in unicellular organisms
directly with the environment
An example of a specialized exchange system in animals
gills - O2 diffuses from the water into blood vessels and CO2 diffuses from blood into the water
How do small molecules move between cells and their surroundings?
diffusion
Why is diffusion only efficient over small distances
the time it takes to diffuse is proportional to the square of the distance - thus diffusion time increases exponentially with distance
How do most animals exchange materials with the environment
a fluid-filled circulatory system
What does a gastrovascular cavity funcion in?
the digestion and distribution of substances throughout the body
What does a circulatory system have?
- a circulatory fluid
- a set of interconnecting vessels
- a muscular pump (heart)
The circulatory system connects the fluid that surrounds cells with the organs that:
- exchange gases
- absorb nutrients
- dispose of wastes
In insects, other arthropods, and some molllusce, what is the circulatory fluid called?
Hemolymph
Hemolymph
bathes the organs directly in an open circulatory system
What has closed circulatory systems?
Annelids, cephalopods, and vertebrates
What is the closed circulatory system of humans and other vertebrates called?
the cardiovascular system
The three main types of blood vessels
arteries, veins, and capillaries
What do arteries branch into?
arterioles
What do arteries do?
carry blood away from the heart to capillaries
What are networks of capillaries called?
capillary beds
Capillary beds
the sites of chemical exchange between the blood and interstitial fluid
What do venules converge into?
veins
What do venules do?
return blood from capillaries to the heart
What are arteries and veins distinguished b?
the direction of blood flow
How many chambers do vertebrate hearts contain?
Two or more
Where does blood enter through and where is it pumped out through
atrium; ventricle
Single circulation
blood leaving the heart passes through two capillary beds before returning
Double circulation
oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart
In reptiles and mammals, oxygen-poor blood flows through the….
pulmonary circuit to pick up oxygen through the lungs
In amphibians, oxygen-poor blood flows through the…
pulmoncutaneous circuit to pick up oxygen through the lungs and skin
How does oxygen-rich blood deliver oxygen?
through the systemic circuit
What does double circulation maintain that single circulation doesn’t?
higher blood pressure in the organs
Where does the ventricle pump blood?
into a forked artery that splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit
Turtles, snakes, and lizards have a three-chambered heart:
two atria and one ventricle, partially divided by an incomplete septum
In alligators, caimans, and other crocodilians
a septum divides the ventricles but pulmonary and systemic circuits connect where arteries exit the heart
Mammals and birds
have a four-chambered heart with two atria and two ventricles
What does the left side of the heart do?
pumps and receives only oxygen-rich blood
What does the left side of teh heart do?
receives and pumps only oxygen-poor blood
Why are mammalian hearts different in design?
Mammals and birds are endotherms and require more O2 than ectotherms
