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
