Lecture #20 Flashcards
What is diffusion?
Random (Brownian) movement caused by thermal energy
When is diffusion fast or slow?
Slow in long distances; Fast in short distances
What determines where the molecules go through diffusion?
High concentration to Low concentration
When does diffusion across a membrane work best; and when does it not work well?
When the membrane of a cell can be completely surrounded by the ion/molecule trying to diffuse; does not work well with thick walls of cells (tissue) because fewer cells can interact with environment
What does circulation do and why is it effective?
Circulation speeds up transport of ions and molecules. Essentially, it just moves things around the body.
What do animals have when they don’t have circulatory systems?
Gastrovascular cavities
What are gastrovascular cavities?
They are open areas (cavities) that place many cells in contact with the environment.
Where are gastrovascular cavities present/not present?
They are present when animals do not have circulatory systems
What kind of tissue do creatures with gastrovascular tissues have and why?
Thin creatures since tissues are thin enough to allow sufficient diffusion to all cells
Describe how capillaries work in circulatory systems? What purpose do they serve?
Capillaries are the part of the circulatory system that transports blood to every cell. This blood contains all the ions, molecules, and nutrients that every cell in our body needs to survive. Ions and small molecules within the blood diffuse across blood vessel cell membranes into skeletal muscle. Red blood cells move single file fashion through capillaries.
What are the two types of circulatory systems?
Open and Closed
What are the 2 main characteristics of an open circulatory system?
Vessels don’t form complete circuit ; Blood is called hemolymph since it mixes with interstitial fluid in the body
What is the main characteristic of closed circulatory systems?
Blood is enclosed in vessels meaning blood never exits vessels
What is the water vascular systems and what is its main characteristic?
Water vascular system is a circulatory system using sea water instead of blood or hemolymph. Main characteristic: uses hydraulic system for pretty much everything, even moving itself.
How do most pathogens enter the body and why?
They enter through the circulatory system (blood) since it has access to essentially every cell in the body that way (do the most damage)