Lecture 17: Transport in Animals Flashcards
How are materials transported in cnidarians and platyhelminths?
Animals that are only a few cells thick rely entirely on simple diffusion of gases and do not require a circulatory system because all their body cells are able to do gas exchange directly with the medium.
Define the circulatory system and describe its main functions
Circulatory systems transport gasses, nutrients, and other substances between exchange surfaces (respiratory organs/intestines) and body cells.
There are two kinds of circulatory systems in animals:
1. closed
2. open
Define blood and describe its main components and functions
Blood is the circulatory fluid and is isolated within vessels in animals with a closed circulatory system. Interstitial fluid is separate from the blood.
Define interstitial fluid and explain its role in the exchange of materials between blood and body cells
Interstitial fluid is located between animal cells and tissues in both closed and open circulatory systems. All body cells sit in the interstitial fluid, it acts as an intermediary for the diffusion between the capillaries and body cells.
In an open system, body cells also sit in HEMOLYMPH fluid.
How does hemolymph differ from blood? Which circulatory system is hemolymph found in? Which system is blood found in?
Hemolymph is both a circulatory fluid and an interstitial fluid in animals with OPEN circulatory systems.
Whereas, blood is a circulatory fluid that is found only in the vessels of animals with closed systems where interstitial fluid is separate.
Describe the structure and functions of an open circulatory system. Which animals have this?
Open systems have lower pressure that slows transport.
- require less energy to build and maintain
- found in animals with slow/sessile lifestyles (low energy requirements) like ARTHROPODA and SOME MOLLUSCA (mussels, clams, etc.).
- Heart contracts and pumps hemolymph through vessels and out open ends into the sinuses
- heart relaxes and creates vacuum that pulls hemolymph from sinuses back into vessels
- Hemolymph fills sinuses (cavities) around the organs
- Vessels are open to the internal cavities
Describe the structure and function of a closed circulatory system? which animals have this?
Closed systems are high pressure and allow fast, efficient transport of GASSES AND NUTRIENTS.
- require more energy to build and maintain
- good for active animals with high energy requirements (Some Mollusca, Annelids, all vertebrates)
Structures:
- blood is the circulatory fluid that fills the vessels
- interstitial fluid fills body cavity (coelom) and spaces between cells
- Heart pumps blood into large vessels that branch into increasingly smaller vessels (the smallest being capillaries).
What are the advantages and disadvantages of an open circulatory system?
d
T or F: insect circulatory system transports gases and nutrients. why/why not?
FALSE. Insect circulatory systems only transport nutrients because insects are very active and O2 is transported through the air-filled tracheal system and they use an open circulatory system to transport nutrients because it requires less energy to build and maintain.
Describe the structure and function arteries
Large vessels that carry blood AWAY from the heart
Describe the structure and function veins
Large vessels that carry blood BACK to the heart
Describe the structure and function capillaries
Fine branched vessels that form net-like structures in body tissues and converge into venues and then veins.
Describe the pathway of blood through a closed circulatory system with a 2-chambered heart. Which animal has this?
Animals: bony fish, sharks, rays.
Blood passes through the heart once per circuit and there is only one circuit of blood flow. Ie: blood does not go back to the heart after going to the gills…
This is a low pressure, relatively slow transport.
There is 1 atrium and 1 ventricle in the heart.
- atrium receives low [O2] blood from body
- ventricle pumps blood to capillaries in gills where CO2 is exchanged for O2.
- oxygenated blood travels through the body
- O2 is exchanged for CO2 in capillaries surrounding body cells
- low [O2] blood returns to atrium
ie: highly oxygenated blood doesn’t return to the heart, it instead goes out to the body and does gas exchange with body cells before returning as low oxygenated blood.
Describe the pathway of blood through a closed circulatory system with a 3-chambered heart. Which animals have this?
Animals: amphibians and reptiles (not birds).
- blood passes through heart twice per complete circuit through body
- double circulation
- separated into PULMONARY and SYSTEMIC CIRCUITS
- higher pressure, faster transport
structure: 2 atria and 1 ventricle
steps:
1. Pulmonary: right atrium receives low [O2] blood from body
2. Pulmonary: ventricle pumps blood to gas exchange surfaces (lungs/skin) to exchange CO2 for O2
3. Systemic: high [O2] blood returns to left atrium
4. Systemic: ventricle pumps oxygenated blood to body cells
Describe the pathway of blood through a closed circulatory system with a 4-chambered heart. Which animals have this?
Animals: mammals and birds
structure: 2 ventricles, 2 atria
Double circulation steps:
- Pulmonary: right atrium receives low [O2] blood from body
- pulmonary: right ventricle pumps it to the lungs
- Systemic: left atrium receives high [O2] blood from lungs
- systemic: left ventricle pumps it to the body
- ventricles are isolated and there is no mixing of low and high [O2] blood in the heart. - veins carry blood to the atria (atrium, s.) of the heart
- contraction of the atrium wall pumps blood
- ventricles receive blood from the atria
- contraction of the ventricle wall pumps blood out to the arteries
- arteries carry blood to either lungs or other parts of body
veins -> atrium -> ventricles -> arteries -> body/lungs
