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Animal Circulation and Gas Exchange

Terms in this set (20)

What is the big picture between Animal Circulation and Gas Exchange?
Direct exchange between every cell and the environment is not possible in all animals
- Special structures for exchange and transport needed

Respiratory Systems: allow for the exchange (gas exchange o2 in Co2 out) of substances with the surrounding environment

Circulatory Systems: provides transport of substances from the sites of exchange (respiratory structures) to internal structures

Internal transport and gas exchange are functionally related
What is Molecular Trading?
Diffusion is only efficient over small distances

Molecular trading in animals occurs for every cell!
- Gain O2 and nutrients
- Release CO2 and waste products

Simple body plans: flat worms are large surface area compared to volume so diffusion works very well
Complex body plans: volume inceases reducing outside surface area and not all cells are exposed to environment so systems are needed for uptake and transport of nutrients
Animals with gastrovascular cavities (Simple body plans)
Many animals have lots of cells in contact with environment
- Hydras, jellyfish, flatworms

Central gastrovascular cavity functions to distribute substances
- Opening at one end connects cavity to water
- Allows fluid to bath inner and outer tissues
- Diffusion distance kept short
Animals with circulatory systems (complex body plans)
Circulatory systems have 3 components

1. Heart: powers circulation using energy and pressure
2. vessels: interconnecting hollow tubes for transport
3. circulatory fluid: carries substances

Fluid transport, via vessels, connects cytoplasm of cells to organs for gas exchange

In mammals, O2 diffuses over 2 cell layers in lungs to reach blood
- Molecule trading works like a circuit
Open and closed circulatory systems (hemolymph vs blood)
Open circulatory systems are common in arthropods. Tubular heart that is connected to pores to outside environment. As heart pumps hemolymph push oxygen and hemolymph across body organs. As heart contracts the oxygen is taken back to the heart. Cycle continues

Closed circulatory systems have blood. Heart is connected via a bunch of interconnected pipes (vessels)
Vertebrate Circulatory systems
Cardiovascular system: blood to heart to vessels
- Length of vessles can be very staggering

3 main types of vessels

1. Arteries: carry blood AWAY from heart to organs
2. Veins: carry blood back to the heart
3. Capillaries: super small versions of vessels that have tiny pores and infiltrate organs or tissues (where exchange occurs)

Hearts of vertebrates have 2+ muscular chambers
- Atria: receive blood from veins
- Ventricles: pump blood out of heart

Numbers of chambers related to form and function of animal
Animals can have single or double circulation
Single we start in heart. Artery pumps blood to the gills. The gills allow the intake for oxygen and the capillaires make the blood oxygen rich. This oxygen rich blood is pumped to body capillaires and is the oxygen is exchanged. The blood is now oxygen poor blood. The blood is returned to heart by veins and the cycle continues

Double Circulation we have heart with 4 chambers. 2 for pumping and 2 for receiving
Evolutionary variation: 3 chambered heart
Amphibians and reptile hearts have 1 ventricle
- Still use double circulation

Do not always fill their lungs
- Pass long periods without gas exchange
- Or use another tissue (skin)

Ex: frogs use skin when underwater
Ex: crocodiles shunt blood from lungs when underwater
Mammalian Circulation
The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle. The right ventricle pumps oxygen poor blood via arteries to lungs. These arteries turn into capillairies where gas exchange occurs. Blood flows through capillaries into lungs and loads O2 and unloads CO2
O2 rich blood returns from lungs via veins to left atrium.

(Second Circuit)
Blood flows to left ventricle and pumped to tissues via arteries into capillaries
- First branches supply the heart
- Further branches lead to organs and hind limbs
O2 diffues from blood to tisuses and CO2 from tissues to blood.
Capillaries rejoin conveying blood to veins
- Poor blood goes back to heart and the cycle continues
Explain blood flow?
Physical laws govern movement of fluids through pipes
- Affect blood flow and pressure

Blood flows from rea of higher pressure to low

Blood flow is slowest is capillaries
This is necessary for gas exchange.
Gas exchange over respiratory surfaces
Gas exchange= uptake of o2 and release of c02
- O2 is abundant in the air (21%)
- Fairly easy to breath

Water is more demanding for gas exchange
-disloved O2 is variable but always less than air

Efficient surfaces for gas exchange have evolved
Respiratory Surfaces
Differs across animal phylogeny
- Sponges, cnidaria, flatworm = cells directly
- Earthworms and amphibians = skin

Other animals lack enough surface area
- To much volume to supply with O2

Gills= outfoldings of body surface optimized with a high surface area

Trachea in insects= network of air tubes
- Lining of cells for gas exchange internally
Coordination of Circulation and Gas Exchange
Most animals need to exchange large amounts of O2 and CO2
- to meet metabolic needs· During inhalation, fresh air fills in lung
- molecule trading occurs via diffusion
· Blood is then pumped through circuit- O2 carried in pigments (metal bound to protein)
In which of the following animals are the blood and the interstitial fluid considered to be the same body fluid?
grasshoppers
Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have _____.
a closed circulatory system
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