Circulation & Gas Exchange O1.

Draw a picture of countercurrent flow for gas exchange with blood in fish gills, describing its advantage as compared to concurrent flow.

As blood enter a gill capillary, it encounters water that is completing it's passage through the gill. Even though the water is depleted of if most of it's O2 it still have a high partial pressure, than the blood. As the bood continues to it's passage it's partial pressue increase. The water's partial pressure increases also because the blood travel corresponds to an earlier position in the water. Thus, a partial pressure gradient favoring the diffusion of O2 from the water to the blood exist along the entire length of the capillary An advantage would be that diffusion occurs through the whole length of the caliparry & the diffsuion never reaches a equilbrium. This results in a maximum exchange in substances.

What is a closed circulatory system? And what animals have this type of circulatory system?

Close circulatory system: circulatory fluid is blood is confined to vessels and is distinct from the interstitial fluid. One of more hearts pump blood into large vessels that branch into smaller ones that infiltrate the organs. Chemical exchange does occur between the blood and the interstitial fluid, and interstitial fluid and body cells. Animals that have close circulatory are annelids, cephalopods, and all vertebrates have closed circulatory systems.

Decribes the different chambered hearts in Animals.

Fish: They have single circulation. Here, the blood passes through the heart once in each complete circuit. The heart consists of 2 chambers: an atrium and a ventricle. The atrium receives blood, the ventricle pumps out. In single circulation, blood that leaves the heart passes through two capillary beds before returning to the heart. Blood here mixes. Amphibians, Reptiles, and mammals: have double circulation. Here the atrium and the ventricle are a single organ, the heart. Divided by a septum. Increases effienticy The right side of the heart delivers oxygen-poor blood to the capillary beds of the gas exchange tissues, where there is a movement of O2 into the blood and CO2 out. This is pulmonary circuit if this happens all in the lungs (reptiles and mammals) It's called pulmoctaneous circuit if it includes the capillaries in both the lungs and the skin (Amphibians) After the oxygen-rich blood leaves the gas exchange, it enters the left side of the heart, which is the other pump. Contraction of the heart propels the blood to capillary beds in organs and tissues throughout the body. Following the exchange of O2 and CO2, the now oxygen-poor blood returns to the heart completing the systemic circuit. Notice that double circulation provides a more vigorous flow of blood to the brains, muscles, and other organs because the heart is constantly depressurizing. Single circulation doesn't as much. Variation in double circulation: Amphibians have a heart with 3 chambers, two atria and on ventricle. They are divided by a ridge. When the frog is underwater, the incomplete division of the ventricles allows the frog to adjust its circulation, shutting off blood flow to it's ineffective lungs but to the skin, so gas exchange can still happen. Turtles, snakes and lizards have an incomplete septum that partially divides the single ventricle into separate right and left chambers. Two major arteries, lead to the systemic circulation. Like amphibians this gives them control of their blood flow. Alligators and other crocodilians: Have a four chambered heart, however the pulmonary and systemic circuits connect where the arteries exit the heart. In birds and Humans: They are two atria and two completely divided ventricles. Birds and mammals cannot vary blood flow to lungs without varying blood to other parts of the body.

Describe gas exchange across membranes, including the role of partial pressure and media type, as well as evolutionary strategies for maximizing gas diffusion.

Gas exchange: the uptake of molecular O2 from the environment and discharge of CO2 to the environment. Partial pressure: the pressure exerted by a particular gas in a mixture of gases. A gas always undergoes diffusion from a region of higher partial pressure to a region of lower partial pressue. Pressure that a gas exerts x fraction of the mixture represented by a particular gas. Media type: Water and Air. Obviously, breathing air is easy. Gas exchange with water is more demanding. The amount of O2 dissolved from water varies but it is always less than what you would dissolve from air with an equivalent volume. Also, the more warmer or saltier the water.. they less dissolved O2 it can hold. This means that animals who live under water must use more energy to dissolve O2 from water. Adaptations have evolved that enable most aquatic animals to be more efficient.. which involves the surfaces dedicated to exchange. Respiratory Surfaces: Parts of the body where gas exchange occurs. Gas exchange is fast when the area for diffusion is large and the path for diffusion is short. Because of this respiratory surfaces tend to be thin and short. In animal such as earthworms and some amphibians, the skin serves as a respiratory organ. A dense network of capillaries just below the skin facilitates the exchange of gases between the circulatory system and the environment. For most animals, the general body surface lacks sufficient area to exchange gases for the whole organism. Adaptations such as gills, lungs and trache are formed in animals.

4. Describe how gills work, including both their advantages and disadvantages as respiratory surfaces. More Detail!

Gills: outfoldings of the body surface that are suspended in the water. To promote ventilation, most animals with gills move their gills through the water over their gills. Ex cray-fish paddle like appendes that drive a current of water over the gills. Fishes use locomotion of swimming or coordinated movements of the mouth and gill covers to ventilate their gills. Ventilation: the movement of the respiratory medium over the respiratory surface. Pros: High Area, Short Distance High Pressure, Because of the 1 way flow. Con: Need support & Fragile

What are some characteristics of open circulatory system?

Low pressure, organs bathed, less well regulation, the ciculatory fluid return is slow.

What is an open circulatory system? Also what animals have this type of circulation system?

Open circulatory system: the circulatory fluid called hemolymph is also the interstitial fluid that bathes the body cells. The Heart contraction pumps the hemolymph through the circulatory vessles into interconnected sinuses, spaces surrounding the organs. In the sinuses, chemical exchange occurs between the hemolymph and body cells. Rexaltion of the heart draws hemolymph back in through the pores, which are equipped with valves that close when the heart contracts. Animals that have an open circulatory system are: anthropods, such as grasshoppers and some mollucs including clams, Lobsters and crabs.

6. Describe how the tracheal system functions in insects.

The most common respiratory organ. Tracheal system: a network of air tubes that branch throughout the body. The respirator system of an insect consists of branched internal tubes. The largest tubes are the trachea. They are connected to external openings spaced along the insect's body. Air sac formed from enlarged portions of the trachea are found near organs that need the most oxygen. Rings of chitin keep the trachea open, allowing air to enter and pass into smaller tubes (tracheoles). These smaller tubes deliver the oxygen directly to the cells of the body. Becauae of this animals who have a tranchea system don't need a circulatory system. The tracheoles have closed ends that contain fluid. When the insect is active the fluid is withdrawn so more air can enter the tracheoles.

What are some characteristics of a close circulatory system?

high pressure, blood conveyed directly to organs.