bio final

The transfer of energy from various molecules to produce ATP; occurs in the mitochondria of eukaryotes, the cytoplasm of prokaryotes. In the process, oxygen is consumed and carbon dioxide is generated.

circulatory system transports oxygen, carbon dioxide, nutrients, and waste products between cells and the respiratory system and carries chemical signals from the endocrine system; consists of the blood, heart, and blood vessels.

Cnidarians, such as Hydra, have a fluid filled internal gastrovascular cavity, this cavity serve both a digestive& circulatory system. this cavity supplies nutrients for all body sells lining the cavity, obtains oxygen from the water in the cavity, and releases carbon dioxide and other wastes into it by diffusion.

In the planarian, branches penetrate to all parts of the body.

Diffusion distances for nutrients, gases, and wastes are small.

• Body movement helps distribute materials to various parts of the body.
• have to keep moving, because they have a gastrovascular cavity therefore no need for a circulatory system since digestive system is branch out and all over, cells are close to nutrients.
• they don't need a circulatory system.
• However, one disadvantage of this system is that it limits these animals to relatively small sizes or to shapes that maintain low diffusion distances.

• Body cavity is a pseudocoel, body fluid under high pressure.Has no circulatory system (no blood system)
• Fluid in psuedocoelom with contracting longitudinal muscle. digestive tract can serve as a circulatory system too because they are thin enough

A closed circulatory system is present in most polychaetes. Characteristics of the circulatory system vary within the phylum. The blood usually contains hemoglobin, a red oxygen-carrying pigment; some annelids have a green oxygen-carrying pigment, and others have unpigmented blood. The circulatory system is usually closed, i.e., confined within well-developed blood vessels; in some polychaetes and leeches the circulatory system is partly open, with blood and coelomic fluid mixing directly in the sinuses of the body cavity. Blood flows toward the head through a contractile vessel above the gut and returns to the terminal region through vessels below the gut; it is distributed to each body compartment by lateral vessels. Some of the lateral vessels are contractile and serve as hearts, i.e., pumping organs for driving the blood.

• have open circulatory system. This type of system has a heart and a few major arteries veins. There are very few capillaries connecting the arteries and veins. The blood spills into the body cavity where it is picked up and taken back to the heart. Arthropods are limited in size because of this inefficient circulatory system.
• The insects, who have no need for an efficient circulatory system, have what is called an open circulatory system. They have a heart which pumps the blood into open-ended arteries and the "blood" sloshes around to reach the cells of the body. It is passively recollected by open-ended veins to be returned to the heart.

• Arthropods, like insects and spiders, have an open circulatory system, in which the blood is pumped forward by the heart, but then flows through the body cavity, directly bathing the internal organs.
• Vertebrates, like humans, have a closed circulatory system in which the blood stays in the circulatory system as it circulates, and chemicals are exchanged by diffusion.
• In a closed system, blood is always contained within vessels (arteries, veins, capillaries, or the heart itself). In an open system, blood (usually called hemolymph) spends much of its time flowing freely within body cavities where it makes direct contact with all internal tissues and organs.
• evolutionary advantage for a closed system: allow to walk on land will need strong muscle

Thick-walled vessels that carry blood away from the heart. The wall of the arterioles, contains less elastic fibers but more smooth muscle cells than that of the aorta. The arterioles represent the major site of the resistance to blood flow and small changes in their caliber cause large changes in total peripheral resistance.

Thin-walled vessels that carry blood to the heart. Units of the circulatory system that carry blood to the heart.

Small, thin-walled blood vessels that allow oxygen to diffuse from the blood into the cells and carbon dioxide to diffuse from the cells into the blood.

• In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues. This is known as single cycle circulation. The heart of fish is therefore only a single pump. Blood collected from throughout the fish's body enters a thin-walled receiving chamber, the atrium.
• As the heart relaxes, the blood passes through a valve into the thick-walled, muscular ventricle.
• Contraction of the ventricle forces the blood into the capillary networks of the gills where gas exchange occurs.
• The blood then passes on to the capillary networks that supply the rest of the body where exchanges with the tissues occur.
• Then the blood returns to the atrium.

• two atria and a single ventricle.
• The atrium receives deoxygenated blood from the blood vessels (veins) that drain the various organs of the body.
• The left atrium receives oxygenated blood from the lungs and skin (which also serves as a gas exchange organ in most amphibians).
• when the ventricle contracts,

• oxygenated blood from the left atrium is sent, relatively pure, into the carotid arteries taking blood to the head (and brain);
• deoxygenated blood from the right atrium is sent, relatively pure, to the pulmocutaneous arteries taking blood to the skin and lungs where fresh oxygen can be picked up.
• Only the blood passing into the aortic arches has been thoroughly mixed, but even so it contains enough oxygen to supply the needs of the rest of the body.
• in contrast to the fish, both the gas exchange organs and the interior tissues of the body get their blood under full pressure.

• have a muscular septum which partially divides the ventricle.
• When the ventricle contracts, the opening in the septum closes and the ventricle is momentarily divided into two separate chambers.
• This prevents mixing of the two bloods.

• The left half of the ventricle pumps oxygenated blood (received from the left atrium) to the body.
• The right half pumps deoxygenated blood (received from the right atrium) to the lungs.

amphibians and reptile have double circuit.

• mammals show complete separation of the heart into two pumps, for a total of four heart chambers.
• pulmonary for gas exchange with the environment and
• systemic for gas exchange (and all other exchange needs) of the rest of the body.
• The efficiency that results makes possible the high rate of metabolism on which the endothermy ("warm-bloodedness") of birds and mammals depends.

• The circulatory system is made up of the vessels and the muscles that help and control the flow of the blood.
• primary function is the of transport: transport of gases, nutrients, hormones, toxic, and excess molecules.
• Maintains a stable and narrow internal body environment (homeostasis).
• Transport

• H2 O and nutrients from the intestine to the cells or to a storage site.
• O2 from the respiratory organ to the cells and CO2 from the cells back to the respiratory organ.
• hormones from endocrine glands.
• toxic or waste molecules to the excretory organ.
• Protection

• of the organism from foreign invaders (immune system)
• of itself from loss of blood (clotting mechanism)

endothermic animal regulate their body temperature thru metabolism. A more efficient circulatory system will support the high metabolic rate required for maintance of internal body temperature.

A respiratory surface is covered with thin, moist epithelial cells that allow oxygen and carbon dioxide to exchange. Those gases can only cross cell membranes when they are dissolved in water or an aqueous solution, thus respiratory surfaces must be moist.

[[i] surface area per unit volume, or surface-are to volume ratio, not just surface area because that the need for exchange is proportional to the amount of active tissue. [ii] very small animals can rely on diffusion across body surfaces alone [iii] large animals have a larger volume per unit exterior surface area, and the consequent need for exchange is not adequately met by body surface and diffusion alone; gas exchange is dealt with by having proliferated and specialised exchange surfaces and circulatory systems

they increase pressure difference, organisms create a water current by beating cilia, because this continuous replenishment of water, the external oxygen concentration does not decrease along the diffusion pathway.

increase area, posses respiratory organs: gills, tracheae, lungs

and decrease distance.

Respiration occurs in 2 stages. The oral valve in the mouth is opened and the jaw is depressed, drawing water into the mouth cavity while the opercular cavity is closed. the oral valve is closed and the operculum is opened, drawing water through the gills to the outside