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Form and Function (Circulation and Gas Exchange (organization (single…
Form and Function
Circulation and Gas Exchange
Types of circulatory systems
closed
heart pumps blood into large vessels that branch into smaller ones that infiltrate the tissues and organs
blood pressure high enough to provide efficient delivery of oxygen and nutrients in larger animals
blood is confined to vessels and distinct from interstitial fluid; chemical exchange occurs between blood and interstitial fluid and interstitial fluid and body cells
open
contraction of heart pumps hemolymph (interstitial fluid) through the circulatory vessels into interconnected sinuses surrounding the organs
exchange of gas and chemicals occurs in the sinuses and movement squeezes these to promote circulation
relaxation of the heart draws hemolymph back in the pores, which have valves that close when the heart contracts
lower energy needed
organization
single circulation
blood travels thru the body and returns to its starting point in a single circuit
consists of 2 chambers- 1 atrium and 1 ventricle
blood enters heart to atrium, then the ventricle where it contracts and forces movement to capillary beds (gills in fish), net diffusion of oxygen in the blood occurs and carbon dioxide leaves the blood. As blood leaves the capillaries, it's converges into a vessel that carryies oxygen rich blood to capillaries throughout the body
double circulation
consists of 3 or 4 chambers - 2 atria and 1 ventricle or 2 atria and 2 ventricles
2 circuits of blood flow
1st circuit (pulmonary in humans and pulmocutaneous in amphibians)- right side of heart pumps oxygen poor blood to capillary beds of gas exchange (lungs) tissues where net movement of oxygen occurs in the blood and carbon dioxide out of the blood
2nd circuit (systemic)- left side of heart pumps oxygen rich blood from gas exchange surface to capillary beds in organs and tissues, after diffusion of o2 and co2 the now oxygen poor blood returns to the heart
arteries- carry blood from heart to organs
veins- carry blood from organs to the heart
capillaries- infiltrate tissues; the network of capillaries (capillary bed) is where gases and chemicals are exchanged by diffusion between the blood and interstitial fluid around the tissue cells
blood
blood pressure-contraction of heart muscle generates this and exerts force in all directions (down the artery and stretches the walls to dilate is the highest BP); recoil of elastic arterial walls helps maintain BP and hence blood flow
used: as a solvent, in defense, transporting oxygen and other nutrients as well as waste gases, some carbon dioxide, for clotting, regulating osmotic balance and pH buffering
connective tissue consisting of cells suspended in plasma
consists of 55% plasma (water, blood electrolytes, plasma proteins like albumin and immunoglobulins) and 45% cellular elements (Platelets, Erythrocytes, Leukocytes: Basophils, Eosinophils, Neutrophils, Lymphocytes, Monocytes)
connects aqueous environment of the body cells to the organs that exchange gases, absorb nutrients and dispose of wastes
lymph circulation
1.)fluid leaked out of capillaries is returned to the blood via the lymphatic system
2.)fluid goes into interstitial fluid and diffuses into lymphatic vessels and now called lymph
3.)lymph circulates in lymphatic system before being draining into large veins of the cardiovascular system at the base of the neck
respiratory
movement of oxygen and carbon dioxide across respiratory surfaces takes place by diffusion
1.)skin serves as the respiratory organ for sponges, cnidarians, flatworms and some amphibians by facilitating gas exchange between the circulatory system and the environment
2.)gills serve as the respiratory organ for most fish, octopuses, squid, and some mammals (dolphins) by maintaining partial pressure gradients of oxygen and carbon dioxide across the gill and maximized by the exchange of substance or heat between the two fluids (blood and water) flowing in opposite directions
3.)tracheal systems serve as the respiratory organ for most insects by using a network of air tubes throughout the body and enable gas exchange by diffusion at the tips of the air tubes. They do not need a circulatory system due to the short distance air comes in/out (oxygen and carbon dioxide)
4.)lungs serve as the respiratory organ for the majority of mammals and some arachnids by the branching ducts located within (not in direct contact with other organs/tissues so it needs a circulatory system to transport gases) the lungs. Gas exchange occurs at the very end of the ducts via alveoli and diffuses into the capillaries
negative pressure- (mammals) pulling air into the lungs
positive pressure- (amphibians and birds) inflating the lungs with forced air flow or pushing air into the lungs
uptake of oxygen from the environment and discharge of carbon dioxide to the environment
Osmoregulation and Excretion
osmosis
movement of water thru a semi-permeable membrane from a hypotonic side to a hypertonic side
osmoregulation-process by which we control solute concentrations and balance water gain and loss
water can pass, solutes cannot; occurs when there is a barrier that blocks diffusion and stops when your isotonic
marine animals: if they are hypertonic and are put in a hypotonic environment, all the water comes into the cells and causes their cells to burst
osmoconformer will maintain water balance if the environment is the same concentration as them with a constant internal osmolarity and osmoregulator will regulate water balance to deal with the environment
freshwater animals: if they are hypotonic and are put in a hypertonic environment, all the water is expelled from their cells and causes them to shrivel
excretory organs
ureter-transporting urine from kidney to bladder (metabolic waste)
bladder-storing urine (metabolic waste)
kidney- osmoregulation and excretion; consist of tubules arranged with ~1 million nephrons in each kidney and important for the production of urine
parts of the nephron
proximal tubule-reabsorption of water, ions and nutrients, secretion of H ions and Ammonia
descending loop of henle- water channels formed by aquaporin make the transport epithelium freely permeable to water, low permeability for solutes, increasing concentration
Bowmans capsule- beginning of nephron; filtrate enters via glomerulus (capillaries) and continuing to proximal tubule
ascending loop of henle- lacks water channels, solutes flow out, more and more dilute
distal tubule-plays a big role in regulating potassium secreted and NaCl reabsorbed in the filtrate, secretion of H ions and reabsorbtion of bicarbonate
collecting duct- processes filtrate into urine, which carries to the renal pelvis; hormonal control of permeability and transport determines how concentrated the urine is
urethra-transport of urine to outside elements
metabolic waste "nitrogenous"
ammonia- most fish and dilutes
uric acid- birds and reptiles (not toxic and very acidic)
urea- less toxic mammals